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

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.

SUBMITTER: Querejeta M

PROVIDER: S-EPMC6206195 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Evolutionary history of the endemic water shrew <i>Neomys anomalus</i>: Recurrent phylogeographic patterns in semi-aquatic mammals of the Iberian Peninsula.

Querejeta Marina M Castresana Jose J

Ecology and evolution 20180927 20

The Cabrera's water shrew (<i>Neomys anomalus</i>) 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 distributi ...[more]

PMID: 30397453

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Project description:Several species of the Gypsophila genus are endemic to the Iberian Peninsula, including gypsophytes of particular ecological, evolutionary and biochemical interest, and taxa that have undergone both sympatric and allopatric genetic differentiation. The niche shift among these taxa has been assessed using ecological niche modelling and ordination techniques, adopting a niche overlap approach to compare the similarity and equivalency of the ecological niches. We used the Maximum Entropy method to study the potential distribution of these taxa in different eras: the Last Glacial Maximum (LGM), the Mid Holocene and the current conditions. We present evidence of niche shift during the speciation of G. bermejoi, with a strong niche overlap between the parental taxa (G. struthium subsp. struthium and G. tomentosa), yet both overlap much more weakly with the hybrid species. This phenomenon may be explained by genetic and epigenetic interactions, and it has been described in other species. We also studied the sister subspecies G. struthium subsp. struthium and G. struthium subsp. hispanica, with mostly allopatric distributions and with the Iberian System mountain range acting as a geographical barrier. The Iberian System and other mountain ranges may have favored differences in the climatic conditions on either side of the mountain range, which is consistent with an incipient process of bioclimatic ecological speciation. These results seem to indicate that niche shift can occur over very different timespans. In the case of G. bermejoi, speciation may have produced significant niche shifting in one or two generations due to its alloploid nature. By contrast, G. struthium subsp. struthium and G. struthium subsp. hispanica seem to have undergone a more gradual process of allopatric genetic differentiation driven by bioclimatic factors. Both these processes are relatively recent and they will have been strongly influenced by the climate change at the end of LGM.

Project description:BACKGROUND:Animal toxins can have medical and therapeutic applications. Principally, toxins produced by insects, arachnids, snakes and frogs have been characterized. Venomous mammals are rare, and their venoms have not been comprehensively investigated. Among shrews, only the venom of Blarina brevicauda has been analysed so far, and blarina toxin has been proven to be its main toxic component. It is assumed that Neomys fodiens employs its venom to hunt larger prey. However, the toxic profile, properties and mode of action of its venom are largely unknown. Therefore, we analysed the cardio-, myo- and neurotropic properties of N. fodiens venom and saliva of non-venomous Sorex araneus (control tests) in vitro in physiological bioassays carried out on two model organisms: beetles and frogs. For the first time, we fractionated N. fodiens venom and S. araneus saliva by performing chromatographic separation. Next, the properties of selected compounds were analysed in cardiotropic bioassays in the Tenebrio molitor heart. RESULTS:The venom of N. fodiens caused a high decrease in the conduction velocity of the frog sciatic nerve, as well as a significant decrease in the force of frog calf muscle contraction. We also recorded a significant decrease in the frog heart contractile activity. Most of the selected compounds from N. fodiens venom displayed a positive chronotropic effect on the beetle heart. However, one fraction caused a strong decrease in the T. molitor heart contractile activity coupled with a reversible cardiac arrest. We did not observe any responses of the insect heart and frog organs to the saliva of S. araneus. Preliminary mass spectrometry analysis revealed that calmodulin-like protein, thymosin ?-10, hyaluronidase, lysozyme C and phospholipase A2 are present in the venom of N. fodiens, whereas thymosin ?4, lysozyme C and ?-defensin are present in S. araneus saliva. CONCLUSION:Our results showed that N. fodiens venom has stronger paralytic properties and lower cardioinhibitory activity. Therefore, it is highly probable that N. fodiens might use its venom as a prey immobilizing agent. We also confirmed that S. araneus is not a venomous mammal because its saliva did not exhibit any toxic effects.

Dataset Information

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

Publications

Evolutionary history of the endemic water shrew <i>Neomys anomalus</i>: Recurrent phylogeographic patterns in semi-aquatic mammals of the Iberian Peninsula.

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