Freethinker.nl

Peter schreef:Overigens heb ik in de links niets gevonden dat ondersteunt dan Margulis zoiets beweerd heeft.

video-index schreef:http://www.voicesfromoxford.com/homagedarwin_part2.html
00:00 Margulis. Intro + film
2:00 Not a tree but a web. Genetic material from 1 branch to another
4:00 The farming within the body between the foriminifore & the algae
5:40 The little evidence for mutations as vehicle for speciation
. . .

Margulis schreef:The components of evolution (I don’t think any scientist disagrees) that exist because there's so much data for them are: (1) the tendency for exponential growth of all populations -- that is growth beyond a finite world; and (2) since the environment can’t sustain them, there’s an elimination process of natural selection.

The point of contention in science is here: (3) Where does novelty that’s heritable come from? What is the source of evolutionary innovation? Especially positive inherited innovation, where does it come from?

It is here that the neo-Darwinist knee-jerk reaction kicks in. "By random mutations that accumulate so much that you have a new lineage." This final contention, their mistake in my view, is really the basis of nearly all our disagreement.

Everybody agrees: Heritable variation exists, it can be measured. Everybody agrees, as Darwin said, it’s heritable variation "that’s important to us" because variation is inherited. Everyone agrees "descent with modification" can be demonstrated. And furthermore, because of molecular biology, everybody agrees that all life on Earth today is related through common ancestry, as Darwin showed.

Everybody agrees with ultimate common ancestry of Earth's life, because the DNA, RNA messenger, transfer RNA, membrane-bounded cell constituents (lipids, the phospholipids) that we share – they’re all virtually identical in all life today, it's all one single lineage. So that part of Darwinism – that we’re all related by common ancestry –no scientist disagrees with.

The real disagreement about what the neo-Darwinists tout, for which there's very little evidence, if any, is that random mutations accumulate and when they accumulate enough, new species originate. The source of purposeful inherited novelty in evolution, the underlying reason the new species appear, is not random mutation rather it is symbiogenesis, the acquisition of foreign genomes.

When Salthe says we haven't seen that, he’s talking about new species. He’s not saying we haven’t seen natural selection, he's saying we haven't seen natural selection produce new species, this particular aspect of neo-Darwinism.

Heeck schreef:

Margulis schreef:The real disagreement about what the neo-Darwinists tout, for which there's very little evidence, if any, is that random mutations accumulate and when they accumulate enough, new species originate. The source of purposeful inherited novelty in evolution, the underlying reason the new species appear, is not random mutation rather it is symbiogenesis, the acquisition of foreign genomes.

Margulis in Acquiring Genomes p.94 schreef:Two live beings belong to the same species when the content and the number of integrated, formerly independent genomes that constitute them are the same. E. Mayr's species concept of 1948, which states that organisms may be assigned to the same species if, in nature, they mate and produce fertile offspring, becomes one example of our general rule.

. . Hij haalt talloze studies aan, brengt bezoeken aan laboratoria en proefvelden, beschrijft uiteenlopende hypotheses en interacties, en laat de lezer kennismaken met bekende en minder bekende oecologen.
Hij laat daarbij zien welke kettingreacties er kunnen optreden bij introductie van exoten en andere milieuverstoringen. Neem bijvoorbeeld de overbejaging van de zeeotter in de Stille Oceaan: daardoor groeit het aantal zee-egels, die op hun beurt het oerwoud van bruinwierlinten in een onderwaterwoestijn doen veranderen.

Recent work has brought Darwin's idea back into limited favor. It is now agreed that there is no single kind of speciation, and experiments and some historical cases have shown that sympatric speciation can occur. A fruit fly in California, Rhagoletis pomonella, that lived on the Hawthorn (or dogwood) tree shifted to introduced apple trees during the late nineteenth century. Since the introduction date is known, it is known how long this took - and it appears that it took less than fifty years. The two varieties are now isolated, and do not mate, for a simple reason: the hawthorn and the apple fruit at different times of the year. Hybrids are neither Arthur nor Martha, and are thus less fit than either variety, forcing them to adapt not only to their host trees, but to the preferred time of year each has for mating. Thus, they are forced apart.

Heeck schreef:De reden waarom uitsterven me al tijden langer belangrijk lijkt is dat de overlevenden ook overleven met mutaties die geen gewicht in de schaal leggen. Dwz die worden niet weggeselecteerd, noch geven ze een voldoende verschillend geboorte-oversschot.
Juist de onvoldoende omgevings-aangepasten worden weggeselecteerd. Of langzaam, of per catastrofe.

siger schreef:Als ik me niet afvraag wat een soort is, maar de verscheidenheid van leven op aarde neem zoals ze is...

Lyn Margulis, [i]Five Kingdoms[/i] schreef:...classification schemes are an invention; the human hand attempting to sort, group, and rank the types of life that share Earth with us. Because no person witnessed the more than 3.000 million years of the history of life, our domains, kingdoms, phyla, classes, and genera are approximations.

Peter van Velzen schreef:Ik vraag me echter af of het verschil tussen een paard en een ezel nu echt zo groot is dat het niet door random mutaties kan zijn ontstaan. Natuurlijk kun je daar weer makkelijk van af komen, door ze niet als aparte soorten te zien, maar dat lijkt me een cirkelredenering.