Fine-scale genetic structure in a salamander with two reproductive modes: Does reproductive mode affect dispersal?

Abstract

Reproduction is intimately linked with dispersal, but the effects of changes in reproductive strategies on dispersal have received little attention. Such changes have occurred in many taxonomic groups, resulting in profound alterations in life-history. In amphibians, many species shifted from oviparous/larviparous aquatic reproduction (deposition of eggs or pre-metamorphic larvae in water) to pueriparous terrestrial reproduction (parturition of terrestrial juveniles). The latter provides greater independence from water by skipping the aquatic larval stage; however, the eco-evolutionary implications of this evolutionary step have been underexplored, largely because reproductive modes rarely vary at the intraspecific level, preventing meaningful comparisons. We studied the effects of a transition to pueriparity on dispersal and fine-scale genetic structure in the fire salamander (Salamandra salamandra), a species exhibiting two co-occurring reproductive modes: larviparity and pueriparity. We performed genetic analyses (parentage and genetic spatial autocorrelation) using 11 microsatellite loci to compare dispersal and fine-scale genetic structure in three larviparous and three pueriparous populations (354 individuals in total). We did not find significant differences between reproductive modes, but in some larviparous populations movement patterns may be influenced by site-specific features (type of water bodies), possibly due to passive water-borne dispersal of larvae along streams. Additionally, females (especially larviparous ones) appeared to be more philopatric, while males showed greater variation in dispersal distances. This study also points to future avenues of research to better understand the eco-evolutionary implications of changes in reproductive modes in amphibians.