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pipika
Pridružen/-a: 17.08. 2007, 22:19
Prispevkov: 2397
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 Objavljeno: Četrtek 26 Jun 2008 22:37 Naslov sporočila: |
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| kalija je napisal/a: |
| jakacan je napisal/a: |
Če se dobro spomnim, si ti pa ena tistih, ki verujejo, da je Bog ustvaril vesolje v šestih dneh?  |
jp |
In po šestih dneh je bilo več ali manj takšno kot danes? |
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ucen
pipika
Pridružen/-a: 19.08. 2007, 15:00
Prispevkov: 898
Kraj: pipjigor
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| Objavljeno: Četrtek 26 Jun 2008 22:41 Naslov sporočila: |
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| jakacan je napisal/a: |
| ucen je napisal/a: |
| Kaj naj poreče učenec, ki je tudi učitelje (na RKCf) že podobno spraševal?! |
Lahko izrazi vsaj dvom ali zgražanje, ko prebira pasuse, kjer piše o tem ,da je treba do smrti kamenjati žene, otroke, "grešnike", na mestih, kjer bog zaukaže pomore ali jih sam izvrši, na mestih, kjer se dviga vsebina žalodca spričo nedoslednosti, zgrešenostih itd. |
Sem že marsi-kdaj, a dajmo zopet:
Izražam dvom in zgražanje. V sklopu tega, da bi bilo bolj strpno, ker ni dovolj storjenega - ko se pošilja brati (celo) SP, pa ga celovito dojeti ipd. - da bi se "vse skupaj" in tudi take zadeve posebej "korektno" dojemale ... |
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ucen
pipika
Pridružen/-a: 19.08. 2007, 15:00
Prispevkov: 898
Kraj: pipjigor
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| Objavljeno: Četrtek 26 Jun 2008 22:53 Naslov sporočila: |
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| jakacan je napisal/a: |
| ucen je napisal/a: |
| "Žal" jo "moram" sprejemati za božjo besedo. |
Tudi meni je žal, če je temu tako. Pa vendar, kako lahko sprejemaš kot božjo besedo nekaj, kar vsebije toliko nasilja, maščevanja, znanstvenih in zgodovinski neresnic, nemoralnosti, ki jih danes, v 21. stoletju ne le, da ne moremo sprejemati - moramo jih tudi obsoditi! |
Kot ne-ucen se ne obremenjujem z ali-ne-sprejemanjem.
Kot ucen pa sem skušal (in drugo leto zopet nameravam) nekoliko delovati "v dobro" (tudi) tistih, ki jim "ni vseeno".
Pa še nekoliko bolj posplošeno: sprejemati je moč, ker "moraš", pa zaradi "opranosti", tudi presežnosti tistega.
Sam skušam (oz. "si želim" - se pa čuti, kako slabotno je) izhajati kot "del" Boga. Preprosto nakazano: Tisti "vse..." Bog se npr. z učlovečenjem (pa tudi že prej, recimo z ukvarjanjem z ljudmi) spusti na nivo, ki je daleč pod Njim. In potem je nastalo tudi to, kar je; na način, kakršen je ... |
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ucen
pipika
Pridružen/-a: 19.08. 2007, 15:00
Prispevkov: 898
Kraj: pipjigor
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| Objavljeno: Četrtek 26 Jun 2008 22:55 Naslov sporočila: |
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| matiček mate je napisal/a: |
| Po mojem je problem v tem, da večina 'preleti' le otroško verzijo v sliki in besedi. |
Po mojem je ravno s tem problem (na zunaj) veliko manjši. |
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jakacan
pipika
Pridružen/-a: 08.10. 2007, 18:14
Prispevkov: 1102
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| Objavljeno: Petek 27 Jun 2008 00:48 Naslov sporočila: |
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| kalija je napisal/a: |
| jakacan je napisal/a: |
| Če se dobro spomnim, si ti pa ena tistih, ki verujejo, da je Bog ustvaril vesolje v šestih dneh? |
jp
Meni so čudni vsi poskusi prilagoditi Biblijo teoriji evolucije, kar je naredila (že) večina krščanskega sveta. Jaz nisem, zato sem opredeljena kot fanatik in fundamentalist. |
Zanimivo.
Si ena redkih versko opredeljenih, ki jih ne bi označil kot verske ekstremiste. Že res, da verjameš v po mojem mnenju popolno iluzijo, pravljico, če hočeš - toda obenim se zdijo tvoje opredelitve in izjave življenjske, razumske, demokratične, konstruktivne.
Ravno ob takih, kot si ti, imam včasih slabo vest, ko svojo kritiko religije in religioznega naslavljam tako ostro. In potem izgleda, da streljam vse povprek, v resnici pa bi želel streljati selektivno...
In vsebinsko vprašanje za konec. Kako lahko spregledaš dokaze evolucije, pričevalce postopnega, naključnega in prav nič z Bogom povezanega razvoja? Zakaj ne (p)ostati deist, če že ne gre brez presežnega, a vendar v znak spoštovanja zdrave pameti in razumske presoje zavrniti to pisano in izumljeno mitologijo, ki jo artikulirajo kot "večno resnico"?
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To je Božja beseda. Bobu hvala.  |
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jakacan
pipika
Pridružen/-a: 08.10. 2007, 18:14
Prispevkov: 1102
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| Objavljeno: Petek 27 Jun 2008 01:01 Naslov sporočila: |
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| ucen je napisal/a: |
| Bog se npr. z učlovečenjem |
Zakaj bi se Bog učlovečil? Zakaj bi postal del ustvarjenega, samega sebe morilec? Le kaj je Bogu tega treba? Se res kot homo sapiens šteješ toliko (bolj) vrednega od vsega ostalega ustvarjenega in živega, da moreš verjeti, da bi se Absolutno (nepredstavljivo) spustilo v živalsko kožo, 33 let "trpelo" vse to človeško sranje, angine, zaprtja, driske, žejo, trdega lulčka ob jutranjem prebujanju ... samo zato, da bi po bližnjevzhodno lokalnih verskih spisih odrešilo neko živaljsko vrsto na tretjem kamnu od sonca?
Razsvetlite me že enkrat, zakaj in kako je mogoče verjeti kaj tako neverjetnega, nepredstavljivega in absurdnega! Prosim!
| Citiram: |
| (pa tudi že prej, recimo z ukvarjanjem z ljudmi) spusti na nivo, ki je daleč pod Njim. In potem je nastalo tudi to, kar je; na način, kakršen je ... |
Kako naj ne rečem sedaj, da prvo pomislim na tistega svizca iz švicarske reklame, ki zavija čokolado!?! Sem res popolnoma zaprt za "presežno" ali vendar toliko pri sebi, da se ne pustim ujeti tej/takšni sanjavosti ...
... ker bi v nekem drugem času in na drugem kraju prav lahko verjel tudi v Iro, boginjo jeze, Bolula, boga dežja ali kakšnega drugega antropomorfnega delilca pravice in kazni?!?!
Milost!
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To je Božja beseda. Bobu hvala. |
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cr
pipika
Pridružen/-a: 17.08. 2007, 22:25
Prispevkov: 3305
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| Objavljeno: Petek 27 Jun 2008 07:54 Naslov sporočila: |
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Naslov teme je "Znanost" v Bibliji".
There is none  ITs a fucking fairy tale.
_________________
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Every single Jedi is now the enemy of the Republic. |
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kalija
pipika
Pridružen/-a: 31.08. 2007, 13:48
Prispevkov: 1262
Kraj: gnezdišče
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| Objavljeno: Petek 27 Jun 2008 12:11 Naslov sporočila: |
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| jakacan je napisal/a: |
Zanimivo.
Si ena redkih versko opredeljenih, ki jih ne bi označil kot verske ekstremiste. Že res, da verjameš v po mojem mnenju popolno iluzijo, pravljico, če hočeš - toda obenim se zdijo tvoje opredelitve in izjave življenjske, razumske, demokratične, konstruktivne.
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Pa vendar sem tako opredeljena. Sem po mnogih kriterijih celo večji verski ekstremist kot kakšen rimokatolik.
