Using relatedness networks to infer contemporary dispersal: Application to the endangered mammal Galemys pyrenaicus

Abstract

Information about the degree of contemporary dispersal is important when trying to understand how populations interchange individuals and identify the specific barriers that prevent these movements. In the case of endangered species, this can represent crucial information when designing appropriate conservation strategies. Here we analyse relatedness between individuals from different localities and use these data to infer whether dispersal occurred in recent generations. We applied this approach to the Pyrenean desman (Galemys pyrenaicus), a semiaquatic and endangered species endemic to the Iberian Peninsula. We studied this species in four primary rivers in the Iberian Range, where two ancient mitochondrial lineages are separated by a strict contact zone, suggesting the existence of complex dispersal patterns. Using next-generation sequencing, we obtained 912 SNPs from each specimen and estimated relatedness values between them. While relatedness networks were dense within each river, we found surprisingly few relationships between individuals from different rivers despite their close proximity in some cases, indicating much lower dispersal between rivers compared to dispersal within a single river. In agreement with this result, the degree of inbreeding was exceedingly high in most individuals. These data show that relatedness information can be crucial to understand the contemporary dispersal patterns and conservation status of specific populations of endangered species.

Quantitative analysis of connectivity in populations of a semi‐aquatic mammal using kinship categories and network assortativity

“…Additionally, mean relatedness for female dyads from the same locality was significantly higher than for males, pointing to a higher degree of female philopatry. In a previous study of the Pyrenean desman in the Iberian Range (see Figure a for the location of this population), similar relatedness values were found for female and male dyads (Escoda et al, ); these different results may be explained because overall relatedness within the same locality and inbreeding were much higher in the Iberian Range, probably due to more serious dispersal problems than in the area studied here.…”

“…However, these approaches, based on the monitoring of individuals during usually brief time periods, allow small movements to be easily recorded while large‐distance movements, if present, are more difficult to detect, so a complete overview of the dispersal patterns of this species is still lacking. The strategy introduced by Escoda, González‐Esteban, Gómez, and Castresana (), based on the analysis of the relatedness networks of individuals, allowed the study of effective contemporary dispersal over a larger area and through several generations. These authors found low levels of inter‐river dispersal compared to intra‐river dispersal, demonstrating that desmans do not frequently move between different river basins.…”

Genotyping‐by‐sequencing for estimating relatedness in nonmodel organisms: Avoiding the trap of precise bias

“…The closest study found to ours was by Escoda et al. (), who assessed a genotyping‐by‐sequencing data set for estimating relatedness based on perfectly genotyped simulations. Similar to our study, they found all estimators had >0.97 correlation to true relatedness.…”

Comparison of diet and prey selectivity of the Pyrenean desman and the Eurasian water shrew using next-generation sequencing methods

“…The alarming decline of G. pyrenaicus populations over the recent decades across its whole range Gisbert and García-Perea, 2014) has encouraged local, national and European conservation initiatives (e.g., in France: Life+ Desman, 2013;Némoz et al, 2011). Yet, in spite of an increasing number of studies focusing on this species (e.g., Aymerich and Gosàlbez, 2015;Biffi et al, 2016;Charbonnel et al, 2016;Escoda et al, 2017), the respective influence of prey, competitors and predators on its survival and distribution still remains to be explored.…”