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Genomic signatures of divergent selection and speciation patterns in a ‘natural experiment’, the young parallel radiations of N icaraguan crater lake cichlid fishes
Author(s) -
Kautt Andreas F.,
Elmer Kathryn R.,
Meyer Axel
Publication year - 2012
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/j.1365-294x.2012.05738.x
Subject(s) - allopatric speciation , cichlid , sympatric speciation , biology , crater lake , adaptive radiation , evolutionary biology , disruptive selection , natural selection , ecological speciation , parallel evolution , ecology , impact crater , population , phylogenetics , genetic variation , gene flow , genetics , astrobiology , fishery , gene , fish <actinopterygii> , demography , sociology
Divergent selection is the main driving force in sympatric ecological speciation and may also play a strong role in divergence between allopatric populations. Characterizing the genome‐wide impact of divergent selection often constitutes a first step in unravelling the genetic bases underlying adaptation and ecological speciation. The M idas cichlid fish ( A mphilophus citrinellus ) species complex in N icaragua is a powerful system for studying evolutionary processes. Independent colonizations of isolated young crater lakes by M idas cichlid populations from the older and great lakes of N icaragua resulted in the repeated evolution of adaptive radiations by intralacustrine sympatric speciation. In this study we performed genome scans on two repeated radiations of crater lake species and their great lake source populations (1030 polymorphic AFLP s, n ∼ 30 individuals per species). We detected regions under divergent selection (0.3% in the crater lake X iloá flock and 1.7% in the older crater lake A poyo radiation) that might be responsible for the sympatric diversifications. We find no evidence that the same genomic regions have been involved in the repeated evolution of parallel adaptations across crater lake flocks. However, there is some genetic parallelism apparent (seven out of 51 crater lake to great lake outlier loci are shared; 13.7%) that is associated with the allopatric divergence of both crater lake flocks. Interestingly, our results suggest that the number of outlier loci involved in sympatric and allopatric divergence increases over time. A phylogeny based on the AFLP data clearly supports the monophyly of both crater lake species flocks and indicates a parallel branching order with a primary split along the limnetic‐benthic axis in both radiations.