V knjigi 'Svetovne religije, avtor: Marjan Smrke, Fakulteta za družbene vede, izdaja leta 2000, je v poglavju 'Krščanstvo' naslednja tabela:
| Koda: |
liberlani zmerni fundamentalisti
RKC +
luteranci +
kvekerji +
holiness +
metodisti +
južni baptisti +
unitarci +
binkoštniki +
episkopalci +
mormoni +
adventisti + |
Tabela je rezultat dela Toma Smitha, 'enega vodilnih proučevalcev ameriškega fundamentalizma', ki je izbral 154 cerkva in jih razvrstil v liberalne, zmerne in fundamentalistične.
| jakacan je napisal/a: |
| Ravno ob takih, kot si ti, imam včasih slabo vest, ko svojo kritiko religije in religioznega naslavljam tako ostro. In potem izgleda, da streljam vse povprek, v resnici pa bi želel streljati selektivno... |
Nič ni narobe s kritiko. Problem je le, da se pod loncem krščanstva skrivajo zelo različna razmišljanja, zato kritike ne moreš uniformirati na posameznika in streljati vse povprek izključno zato, ker je pod istim loncem. Znotraj vsake denominacije so posamezniki z različnimi pogledi (liberalni, konzervativni, progresivni, fundametalističnii) in razlike so med denominacijami. Zato je potrebno usmerjeno streljati dokazano napačna dejanja in dokazano zgrešene smeri razmišljanja in ne vse povprek.
| jakacan je napisal/a: |
| In vsebinsko vprašanje za konec. Kako lahko spregledaš dokaze evolucije, pričevalce postopnega, naključnega in prav nič z Bogom povezanega razvoja? Zakaj ne (p)ostati deist, če že ne gre brez presežnega, a vendar v znak spoštovanja zdrave pameti in razumske presoje zavrniti to pisano in izumljeno mitologijo, ki jo artikulirajo kot "večno resnico"? |
Katere dokaze?  |
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| Nazaj na vrh |
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jakacan
pipika
Pridružen/-a: 08.10. 2007, 18:14
Prispevkov: 1102
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| Objavljeno: Petek 27 Jun 2008 19:32 Naslov sporočila: |
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| kalija je napisal/a: |
| jakacan je napisal/a: |
| In vsebinsko vprašanje za konec. Kako lahko spregledaš dokaze evolucije, pričevalce postopnega, naključnega in prav nič z Bogom povezanega razvoja? Zakaj ne (p)ostati deist, če že ne gre brez presežnega, a vendar v znak spoštovanja zdrave pameti in razumske presoje zavrniti to pisano in izumljeno mitologijo, ki jo artikulirajo kot "večno resnico"? |
Katere dokaze? |
Te dokaze:
In his pivotal opus Origin of Species (1859) Darwin presented various evidences for proof of evolution. Among these he sited domestic breeding, anatomical similarities among species (“homology”), the sequential order of fossils, the presence of “vestigial” organs, and the natural phenomenon which he dubbed “natural selection.”
In the century-and-a-half since Darwin published his work, advances in science have made some of these various evidences for evolution dubious. For example, in Darwin’s day it was believed that there were dozens of vestigial organs in the human body. Estimates have ranged from 80 to 200. Scientists at the time did not know what purpose these organs served so they assumed that they were useless vestiges from our evolutionary past. One-hundred fifty years later, only a handful of so-called vestigial organs remain. Scientists have discovered biological functions for the rest. Moreover, critics of Darwin’s theory point out that if vestigial organs are truly useless, the progression is towards a loss of function, not new function. Darwinian evolution requires biological innovation.
Advances in genetics have also shown new light upon the dynamics of homology (anatomical similarities among species) and domestic breeding (the ability of breeders to produce dramatic changes in domestic animal populations by selecting individuals to breed, thereby suppressing and emphasizing traits gradually over time). It is now known that structural similarities do not necessary equal genetic relationship and there appear to be genetic limits to the potential for biological change. A bird can adapt to its environment to a certain degree but it is doubtful that it could cross genetic boundaries to evolve into a reptile, for example.
Advocates for Darwinian evolution believe that genetics have provided a new mechanism for biological innovation in the form of genetic mutation. The incorporation of genetics into Darwinian evolution has produced what is now known as the Neo-Darwinian Synthesis. Nevertheless, the debate rages on whether or not mutations simply destroy existing genetic structure or whether they can provide new genetic information, which Darwinian evolution requires. While Darwinian evolution remains the dominant biological paradigm, there is a growing minority of scientists who “are skeptical of claims for the ability of random mutation and natural selection to account for the complexity of life. Careful examination of the evidence for Darwinian theory should be encouraged.” (From A Scientific Dissent From Darwinism, signed by over 680 Ph.D. scientists.)
In pravljice se podrejo kot hiška iz kart. Za tiste, ki želijo in zmorejo videti.
(Mojzes 1,1-2,3)
1 Tako sta bila narejena nebo in zemlja in vsa njuna vojska. 2 Sedmi dan je Bog dokončal delo, ki ga je naredil, in počival je sedmi dan od vsega dela, ki ga je storil. 3 In Bog je blagoslovil sedmi dan in ga posvetil, kajti ta dan je počival od vsega svojega dela, ki ga je storil, ko je ustvarjal.
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To je Božja beseda. Bobu hvala. |
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kalija
pipika
Pridružen/-a: 31.08. 2007, 13:48
Prispevkov: 1262
Kraj: gnezdišče
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| Objavljeno: Petek 27 Jun 2008 21:07 Naslov sporočila: |
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| jakacan je napisal/a: |
Te dokaze:
In his pivotal opus Origin of Species (1859) Darwin presented various evidences for proof of evolution. Among these he sited domestic breeding, anatomical similarities among species (“homology”), the sequential order of fossils, the presence of “vestigial” organs, and the natural phenomenon which he dubbed “natural selection.”
In the century-and-a-half since Darwin published his work, advances in science have made some of these various evidences for evolution dubious. For example, in Darwin’s day it was believed that there were dozens of vestigial organs in the human body. Estimates have ranged from 80 to 200. Scientists at the time did not know what purpose these organs served so they assumed that they were useless vestiges from our evolutionary past. One-hundred fifty years later, only a handful of so-called vestigial organs remain. Scientists have discovered biological functions for the rest. Moreover, critics of Darwin’s theory point out that if vestigial organs are truly useless, the progression is towards a loss of function, not new function. Darwinian evolution requires biological innovation.
Advances in genetics have also shown new light upon the dynamics of homology (anatomical similarities among species) and domestic breeding (the ability of breeders to produce dramatic changes in domestic animal populations by selecting individuals to breed, thereby suppressing and emphasizing traits gradually over time). It is now known that structural similarities do not necessary equal genetic relationship and there appear to be genetic limits to the potential for biological change. A bird can adapt to its environment to a certain degree but it is doubtful that it could cross genetic boundaries to evolve into a reptile, for example.
Advocates for Darwinian evolution believe that genetics have provided a new mechanism for biological innovation in the form of genetic mutation. The incorporation of genetics into Darwinian evolution has produced what is now known as the Neo-Darwinian Synthesis. Nevertheless, the debate rages on whether or not mutations simply destroy existing genetic structure or whether they can provide new genetic information, which Darwinian evolution requires. While Darwinian evolution remains the dominant biological paradigm, there is a growing minority of scientists who “are skeptical of claims for the ability of random mutation and natural selection to account for the complexity of life. Careful examination of the evidence for Darwinian theory should be encouraged.” (From A Scientific Dissent From Darwinism, signed by over 680 Ph.D. scientists.) |
Ali si to sploh prebral?
Kup Darwinovih trditev ki je ovrženih.
Temu bi jaz rekla rušenje dokazov evolucije in ne postavljanje. 
rudimentarni organi = ovrženi, saj spoznanja vodijo celo v drugo smer torej v raziskano funkcijo takega organa (nefunkcionalnost je itak pod vprašanjem, ker jo je empirijsko nemogoče dokazati zato nima znanstvenega pomena)
Recimo šolski primer rudimentarnega organa
*slepič na črevesu človeka namreč opravlja pomembno funkcijo imunskega sistema v prvih letih življenja, kot obramba pred infekcijskimi boleznimi in nadzor črevesne flore.
