Data from: Comparative landscape genetics reveals the evolution of viviparity reduces genetic connectivity in fire salamanders

Evolutionary changes in reproductive mode may affect co-evolving traits,
such as dispersal, though this subject remains largely underexplored. The
shift from aquatic oviparous or larviparous reproduction to terrestrial
viviparous reproduction in some amphibians entails skipping the aquatic
larval stage and, thus, greater independence from water. Accordingly,
amphibians exhibiting terrestrial viviparous reproduction may potentially
disperse across a wider variety of sub-optimal habitats and increase
population connectivity in fragmented landscapes compared to
aquatic-breeding species. We investigated this hypothesis in the fire
salamander (Salamandra salamandra), which exhibits both aquatic-
(larviparity) and terrestrial-breeding (viviparity) strategies. We
genotyped 426 larviparous and 360 viviparous adult salamanders for 13
microsatellite loci and sequenced a mitochondrial marker for 133
larviparous and 119 viviparous individuals to compare population
connectivity and landscape resistance to gene flow within a landscape
genetics framework. Contrary to our predictions, viviparous populations
exhibited greater differentiation and reduced genetic connectivity
compared to larviparous ones. Landscape genetic analyses indicate
viviparity may be partially responsible for this pattern, as water courses
comprised a significant barrier only in viviparous salamanders, likely due
to their fully terrestrial life cycle. Agricultural areas and, to a lesser
extent, topography also decreased genetic connectivity in both larviparous
and viviparous populations. This study is one of very few to explicitly
demonstrate the evolution of a derived reproductive mode affects patterns
of genetic connectivity. Our findings open avenues for future research to
better understand the eco-evolutionary implications underlying the
emergence of terrestrial reproduction in amphibians.