Pronounced within-individual plasticity in sperm morphometry across social environments

Simone Immler*, Sarah R. Pryke, Tim R. Birkhead, Simon C. Griffith

*Corresponding author for this work

Research output: Contribution to journalArticle

72 Citations (Scopus)

Abstract

Sperm morphometry (i.e., size and shape) and function are important determinants of male reproductive success and are thought to be under stabilizing selection. However, recent studies suggest that sperm morphometry can be a phenotypically plastic trait, which can be adjusted to varying conditions. We tested whether different behavioral strategies in aggression between aggressive red and nonaggressive black males of the color polymorphic Gouldian finch (Erythrura gouldiae) can influence sperm morphometry. We show pronounced within-individual phenotypic plasticity in sperm morphometry of male Gouldian finches in three different social environments. Both red and black males placed in intermediate to high competitive environments (high frequency of red males) increased the relative length of their sperm midpiece. By contrast, red males placed in low to intermediate competitive environments (higher frequency of black males) increased the length of the sperm flagellum. Significant changes in stress and sex steroid hormone levels (in response to the competitive environment) appear to influence sperm traits in red but not in black males, suggesting that changes in hormonal levels are not solely responsible for the observed changes in sperm morphometry. These findings imply that males can adjust sperm morphometry across social environments.

Original languageEnglish
Pages (from-to)1634-1643
Number of pages10
JournalEvolution
Volume64
Issue number6
DOIs
Publication statusPublished - Jun 2010

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