Direct and indirect estimates of dispersal support strong juvenile philopatry and male-biased dispersal in a freshwater turtle species (Emys orbicularis)

Dispersal has major impacts on population dynamics, population genetics and evolution, and also is critical for population management and conservation. Dispersal is frequently sex- and age-specific, but current knowledge is strongly taxonomically biased toward birds and mammals. Here, we provide estimates of dispersal in a threatened freshwater turtle species, the European pond turtle Emys orbicularis. Based on 15 years of capture-mark-recapture (CMR) monitoring and DNA samples from 194 individuals, we quantified both demographic and genetic dispersal between three sites separated by 1.5-3.5 km. We also investigated the effect of age and sex on dispersal.Direct (CMR) and indirect (genetic) approaches provided consistent results, showing that the studied sites are connected with a flow of about one to three dozen migrants per generation. Dispersal was both age- and sex-biased in this species, with frequent dispersal of adult males and a strong philopatry of juveniles (of both sexes) and adult females.The network of canals and marshes allow effective dispersal to occur among the three study sites despite the relatively large distance separating them (=3.5 km).The strong philopatry of juveniles contrasts with the frequently higher dispersal rate in young birds and mammals and shows the relevance of investigating dispersal in various taxonomic groups. Our results provide useful information for the conservation of European pond turtle populations.