SEXUAL DIMORPHISM IN NORTHERN TEMPERATE SPIDERS - IMPLICATIONS FOR THE DIFFERENTIAL MORTALITY MODEL

We examined sexual size dimorphism in 627 species from 123 genera and 32 families of northern temperate spiders from Great Britain and Irela nd with different life histories, using phylogenetically independent c ontrasts. Web-building and non-web-building, sit-and-wait predators we re compared with non-web-building, active hunting spiders. After accou nting for phylogenetic effects, we find no evidence of differences in sexual size dimorphism in northern temperate spiders with differing li fe history/predatory strategies. We discuss the implications of our fi ndings for the generality of the differential mortality hypothesis (Vo llrath & Parker, 1992) with respect to spiders with different predator y modes from different habitats and environments. This recent theory p roposed that extreme sexual dimorphism in spiders resulted from differ ential adult mortality as a consequence of different adult life histor ies. We conclude that this model cannot explain the less extreme dimor phism found in temperate spiders.