Male harassment, female movements, and genetic diversity in a fragmented metapopulation

Interactions with males often alter the short-term behaviors of reproductive females. Yet, the influence of different internal and external factors, such as sexual conflict, on animal movement and patch dynamics is not well understood. We studied associations between courtship, movements of reproductive females, and genetic diversity in a small, fragmented network of Euphydras editha taylori (Taylor's checkerspot butterfly). In the absence of courtship, female movements (step lengths) were restricted (< 2 m) and tortuous, and females never departed reproductive habitat. However, when courted by males, step lengths increased markedly and movements were straighter (less tortuous). Female habitat departures were associated with interactions between patch identity and courtship. All tracked females remained in reproductive habitat in the smallest patch, whereas 32% of females departed the larger patch (over forest) while eluding courting males. Genotyping (simple sequence repeats - SSRs) suggested low levels of genetic differentiation (F-st similar to 0.02; Analysis of molecular variance p = 0.02) with inter-patch distances of <= 0.3 km. Tests for a recent genetic bottleneck were negative, but heterozygous deficient deviations from Hardy-Weinberg equilibrium expectations may indicate a developing bottleneck. Patch-specific female movement behaviors and the distribution of SSR alleles across the network suggest the possibility of a predominantly unidirectional transfer of reproducing females from the largest to smaller patches, with the smaller patches mostly closed to emigration. Our study suggests short-lived intraspecific interactions may influence dispersal in unanticipated ways and that understanding these interactions will provide a more holistic view of habitat fragmentation and network functioning.