The role of landscape and history on the genetic structure of peripheral populations of the Near Eastern fire salamander, Salamandra infraimmaculata, in Northern Israel

Genetic studies on core versus peripheral populations have yielded many patterns. This diversity in genetic patterns may reflect diversity in the meaning of peripheral populations as defined by geography, gene flow patterns, historical effects, and ecological conditions. Populations at the lower latitude periphery of a species' range are of particular concern because they may be at increased risk for extinction due to global climate change. In this work we aim to understand the impact of landscape and ecological factors on different geographical types of peripheral populations with respect to levels of genetic diversity and patterns of local population differentiation. We examined three geographical types of peripheral populations of the endangered salamander, Salamandra infraimmaculata, in Northern Israel, in the southernmost periphery of the genus Salamandra, by analyzing the variability in 15 microsatellite loci from 32 sites. Our results showed that: (1) genetic diversity decreases towards the geographical periphery of the species' range; (2) genetic diversity in geographically disjunct peripheral areas is low compared to the core or peripheral populations that are contiguous to the core and most likely affected by a founder effect; (3) ecologically marginal conditions enhance population subdivision. The patterns we found lead to the conclusion that genetic diversity is influenced by a combination of geographical, historical, and ecological factors. These complex patterns should be addressed when prioritizing areas for conservation.Peer reviewe

Predicting the impact of climate change: genomic measures of local adaptation in the Near Eastern Fire Salamander (Salamandra infraimmaculata)

The Near Eastern fire salamander (Salamandra infraimmaculata) is an endangered species in Israel and the Israeli populations occupy the southernmost, and most xeric habitats of the Salamandra genus worldwide. Due to its geographic distribution, restricted to a typical Mediterranean region, S. infraimmaculata is potentially vulnerable to strong environmental changes, such as an increase in temperature or a decrease in the water level. One main problem is that rates of climate change often exceed the rate at which many species can shift their range to find new suitable conditions, and therefore species survival will depend on phenotypic plasticity or adaptive capacity. Although species persistence and local adaptation are directly related to genetic diversity, most of the studies about climate change usually ignore genetic effects on species persistence. In our study we use a Climate Change Vulnerability Assessment to identify the most vulnerable populations of S. infraimmaculata in Israel, to prioritize conservation efforts and resources. We use population specific information on exposure, sensitivity and adaptability from 18 populations of S. infraimmaculata, incorporating estimates of adaptive potential and local adaptation. Since temperature is a parameter that affects almost every aspect of development and metabolism, we choose to estimate exposure to temperature for both larvae (data collected in the field during the whole reproductive period, November-May) and adults (data obtained from Movebank). We assess the physiological sensitivity by using the thermal development optimum (growth curves), critical thermal maximum (CTmax) and acclimation capacity values, that we experimentally obtained. To estimate the potential for each population to tolerate or adapt to climate change, we estimate the demographic adaptive capacity as number of populations and local abundance. We measure the genetic adaptive capacity using allelic richness (estimated from microsatellite data) and we are testing the different populations for local adaptation. Mapping RNA sequencing reads against the available transcriptomes for S. infraimmaculata, we look for SNPs in genes that can be important for local adaptation processes, such as genes involved in oxygen response, growth or development, energy metabolism, etc. We found about 2000 SNPs for one geographic region, and the analyses for the other regions are in progress. The identification of outlier SNPs in some populations can reveal a signal of local adaptation and shed light on the relationships of the genes involved in the adaptation process to specific environmental features. Combining exhaustive information about ecology and genetics for each population will be integral for guiding local conservation management in the most efficient way.peerReviewe