* trtične kosti "rudimentarni ostanek repa" so prav tako potrebne za pritrditev različnih mišic medenice in sklepov kolka, ki podpirajo medenične organe. Nujno potrebno za pokončno hojo človeka in prav tako je gibljivost trtice nujno potrebna ob porodu nosečnice.
*"zakrnele kitove noge" - kosti v trebušni votlini pomembne za pripenjanje trebušnih mišic in medeničnih organov, brez tega brejost in porod kita ne bi bila mogoča prav tako ne iztrebljanje v globinah kjer je pritisk na telo velik. "Rudimentarne trebušne kosti" kita seveda imajo tudi homologno podobnost strukturam kosti kopnih sesalcev.
*itd.
Rudimentarni organi torej niso dokaz evolucije, saj jih ne moreš interpretirati, kot napredek ampak v najboljšem primeru lahko dokažejo, da organi lahko zakrnijo.
Torej mikroevolucijska degeneracija, ki jo zagovarja SP.
Naj še ob tem odgovorim na Matičkovo vprašanje:
| matiček mate je napisal/a: |
| kalija je napisal/a: |
| jakacan je napisal/a: |
| Če se dobro spomnim, si ti pa ena tistih, ki verujejo, da je Bog ustvaril vesolje v šestih dneh? |
jp |
In po šestih dneh je bilo več ali manj takšno kot danes? |
Ne. Ni bilo tako. Bilo je ustvarjeno popolno, kasneje je nastopila sprememba v smeri degeneracije - nepopolnost zaradi greha. SP pove, da so se odigrale pomembne sprememb v življenjskem okolju in na živih bitjih (padec v greh, pojav trnja, plevela, spremenjen način prehrane, značaj živali, potop, ki prinese cel kup sprememb...)
Torej degeneracija in ne napredek.
uh, jakačan, si dal toliko materiala, da je nemogoče na vse odgovoriti.
Ampak to trditev polno podpiram:
| Citiram: |
| Careful examination of the evidence for Darwinian theory should be encouraged.” |
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| Nazaj na vrh |
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kalija
pipika
Pridružen/-a: 31.08. 2007, 13:48
Prispevkov: 1262
Kraj: gnezdišče
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| Objavljeno: Petek 27 Jun 2008 21:32 Naslov sporočila: |
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| pipika je napisal/a: |
| kalija je napisal/a: |
| Stražar je napisal/a: |
" Povem vam: Tisto noč bosta dva na eni postelji; eden bo sprejet, drugi puščen. Dva bosta na polju; eden bo sprejet, drugi puščen." ( Lk 17, 34 - 36 )
Za ateiste: Ko bo Kristus ponovno prišel na zemljo, bo na eni obli noč in tam bodo ljudje spali, na drugi pa bo dan in tam bodo ljudje delali na polju. |
Se ne strinjam s to interpretacijo. |
Stražar ga pa pihne
Za Stražarja: Kdaj bo Kristus ponovno prišel na zemljo? Nihče ne ve ne ure ne dneva, zato več možnosti, kje vse zna koga dogodek presenetiti:
- Tisto noč bosta dva na eni postelji;
- Dva bosta na polju;
- Dve bosta mleli žito;
- ...
izmed teh (podani so primeri na zunaj enakovrednih v dvojici) bo eden sprejet v nebeško kraljestvo, drugi puščen. Zakaj? Zato!
ajetko Kalija  |
Priližno.
Preveč me prsti srbijo, da bi to pustila neodgovorjeno (in malo razkažem da ne blefiram o fanatizmu ).
Dodala bi, tri točke, ki to dodatno pojasnjujejo:
1. Raz 1,7 ko bo Kristus prišel na zemljo, ga bo videlo vsako oko.
Kako lahko vsi na zemlji vidijo Kristusov prihod, ko od nekod pride? Na eni polobli ga lahko vidijo, na drugi ne. Preprost odgovor se ponuja, da to ne bo dogodek ene minute temveč vsaj 24 ur, kolikor zemlja potrebuje da se obrne okrog svoje osi. Tako ga bodo lahko videli vsi. Torej ne bo pomembno ali bo na eni strani noč ob prihodu ali ne.
2. Mt 24,27 Kakor namreč pride blisk od vzhoda in posveti do zahoda, tako bo tudi s prihodom Sina človekovega.
Nakazano smer vzhod-zahod (smer rotacije zemlje). Blisk se ne vidi po vsej zemlji hkrati.
3. Raz 8,1 nastane molk v nebesih za po ure. V preroških knjigah se uporablja preroški čas (dan za leto). V tem primeru je pol ure preroškega časa enako 7 dni in pol.
24 ur ~ 360 dni (približni hebrejski lunarni koledar)
1/2 ure ~ x dni
Zakaj bi nastal molk v nebesih, kjer običajno ni tišine in se odvija čaščenje Boga? Morda zato, ker ne bo nikogar v nebesih, saj bo Kristus prišel z vsemi svojimi angeli in tako ne bo ostal nihče v nebesih, ki bi častil Boga. Sedem dni in pol. Prihod na zemljo, zbiranje vstalih po vsej zemlji, ki bodo odneseni naproti v zrak, odhod v nebesa.
Da bo en vzet drugi pa puščen govori preprosto o tem, da bodo nekateri vstali in odšli s Kristusom v prostor, ki ga je pripravljal (Jn 14,1), drugi pa ne.
Zakaj? Zato. |
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Zwicky
pipika
Pridružen/-a: 01.10. 2007, 20:26
Prispevkov: 2054
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| Objavljeno: Petek 27 Jun 2008 21:38 Naslov sporočila: |
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| kalija je napisal/a: |
Bilo je ustvarjeno popolno, kasneje je nastopila sprememba v smeri degeneracije - nepopolnost zaradi greha. SP pove, da so se odigrale pomembne sprememb v življenjskem okolju in na živih bitjih (padec v greh, pojav trnja, plevela, spremenjen način prehrane, značaj živali, potop, ki prinese cel kup sprememb...)
Torej degeneracija in ne napredek. |
Nič, kar je funkcionalno in služi nekemu namenu, ne more biti (in ni) degeneracija.
Jakačan se je sicer zelo potrudil - tisto, kar v množici dokazov evolucije najbolj prepriča mene, je genetika. Natančneje - na primer človeški kromosom številka 2.
| Citiram: |
The correspondence of chromosome 2 to two ape chromosomes. The closest human relative, the chimpanzee, has near-identical DNA sequences to human chromosome 2, but they are found in two separate chromosomes. The same is true of the more distant gorilla and orangutan.
Chromosome 2 is thus strong evidence in favour of the common descent of humans and other apes. According to researcher J. W. IJdo, "We conclude that the locus cloned in cosmids c8.1 and c29B is the relic of an ancient telomere-telomere fusion and marks the point at which two ancestral ape chromosomes fused to give rise to human chromosome 2." |
http://en.wikipedia.org/wiki/Chromosome_2_(human)
Še ena krasna razlaga Kena Millerja, ob kateri kreacionisti ponavadi izgubijo živce, ker jim zmanjka "argumentov" :
http://www.youtube.com/watch?v=zi8FfMBYCkk
Drugače pa večina ljudi, ki nasprotujejo evoluciji, kot mantro ponavlja še eno laž - da evolucije nismo nikoli opazili na delu.
| Citiram: |
Biologists define evolution as a change in the gene pool of a population over time. One example is insects developing a resistance to pesticides over the period of a few years. Even most Creationists recognize that evolution at this level is a fact. What they don't appreciate is that this rate of evolution is all that is required to produce the diversity of all living things from a common ancestor. 
The origin of new species by evolution has also been observed, both in the laboratory and in the wild.
Even without these direct observations, it would be wrong to say that evolution hasn't been observed. Evidence isn't limited to seeing something happen before your eyes. Evolution makes predictions about what we would expect to see in the fossil record, comparative anatomy, genetic sequences, geographical distribution of species, etc., and these predictions have been verified many times over. The number of observations supporting evolution is overwhelming.
