Research On The Variation And Evolutionary Driving Forces Of Vocal Dialects Of Greater Horseshoe Bat, Rhinolophus Ferrumequinum

The greater horseshoe bat, Rhinolophus ferrumequinum (Chiroptera:Rhinolophidae) spreads broadly in China including many provinces across northern China to Southwest China. It is the Rhinolophidae species that distributes up to highest latitude. It has been listed as the Least Concern species in the Red List of Rare Species by IUCN, the International Union for Conservation of Nature, because of a sharp decrease in the population especially in most European areas. In this study, from2012to2013, detailed filed sampling, socail calls recording and statistical analysis were used to determine whether significant differences were shown in social calls across geographic populations, i.e. whether dialects exist in greater horseshoe bats. If dialects do exist, we further explored the relationship between the acoustic divergence and several promising factors as body size, climate conditions, geographic distance, the presence of barriers and genetic distance in order to clarify the driving forces in the process of dialect origin and maintenance. This study helps to understand the evolutionary process in sensory driven speciation and the rise of biodiversity. Also we provide the scientific basis for the conservation of bat species in the new concept of animal culture preservation. The main conclusions were as follows:1. A detailed analysis on the recordings of social calls had revealed that the greater horseshoe bats have an extremely rich repertoire including20simple syllable types and23composite syllable types.2. Nested AN OVA and MAN OVA were used to analyze the8acoustic parameters measured from the12common syllable types in all9populations. Significant differences were detected across the9locations in each parameter of each syllable type except a few ones and a combined analysis on all the parameter of all syllable types had confirmed the differences on the region level as well as the colony level, which in all, indicates the existence of dialects in the social calls of greater horseshoe bats.3. Mantel tests were used to determine the driving forces in the origin of dialects. Significant correlations between the acoustic distance and geographic distance as well as the genetic distance based on mitochondrion indicates that cultural drift had played a key role in the origin and maintenance of bat dialects.4. Causal modeling was built to further clarify the relations between the factors that may have contributed to the formation of dialects. In the model, geographic distance and the presence of barriers have direct effect on the origin the maintenance of bat dialects, while the genetic distances has no direct effect even they are also directly affected by the geographic distance and the presence of barriers.5. In order to further illuminate the role of geographic barrier, we zoomed in and focused on the4locations that lie on either side of Qinling Mountain. ANOVA was conducted on the acoustic parameters of12syllable types. Results showed that the vocal signals recorded from populations on different side of the Mountains differed significantly from the same side ones which again support the major effect of barrier during the process of dialect formation. The cluster analysis was used to divide the distribution areas of greater horseshoe bats into3main dialect districts which are the northeast district, the central-east district(on the northern side of Qinling Mountain) and the southwest district(on the southern side of Qinling Mountain). The results are in concordance with the previous analysis showing the presence of barrier promotes the origin and maintenance of bat dialects.