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posted Sep 29, 2014, 2:04 AM by Bruno Buzatto   [ updated Sep 29, 2014, 2:06 AM ]
Behavioral Ecology has just published a paper that I co-authored with my friends Danilo Muniz, Paulo Guimarães (Miúdo) and Glauco Machado, from the University of São Paulo. In this paper we used data that I collected years ago (for my MSc thesis) on territoriality and copulations in the harvestman Serracutisoma proximum (Arachnida: Opiliones), a species with alternative mating tactics. Majors of S. proximum are territorial and hold harems of up to six females, whereas minors invade territories and sneak copulations inside them. We used data on naturally observed
copulations to build sexual networks for the species. Next, we used these networks to analyze and compare the sperm competition intensity (SCI) faced by sneakers and territorials, and to test hypotheses about the influence of harem size and spatial distribution of harems on the SCI faced by territorials. We found that sneakers faced higher SCI than territorials, but the SCI faced by territorials varied more than that of sneakers. We also show that owners of large harems faced less intense sperm competition than owners of small harems, which is a surprising result. We conclude that the spatial distribution of harems strongly influences the sexual network, and that our spatially explicit approach can bring insights to the study of sperm competition and mating systems in general. You can find the full paper here.