| Popis: |
Investigation into the mechanisms responsible for community assembly (habitat filtering, niche differentiation) is essential for understanding the processes maintaining coexistence of species rich natural communities. Studies of such mechanisms have up to now been almost exclusively limited to communities of primary producers or consumers, and very few are focused on coexistence of predatory communities. Top-down regulation by predators is on the other hand essential in structuring communities of primary consumers. We therefore present a study focusing on coexistence and assembly in a species rich community of dung-inhabiting predators, investigating the potential effect of their temporal trends (succession, seasonality) on lowering their negative interactions (competition and intra-guild predation). We used field derived predator-prey co-occurrence data in combination with previous observations of trophic interactions and morphological constraints to describe the potential food web of dung-inhabiting insects. We used that food web to establish all combinations of negative interactions among individual species. We then analyzed whether interaction between species successional and seasonal optima could lower or eliminate their negative interactions. The predator prey ratio increased throughout dung pat succession, remaining constant among seasons. We found that the predator size decreased along the successional gradient, while similarly sized predators were evenly distributed across seasons. The succession of dung-inhabiting predators therefore displayed potential for environmental filtering. In contrast, seasonality niche differentiation seems to promote coexistence of species co-occurring along succession. The interaction of both species temporal patterns should significantly reduce or even eliminate the potential negative interactions between dung-inhabiting predators and thus promote high species richness in communities of dung-inhabiting insects. |
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