TY - JOUR

T1 - Historical isolation facilitates species radiation by sexual selection

T2 - Insights from Chorthippus grasshoppers

AU - Nolen, Zachary J

AU - Yildirim, Burcin

AU - Irisarri, Iker

AU - Liu, Shanlin

AU - Groot Crego, Clara

AU - Buchvaldt Amby, Daniel

AU - Mayer, Frieder

AU - Gilbert, M Thomas P

AU - Pereira, Ricardo J

N1 - This article is protected by copyright. All rights reserved.

PY - 2020

Y1 - 2020

N2 - 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 behavioral isolation while lacking noticeable eco-morphological 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 the 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.

AB - 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 behavioral isolation while lacking noticeable eco-morphological 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 the 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.

U2 - 10.1111/mec.15695

DO - 10.1111/mec.15695

M3 - Journal article

C2 - 33065760

VL - 29

SP - 4985

EP - 5002

JO - Molecular Ecology

JF - Molecular Ecology

SN - 0962-1083

IS - 24

ER -