The consequences of genomic architecture on ecological speciation in postglacial fishes

Abstract

The quest for the origin of species has entered the genomics era. Despite decades of evidence confirming the role of the environment in ecological speciation, an understanding of the genomics of ecological speciation is still in its infancy. In this review, we explore the role of genomic architecture in ecological speciation in postglacial fishes. Growing evidence for the number, location, effect size, and interactions among the genes underlying population persistence, adaptive trait divergence, and reproductive isolation in these fishes reinforces the importance of considering genomic architecture in studies of ecological speciation. Additionally, these populations likely adapt to new freshwater environments by selection on standing genetic variation, as de novo mutations are unlikely under such recent divergence times. We hypothesize that modular genomic architectures in postglacial fish taxa may be associated with the probability of population persistence. Empirical studies have confirmed the genic nature of ecological speciation, implicating surprisingly extensive linkage disequilibrium across the genome. An understanding of these genomic mosaics and how they contribute to reproductive barriers remains unclear, but migration rates and the strength of selection at these loci is predicted to influence the likelihood of population divergence. Altogether, understanding the role of genomic architecture is an important component of speciation research and postglacial fishes continue to provide excellent organisms to test these questions, both from the perspective of variation in architectures among taxa, and with respect to the distinct environments they have colonized. However, more empirical tests of ecological speciation predictions are needed [Current Zoology 59 (1): [53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71] 2013].

Lakes and ponds as model systems to study parallel evolution

“…Studies of genetically and demographically independent replicate populations derived from the same common ancestors (such as many post-glacially established freshwater populations of temperate zone fishes) have provided numerous examples of this (Taylor, 1999;Schluter, 2000;Rogers et al, 2013). Here, my argument has been that these study systems may yield even more.…”

Speciation through the lens of biomechanics: locomotion, prey capture and reproductive isolation

“…As function diverges, as a result of altered or similar selective pressures, lower-level morphological and physiological traits also diverge (figure 1). Population divergence can lead to reproductive incompatibility, either in the presence or absence of gene flow, and can occur during the expansion of populations into new habitats [18,19] or as habitats are fragmented or modified [20,21]. Although genetic drift and intrinsic incompatibilities may contribute to RI in these circumstances, here we focus on extrinsic forms of isolation resulting from functional mismatches (e.g.…”

A linkage disequilibrium perspective on the genetic mosaic of speciation in two hybridizing Mediterranean white oaks

“…Linkage disequilibrium (LD) is a powerful tool for studying the genomic architecture of ecological speciation, including the detection of divergently selected markers, the analysis of the length and location of differentiation regions, or the search for associations between LD and signatures of divergent selection (Goicoechea et al, 2012;Hohenlohe et al, 2012;Nosil, 2012;Rogers et al, 2013). However, examples of LD estimates are relatively rare in the ecological speciation literature.…”