Applying genetic and genomic methodologies for the conservation of salamandrina perspicillata, euproctus platycephalus and rana italica

Abstract

Because of a global crisis of biodiversity numerous plant and animal species are rapidly disappearing, and among vertebrates amphibians represent the most threatened group. Together with species diversity, also the ancient and extremely diversified amphibian genome is at risk of extinction. Since they are the most ancient landdwelling animals, their genome very likely holds important keys to understand crucial evolutionary events, among which vertebrate terrestrialisation. For this reason, amphibian conservation is a global priority. Being genetic variability one of the key requisite for species to adapt to environmental changes, the conservation of genetic diversity became one of the objectives of crucial importance in conservation biology. The general aim of this thesis is to provide new insights about the mechanisms that contribute in shaping the pattern of genetic diversity observed in three Italian endemic amphibian species. All of them are species of conservation concern, protected by European and National laws. Due to their different conservation status and specific research issues, their study was approached with different methodologies and perspectives. As for Salamandrina perspicillata, an investigation at a very thin resolution scale (one population) was carried out by using microsatellite markers. The main aim of this study was to clarify the mating strategy adopted by females and understand how they can improve their fitness. This study provided the first evidence of polygynandry in a salamandrid species and the first report, in natural conditions, of salamander females that choose males genetically dissimilar from themselves to obtain indirect benefit (higher offspring heterozygosity). As for Euproctus platycephalus, due to its condition of endangered species (IUCN 2014), the analyses focused on the investigation of the actual population genetic structure. In particular, the aim of this study was to identify the possible Evolutionarily Significant Units (ESUs), along the whole distribution area of the species, in order to plan adult individuals’ collection for an ex-situ breeding project. Since there were no other genetic markers available for the species, apart from mitochondrial DNA (which would have not provided the necessary resolution power), the novel Genotyping By Sequencing technique have been used. Clusterization analyses revealed the presence of four ESUs, very likely comprising also adaptive groups. The same genomic approach has been used for the third target species, Rana italica, with the aim of investigating its current genetic structure at a regional scale (Latium region). In this case the clusterization analyses suggest the presence of two different genetic groups. Further analyses focused on the estimation of individual heterozigosity, in preparation for Heterozygosity-Fitness-Correlation evaluations. Thus, before of GBS application on the above mentioned species, another goal of this project was to produce the first genomic tools for these amphibian species.