Does polyandry control population sex ratio via regulation of a selfish gene?
The extent of female multiple mating (polyandry) can strongly impact on the intensity of sexual selection, sexual conflict, and the evolution of cooperation and sociality. More subtly, polyandry may protect populations against intragenomic conflicts that result from the invasion of deleterious selfish genetic elements (SGEs). SGEs commonly impair sperm production, and so are likely to be unsuccessful in sperm competition, potentially reducing their transmission in polyandrous populations. Here, we test this prediction in nature. We demonstrate a heritable latitudinal cline in the degree of polyandry in the fruitfly Drosophila pseudoobscura across the USA, with northern population females remating more frequently in both the field and the laboratory. High remating was associated with low frequency of a sex-ratio-distorting meiotic driver in natural populations. In the laboratory, polyandry directly controls the frequency of the driver by undermining its transmission. Hence we suggest that the cline in polyandry represents an important contributor to the cline in sex ratio in nature. Furthermore, as the meiotic driver causes sex ratio bias, variation in polyandry may ultimately determine population sex ratio across the USA, a dramatic impact of female mating decisions. As SGEs are ubiquitous it is likely that the reduction of intragenomic conflict by polyandry is widespread.
Biosciences, College of Life and Environmental Sciences, University of Exeter, , Cornwall Campus, Penryn TR10 9EZ, UK, School of Biology, University of Leeds, , Leeds LS2 9JT, UK, Centro de Biología Molecular 'Severo Ochoa' (CSIC-UAM), Universidad Autónoma de Madrid, , Cantoblanco, 28049 Madrid, Spain, Department of Animal and Plant Sciences, University of Sheffield, , Sheffield S10 2TN, UK, Institute of Integrative Biology, University of Liverpool, , Liverpool L69 7ZB, UK.
Tom A R
TA
Price
Amanda
A
Bretman
Ana C
AC
Gradilla
Julia
J
Reger
Michelle L
ML
Taylor
Paulina
P
Giraldo-Perez
Amy
A
Campbell
Gregory D D
GD
Hurst
Nina
N
Wedell
D000818:Animals; D004247:DNA / Q000235:genetics; D004330:Drosophila / Q000235:genetics / Q000502:physiology*; D005260:Female; D049750:Genome, Insect; D040582:Inheritance Patterns; D008297:Male; D052586:Mating Preference, Animal; D008540:Meiosis; D012091:Repetitive Sequences, Nucleic Acid; D012744:Sex Ratio
D004247:DNA
geographical cline; meiotic drive; polyandry; sex ratio distorter; sexual selection; sperm competition