Morphometric and advertisement call geographic variation in polyploid green toads

We describe the spatial pattern of variation of morphometric characters and call acoustic properties of tetraploid green toads (Bufo viridis complex) from eight populations in Central Asia, and we analyse the causal agents re sponsible for the patterns observed, by means of partial Mantel tests. Popu lations significantly differ with respect to both body size and body shape. Since animals inhabiting the driest regions are smaller, but not younger, than animals from less dry areas, we suggest that their small body size is due to the limiting effect of arid climate on growth rate. Differences in b ody shape are positively associated only with geographic distances, and we suggest that isolation by distance might have played an important role in d etermining the pattern of variation. Populations significantly differ also with respect to the acoustic properties of the call, in particular, with re spect to temperature-adjusted pulse rate and body size-adjusted fundamental frequency; that is, with respect to those properties which are under the s trongest morphological or physiological constraints, and that show the lowe st variability within individuals (static properties). The pattern of varia tion of calls shows positive association with geographic distances, but not with climatic distances. Calls do vary, and in this region the main causal agent responsible for call variation might have been the isolation by dist ance. The evolutionary implications of these results are discussed. (C) 200 0 The Linnean Society of London.