Abstract
The Cabrera's water shrew (Neomys anomalus) is a small semi‐aquatic mammal whose taxonomic status was recently elevated from subspecies to species; as a consequence of this change, this species is now endemic to the Iberian Peninsula. In this study, we looked at its evolutionary history by combining phylogeography, the spatial distribution of genetic diversity, and species distribution modeling. To perform these analyses, we used noninvasive samples collected across the species distribution range and sequenced partial mitochondrial cytochrome b and D‐loop genes. Maximum‐likelihood and Bayesian phylogenetic trees derived from these sequences indicated that N. anomalus is divided into two main phylogroups that correlate strongly with geography, with two contact zones between the groups that showed limited spatial mixing between them. River basins were responsible for only a small percentage of the structure of the genetic diversity of this species despite its riparian habitat. The nucleotide diversity variation map showed the highest genetic diversity to be in the north of the Iberian Peninsula. Finally, species distribution modeling allowed the inference of an optimal area during the Last Interglacial in the north of the Iberian Peninsula, and multiple glacial refugia during the Last Glacial Maximum. The phylogeographic pattern of N. anomalus is strikingly similar to that of another semi‐aquatic Iberian mammal, the Pyrenean desman (Galemys pyrenaicus), revealing how Pleistocene glaciations could have had equivalent effects on species of similar ecology and distribution. This phylogeographic structure is consistent with N. anomalus having been isolated for long periods in multiple glacial refugia within the Iberian Peninsula, in agreement with the “refugia‐within‐refugia” hypothesis, and further supporting its status as a distinct species.
Highlights
The Iberian Peninsula was one of the most important glacial refugia in Europe during the Pleistocene (Hewitt, 1999, 2000)
We aim to study the evolutionary history of the Cabrera’s water shrew by addressing the following questions: (a) Is there some kind of genetic structure in this Iberian endemic species? (b) If so, did river basins play a role in shaping this genetic structure? (c) Which were the potential refugia during past glacial cycles? and (d) Is there a common phylogeographic pattern with the distributed Pyrenean desman? To achieve these aims, we combined a phylogeographic and genetic diversity approach with species distribution modeling, as the combination of these techniques may provide a better picture of evolutionary scenarios (Graham, Ron, Santos, Schneider, & Moritz, 2004)
After the split of the N. anomalus and N. milleri lineages around 0.40 Myr ago (Igea et al, 2015), we can envisage a scenario in which N. anomalus became isolated from its sister lineage in the north and northwest of the Iberian Peninsula, as suggested by the optimal areas predicted for the Last Interglacial projection (Figure 3a)
Summary
The Iberian Peninsula was one of the most important glacial refugia in Europe during the Pleistocene (Hewitt, 1999, 2000). Pleistocene glaciations could have affected its distribution and genetic structure by generating isolated populations in glacial refugia within the Iberian Peninsula (Gomez & Lunt, 2007) In this sense, it would be 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, 1983), which was found to have a strong phylogeographic structure (Escoda, González- Esteban, Gómez, & Castresana, 2017; Igea et al, 2013; Querejeta et al, 2016, 2017). We aim to study the evolutionary history of the Cabrera’s water shrew by addressing the following questions: (a) Is there some kind of genetic structure in this Iberian endemic species? (b) If so, did river basins play a role in shaping this genetic structure? (c) Which were the potential refugia during past glacial cycles? and (d) Is there a common phylogeographic pattern with the distributed Pyrenean desman? To achieve these aims, we combined a phylogeographic and genetic diversity approach with species distribution modeling, as the combination of these techniques may provide a better picture of evolutionary scenarios (Graham, Ron, Santos, Schneider, & Moritz, 2004)
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