Document Type

Article

Publication Date

2009

Publication Title

Journal of Evolutionary Biology

Volume

22

Issue

2

First Page

424

Last Page

429

DOI

10.1111/j.1420-9101.2008.01646.x

Keywords

compatible genes, directional selection, heterozygosity, lek paradox, mate choice, sexual selection, song sparrow

Abstract

The lek paradox asserts that strong directional selection via female choice should deplete additive genetic variation in fitness and consequently any benefit to females expressing the preference. Recently, we have provided a novel resolution to the paradox by showing that nonadditive genetic effects such as overdominance can be inherited from parent to offspring, and populations with females that express a mating preference for outbred males maintain higher genetic variation than populations with females that mate randomly. Here, we test our dynamic model using empirical data previously published from a small island population of song sparrows (Melospiza melodia). The model assumes that fitness and male trait expression display overdominance effects. The results demonstrate that female choice for outbred males mediated by directional selection on song repertoire size provides a heritable benefit to offspring through reduced inbreeding depression. Within the population, we estimate the heritability of the inbreeding coefficient to be 0.18 +/- 0.08 (SD). Furthermore, we show that mate choice for outbred males increases fitness-related genetic variation in the population by 12% and thereby reduces inbreeding depression by 1% per generation in typical years and upwards of 15% in severe years. Thus, mate choice may help to stave off population extinction in this and other small populations.

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