Document: TIM-3-52-40

Exploring mechanisms behind species diversity differences: Comparing Markov models of mussel beds and coral reefs.

WOOTTON, J.T.*

The University of Chicago, Chicago, IL 60637 USA. ¹

Abstract:
Ecologists have generated numerous hypotheses to explain community-wide differences in diversity among different habitats, most of which are based on widespread effects of dynamic processes such as disturbance, patterns and strengths of species interactions, and colonizing ability. Yet measuring these processes across many species is logistically daunting. Transitions in multi-species Markov models are relatively easy to obtain empirically and potentially reflect community-wide rates of processes hypothesized to affect diversity. I explored potential mechanisms leading to marked diversity differences by comparing Markov models from exposed pool and crest habitats of coral reefs in Australia (Ecology; richness = 81, evenness = 0.46-0.49) to a Washington state mussel bed model (richness = 32, evenness = 0.17). Species replacement rates, disturbance rates and colonization rates on coral reefs were 4.5, 5.8 and 0.27 times those in mussel beds, respectively, consistent with several diversity hypotheses. Hypothesized tradeoffs between displacement ability or displacement risk and either disturbance risk or colonizing ability were not observed in either community. Contrary to expectations, asymmetry of interactions among taxa was slightly higher on mussel beds than coral reefs, indicating that dominance intransitivities were not generally important in promoting diversity. The results illustrate that a comparative Markov model approach may shed light on a community-wide basis on multiple, simultaneously-acting processes affecting diversity in different communities.

Keywords: Species Diversity, Markov models, coral reef, rocky intertidal

This abstract is being presented at: 11:15 AM in session:
Oral Session #7: Aquatic Ecology: Shellfish to Snails.