Dispersal is a key factor in shaping the genetic structure and population dynamics of species; thus, its understanding is a fundamental requirement in formulating appropriate conservation strategies. Higher rates of dispersal in one sex than the other are widespread in vertebrate species and often attributed to the genetic advantages of reduced inbreeding. This is well documented in birds and mammals but has rarely been reported in other vertebrate taxa. Here, we use 12 microsatellite loci to detect signatures of sex-biased dispersal in the Hot Spring Snake, Thermophis baileyi. This colubrid species is endemic to the Tibetan Plateau and strongly linked to habitats with hot springs. It is one of the world's highest altitude snake species, reaching up to 5000 m above sea level, and it is considered as endangered because of its limited range and the reduction of its natural habitat. Former studies have revealed a restricted gene flow and a high degree of population structure in this species. Here, we find a significantly higher variance of the assignment index and a significant heterozygote deficit in males. Accordingly, first-generation dispersers are identified only in males using frequency-based assignments with prior population information. Spatial autocorrelation analysis suggests a higher level of relatedness among females at smaller geographic scales compared with males. Mate-searching activities and female natal homing are suggested as major traits explaining greater female philopatry in T. baileyi. Our findings are important in the scope of conservation and management planning for the Hot Spring Snake in the future.

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