History repeats itself: genomic divergence in copepods

Abstract

Press stop, erase everything from now till some arbitrary time in the past and start recording life as it evolves once again. Would you see the same tape of life playing itself over and over, or would a different story unfold every time? The late Steven Jay Gould called this experiment replaying the tape of life and argued that any replay of the tape would lead evolution down a pathway radically different from the road actually taken (Gould 1989). This thought experiment has puzzled evolutionary biologists for a long time: how repeatable are evolutionary events? And if history does indeed repeat itself, what are the factors that may help us predict the path taken? A powerful means to address these questions at a small evolutionary scale is to study closely related populations that have evolved independently, under similar environmental conditions. This is precisely what Pereira et al. (2016) set out to do using marine copepods Tigriopus californicus, and present their results in this issue of Molecular Ecology. They show that evolution can be repeatable and even partly predictable, at least at the molecular level. As expected from theory, patterns of divergence were shaped by natural selection. At the same time, strong genetic drift due to small population sizes also constrained evolution down a similar evolutionary road, and probably contributed to repeatable patterns of genomic divergence.

Recurrent selection explains parallel evolution of genomic regions of high relative but low absolute differentiation in a ring species

“…has captured the interest and imagination of generations of scientists and motivated much empirical and theoretical research (e.g. Gould 1990;Travisano et al 1995;Wichman et al 1999;Wood et al 2005;Conte et al 2012;Meyer et al 2012;Renaut et al 2014;Bauer & Gokhale 2015;Pereira et al 2016;Renaut & Dion-Côt e 2016).…”

“…; Bauer & Gokhale ; Pereira et al . ; Renaut & Dion‐Côté ). Thought experiments and empirical investigations of this question have mostly focused on phenotypic patterns and/or genetic changes in particular genes of interest, and answers appear to depend on the timescale considered.…”

Lack of gene flow: Narrow and dispersed differentiation islands in a triplet of Leptidea butterfly species

“…Second, the repeatability of evolutionary trajectories has been a long-standing topic (Conte, Arnegard, Peichel, & Schluter, 2012;Gould, 1990;Meyer et al, 2012). This has been actualized by recent observations of conserved genomic diversity and differentiation across rather distant species pairs (Colosimo et al, 2005;Pereira, Barreto, Pierce, Carneiro, & Burton, 2016;Renaut & Dion-Cote, 2016;Renaut, Owens, & Rieseberg, 2014;Van Doren et al, 2017;Vijay et al, 2016). These studies point towards repeated patterns of diversity and differentiation in independent lineages, likely a consequence of conserved recombination landscapes in these organisms (Burri, 2017;.…”