A test of genetic models for the evolutionary maintenance of same-sex sexual behaviour
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The evolutionary maintenance of same-sex sexual behaviour (SSB) has received increasing attention because it is perceived to be an evolutionary paradox. The genetic basis of SSB is almost wholly unknown in non-human animals, though this is key to understanding its persistence. Recent theoretical work has yielded broadly applicable predictions centred on two genetic models for SSB: overdominance and sexual antagonism. Using Drosophila melanogaster, we assayed natural genetic variation for male SSB and empirically tested predictions about the mode of inheritance and fitness consequences of alleles influencing its expression. We screened 50 inbred lines derived from a wild population for male–male courtship and copulation behaviour, and examined crosses between the lines for evidence of overdominance and antagonistic fecundity selection. Consistent variation among lines revealed heritable genetic variation for SSB, but the nature of the genetic variation was complex. Phenotypic and fitness variation was consistent with expectations under overdominance, although predictions of the sexual antagonism model were also supported. We found an unexpected and strong paternal effect on the expression of SSB, suggesting possible Y-linkage of the trait. Our results inform evolutionary genetic mechanisms that might maintain low but persistently observed levels of male SSB in D. melanogaster, but highlight a need for broader taxonomic representation in studies of its evolutionary causes.
Hoskins , J , Ritchie , M G & Bailey , N W 2015 , ' A test of genetic models for the evolutionary maintenance of same-sex sexual behaviour ' Proceedings of the Royal Society of London Series B: Biological Sciences , vol 282 , 20150429 . DOI: 10.1098/rspb.2015.0429
Proceedings of the Royal Society of London Series B: Biological Sciences
Copyright 2015 The Author(s) Published by the Royal Society. All rights reserved. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://dx.doi.org/10.1098/rspb.2015.0429
This study was supported by Natural Environment Research Council (NERC) fellowships to NWB (NE/G014906/1, NE/L011255/1) and a NERC grant to NWB and MGR (NE/I016937/1).
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