Islands within an island: Population genetic structure of the endemic Sardinian newt,Euproctus platycephalus

Abstract

The identification of historic and contemporary barriers to dispersal is central to the conservation of endangered amphibians, but may be hindered by their complex life history and elusive nature. The complementary information generated by mitochondrial (mtDNA) and microsatellite markers generates a valuable tool in elucidating population structure and the impact of habitat fragmentation. We applied this approach to the study of an endangered montane newt, Euproctus platycephalus. Endemic to the Mediterranean island of Sardinia, it is threatened by anthropogenic activity, disease, and climate change. We have demonstrated a clear hierarchy of structure across genetically divergent and spatially distinct subpopulations. Divergence between three main mountain regions dominated genetic partitioning with both markers. Mitochondrial phylogeography revealed a deep division dating to ca. 1 million years ago (Mya), isolating the northern region, and further differentiation between the central and southern regions ca. 0.5 Mya, suggesting an association with Pleistocene severe glacial oscillations. Our findings are consistent with a model of southward range expansion during glacial periods, with postglacial range retraction to montane habitat and subsequent genetic isolation. Microsatellite markers revealed further strong population structure, demonstrating significant divergence within the central region, and partial differentiation within the south. The northern population showed reduced genetic diversity. Discordance between mitochondrial and microsatellite markers at this scale indicated a further complexity of population structure, in keeping with male‐biased dispersal and female philopatry. Our study underscores the need to elucidate cryptic population structure in the ecology and conservation strategies for endangered island‐restricted amphibians, especially in the context of disease and climate change.

Jailed in the mountains: Genetic diversity and structure of an endemic newt species across the Pyrenees

“…arnoldi (weighted average Ar = 3.398 and H E = 0.441)[ 26 ]. These values are also consistent compared to other mountain brook newts, such as Euproctus platycephalus on Sardinia (weighted average Ar = 2.376 and H E = 0.6 [ 65 ]) and are within the typical range of other urodeles and temperate amphibians (0.4–0.6; [ 66 ] and references therein). In accordance with other Pyrenean species, such as the Ericaceae Rhododendron ferrugineum [ 8 ], we found that genetic diversity of C .…”

“…In some species there is no correlation found between the altitudinal gradient and the population differentiation or genetic diversity (e.g. Rana chensinensis [ 69 ]; Euproctus platycephalus [ 65 ]). In other species, the genetic diversity is negatively correlated with altitude (e.g.…”

“…Another ecologically similar mountain newt, Euproctus platycephalus endemic to the island Sardinia (Italy) presents a maximum level of pairwise population differentiation considerably lower than C . asper (0.297 among two localities separated by 168 km; [ 65 ]). Lower F ST values were also found for the long-toed salamander Ambystoma macrodactylum ( F ST of 0.27 [ 19 ]).…”

Current State of Conservation Physiology for Amphibians: Major Research Topics and Physiological Parameters

“…Population decline and extinction threaten amphibians due to habitat loss, climate change, pollution, and disease [77]. Conservation genetics focuses on genetic diversity, population structure, and gene flow in amphibians [78], while population ecology studies statistical processes regulating populations, such as birth rates, death rates, and interpopulation movement [79]. Research in these areas also involves genetic resource management, hormone induction in breeding systems, and suitable habitat models (Figure 4b).…”

Landscape genetics reveal broad and fine‐scale population structure due to landscape features and climate history in the northern leopard frog (Rana pipiens) in North Dakota

“…As exothermic vertebrates dependent on both terrestrial and aquatic environments, amphibians are particularly susceptible to changes in the environment (Araújo et al, 2008;Mushet, Euliss, Chen, & Stockwell, 2013;Zeisset & Beebee, 2008). The signatures of past climate change are present in the genetic structure of many amphibian species (Ball et al, 2017;Lee-Yaw, Irwin, & Green, 2008;Wielstra et al, 2013;Zeisset & Beebee, 2008;Zhou et al, 2017), and understanding how ancient climates affected current population structure can provide key insights into predicting how future climate change might impact amphibian populations.…”