Spatial separation of Afrotropical dung beetle guilds: A trade-off between competitive superiority and energetic constraints (Coleoptera: Scarabaeidae)

In the forest-savanna mosaic of Côte d'Ivoire (Parc National de la Comoé), we studied the guild structure of dung beetle assemblages of fresh buffalo faeces (60 samples, 19626 specimens) in three adjacent habitats: savanna parkland, gallery forest, grassland of the river valley. We found clear patterns at the guild level determined by the habitat type and time of day: in the savanna parkland during the day, telecoprids (rollers) and their kleptoparasites are dominant. At night, paracoprids (tunnelers) and endocoprids (dwellers) dominate the dung beetle assemblages. In the river valley during the day and the gallery forest all day and night, the abundance of dung beetles is very low and does not reach a competitive level. In the river valley at night, endocoprids are quite abundant. Abundances of kleptoparasites and their hosts are positively correlated. The telecoprids are the most competitively superior guild since they use the resource most rapidly, but their abundance is correlated with temperature of faeces and soil. This is probably because their mode of resource utilization is energetically costly, so they require higher temperatures in order to maximize their competitiveness. Their ecological tolerance is therefore narrow and they are only present in the savanna parkland during the day. The endocoprids are the least competitive guild, since they do not relocate the resource and so are not able to monopolize parts of it. However, their mode of resource utilization is less energetically costly. They seem to be more tolerant of temperature fluctuation and more able to cross barriers such as the gallery forest. Spatial separation of Afrotropical dung beetle guilds is likely to be due to a trade-off between competitive superiority and energetic constraints.