Tópico: Protegido de Margulis diz que lagartas evoluíram de perípatos por hibridação

[Buckaroo Banzai]

Perípato


Lagarta

Caterpillars evolved from onychophorans by hybridogenesis
Donald I. Williamson,1
Marine Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom

Communicated by Lynn Margulis, University of Massachusetts Amherst, Amherst, MA, July 24, 2009 (received for review May 19, 2009)
Abstract

I reject the Darwinian assumption that larvae and their adults evolved from a single common ancestor. Rather I posit that, in animals that metamorphose, the basic types of larvae originated as adults of different lineages, i.e., larvae were transferred when, through hybridization, their genomes were acquired by distantly related animals. “Caterpillars,” the name for eruciforms with thoracic and abdominal legs, are larvae of lepidopterans, hymenopterans, and mecopterans (scorpionflies). Grubs and maggots, including the larvae of beetles, bees, and flies, evolved from caterpillars by loss of legs. Caterpillar larval organs are dismantled and reconstructed in the pupal phase. Such indirect developmental patterns (metamorphoses) did not originate solely by accumulation of random mutations followed by natural selection; rather they are fully consistent with my concept of evolution by hybridogenesis. Members of the phylum Onychophora (velvet worms) are proposed as the evolutionary source of caterpillars and their grub or maggot descendants. I present a molecular biological research proposal to test my thesis. By my hypothesis 2 recognizable sets of genes are detectable in the genomes of all insects with caterpillar grub- or maggot-like larvae: (i) onychophoran genes that code for proteins determining larval morphology/physiology and (ii) sequentially expressed insect genes that code for adult proteins. The genomes of insects and other animals that, by contrast, entirely lack larvae comprise recognizable sets of genes from single animal common ancestors.

http://www.pnas.org/content/early/2009/08/25/0908357106.abstract

Réplica:

Caterpillars did not evolve from onychophorans by hybridogenesis
Michael W. Harta,1 and Richard K. Grosbergb

+
Author Affiliations
aDepartment of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada V5A 1S6; and
bCollege of Biological Sciences and Center for Population Biology, University of California, Davis, CA 95616

Edited by David M. Hillis, University of Texas, Austin, TX, and approved October 13, 2009 (received for review September 14, 2009)
Abstract

The evolution and loss of distinctive larval forms in animal life cycles have produced complex patterns of similarity and difference among life-history stages and major animal lineages. One example of this similarity is the morphological forms of Onychophora (velvet worms) and the caterpillar-like larvae of some insects. Williamson [(2009) Proc Natl Acad Sci USA 106:15786–15790] has made the astonishing and unfounded claim that the ancestors of the velvet worms directly gave rise to insect caterpillars via hybridization and that evidence of this ancient “larval transfer” could be found in comparisons among the genomes of extant onychophorans, insects with larvae, and insects without larvae. Williamson has made a series of predictions arising from his hypothesis and urged genomicists to test them. Here, we use data already in the literature to show these predictions to be false. Hybridogenesis between distantly related animals does not explain patterns of morphological and life-history evolution in general, and the genes and genomes of animals provide strong evidence against hybridization or larval transfer between a velvet worm and an insect in particular.


http://www.pnas.org/content/early/2009/10/22/0910229106

A única coisa interessante, ainda que acho que esteja muito longe de fazer da idéia algo digno de maior consideração:

LARVAL TRANSFER: A RECENT EVOLUTIONARY THEORY
Donald I Williamson and Sonya E Vickers

[...]

And in conclusion
For those who doubt that errant sperm can fertilize eggs from very
different animals, we offer a parting shot. Eggs of an ascidian, a member of the chordate
phylum and therefore related to us, were fertilized with the sperm of a sea urchin, a
member of the echinoderm phylum (Williamson, 2003), and also eggs of a sea urchin
were fertilized with ascidian sperm (Williamson, in press). In the first experiment,
fertilized ascidian eggs developed as sea-urchin larvae, three of which grew into fertile
adult sea urchins. The great majority of the sea-urchin larvae, however, retracted their
arms to become spheroids, which did not develop further. In the second experiment, all
the fertilized sea-urchin eggs started to develop as sea-urchin larvae, but they then
resorbed their arms to become spheroids. A few of these came to resemble juvenile
ascidians, but these did not grow into adult ascidians. It seems that genes coded for larval
and adult forms remain capable of producing these forms after hybridization, another
result in line with larval transfer but not with the same-stock assumption. If such crosses
can occur in the laboratory, who can say they never take place in the nature?

[Atheist]

Caramba... Essa Margulis, Lovelock e afins estão perdendo parafusos conforme o tempo passa... Como é que afirma um absurdo assim sem ter nenhuma evidência da genética?