Cryptic Genetic Variation Can Make Irreducible Complexity a Common Mode of Adaptation
Meredith V. Trotter, Daniel B. Weissman, Grant I. Peterson, Kayla M. Peck, Joanna Masel
(Submitted on 22 Oct 2013)
The existence of complex (multiple-step) genetic adaptations that are "irreducible" (i.e., all partial combinations are less fit than the original genotype) is one of the longest standing problems in evolutionary biology. In standard genetics parlance, these adaptations require the crossing of a wide adaptive valley of deleterious intermediate stages. Here we demonstrate, using a simple model, that evolution can cross wide valleys to produce "irreducibly complex" adaptations by making use of previously cryptic mutations. When revealed by an evolutionary capacitor, previously cryptic mutants have higher initial frequencies than do new mutations, bringing them closer to a valley-crossing saddle in allele frequency space. Moreover, simple combinatorics imply an enormous number of candidate combinations exist within available cryptic genetic variation. We model the dynamics of crossing of a wide adaptive valley after a capacitance event using both numerical simulations and analytical approximations. Although individual valley crossing events become less likely as valleys widen, by taking the combinatorics of genotype space into account, we see that revealing cryptic variation can cause the frequent evolution of complex adaptations. This finding also effectively dismantles "irreducible complexity" as an argument against evolution by providing a general mechanism for crossing wide adaptive valleys.
Subjects: Populations and Evolution (q-bio.PE)
Cite as: arXiv:1310.6077 [q-bio.PE]
(or arXiv:1310.6077v1 [q-bio.PE] for this version)
Submission history
From: Meredith Trotter [view email]
[v1] Tue, 22 Oct 2013 23:34:57 GMT (989kb)
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FREE PDF GRATIS: ArXiv
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EXCERPT/EXCERTO
"When a population is well adapted to its environment, the vast majority of new mutations will be neutral or negative. If a higher fitness genotype exists that requires multiple mutations, but each intermediate mutation combination is deleterious, the population must traverse a metaphorical "adaptive valley" of low fitness to access the superior adaptation (Wright 1932). Such adaptations are called "irreducibly complex" by the intelligent design lobby, which uses the term to assert that evolution cannot cross multi-step adaptive valleys. Detailed investigations into the evolution of specific complex adaptations (Bridgham et al. 2006; Weinreich et al. 2006; PoelwijkFJ et al. 2007; Egelman 2010) have shown that in these particular cases, evolved complexity is not irreducible. Many biologists assume, in agreement with the intelligent design lobby, that irreducible complexity rarely, if ever, evolves."
EXCERPT/EXCERTO
"When a population is well adapted to its environment, the vast majority of new mutations will be neutral or negative. If a higher fitness genotype exists that requires multiple mutations, but each intermediate mutation combination is deleterious, the population must traverse a metaphorical "adaptive valley" of low fitness to access the superior adaptation (Wright 1932). Such adaptations are called "irreducibly complex" by the intelligent design lobby, which uses the term to assert that evolution cannot cross multi-step adaptive valleys. Detailed investigations into the evolution of specific complex adaptations (Bridgham et al. 2006; Weinreich et al. 2006; PoelwijkFJ et al. 2007; Egelman 2010) have shown that in these particular cases, evolved complexity is not irreducible. Many biologists assume, in agreement with the intelligent design lobby, that irreducible complexity rarely, if ever, evolves."
NOTA DESTE BLOGGER:
Repare que neste artigo que afirma ter desmantelado o conceito de "complexidade irredutível" como argumento contra a evolução gradualista darwinista, nenhuma vez cita Michael Behe. NOTA BENE: NENHUMA VEZ! A não ser pejorativamente - intelligent design lobby!
Ora, se é ;obby, como que que você se propõe demonstrar cientificamente falso a tese do Design Inteligente se você não cita um trabalho do seu oponente? Estranho esse comportamento dos autores.
Ora, se é ;obby, como que que você se propõe demonstrar cientificamente falso a tese do Design Inteligente se você não cita um trabalho do seu oponente? Estranho esse comportamento dos autores.
Todavia, nessa tentativa de falsificar a tese do Design Inteligente, em termos popperianos, esses autores estão confirmando que a tese do DI é uma tese científica, pois se sujeita à falsificação/falseamento. Mas não citar quem trouxe para o centro do discussão científica a complexidade irredutível de sistemas biológicos é CENSURA DITATORIAL da Nomenklatura que não vê, não ouve nem fala em Design Inteligente. Só quando lhe convém!
Ah, adaptação não explica a macroevolução - um Australopithecus afarensis se transmutar em Antropólogo amazonense... E sem isso, Darwin continua blefando teoricamente...
Torquemadas pós-modernos, chiques e perfumados a la Dawkins...
Ah, adaptação não explica a macroevolução - um Australopithecus afarensis se transmutar em Antropólogo amazonense... E sem isso, Darwin continua blefando teoricamente...
Torquemadas pós-modernos, chiques e perfumados a la Dawkins...
Pobre ciência...