What hasn't been observed is one animal abruptly changing into a radically different one, such as a frog changing into a cow. This is not a problem for evolution because evolution doesn't propose occurrences even remotely like that. In fact, if we ever observed a frog turn into a cow, it would be very strong evidence against evolution. |
Še "nekaj" primerov evolucije na delu:
| Citiram: |
5.0 Observed Instances of Speciation
The following are several examples of observations of speciation.
5.1 Speciations Involving Polyploidy, Hybridization or Hybridization Followed by Polyploidization.
5.1.1 Plants
(See also the discussion in de Wet 1971).
5.1.1.1 Evening Primrose (Oenothera gigas)
While studying the genetics of the evening primrose, Oenothera lamarckiana, de Vries (1905) found an unusual variant among his plants. O. lamarckiana has a chromosome number of 2N = 14. The variant had a chromosome number of 2N = 28. He found that he was unable to breed this variant with O. lamarckiana. He named this new species O. gigas.
5.1.1.2 Kew Primrose (Primula kewensis)
Digby (1912) crossed the primrose species Primula verticillata and P. floribunda to produce a sterile hybrid. Polyploidization occurred in a few of these plants to produce fertile offspring. The new species was named P. kewensis. Newton and Pellew (1929) note that spontaneous hybrids of P. verticillata and P. floribunda set tetraploid seed on at least three occasions. These happened in 1905, 1923 and 1926.
5.1.1.3 Tragopogon
Owenby (1950) demonstrated that two species in this genus were produced by polyploidization from hybrids. He showed that Tragopogon miscellus found in a colony in Moscow, Idaho was produced by hybridization of T. dubius and T. pratensis. He also showed that T. mirus found in a colony near Pullman, Washington was produced by hybridization of T. dubius and T. porrifolius. Evidence from chloroplast DNA suggests that T. mirus has originated independently by hybridization in eastern Washington and western Idaho at least three times (Soltis and Soltis 1989). The same study also shows multiple origins for T. micellus.
5.1.1.4 Raphanobrassica
The Russian cytologist Karpchenko (1927, 1928) crossed the radish, Raphanus sativus, with the cabbage, Brassica oleracea. Despite the fact that the plants were in different genera, he got a sterile hybrid. Some unreduced gametes were formed in the hybrids. This allowed for the production of seed. Plants grown from the seeds were interfertile with each other. They were not interfertile with either parental species. Unfortunately the new plant (genus Raphanobrassica) had the foliage of a radish and the root of a cabbage.
5.1.1.5 Hemp Nettle (Galeopsis tetrahit)
A species of hemp nettle, Galeopsis tetrahit, was hypothesized to be the result of a natural hybridization of two other species, G. pubescens and G. speciosa (Muntzing 1932). The two species were crossed. The hybrids matched G. tetrahit in both visible features and chromosome morphology.
5.1.1.6 Madia citrigracilis
Along similar lines, Clausen et al. (1945) hypothesized that Madia citrigracilis was a hexaploid hybrid of M. gracilis and M. citriodora As evidence they noted that the species have gametic chromosome numbers of n = 24, 16 and 8 respectively. Crossing M. gracilis and M. citriodora resulted in a highly sterile triploid with n = 24. The chromosomes formed almost no bivalents during meiosis. Artificially doubling the chromosome number using colchecine produced a hexaploid hybrid which closely resembled M. citrigracilis and was fertile.
5.1.1.7 Brassica
Frandsen (1943, 1947) was able to do this same sort of recreation of species in the genus Brassica (cabbage, etc.). His experiments showed that B. carinata (n = 17) may be recreated by hybridizing B. nigra (n = 8) and B. oleracea, B. juncea (n = 18) may be recreated by hybridizing B. nigra and B. campestris (n = 10), and B. napus (n = 19) may be recreated by hybridizing B. oleracea and B. campestris.
5.1.1.8 Maidenhair Fern (Adiantum pedatum)
Rabe and Haufler (1992) found a naturally occurring diploid sporophyte of maidenhair fern which produced unreduced (2N) spores. These spores resulted from a failure of the paired chromosomes to dissociate during the first division of meiosis. The spores germinated normally and grew into diploid gametophytes. These did not appear to produce antheridia. Nonetheless, a subsequent generation of tetraploid sporophytes was produced. When grown in the lab, the tetraploid sporophytes appear to be less vigorous than the normal diploid sporophytes. The 4N individuals were found near Baldwin City, Kansas.
5.1.1.9 Woodsia Fern (Woodsia abbeae)
Woodsia abbeae was described as a hybrid of W. cathcariana and W. ilvensis (Butters 1941). Plants of this hybrid normally produce abortive sporangia containing inviable spores. In 1944 Butters found a W. abbeae plant near Grand Portage, Minn. that had one fertile frond (Butters and Tryon 1948). The apical portion of this frond had fertile sporangia. Spores from this frond germinated and grew into prothallia. About six months after germination sporophytes were produced. They survived for about one year. Based on cytological evidence, Butters and Tryon concluded that the frond that produced the viable spores had gone tetraploid. They made no statement as to whether the sporophytes grown produced viable spores.
5.1.2 Animals
Speciation through hybridization and/or polyploidy has long been considered much less important in animals than in plants [[[refs.]]]. A number of reviews suggest that this view may be mistaken. (Lokki and Saura 1980; Bullini and Nascetti 1990; Vrijenhoek 1994). Bullini and Nasceti (1990) review chromosomal and genetic evidence that suggest that speciation through hybridization may occur in a number of insect species, including walking sticks, grasshoppers, blackflies and cucurlionid beetles. Lokki and Saura (1980) discuss the role of polyploidy in insect evolution. Vrijenhoek (1994) reviews the literature on parthenogenesis and hybridogenesis in fish. I will tackle this topic in greater depth in the next version of this document.
5.2 Speciations in Plant Species not Involving Hybridization or Polyploidy
5.2.1 Stephanomeira malheurensis
Gottlieb (1973) documented the speciation of Stephanomeira malheurensis. He found a single small population (<250> 25,000 plants) of S. exigua in Harney Co., Oregon. Both species are diploid and have the same number of chromosomes (N = 8). S. exigua is an obligate outcrosser exhibiting sporophytic self-incompatibility. S. malheurensis exhibits no self-incompatibility and self-pollinates. Though the two species look very similar, Gottlieb was able to document morphological differences in five characters plus chromosomal differences. F1 hybrids between the species produces only 50% of the seeds and 24% of the pollen that conspecific crosses produced. F2 hybrids showed various developmental abnormalities.
5.2.2 Maize (Zea mays)
Pasterniani (1969) produced almost complete reproductive isolation between two varieties of maize. The varieties were distinguishable by seed color, white versus yellow. Other genetic markers allowed him to identify hybrids. The two varieties were planted in a common field. Any plant's nearest neighbors were always plants of the other strain. Selection was applied against hybridization by using only those ears of corn that showed a low degree of hybridization as the source of the next years seed. Only parental type kernels from these ears were planted. The strength of selection was increased each year. In the first year, only ears with less than 30% intercrossed seed were used. In the fifth year, only ears with less than 1% intercrossed seed were used. After five years the average percentage of intercrossed matings dropped from 35.8% to 4.9% in the white strain and from 46.7% to 3.4% in the yellow strain.
5.2.3 Speciation as a Result of Selection for Tolerance to a Toxin: Yellow Monkey Flower (Mimulus guttatus)
At reasonably low concentrations, copper is toxic to many plant species. Several plants have been seen to develop a tolerance to this metal (Macnair 1981). Macnair and Christie (1983) used this to examine the genetic basis of a postmating isolating mechanism in yellow monkey flower. When they crossed plants from the copper tolerant "Copperopolis" population with plants from the nontolerant "Cerig" population, they found that many of the hybrids were inviable. During early growth, just after the four leaf stage, the leaves of many of the hybrids turned yellow and became necrotic. Death followed this. This was seen only in hybrids between the two populations. Through mapping studies, the authors were able to show that the copper tolerance gene and the gene responsible for hybrid inviability were either the same gene or were very tightly linked. These results suggest that reproductive isolation may require changes in only a small number of genes.
5.3 The Fruit Fly Literature
5.3.1 Drosophila paulistorum
Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).
