Postglacial dispersal patterns and mitochondrial genetic structure of the Pyrenean desman (Galemys pyrenaicus) in the northwestern region of the Iberian Peninsula

Abstract

The genetic structure of small semiaquatic animals may be influenced by dispersal across both rivers and land. The relative importance of these two modes of dispersal may vary across different species and with ecological conditions and evolutionary periods. The Pyrenean desman (Galemys pyrenaicus) is an endemic mammal of the Iberian Peninsula with a strong phylogeographic structure and semiaquatic habits, thus making it an ideal model to study the effects of river and overland dispersal on its genetic structure. Thanks to different types of noninvasive samples, we obtained an extensive sampling of the Pyrenean desman from the northwestern region of the Iberian Peninsula and sequenced two mitochondrial DNA fragments. We then analyzed, using an isolation-by-distance approach, the correlation between phylogenetic distances and geographical distances measured along both river networks and land to infer the relative importance of river and overland dispersal. We found that the correlations in the whole area and in a large basin were consistent with an effect of overland dispersal, which may be due to the postglacial colonization of new territories using terrestrial corridors and, possibly, a more extensive fluvial network that may have been present during the Holocene. However, in a small basin, likely to be less influenced by the impact of ancient postglacial dispersal, the correlations suggested significant overall effects of both overland and river dispersal, as expected for a semiaquatic mammal.Therefore, different scales and geographical regions reflect different aspects of the evolutionary history and ecology of this semiaquatic species using this isolation-bydistance method. The results we obtained may have crucial implications for the conservation of the Pyrenean desman because they reinforce the importance of interbasin dispersal for this species in the studied area and the need to protect the whole riverine ecosystem, including rivers, upland streams and terrestrial corridors between basins. K E Y W O R D Sdispersal, Galemys pyrenaicus, genetic diversity, Iberian Peninsula, isolation-by-distance, mitochondrial DNA

Evolutionary history of the endemic water shrew Neomys anomalus: Recurrent phylogeographic patterns in semi‐aquatic mammals of the Iberian Peninsula

“…The species distribution models for the Last Glacial Maximum are consistent in showing the western area of the Iberian Peninsula as an optimal region for N. anomalus . This is largely coincident with the major refugium predicted for G. pyrenaicus (Igea et al., ; Querejeta et al., ). There is another optimal area situated in the Central System and a minor one in the Central Plateau.…”

“…This indicates that glacial refugia do not always lead to areas of current high genetic diversity. This could be due to complex scenarios involving local extinctions, recolonizations, and expansions from refugia to other areas during the Holocene (Godinho, Crespo, & Ferrand, ; Querejeta et al., ). In addition, the possibility of mitonuclear discordance makes that nuclear data may be necessary to reveal further details on the glacial history of the species (see below).…”

“…Despite the interest of this endemic water shrew, no previous studies have been carried out on the evolutionary history of N. anomalus . Being a semi‐aquatic species, it is more challenging to study, as factors such as the configuration of the river networks may play an important role in shaping its genetic structure (Byrne, Quintana, Bolkovic, Cassini, & Túnez, ; Igea et al., ; Querejeta, Fernández‐González, Romero, & Castresana, ; Vignieri, ). Additionally, Pleistocene glaciations could have affected its distribution and genetic structure by generating isolated populations in glacial refugia within the Iberian Peninsula (Gomez & Lunt, ).…”

“…Additionally, Pleistocene glaciations could have affected its distribution and genetic structure by generating isolated populations in glacial refugia within the Iberian Peninsula (Gomez & Lunt, ). In this sense, it would be particularly interesting to compare the genetic structure of N. anomalus with that of the Pyrenean desman ( Galemys pyrenaicus ), another semi‐aquatic mammal endemic to the Iberian Peninsula (Palmeirim & Hoffmann, ), which was found to have a strong phylogeographic structure (Escoda, González‐Esteban, Gómez, & Castresana, ; Igea et al., ; Querejeta et al., , ). As both species have a similar distribution and habitat, comparing their phylogeographic patterns could provide new insights into the biogeographical forces behind the origin and distribution of the Iberian fauna.…”

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

“…To estimate dispersal distances, we first calculated the matrix of distances between all pairs of individuals as the shortest distance along the course of the river, as previously done (Querejeta et al, ). First, a shapefile of the river network in the studied area was obtained from the web page of the river authority (Confederación Hidrográfica del Duero; http://www.chduero.es).…”