Climatic data
To characterize summer conditions at sites of origin, we selected the
following five bioclimatic variables from the WorldClim database (Fick
and Hijmans 2017): annual mean temperature, maximum temperature of
warmest month, mean temperature of warmest quarter, annual
precipitation, precipitation of warmest quarter (see Fig. 2Aand B , and Table S2 for regional ranges). For all
sites, the warmest quarter of the year occurs between June and September
(Fig. 2A and B ).