RESUMEN
This study used eight polymorphic microsatellite loci to examine the relative effects of social organization and dispersal on fine-scale genetic structure in an obligately cooperative breeding bird, the white-winged chough (Corcorax melanorhamphos). Using both individual-level and population-level analyses, it was found that the majority of chough groups consisted of close relatives and there was significant differentiation among groups (F(ST) = 0.124). However, spatial autocorrelation analysis revealed strong spatial genetic structure among groups up to 2 km apart, indicating above average relatedness among neighbours. Multiple analyses showed a unique lack of sex-biased dispersal. As such, choughs may offer a model species for the study of the evolution of sex-biased dispersal in cooperatively breeding birds. These findings suggest that genetic structure in white-winged choughs reflects the interplay between social barriers to dispersal resulting in large family groups that can remain stable over long periods of times, and short dispersal distances which lead to above average relatedness among neighbouring groups.
Asunto(s)
Passeriformes/genética , Conducta Social , África , Envejecimiento , Animales , Evolución Biológica , Cruzamiento , ADN/sangre , ADN/genética , ADN/aislamiento & purificación , Ecosistema , Europa (Continente) , Femenino , Variación Genética , Masculino , Passeriformes/anatomía & histología , Polimorfismo Genético , Estaciones del Año , Caracteres Sexuales , Alas de Animales/anatomía & histologíaRESUMEN
Dispersal influences evolution, demography, and social characteristics but is generally difficult to study. Here we combine long-term demographic data from an intensively studied population of superb fairy-wrens (Malurus cyaneus) and multivariate spatial autocorrelation analyses of microsatellite genotypes to describe dispersal behavior in this species. The demographic data revealed: (1) sex-biased dispersal: almost all individuals that dispersed into the study area over an eight-year period were female (93%; n = 153); (2) high rates of extragroup infidelity (66% of offspring), which also facilitated local gene dispersal; and (3) skewed lifetime reproductive success in both males and females. These data led to three expectations concerning the patterns of fine-scale genetic structure: (1) little or no spatial genetic autocorrelation among females, (2) positive spatial genetic autocorrelation among males, and (3) a heterogeneous genetic landscape. Global autocorrelation analysis of the genotypes present in the study population confirmed the first two expectations. A novel two-dimensional local autocorrelation analysis confirmed the third and provided new insight into the patterns of genetic structure across the two-dimensional landscape. We highlight the potential of autocorrelation analysis to infer evolutionary processes but also emphasize that genetic patterns in space cannot be fully understood without an appropriate and intensive sampling regime and detailed knowledge of the individuals genotyped.