5.3.2 Disruptive Selection on Drosophila melanogaster
Thoday and Gibson (1962) established a population of Drosophila melanogaster from four gravid females. They applied selection on this population for flies with the highest and lowest numbers of sternoplural chaetae (hairs). In each generation, eight flies with high numbers of chaetae were allowed to interbreed and eight flies with low numbers of chaetae were allowed to interbreed. Periodically they performed mate choice experiments on the two lines. They found that they had produced a high degree of positive assortative mating between the two groups. In the decade or so following this, eighteen labs attempted unsuccessfully to reproduce these results. References are given in Thoday and Gibson 1970.
5.3.3 Selection on Courtship Behavior in Drosophila melanogaster
Crossley (1974) was able to produce changes in mating behavior in two mutant strains of D. melanogaster. Four treatments were used. In each treatment, 55 virgin males and 55 virgin females of both ebony body mutant flies and vestigial wing mutant flies (220 flies total) were put into a jar and allowed to mate for 20 hours. The females were collected and each was put into a separate vial. The phenotypes of the offspring were recorded. Wild type offspring were hybrids between the mutants. In two of the four treatments, mating was carried out in the light. In one of these treatments all hybrid offspring were destroyed. This was repeated for 40 generations. Mating was carried out in the dark in the other two treatments. Again, in one of these all hybrids were destroyed. This was repeated for 49 generations. Crossley ran mate choice tests and observed mating behavior. Positive assortative mating was found in the treatment which had mated in the light and had been subject to strong selection against hybridization. The basis of this was changes in the courtship behaviors of both sexes. Similar experiments, without observation of mating behavior, were performed by Knight, et al. (1956).
5.3.4 Sexual Isolation as a Byproduct of Adaptation to Environmental Conditions in Drosophila melanogaster
Kilias, et al. (1980) exposed D. melanogaster populations to different temperature and humidity regimes for several years. They performed mating tests to check for reproductive isolation. They found some sterility in crosses among populations raised under different conditions. They also showed some positive assortative mating. These things were not observed in populations which were separated but raised under the same conditions. They concluded that sexual isolation was produced as a byproduct of selection.
5.3.5 Sympatric Speciation in Drosophila melanogaster
In a series of papers (Rice 1985, Rice and Salt 1988 and Rice and Salt 1990) Rice and Salt presented experimental evidence for the possibility of sympatric speciation. They started from the premise that whenever organisms sort themselves into the environment first and then mate locally, individuals with the same habitat preferences will necessarily mate assortatively. They established a stock population of D. melanogaster with flies collected in an orchard near Davis, California. Pupae from the culture were placed into a habitat maze. Newly emerged flies had to negotiate the maze to find food. The maze simulated several environmental gradients simultaneously. The flies had to make three choices of which way to go. The first was between light and dark (phototaxis). The second was between up and down (geotaxis). The last was between the scent of acetaldehyde and the scent of ethanol (chemotaxis). This divided the flies among eight habitats. The flies were further divided by the time of day of emergence. In total the flies were divided among 24 spatio-temporal habitats.
They next cultured two strains of flies that had chosen opposite habitats. One strain emerged early, flew upward and was attracted to dark and acetaldehyde. The other emerged late, flew downward and was attracted to light and ethanol. Pupae from these two strains were placed together in the maze. They were allowed to mate at the food site and were collected. Eye color differences between the strains allowed Rice and Salt to distinguish between the two strains. A selective penalty was imposed on flies that switched habitats. Females that switched habitats were destroyed. None of their gametes passed into the next generation. Males that switched habitats received no penalty. After 25 generations of this mating tests showed reproductive isolation between the two strains. Habitat specialization was also produced.
They next repeated the experiment without the penalty against habitat switching. The result was the same -- reproductive isolation was produced. They argued that a switching penalty is not necessary to produce reproductive isolation. Their results, they stated, show the possibility of sympatric speciation.
5.3.6 Isolation Produced as an Incidental Effect of Selection on several Drosophila species
In a series of experiments, del Solar (1966) derived positively and negatively geotactic and phototactic strains of D. pseudoobscura from the same population by running the flies through mazes. Flies from different strains were then introduced into mating chambers (10 males and 10 females from each strain). Matings were recorded. Statistically significant positive assortative mating was found.
In a separate series of experiments Dodd (1989) raised eight populations derived from a single population of D. Pseudoobscura on stressful media. Four populations were raised on a starch based medium, the other four were raised on a maltose based medium. The fly populations in both treatments took several months to get established, implying that they were under strong selection. Dodd found some evidence of genetic divergence between flies in the two treatments. He performed mate choice tests among experimental populations. He found statistically significant assortative mating between populations raised on different media, but no assortative mating among populations raised within the same medium regime. He argued that since there was no direct selection for reproductive isolation, the behavioral isolation results from a pleiotropic by-product to adaptation to the two media. Schluter and Nagel (1995) have argued that these results provide experimental support for the hypothesis of parallel speciation.
Less dramatic results were obtained by growing D. willistoni on media of different pH levels (de Oliveira and Cordeiro 1980). Mate choice tests after 26, 32, 52 and 69 generations of growth showed statistically significant assortative mating between some populations grown in different pH treatments. This ethological isolation did not always persist over time. They also found that some crosses made after 106 and 122 generations showed significant hybrid inferiority, but only when grown in acid medium.
5.3.7 Selection for Reinforcement in Drosophila melanogaster
Some proposed models of speciation rely on a process called reinforcement to complete the speciation process. Reinforcement occurs when to partially isolated allopatric populations come into contact. Lower relative fitness of hybrids between the two populations results in increased selection for isolating mechanisms. I should note that a recent review (Rice and Hostert 1993) argues that there is little experimental evidence to support reinforcement models. Two experiments in which the authors argue that their results provide support are discussed below.
Ehrman (1971) established strains of wild-type and mutant (black body) D. melanogaster. These flies were derived from compound autosome strains such that heterotypic matings would produce no progeny. The two strains were reared together in common fly cages. After two years, the isolation index generated from mate choice experiments had increased from 0.04 to 0.43, indicating the appearance of considerable assortative mating. After four years this index had risen to 0.64 (Ehrman 1973).
Along the same lines, Koopman (1950) was able to increase the degree of reproductive isolation between two partially isolated species, D. pseudoobscura and D. persimilis.
5.3.8 Tests of the Founder-flush Speciation Hypothesis Using Drosophila
The founder-flush (a.k.a. flush-crash) hypothesis posits that genetic drift and founder effects play a major role in speciation (Powell 1978). During a founder-flush cycle a new habitat is colonized by a small number of individuals (e.g. one inseminated female). The population rapidly expands (the flush phase). This is followed by the population crashing. During this crash period the population experiences strong genetic drift. The population undergoes another rapid expansion followed by another crash. This cycle repeats several times. Reproductive isolation is produced as a byproduct of genetic drift.
Dodd and Powell (1985) tested this hypothesis using D. pseudoobscura. A large, heterogeneous population was allowed to grow rapidly in a very large population cage. Twelve experimental populations were derived from this population from single pair matings. These populations were allowed to flush. Fourteen months later, mating tests were performed among the twelve populations. No postmating isolation was seen. One cross showed strong behavioral isolation. The populations underwent three more flush-crash cycles. Forty-four months after the start of the experiment (and fifteen months after the last flush) the populations were again tested. Once again, no postmating isolation was seen. Three populations showed behavioral isolation in the form of positive assortative mating. Later tests between 1980 and 1984 showed that the isolation persisted, though it was weaker in some cases.
Galina, et al. (1993) performed similar experiments with D. pseudoobscura. Mating tests between populations that underwent flush-crash cycles and their ancestral populations showed 8 cases of positive assortative mating out of 118 crosses. They also showed 5 cases of negative assortative mating (i.e. the flies preferred to mate with flies of the other strain). Tests among the founder-flush populations showed 36 cases of positive assortative mating out of 370 crosses. These tests also found 4 cases of negative assortative mating. Most of these mating preferences did not persist over time. Galina, et al. concluded that the founder-flush protocol yields reproductive isolation only as a rare and erratic event.
