Patterns of Niche Partitioning and Alternative Reproductive Strategies in an East African Dung Beetle Assemblage

Abstract

Sympatric species of coprophagus dung beetles rely on essentially the same resource for provisioning broods, which raises the question of how local species diversity is maintained. Interspecific competition may be mitigated to some extent by large-scale spatial (e.g., habitat type) and temporal (e.g., seasonal) variation in activity. Niche partitioning also occurs at the scale of individual dung pads. We examined the extent to which inter-and intraspecific variation in adult morphology and behavior contribute to spatial and temporal partitioning above and below the dung pad in the dung beetle community of Kibale Forest, Uganda. Excavations in the vicinity of dung pads revealed significant heterogeneity among species and guilds in the lateral distance between tunnels and dung, and in tunnel depth. Patterns of succession and diel activity demonstrated strong temporal dissociations among guilds. In one species, Onthophagus multicornis, we found a bimodal distribution of male horn sizes and a tunneling pattern consistent with alternative reproductive tactics.

Temporal Segregation between Dung-Inhabiting Beetle and Fly Species

“…Temporal patterns of colonization of such habitats have been studied almost exclusively in insect representatives of Arthropods (all occupancy patterns). The temporal segregation among insects, at all three levels, is traditionally considered to be associated with niche differentiation due to instability and the limited mass of their primary resource [28, 29]. However, there is evidence for potential habitat filtering: for succession, for example mediated through dung moisture tolerance [30], and on the seasonal scale, for example mediated through temperature [31, 32] or drought tolerance [33].…”

“…24, 37] and sub-tropical and tropical regions [e.g. 28, 38]. However, in contrast to beetles, fly temporal patterns have been studied quantitatively only infrequently [39, 40] and in a rather qualitative manner only [41, 42].…”

Disappearance rate of chimpanzee scats: Implications for census work on Pan troglodytes

“…When compared to data on dung beetle presence on scats during PDR sessions, six of the 11 taxa (from four genera) identified were recorded on scats visited in both the wet and dry seasons (Table ), with Diastellopalpus gilleti occurring most frequently (42% of scats); 82% of these scats from the wetter period ( N = 23 of 28 scats). This dung beetle was recorded for Uganda only recently (Chao et al., ). Of the six taxa identified during visits to scats, all but Oniticellus pseudoplanatus were recorded within the first 3 hr on 45 scats; this beetle was also found on scats in the wet season only (Table , Figure ).…”

“…Eleven taxa of dung beetle from six genera were identified by DM from the 21 beetles collected (Figure ). All have been recorded in primate scats (Chao, Simon‐Freeman, & Grether, ) and in both primary and disturbed forested regions in Kibale National Park (Nummelin & Hanski, ). These were further categorized into the following guilds: rollers ( N = 4, roll balls of faecal matter and transport to nest to create brood chamber), tunnellers ( N = 6, drag faecal matter under the scat into nest) or endocoprids ( N = 1, makes a brood chamber within the scat).…”

“…Chao et al. () suggested that rollers removed faecal matter before the arrival of large tunnellers as the latter are able to hoard larger quantities of faecal matter in a short timeframe. Our findings show large tunnellers (and not just rollers) arriving on chimpanzee scats in the early stages of decay of <3 hr, not just rollers across both wet and dry periods.…”