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

Bedrock may dictate the distribution of the fire salamander in the southern border of its global range

Understanding the factors that determine the spatial distribution of species is crucial for conservation planning. In this short communication, we review previous distribution models of the fire salamander (Salamandra infraimmaculata) in northern Israel, produced by the group of the late Prof. Leon Blaustein, while suggesting a biologically-informed reinterpretation of their main predictions. We argue for the prime importance of bedrock, specifically hard limestone, because it is tightly associated with the availability of karstic formations that are key to adult survival throughout the summer. Furthermore, we suggest that the spatial distribution of limestone bedrock also determines large-scale inter-population connectivity, and may explain the observed genetic differentiation among populations, as well as the southernmost limit of the species’ global distribution.

Phenotypic plasticity and local adaptations to dissolved oxygen in larvae fire salamander (Salamandra infraimmaculata)

A key environmental factor that varies both spatially and temporally in surface waters is dissolved oxygen (DO). In stagnant ephemeral freshwater ponds, DO can fluctuate diurnally and seasonally, while the constant mixing of water in streams typically maintain DO levels close to saturation with only minor fluctuations. Larvae of the Near Eastern fire salamander (Salamandra infraimmaculata) develop in a range of waterbodies that vary in flow and permanence. To study inter-population variation in larval response to environmental change, we translocated larvae between stream and pond habitats and exposed larvae sampled from different habitat types to hypoxic and normoxic conditions in the laboratory. Larvae transferred from stream to pond retain gill size, while larvae transferred from pond to stream show a reduction in gill size. Larvae that were caged within their native habitat, either stream or pond, display a decrease in gill size similar to larvae transferred from pond to stream. When exposed to experimentally manipulated levels of DO in the laboratory larvae, respectively, increase and decrease gill size under hypoxic and normoxic conditions. Habitat-type origin had a significant effect on the degree of change in gill size with larvae from permanent streams demonstrating the lowest absolute variation in gill size. There was no interaction between DO level (hypoxic/normoxic) and the larvae habitat-type origin. These results suggest that S. infraimmaculata larvae are locally adapted to their aquatic breeding habitat through the plastic ability to respond to the prevailing respiratory conditions by rapidly decreasing or increasing gill size.