Patterns of termite functional diversity : From local ecology to continental history

In this thesis I investigated the community ecology of local African and south American forest termite assemblages. Additionally, I went on to study the influence of local ecology and biogeographical history upon local patterns of termite functional diversity across the tropics. The African field study established that there were marked differences in body size / energy use relationships between soil and wood feeding species. For the same assemblage, experimental habitat perturbation revealed the greater vulnerability of soil feeders compared with wood feeders. Early successional recovery of assemblage structure was influenced by manipulation of local ecological factors such as the amount of dead wood left on the ground. The south American study looked at patterns of termite assemblage structure across tropical forest islands that had been recently isolated by flooding. The results indicated positive early effects of forest fragmentation on abundance of wood feeders and a negative influence on soil feeders. However, fragmentation effects on species richness were marginal, and species compositional analyses indicated the greater importance of pre-existing spatial features of habitat heterogeneity. A global dataset of 87 standardised diversity transects gathered from 28 study sites across 5 continents revealed marked inter-continental differences in functional diversity, with soil feeders showing the greatest anomalies. These patterns indicated a hierarchy of influences upon local termite assemblages, with local ecological factors being subordinate to the influence of biogeographical history. Nevertheless, a synthesis of findings suggests that the ecological and energetic dichotomies between soil and wood feeding termites are central to the evolution of termite assemblages. Moreover, evidence points to termite evolution down substrate humification gradients as having been intimately associated with the evolution and distribution of tropical rain forests. From this synthesis, a scenario emerges to explain the termite diversity anomaly based on centres of origin, and likely dispersal histories, of termite feeding groups in relation to continental plate tectonic history