Ecological niche modeling of Myotis davidii

Abstract

Myotis davidii is a whiskered bat species distributed in large areas of the Western Palaearctic. It has a cryptic sister species, Myotis mystacinus, which also has a similar distribution range in Europe and western Asia. The distribution of M. davidii extends from the Balkans to the Far East Asia, whereas M. mystacinus is found in Europe, Anatolia, and the Caucasus. They have a sympatric range in an area extending from the Balkans to the Transcaucasia via Anatolia. In this sympatric area, the populations of M. davidii had discordant patterns of mitochondrial and nuclear DNA, indicating that there were gene exchange between these species in the past. In this study, it was aimed to investigate the effects of the past climatic conditions on the evolutionary history of M. davidii and its cryptic sister species, M. mystacinus. The particular aims of this thesis are: 1) to construct the bioclimatic niches of M. davidii and M. mystacinus; 2) to identify their putative refugial areas during the last glacial period; and 3) to assess their responses to current climate change. In order to investigate these aims, ecological niche models were utilized. Ecological niche models aims to predict the distribution range of species by matching the environmental factors with species occurence points. Ecological niche modeling approach has become a common and practical application in conservation and biogeography study, especially with the advent of computer sciences and essential databases. In this study, ecological niche models are constructed by using the R programming language, as implemented in the BIOMOD2 package. A maximum entrophy appoach was used, which is a machine learning method developed for ecological niche modelling applications. The constructed models captured the current range of M. davidii but failed for M. mystacinus. For Myotis mystacinus, the lack of data from the Balkans and Anatolia was the likely reason for the unsuccessful model projections. The models for M. davidii suggest that inaccordance with the genetic lineages there might be to separate ecological units. Past projections suggest that Anatolia and the Balkans might have acted as refugial areas for both of the species during the Last Glacial Maximum. For M. davidii, the coastal regions of the Black Sea and the Mediterranean regions of Anatolia were likely refugial areas. These findings highlights the importance of Anatolia as a glacial refugium. Finally, the future projections suggested that there will major range shifts in the distribution of these species, especially for M. mystacinus moving towards norther Europe.