| Abstract |
Geographical intraspecific variation of acoustic signals has been observed in several groups of animals (invertebrates, mammals, birds). The importance of understanding geographical variation lies, among other things, in its contribution to minimizing the error of identification of these signals. This study investigates and describes geographic variation in echolocation call structure of 16 bat species in Greece. It further describes the call characteristics of 29 of the 34 species found in the country. Seven frequency and time parameters were used from each call, except Rhinolophus species for which only the Constant Frequency (CF) was used. Call patterns from different areas of Greece were investigated using stepwise Discriminant Analysis, and their acoustic relations were illustrated using Hierarchical Cluster Analysis. For four of the five Rhinolophus species found in Greece, acoustic patterns were illustrated using Hierarchical Cluster Analysis and non-metric Multidimensional Scaling (MDS). Results show that there is spatial differentiation in the calls of most species analyzed. The most pronounced differences are observed in cave-dwelling bats, while the calls of very common species tend to show homogeneity among regions. Three geographic patterns were found: a) echolocation calls of bats in Crete were significantly different from those of other parts of the country and were homogeneous; b) echolocation calls of bats in northeastern Greece different significantly from calls in other parts of Greece; and c) echolocation calls of bats in the Peloponnese showed heterogeneity, with the main differences occurring between Parnonas and Taygetos Mountains. Variables typically contributing most in call variability were end frequency (EF), frequency of maximum energy (FMAXE) and start frequency (SF). A correlation between the acoustic Euclidean distance and the geographical distances among the examined areas was found in seven species. In conclusion, at least for some bat species, acoustic identification may not be reliable unless geographical variation of echolocation calls is taken into account.
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Γεωγραφική διαφοροποίηση στις φωνές ηχοεντοπισμού των χειροπτέρων της Ελλάδας