Ahearn (1980) applied the founder-flush protocol to D. silvestris. Flies from a line of this species underwent several flush-crash cycles. They were tested in mate choice experiments against flies from a continuously large population. Female flies from both strains preferred to mate with males from the large population. Females from the large population would not mate with males from the founder flush population. An asymmetric reproductive isolation was produced.
In a three year experiment, Ringo, et al. (1985) compared the effects of a founder-flush protocol to the effects of selection on various traits. A large population of D. simulans was created from flies from 69 wild caught stocks from several locations. Founder-flush lines and selection lines were derived from this population. The founder-flush lines went through six flush-crash cycles. The selection lines experienced equal intensities of selection for various traits. Mating test were performed between strains within a treatment and between treatment strains and the source population. Crosses were also checked for postmating isolation. In the selection lines, 10 out of 216 crosses showed positive assortative mating (2 crosses showed negative assortative mating). They also found that 25 out of 216 crosses showed postmating isolation. Of these, 9 cases involved crosses with the source population. In the founder-flush lines 12 out of 216 crosses showed positive assortative mating (3 crosses showed negative assortative mating). Postmating isolation was found in 15 out of 216 crosses, 11 involving the source population. They concluded that only weak isolation was found and that there was little difference between the effects of natural selection and the effects of genetic drift.
A final test of the founder-flush hypothesis will be described with the housefly cases below.
5.4 Housefly Speciation Experiments
5.4.1 A Test of the Founder-flush Hypothesis Using Houseflies
Meffert and Bryant (1991) used houseflies to test whether bottlenecks in populations can cause permanent alterations in courtship behavior that lead to premating isolation. They collected over 100 flies of each sex from a landfill near Alvin, Texas. These were used to initiate an ancestral population. From this ancestral population they established six lines. Two of these lines were started with one pair of flies, two lines were started with four pairs of flies and two lines were started with sixteen pairs of flies. These populations were flushed to about 2,000 flies each. They then went through five bottlenecks followed by flushes. This took 35 generations. Mate choice tests were performed. One case of positive assortative mating was found. One case of negative assortative mating was also found.
5.4.2 Selection for Geotaxis with and without Gene Flow
Soans, et al. (1974) used houseflies to test Pimentel's model of speciation. This model posits that speciation requires two steps. The first is the formation of races in subpopulations. This is followed by the establishment of reproductive isolation. Houseflies were subjected to intense divergent selection on the basis of positive and negative geotaxis. In some treatments no gene flow was allowed, while in others there was 30% gene flow. Selection was imposed by placing 1000 flies into the center of a 108 cm vertical tube. The first 50 flies that reached the top and the first 50 flies that reached the bottom were used to found positively and negatively geotactic populations. Four populations were established:Population A + geotaxis, no gene flow
Population B - geotaxis, no gene flow
Population C + geotaxis, 30% gene flow
Population D - geotaxis, 30% gene flow
Selection was repeated within these populations each generations. After 38 generations the time to collect 50 flies had dropped from 6 hours to 2 hours in Pop A, from 4 hours to 4 minutes in Pop B, from 6 hours to 2 hours in Pop C and from 4 hours to 45 minutes in Pop D. Mate choice tests were performed. Positive assortative mating was found in all crosses. They concluded that reproductive isolation occurred under both allopatric and sympatric conditions when very strong selection was present.
Hurd and Eisenberg (1975) performed a similar experiment on houseflies using 50% gene flow and got the same results.
5.5 Speciation Through Host Race Differentiation
Recently there has been a lot of interest in whether the differentiation of an herbivorous or parasitic species into races living on different hosts can lead to sympatric speciation. It has been argued that in animals that mate on (or in) their preferred hosts, positive assortative mating is an inevitable byproduct of habitat selection (Rice 1985; Barton, et al. 1988). This would suggest that differentiated host races may represent incipient species.
5.5.1 Apple Maggot Fly (Rhagoletis pomonella)
Rhagoletis pomonella is a fly that is native to North America. Its normal host is the hawthorn tree. Sometime during the nineteenth century it began to infest apple trees. Since then it has begun to infest cherries, roses, pears and possibly other members of the rosaceae. Quite a bit of work has been done on the differences between flies infesting hawthorn and flies infesting apple. There appear to be differences in host preferences among populations. Offspring of females collected from on of these two hosts are more likely to select that host for oviposition (Prokopy et al. 1988). Genetic differences between flies on these two hosts have been found at 6 out of 13 allozyme loci (Feder et al. 1988, see also McPheron et al. 1988). Laboratory studies have shown an asynchrony in emergence time of adults between these two host races (Smith 1988). Flies from apple trees take about 40 days to mature, whereas flies from hawthorn trees take 54-60 days to mature. This makes sense when we consider that hawthorn fruit tends to mature later in the season that apples. Hybridization studies show that host preferences are inherited, but give no evidence of barriers to mating. This is a very exciting case. It may represent the early stages of a sympatric speciation event (considering the dispersal of R. pomonella to other plants it may even represent the beginning of an adaptive radiation). It is important to note that some of the leading researchers on this question are urging caution in interpreting it. Feder and Bush (1989) stated:
"Hawthorn and apple "host races" of R. pomonella may therefore represent incipient species. However, it remains to be seen whether host-associated traits can evolve into effective enough barriers to gene flow to result eventually in the complete reproductive isolation of R. pomonella populations."
5.5.2 Gall Former Fly (Eurosta solidaginis)
Eurosta solidaginis is a gall forming fly that is associated with goldenrod plants. It has two hosts: over most of its range it lays its eggs in Solidago altissima, but in some areas it uses S. gigantea as its host. Recent electrophoretic work has shown that the genetic distances among flies from different sympatric hosts species are greater than the distances among flies on the same host in different geographic areas (Waring et al. 1990). This same study also found reduced variability in flies on S. gigantea. This suggests that some E. solidaginis have recently shifted hosts to this species. A recent study has compared reproductive behavior of the flies associated with the two hosts (Craig et al. 1993). They found that flies associated with S. gigantea emerge earlier in the season than flies associated with S. altissima. In host choice experiments, each fly strain ovipunctured its own host much more frequently than the other host. Craig et al. (1993) also performed several mating experiments. When no host was present and females mated with males from either strain, if males from only one strain were present. When males of both strains were present, statistically significant positive assortative mating was seen. In the presence of a host, assortative mating was also seen. When both hosts and flies from both populations were present, females waited on the buds of the host that they are normally associated with. The males fly to the host to mate. Like the Rhagoletis case above, this may represent the beginning of a sympatric speciation.
5.6 Flour Beetles (Tribolium castaneum)
Halliburton and Gall (1981) established a population of flour beetles collected in Davis, California. In each generation they selected the 8 lightest and the 8 heaviest pupae of each sex. When these 32 beetles had emerged, they were placed together and allowed to mate for 24 hours. Eggs were collected for 48 hours. The pupae that developed from these eggs were weighed at 19 days. This was repeated for 15 generations. The results of mate choice tests between heavy and light beetles was compared to tests among control lines derived from randomly chosen pupae. Positive assortative mating on the basis of size was found in 2 out of 4 experimental lines.
5.7 Speciation in a Lab Rat Worm, Nereis acuminata
In 1964 five or six individuals of the polychaete worm, Nereis acuminata, were collected in Long Beach Harbor, California. These were allowed to grow into a population of thousands of individuals. Four pairs from this population were transferred to the Woods Hole Oceanographic Institute. For over 20 years these worms were used as test organisms in environmental toxicology. From 1986 to 1991 the Long Beach area was searched for populations of the worm. Two populations, P1 and P2, were found. Weinberg, et al. (1992) performed tests on these two populations and the Woods Hole population (WH) for both postmating and premating isolation. To test for postmating isolation, they looked at whether broods from crosses were successfully reared. The results below give the percentage of successful rearings for each group of crosses.WH × WH - 75%
P1 × P1 - 95%
P2 × P2 - 80%
P1 × P2 - 77%
WH × P1 - 0%
WH × P2 - 0%
They also found statistically significant premating isolation between the WH population and the field populations. Finally, the Woods Hole population showed slightly different karyotypes from the field populations.
