Climate change and altitudinal variation in sexual size dimorphism of Arctic wolf spiders

Abstract

Climate change is advancing the onset of the growing season, and this is happening at a particularly fast rate in the Arctic. Although this has recently been shown to affect the sexual size dimorphism (SSD) of a wolf spider species through time, it remains to be shown whether spatial variation in the physical environment is similarly affecting SSD. We studied altitudinal variation in adult body size of male and female wolf spiders on Disko Island, West Greenland. Two species exhibited female-biased SSD (measured by carapace width) at sea level but not at higher altitudes. Males and females of a third species were of equal size at both altitudes, and the 2 remaining species found on Disko Island were only present at 1 low altitude site each. Altitudinal variation in SSD is probably a result of sex differences in body size response to shorter growing seasons with altitude. Our results suggest that climate change may result in increased SSD. Constraints on body size may increase with altitude, and expanding growing seasons due to climate change may predominantly affect SSD at higher altitudes. Such intra-specific effects of climate may be widespread and suggest that further research in this topic is needed. © Inter-Research 2010.