TitleThe Bateman gradient and the cause of sexual selection in a sex-role-reversed pipefish
Publication TypeJournal Article
Year of Publication2000
AuthorsJones, AG, Rosenqvist, G, Berglund, A, Arnold, SJ, Avise, JC
JournalProceedings of the Royal Society B-Biological Sciences
Volume267
Pagination677-680
Keywordsmating success microsatellites sexual selection Syngnathus typhle reproductive success potential reproductive rates mating systems success females ratios males syngnathidae competition investment variance
Abstract

As a conspicuous evolutionary mechanism, sexual selection has received much attention from theorists and empiricists. Although the importance of the mating system to sexual selection has long been appreciated, the precise relationship remains obscure. In a classic experimental study based on parentage assessment using visible genetic markers, more than 50 years ago A. J. Bateman proposed that the cause of sexual selection in Drosophila is 'the stronger correlation, in males (relative to females), between number of mates and fertility (number of progeny)'. Half a century later, molecular genetic techniques for assigning parentage now permit mirror-image experimental tests of the 'Bateman gradient' using sex-role-reversed species. Here we show that, in the male-pregnant pipefish Syngnathus typhie, females exhibit a stronger positive association between number of mates and fertility than do males and that this relationship responds in the predicted fashion to changes in the adult sex ratio. These findings give empirical support to the idea that the relationship between mating success and number of progeny, as characterized by the Bateman gradient, is a central feature of the genetic mating system affecting the strength and direction of sexual selection.