5.8 Speciation Through Cytoplasmic Incompatability Resulting from the Presence of a Parasite or Symbiont
In some species the presence of intracellular bacterial parasites (or symbionts) is associated with postmating isolation. This results from a cytoplasmic incompatability between gametes from strains that have the parasite (or symbiont) and stains that don't. An example of this is seen in the mosquito Culex pipiens (Yen and Barr 1971). Compared to within strain matings, matings between strains from different geographic regions may may have any of three results: These matings may produce a normal number of offspring, they may produce a reduced number of offspring or they may produce no offspring. Reciprocal crosses may give the same or different results. In an incompatible cross, the egg and sperm nuclei fail to unite during fertilization. The egg dies during embryogenesis. In some of these strains, Yen and Barr (1971) found substantial numbers of Rickettsia-like microbes in adults, eggs and embryos. Compatibility of mosquito strains seems to be correlated with the strain of the microbe present. Mosquitoes that carry different strains of the microbe exhibit cytoplasmic incompatibility; those that carry the same strain of microbe are interfertile.
Similar phenomena have been seen in a number of other insects. Microoganisms are seen in the eggs of both Nasonia vitripennis and N. giraulti. These two species do not normally hybridize. Following treatment with antibiotics, hybrids occur between them (Breeuwer and Werren 1990). In this case, the symbiont is associated with improper condensation of host chromosomes.
For more examples and a critical review of this topic, see Thompson 1987.
5.9 A Couple of Ambiguous Cases
So far the BSC has applied to all of the experiments discussed. The following are a couple of major morphological changes produced in asexual species. Do these represent speciation events? The answer depends on how species is defined.
5.9.1 Coloniality in Chlorella vulgaris
Boraas (1983) reported the induction of multicellularity in a strain of Chlorella pyrenoidosa (since reclassified as C. vulgaris) by predation. He was growing the unicellular green alga in the first stage of a two stage continuous culture system as for food for a flagellate predator, Ochromonas sp., that was growing in the second stage. Due to the failure of a pump, flagellates washed back into the first stage. Within five days a colonial form of the Chlorella appeared. It rapidly came to dominate the culture. The colony size ranged from 4 cells to 32 cells. Eventually it stabilized at 8 cells. This colonial form has persisted in culture for about a decade. The new form has been keyed out using a number of algal taxonomic keys. They key out now as being in the genus Coelosphaerium, which is in a different family from Chlorella.
5.9.2 Morphological Changes in Bacteria
Shikano, et al. (1990) reported that an unidentified bacterium underwent a major morphological change when grown in the presence of a ciliate predator. This bacterium's normal morphology is a short (1.5 um) rod. After 8 - 10 weeks of growing with the predator it assumed the form of long (20 um) cells. These cells have no cross walls. Filaments of this type have also been produced under circumstances similar to Boraas' induction of multicellularity in Chlorella. Microscopic examination of these filaments is described in Gillott et al. (1993). Multicellularity has also been produced in unicellular bacterial by predation (Nakajima and Kurihara 1994). In this study, growth in the presence of protozoal grazers resulted in the production of chains of bacterial cells. |
http://www.talkorigins.org/faqs/faq-speciation.html
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What can be asserted without evidence can also be dismissed without evidence. |
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Zwicky
pipika
Pridružen/-a: 01.10. 2007, 20:26
Prispevkov: 2054
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| Objavljeno: Petek 27 Jun 2008 21:44 Naslov sporočila: |
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Aja - glede na temo dokazov o evoluciji, bi pristavila glede kreacionizma kot nasprotja evolucije samo še tisto, kar je že tako ali tako zapisano v mojem podpisu: "What can be asserted without evidence can also be dismissed without evidence."
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What can be asserted without evidence can also be dismissed without evidence. |
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jakacan
pipika
Pridružen/-a: 08.10. 2007, 18:14
Prispevkov: 1102
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| Objavljeno: Petek 27 Jun 2008 21:45 Naslov sporočila: |
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| kalija je napisal/a: |
Ali si to sploh prebral?
Kup Darwinovih trditev ki je ovrženih.
Temu bi jaz rekla rušenje dokazov evolucije in ne postavljanje. |
Prebral, ampak napačni tekst copy pastal. Zagodlo mi jo je preveliko število odprtih strani. Poiščem ponovno tisto, kar sem želel zares prilepiti.
(porkaduš, si štorast Jakačan, pejt u rt!)
p.s. Slikovno gradivo je bilo pa najbolje kar preskočiti, kajne, Kalija?!  Preveč bode v oči ...
_________________
To je Božja beseda. Bobu hvala. |
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kalija
pipika
Pridružen/-a: 31.08. 2007, 13:48
Prispevkov: 1262
Kraj: gnezdišče
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| Objavljeno: Petek 27 Jun 2008 21:59 Naslov sporočila: |
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dolg tzekst. Bom najprej na to odgovorila pa potem angleško prebrala.
| Zwicky je napisal/a: |
| Nič, kar je funkcionalno in služi nekemu namenu, ne more biti (in ni) degeneracija. |
Imaš prav. Pa nimaš prav.
Zmanjšana funkcija je degeneracija.
Namreč udje, ki se ne uporabljajo degenerirajo. Cel kup civilizacijskih bolezni je degeneracija. Debelost, ploske noge, slabost diskusov, preponska kila, hemoroidi, ....
Če se tehnični aparat ne uporablja, zarjavi in se pokvari. Enako je s telesom, ki je mnogo bolj kompleksno, kot kakšen aparat. Telesna aktivnost je nujno potrebna za funkcionalnost človeškega telesa (mišica, ki se ne uporablja, zakrni).
Organi torej pod določenimi pogoji okolice lahko zakrnijo in s tem delno ali popolno izgubijo svojo funkcijo. Ti pojavi so v domeni mikroevolucije in so regresivni.
Podobno, kot jamske ribice, ki izgubijo vid. Oko se najprej normalno razvija in je nujno potrebno za razvoj oblikovanja glave ribe, a nadalje zakrni in je neuporabno. |
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ucen
pipika
Pridružen/-a: 19.08. 2007, 15:00
Prispevkov: 898
Kraj: pipjigor
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| Objavljeno: Petek 27 Jun 2008 22:07 Naslov sporočila: |
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| jakacan je napisal/a: |
| ucen je napisal/a: |
| Bog se npr. z učlovečenjem |
Zakaj bi se Bog učlovečil? Zakaj bi postal del ustvarjenega, samega sebe morilec? Le kaj je Bogu tega treba? Se res kot homo sapiens šteješ toliko (bolj) vrednega od vsega ostalega ustvarjenega in živega, da moreš verjeti, da bi se Absolutno (nepredstavljivo) spustilo v živalsko kožo, 33 let "trpelo" vse to človeško sranje, angine, zaprtja, driske, žejo, trdega lulčka ob jutranjem prebujanju ... samo zato, da bi po bližnjevzhodno lokalnih verskih spisih odrešilo neko živaljsko vrsto na tretjem kamnu od sonca?
Razsvetlite me že enkrat, zakaj in kako je mogoče verjeti kaj tako neverjetnega, nepredstavljivega in absurdnega! Prosim!
| Citiram: |
| (pa tudi že prej, recimo z ukvarjanjem z ljudmi) spusti na nivo, ki je daleč pod Njim. In potem je nastalo tudi to, kar je; na način, kakršen je ... |
Kako naj ne rečem sedaj, da prvo pomislim na tistega svizca iz švicarske reklame, ki zavija čokolado!?! Sem res popolnoma zaprt za "presežno" ali vendar toliko pri sebi, da se ne pustim ujeti tej/takšni sanjavosti ...
... ker bi v nekem drugem času in na drugem kraju prav lahko verjel tudi v Iro, boginjo jeze, Bolula, boga dežja ali kakšnega drugega antropomorfnega delilca pravice in kazni?!?!
Milost! |
(Ali naj posmetim na forumskem nivoju znanstveno razpravo z nečim, kar itak ne bo "odgovorilo" - a zaradi želje po neignoriranju bom ...)
Razlog učlovečenja naj bi bil podan.
A, kdo ga kar tako v dovoljšnjem deležu polnosti dojame?!
