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Historical isolation facilitates species radiation by sexual selection: Insights from Chorthippus grasshoppers
Author(s) -
Nolen Zachary J.,
Yildirim Burcin,
Irisarri Iker,
Liu Shanlin,
Groot Crego Clara,
Amby Daniel Buchvaldt,
Mayer Frieder,
Gilbert M. Thomas P.,
Pereira Ricardo J.
Publication year - 2020
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/mec.15695
Subject(s) - biology , sympatric speciation , reproductive isolation , introgression , evolutionary biology , ecological speciation , ecology , sexual selection , allopatric speciation , sympatry , natural selection , ecological selection , gene flow , selection (genetic algorithm) , genetic variation , population , genetics , gene , demography , artificial intelligence , sociology , computer science
Theoretical and empirical studies have shown that species radiations are facilitated when a trait under divergent natural selection is also involved in sexual selection. It is yet unclear how quick and effective radiations are where assortative mating is unrelated to the ecological environment and primarily results from sexual selection. We address this question using sympatric grasshopper species of the genus Chorthippus , which have evolved strong behavioural isolation while lacking noticeable ecomorphological divergence. Mitochondrial genomes suggest that the radiation is relatively recent, dating to the mid‐Pleistocene, which leads to extensive incomplete lineage sorting throughout the mitochondrial and nuclear genomes. Nuclear data shows that hybrids are absent in sympatric localities but that all species have experienced gene flow, confirming that reproductive isolation is strong but remains incomplete. Demographic modelling is most consistent with a long period of geographic isolation, followed by secondary contact and extensive introgression. Such initial periods of geographic isolation might facilitate the association between male signaling and female preference, permitting the coexistence of sympatric species that are genetically, morphologically, and ecologically similar, but otherwise behave mostly as good biological species.