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The Near Eastern fire salamander, Salamandra infraimmaculata, is considered an endangered species in Israel and is near-threatened regionally. For 25 years, our laboratory has sought ethical sampling methods to protect individuals and populations of Salamandra. To “mark” individuals for estimating dispersal and population size, we use non-invasive individual-specific markings from photographs of larvae and adults. We demonstrated through mesocosm experiments (which are less mortality-driven than in nature) that exotic Gambusia affinis have extreme negative mortality effects on Salamandra larvae. From a compassionate conservation aspect, G. affinis should not be killed and placed in habitats where amphibians are not in danger and mosquitoes can be controlled. We identified breeding-site characteristics demonstrating that permanent breeding sites support larger adult populations than temporary breeding sites. For population genetics studies, we take minimal sized tail tips from adults (which have no adverse effects) for microsatellite data. For gene expression studies, rather than sacrifice entire bodies, we demonstrated that by taking only small larval tail tips, we could follow gene expression. We additionally demonstrated that tail tip removal does not affect survival, time to or size at metamorphosis. We documented high road kill rates at a specific breeding site. To prevent potential disease spread, we sterilize boots and sampling gear. We use results for implementing or recommending conservation of individuals and populations – e.g., identifying: movement corridors for breeding site dispersal; roadkill hotspots for under-road tunnels; suitable habitat for pool construction for more effective conservation; utilizing population genetics for recommending management units; information on demography and genetic diversity to identify hotspots for conservation; removal of Gambusia for amphibian protection.

The size structure of a larval population facilitates interaction asymmetries that, in turn, influence the dynamics of size-structure. In species that exhibit conspicuous aggressive interactions, the competitive effects of the smaller individuals may be overlooked. We manipulated initial size differences between two larval cohorts and young-cohort density of Salamandra infraimmaculata in mesocosms to determine: (1) whether young individuals function primarily as prey or as competitors of older and larger individuals; (2) the resulting dynamics of size variation; and (3) recruitment to the postmetamorph population. Intercohort size differences generally remained constant over time at low young-cohort densities, but reduced over time at high densities due to retardation of the old-cohort growth rate. This suggests a competitive advantage to the young cohort that outweighs the interference advantage of older cohorts previously documented in this species. The increase in mortality from desiccation due to high young-cohort density was an order of magnitude greater in the old cohort than in the young-cohort, further indicating size-dependent vulnerability to competition. However, the conditions least favorable to most of the old-cohort larvae (large size difference and high young-cohort density) promoted cannibalism. Among cannibals, mortality and time to metamorphosis decreased and sizes at metamorphosis increased substantially. Thus, a balance between the competitive advantage to young cohorts, and the interference and cannibalism advantage to old cohorts shapes larval size-structure dynamics. Larval densities and individual expression of cannibalism can shift this balance in opposite directions and alter relative recruitment rates from different cohorts.

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