Saj se je moč podobno vpraševati, zakaj se (tudi za drug drugega) dobro iščoča forumaša tu razhajata in se (še) ne uspevata razsvetliti s spoznanjem. |
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Zwicky
pipika
Pridružen/-a: 01.10. 2007, 20:26
Prispevkov: 2054
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| Objavljeno: Petek 27 Jun 2008 22:09 Naslov sporočila: |
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| kalija je napisal/a: |
dolg tzekst. Bom najprej na to odgovorila pa potem angleško prebrala.
| Zwicky je napisal/a: |
| Nič, kar je funkcionalno in služi nekemu namenu, ne more biti (in ni) degeneracija. |
Imaš prav. Pa nimaš prav.
Zmanjšana funkcija je degeneracija.
Namreč udje, ki se ne uporabljajo degenerirajo. Cel kup civilizacijskih bolezni je degeneracija. Debelost, ploske noge, slabost diskusov, preponska kila, hemoroidi, .... |
Govorila sem o rudimentarnih organih. In to, da imajo neko funkcijo, ne zanika evolucije (tega, kako so se razvili in ohranili), zanika samo tezo, da so neuporabni. Kar je bistvena razlika.
Še en zanimiv primer:
| Citiram: |
| Dandelions, like all flowers, have the proper organs (stamen and pistil) necessary for sexual reproduction, but do not use them. |
Zakaj bi jim jih bog dal, če jih ne uporabljajo? Menda ja ne za okras? 
In zakaj jih ne uporabljajo, če jim jih je dal bog? Zanikajo njegov načrt?
| Citiram: |
Dandelions reproduce without fertilization; they basically clone themselves, and they are quite successful at it. Look at any lawn for the proof. If dandelions were to revert to sexual reproduction, they might not retain whatever traits they have that allow them to be pests to gardeners everywhere. If flowers can begin reproducing in this manner, does that mean animals, even humans could too? Asexual reproduction can be a good strategy in an environment that is constant if a species is well suited to those conditions. It doesn?t take a scientist to figure out that humans wouldn't last long if the condition set forth was no sexual contact with others. Therefore, the human sexual organs are probably in no danger of becoming vestigial. |
Ne razumem, zakaj bi bila to "degeneracija", če pa gre za zelo uspešno strategijo za preživetje vrste.
| kalija je napisal/a: |
Podobno, kot jamske ribice, ki izgubijo vid. Oko se najprej normalno razvija in je nujno potrebno za razvoj oblikovanja glave ribe, a nadalje zakrni in je neuporabno. |
Kar je krasen primer adaptacije na okolje.
_________________
What can be asserted without evidence can also be dismissed without evidence. |
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kalija
pipika
Pridružen/-a: 31.08. 2007, 13:48
Prispevkov: 1262
Kraj: gnezdišče
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| Objavljeno: Petek 27 Jun 2008 22:11 Naslov sporočila: |
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| Zwicky je napisal/a: |
Drugače pa večina ljudi, ki nasprotujejo evoluciji, kot mantro ponavlja še eno laž - da evolucije nismo nikoli opazili na delu.
| Citiram: |
Biologists define evolution as a change in the gene pool of a population over time. One example is insects developing a resistance to pesticides over the period of a few years. Even most Creationists recognize that evolution at this level is a fact. What they don't appreciate is that this rate of evolution is all that is required to produce the diversity of all living things from a common ancestor.
The origin of new species by evolution has also been observed, both in the laboratory and in the wild.
Even without these direct observations, it would be wrong to say that evolution hasn't been observed. Evidence isn't limited to seeing something happen before your eyes. Evolution makes predictions about what we would expect to see in the fossil record, comparative anatomy, genetic sequences, geographical distribution of species, etc., and these predictions have been verified many times over. The number of observations supporting evolution is overwhelming.
What hasn't been observed is one animal abruptly changing into a radically different one, such as a frog changing into a cow. This is not a problem for evolution because evolution doesn't propose occurrences even remotely like that. In fact, if we ever observed a frog turn into a cow, it would be very strong evidence against evolution. |
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Se strinjam s tem. To stvar mi pomaga premostiti pojmi mikroevolucija in makroevolucija ter definicija vrste v smislu osnovnega tipa. |
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kalija
pipika
Pridružen/-a: 31.08. 2007, 13:48
Prispevkov: 1262
Kraj: gnezdišče
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| Objavljeno: Petek 27 Jun 2008 22:49 Naslov sporočila: |
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| jakacan je napisal/a: |
| p.s. Slikovno gradivo je bilo pa najbolje kar preskočiti, kajne, Kalija?! Preveč bode v oči ... |
Ja. Res me je par stvari zbodlo v oko.
Pri teoriji razvoja očesa, me najbolj bode nenaden pojav kompleksnih oči trilobitov. Razlaga nenadnega pojava te kompleksne tvorbe?
Pa arheopteriks me tudi zelo bode. Še posebej če vem, da se v kamninah enakega starostnega obdobja pojavljajo ptice in s tem izgubi naziv vmesnega člena. Poleg tega je arheopetriks prava ptica in bi tudi danes bil uvrščen kot ptica.
Tista obeležja, ki bi naj nakazovala prehod iz kuščarja me tudi ne prepričajo. Še posebej če vem, da tudi danes živijo ptice, ki imajo kremplje na krilih in jih uvrščamo med ptice.
Tudi zobje v kljunu me ne prepričajo v vmesni člen te živali. Res je, da današnje ptice nimajo zob, vendar so nekatere izumrle ptice imele zobe. Poleg tega pa nekateri plazilci imajo zobe, nekateri nimajo zob, nekatere dvoživke imajo zobe in nekatere nimajo zob. Enako je pri ribah, plazilcih, pticah in sesalcih. In če bi sledili analogiji, da so ptice z zobmi primitivnejše od ptic brez zob, potem bi tudi kljunati ježek in kljunaš morala biti naprednejša od ljudi. |
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| Nazaj na vrh |
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kalija
pipika
Pridružen/-a: 31.08. 2007, 13:48
Prispevkov: 1262
Kraj: gnezdišče
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| Objavljeno: Petek 27 Jun 2008 23:07 Naslov sporočila: |
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| Zwicky je napisal/a: |
Še en zanimiv primer:
| Citiram: |
| Dandelions, like all flowers, have the proper organs (stamen and pistil) necessary for sexual reproduction, but do not use them. |
Zakaj bi jim jih bog dal, če jih ne uporabljajo? Menda ja ne za okras?
In zakaj jih ne uporabljajo, če jim jih je dal bog? Zanikajo njegov načrt?
| Citiram: |
Dandelions reproduce without fertilization; they basically clone themselves, and they are quite successful at it. Look at any lawn for the proof. If dandelions were to revert to sexual reproduction, they might not retain whatever traits they have that allow them to be pests to gardeners everywhere. If flowers can begin reproducing in this manner, does that mean animals, even humans could too? Asexual reproduction can be a good strategy in an environment that is constant if a species is well suited to those conditions. It doesn?t take a scientist to figure out that humans wouldn't last long if the condition set forth was no sexual contact with others. Therefore, the human sexual organs are probably in no danger of becoming vestigial. |
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Hmm, nič ne vem o tem pri regratu. Kolikor vidim, žuželke pridno lazijo po regratovem cvetu. Da ob tem do oprašitve ne pride? Žal še o tem nisem slišala nič. 
| Zwicky je napisal/a: |
| kalija je napisal/a: |
Podobno, kot jamske ribice, ki izgubijo vid. Oko se najprej normalno razvija in je nujno potrebno za razvoj oblikovanja glave ribe, a nadalje zakrni in je neuporabno. |
Kar je krasen primer adaptacije na okolje. |
Nimam problema z adaptacijo na okolje. Je nujna v tem spremenljivem svetu. (mikroevolucija je opazovana in dokazana). |
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Ne, ne moreš dodajati novih tem v tem forumu
Ne, ne moreš odgovarjati na teme v tem forumu
Ne, ne moreš urejati svojih prispevkov v tem forumu
Ne, ne moreš brisati svojih prispevkov v tem forumu
Ne ne moreš glasovati v anketi v tem forumu
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