Abstracts (first author)
Disentangling the social, parental and genetic influences on natal dispersal in great tits
Natal dispersal is a key process underpinning the structure and dynamics of populations. Individual variation in dispersal behaviour is substantial, but we know very little about the causes of individual variation in dispersal, and the extent to which this variation is influenced by social processes. Here, we integrate longitudinal data collected over five decades from a wild great tit (Parus major) population with two cross-fostering experiments to disentangle the influence of social processes, parental effects and genetics on dispersal behaviour. We show first that parental dispersal phenotype, whether they are themselves locally hatched or immigrants, has scale-independent effects on dispersal by offspring. Birds with immigrant parents dispersed further within patches and were more likely to disperse outside patches. Using an index of the composition of early social environments, with reference to the immigrant and locally hatched status of neighbours, we then show that dispersal is independent of the local social environment in which birds are raised. We used two large-scale cross-fostering experiments to demonstrate that parental effects on dispersal are primarily intrinsic to offspring, and therefore independent of parental behaviour. Finally, we show that parental dispersal phenotypes show similar fledging success but differing rates of local recruitment of offspring, implying that dispersal phenotypes will be genetically structured across landscapes. Our findings suggest that understanding the underpinning genetics of dispersal will be important for understanding the behaviour of populations in fragmented landscapes. Non-random dispersal of particular types of individuals suggests scope for the emergence of fine-scale population structure and has important consequences for interpretations of selection studies and dispersal theory.