Quantitative measure of sexual selection with respect to the operational sex ratio: a comparison of selection indices

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 274; no. 1606; pp. 143 - 150
• Main Authors: Mills, Suzanne C, Grapputo, Alessandro, Koskela, Esa, Mappes, Tapio
• Format: Journal Article
• Language: English
• Published: London The Royal Society 07.01.2007
• Subjects: Animals; Arvicolinae - anatomy & histology; Arvicolinae - genetics; Arvicolinae - physiology; Body Size; Clethrionomys glareolus; Evolution; Female; Genotype; Index Of Resource Monopolization; Male; Mating behavior; Mating Preference, Animal; Mating System; Mating systems; Morisita Index; Opportunity For Sexual Selection; Population genetics; Reproduction; Reproductive success; Sex Ratio; Sexual selection; Statistical variance; Testosterone; Testosterone - blood; Voles
• ISSN: 0962-8452; 1471-2954
• DOI: 10.1098/rspb.2006.3639

Clethrionomys glareolus
Despite numerous indices proposed to predict the evolution of mating systems, a unified measure of sexual selection has remained elusive. Three previous studies have compared indices of sexual selection under laboratory conditions. Here, we use a genetic study to compare the most widely used measures of sexual selection in natural populations. We explored the mating and reproductive successes of male and female bank voles,
and
and Bateman gradients) and selection coefficients (
′ and
′) to evaluate, for the first time, the genetic mating system of bank voles and compared these measures with alternative indices of sexual selection (index of monopolization and Morisita's index) across the OSRs. We found that all the sexual selection indices show significant positive intercorrelations for both males and females, suggesting that Bateman's principles are an accurate and a valid measure of the mating system. The Bateman gradient, in particular, provides information over and above that of other sexual selection indices. Male bank voles show a greater potential for sexual selection than females, and Bateman gradients indicate a polygynandrous mating system. Selection coefficients reveal strong selection gradients on male bank vole plasma testosterone level rather than body size.
across manipulated operational sex ratios (OSRs) by genotyping all adult and pup bank voles on 13 islands using six microsatellite loci. We used Bateman's principles (