On the limit of altitudinal range shifts - Population genetics of relict butterfly populations
Responses to climate warming vary considerably. Cold-adapted species mostly escape rising temperatures by latitudinal and/or altitudinal range shifts, and often today occur in isolated remnants. In the present study we discuss the genetic consequences of climate warming for five butterfly taxa (Lycaena helle, Erebia epiphron, Erebia sudetica inalpina, Coenonympha darwiniana and C. macromma) which currently show relict-like distributions at least in parts of their distribution ranges. For all these species, genetic data (microsatellite and/or allozyme polymorphisms) already exist. In general, the situation for such high montane/alpine species in the Alps differs from that in the low-altitude mountains, as the considerably higher eleva-tions of the Alps mean that there is still possibility for further altitudinal shifts, while no such possibilities exist in lower mountain ranges. However, there are considerable differences in the general genetic situation of the five taxa analysed. The genetic structure of the Alpine L. helle populations is quite similar to that of the populations in the northern Alps forelands and the lowlands of eastern Europe. However, the lower mountain systems of western Europe all represent considerably differentiated gene pools for this species, so that these might be endan-gered by climate change. At the contrary, the relict population of E. epiphron in the Jesenik Mts is genetically not differentiated from the northern Alps. Taxa such as Erebia sudetica inalpina, Coenonympha darwiniana and C. macromma, which are all confined to certain parts of the Alps, represent endemic gene-pools. Of these taxa, E. sudetica inalpina shows low pop-ulation genetic diversity, while the other two species have high allozyme diversity. Therefore, climate change accompanied by altitudinal range shifts might not have an effect on the genetic composition of the former, but might cause losses of genetic diversity in the latter two taxa. In conclusion, the data of these five taxa show that climate change will have different effects on different species of relict-like distributions.