Resource partitioning in coprophagous beetles
from sheep dung: Phenology and microhabitat preferences
Peter Sowig & Thomas Wassmer
Institute of Biology I (Zoology), Albert-Ludwigs-University, Freiburg
i. Brg., Germany
Abstract:
On a pasture in SW-Germany coprophagous beetles (Scarabaeidae, Hydrophilidae:
Sphaeridiinae and Staphylinidae: Oxytelinae) from sheep droppings were
studied considering the following niche dimensions: season, size, type
and water content of the dropping. 1. Phenological differences were found
especially within endocoprid Scarabaeidae. Dominant Aphodius-species were
clearly separated from each other by their phenology, while nearly all
Hydrophilidae from the genus Cercyon and paracoprid Scarabaeidae were most
abundant in May. 2. Sheep produce different types of droppings, either
compact lumps or small pellets. The latter are mostly deposited in groups.
Since these pellets dry out quickly, but rehydrate during rainfall, a high
variability of humidity conditions makes pellets unattractive to many dung
beetles. 3. Pairwise niche overlap indices in coprophagous beetles from
sheep droppings were calculated regarding two niche dimensions: dropping
size and water content. Cluster trees showed a clear distinction between
species according to these microhabitat factors. Especially Hydrophilidae
tend to avoid small droppings which might be due to unstable humidity conditions
there. Mean intrageneric overlap within genera with more than one species
was equal to or even higher than mean intergeneric overlap rates.
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