Name: Freitas I

Biodeserts supervisors: Martinez-Freiria F, Velo-Antón G

Title: Integrating genetic, morphological and ecological data to investigate reproductive isolation between Iberian lineages of the Lataste’s viper Vipera latastei

Institution: University of Porto

Status: Completed

Abstract

Past climatic and paleogeographical events have shaped the current biodiversity patterns of the Western Mediterranean region, resulting in high levels of endemism and differentiation for many taxa. Amphibians and reptiles have been frequently used as study models to infer the role of past events in shaping genetic and morphological differentiation patterns; consequently, both groups have been recently subjected to important taxonomic revisions.
The Lataste’s viper Vipera latastei inhabits areas with Mediterranean climate in the Iberian Peninsula and North Africa with populations displaying strong patterns of genetic and morphological differentiation within both regions. However, the species' taxonomy remains unclear, hampering a coherent designation of conservation units within this vulnerable species.
In this study we investigate the intraspecific variability of the Vipera latastei-monticola complex and define coherent taxonomic and conservation units using an integrative approach that combines genetic (phylogenetic and population genetic structure analyses), morphological (univariate and multivariate morphological analyses) and ecological analyses (ecological niche-based modelling and niche overlap tests). Mitochondrial DNA (Cytb and ND4) recovered a deep phylogeographic pattern with two main vicariant groups, Iberian and North African lineages, highly structured, while the nuclear genes (PRLP and β-fib) provided insufficient resolution to identify the main mitochondrial lineages within the species. In addition, the microsatellite loci proved to be non informative at an intraspecific level in the southern Iberian populations of V. latastei, precluding further investigation on the reproductive isolation within the main Iberian mitochondrial lineages. Therefore, morphological and ecological comparisons were based on three levels of mitochondrial structure: 1) the two main lineages (Iberia and North Africa), 2) Iberian lineages and 3) sublineages.
Morphological univariate and multivariate analyses over ten meristic traits found a complex pattern of variation across the Strait of Gibraltar and clear morphological differences between the main Iberian lineages. At lower levels of genetic structure, morphological differentiation between northern and southern sublineages suggests local adaptation to environmental gradients.
Ecological niche models (ENM) based on the Maximum Entropy approach suggested reduced ecological variability for North African populations when compared to Iberian populations. Within Iberia, ENMs predicted extensive areas of potential co-existence among main lineages and particularly among sublineages. In concordance, tests of niche overlap, measuring the environmental variability of records and areas of occupancy for lineages and sublineages, suggested a general tendency to niche conservatism within the species.
Overall, this study shed new light into the biogeography and evolutionary history of V. latastei and supports the assignment of the two vicariant lineages, North African and Iberian, as independent evolutionary and conservation units. However, for an accurate assessment of this species taxonomy further investigation is needed, with special focus on current gene flow between the different mitochondrial units.