ABSTRACT
In a study of more than half a hundred European butterfly species, for example, Parmesan et al.[13] found that most of them moved northward in response to a regional warming of 0.8C over the past century. However, in almost all of these northward ‘‘migrations,’’ only the northern boundaries of the ranges moved. Furthermore, the northward range expansions did not displace other butterfly species residing in the newly acquired territories, for essentially none of the southern boundaries of any species shifted. Hence, because of the consequent increased overlapping of ranges, butterfly biodiversity must have increased in many areas of Europe over the past century in response to the warming and atmospheric CO2 increase experienced there.
