Dia 12 de fevereiro é celebrado nauseabundamente o Dia de Darwin pelo mundo inteiro. Este blogger não vai deixar esta data passar em branco, e vai fazer a sua parte para celebrar a ocasião. Afinal de contas, Darwin é o homem que teve a maior ideia que toda a humanidade já teve, e vale a pena celebrar este dia sob a ótica do próprio Darwin:
“Falsos fatos são altamente prejudiciais para o progresso da ciência, pois frequentemente eles duram muito tempo; mas as falsas opiniões, se apoiadas por alguma evidência, causam pouco dano, pois todo mundo toma um prazer salutar em provar a sua falsidade; e quando isso é feito, um caminho para o erro é fechado e a estrada para a verdade, frequentemente, é aberta ao mesmo tempo.”
“False facts are highly injurious to the progress of science, for they often endure long; but false views, if supported by some evidence, do little harm, for everyone takes a salutary pleasure in proving their falseness; and when this is done, one path towards error is closed and the road to truth is often at the same time opened.” Darwin in Descent of Man (1871, p. 385)
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FATO FALSO DE DARWIN 1:
Conflicting phylogenetic signals at the base of the metazoan tree
Antonis Rokas, a,1 Nicole King, a,1 John Finnerty, b and Sean B. Carroll a, *
a Howard Hughes Medical Institute and Laboratory of Molecular Biology, University of Wisconsin-Madison, 1525 Linden Drive,
Madison, WI 53706-1596, USA
b Department of Biology, Boston University, 5 Cummington St., Boston, MA 02215, USA
*Author for correspondence (e-mail: sbcarrol@facstaff.wisc.edu)
SUMMARY
A phylogenetic framework is essential for understanding the origin and evolution of metazoan development. Despite a number of recent molecular studies and a rich fossil record of sponges and cnidarians, the evolutionary relationships of the early branching metazoan groups to each other and to a putative outgroup, the choanoflagellates, remain uncertain. This situation may be the result of the limited amount of phylogenetic information found in single genes and the small number of relevant taxa surveyed. To alleviate the effect of these analytical factors in the phylogenetic reconstruction of early branching metazoan lineages, we cloned multiple protein-coding genes from two choanoflagellates and diverse sponges, cnidarians, and a ctenophore. Comparisons of sequences for a-tubulin, b-tubulin, elongation factor 2, HSP90, and HSP70 robustly support the hypothesis that choanoflagellates are closely affiliated with animals. However, analyses of single and concatenated amino acid sequences fail to resolve the relationships either between early branching metazoan groups or between Metazoa and choanoflagellates. We demonstrate that variable rates of evolution among lineages, sensitivity of the analyses to taxon selection, and conflicts in the phylogenetic signal contained in different amino acid sequences obscure the phylogenetic associations among the early branching Metazoa. These factors raise concerns about the ability to resolve the phylogenetic history of animals with molecular sequences. A consensus view of animal evolution may require investigations of genome-scale characters.
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