Genetic structure and gene flow of fragmented bat populations: consequences for conservation

Species distributed in fragmented populations have particular conservation problems that are related to population genetics. This applies both to species sub-divided in small isolated populations, such as insular species inhabiting archipelagos, and to mainland species that are fragmented in small functional populations, such as colonies. In both cases, genetic structure is one of the most fundamental pieces of information for their conservation and management. This is the case of the study species in the present thesis: the insular the Azorean bat (Nyctalus azoreum), distributed in most islands of the Azores archipelago, and the continental Schreiber’s bent winged bat (Miniopterus schereibersii), with a population fragmented in several separate colonies. Like in most of Europe, bats are one of the most threatened animal groups in Portugal, where some bat species have been studied regarding distribution, abundance and ecology. Yet, the application of molecular data to the knowledge and conservation of Portuguese bat populations has been unexplored until now. In this thesis, mtDNA sequences and nuclear microsatellite loci were used to increase the knowledge about the fragmented populations of the two threatened bat species mentioned above. This study included an examination of the phylogenetic relationships among several species within the genus Nyctalus, and of the genetic divergence between N. azoreum and its mainland ancestor, N. leisleri. It also involved the analysis of the genetic diversity within populations, and genetic differentiation among the studied fragmented populations, thus revealing new insights about their population structure, history and behavioural dispersal. This thesis provided important information to define biologically meaningful conservation units for the studied species. For N. azoreum, two management units were suggested (S. Miguel island and the Central Group), while for M. schreibersii four units were defined (North, West Centre, Marvão and South). These units should be taken into account when planning conservation and management actions.