Parity-specific differences in spatial genetics and dispersal in the common lizard.

Dispersal is a key demographic parameter that plays an important role in determining spatial population dynamic and genetic structure. Linking differences in dispersal patterns to key life-history traits is often confounded by inconsistent environmental pressures experienced by different populations. To explore the link between dispersal and life history, we focus on a site where oviparous and viviparous lineages of the common lizard (Zootoca vivipara) are found adjacent to each other. We take advantage of this shared environment to investigate parity-specific dispersal patterns using high resolution, individual-level spatial genetic autocorrelation and population genomic approaches (11,726 SNPs; 293 oviparous and 310 viviparous individuals). We found isolation-by-distance patterns to be present in both the oviparous and viviparous populations. Density was 2.5 times higher in the viviparous population than the oviparous one, though heterozygosity and genetic diversity measures were similar in the two populations. We found marked differences in the extent of genetic neighbourhoods between the lineages, with the viviparous population showing both dispersal (σ) and spatial genetic autocorrelation (Moran's I) at two-fold greater geographic distances than the oviparous population. We found clear evidence of male-biased dispersal from genetic estimates in the viviparous population. In the oviparous population, evidence of male-biased dispersal is weak or absent. These differences are likely to be closely linked to specific requirements of the alternative reproductive strategies and may be the demographic consequences of mother-offspring interactions. Fine-scale geographic and individual-level measures are key to understanding parity mode differences at microevolutionary scales and to better identifying their ecological and evolutionary impacts.