Effects of diversity-dependent colonization–extinction dynamics on the mid-domain effect

Keith, S.A., and Connolly, S.R. (2013) Effects of diversity-dependent colonization–extinction dynamics on the mid-domain effect. Global Ecology and Biogeography, 22 (7). pp. 773-783.

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Aim: We incorporate diversity-dependent colonization and extinction rates into process-based models of species geographic range dynamics to explore their effects on species richness gradients, and on extent and occupancy of species ranges. In particular, we investigate whether diversity dependence promotes or inhibits the emergence of mid-domain effects (MDEs) in homogeneous environments.

Location: A theoretical one-dimensional domain.

Methods: We formulated diversity-independent (DI) and diversity-dependent (DD) models that simulated colonization, local extinction and speciation within a homogenous domain. In the DD model, colonization and extinction probabilities were functions of diversity, whereas in the DI model, they were constants. For a wide range of parameter values, we examined local and regional species richness gradients and species range size frequency distributions (RSFDs).

Results: In contrast to the DI model, for which MDEs only occurred in a very narrow parameter range, the DD model generated a MDE in regional richness (range overlap) that was robust to colonization and extinction parameters, over a broad range of speciation rates. However, neither model could produce gradients in local richness (patch occupancy). The DD model also produced more realistic RSFDs than the DI model. In the latter, all species generally either became highly pandemic or went globally extinct, depending on the balance of colonization and extinction probabilities.

Main conclusions: Diversity-dependent colonization and extinction rates can have strong effects on species richness gradients and distributions of range extent and occupancy. Models with such diversity dependence amplify MDEs in regional richness, but largely eliminate MDEs in local richness, relative to DI models. DD models also generate more realistic RSFDs. These findings suggest that diffuse species interactions can strongly influence patterns of range size and overlap, but also that environmental gradients are likely to be necessary to explain many species richness patterns in nature, which exhibit both local and regional diversity gradients.

Item ID: 25593
Item Type: Article (Research - C1)
ISSN: 1466-822X
Keywords: colonization; extinction; geometric constraints; indirect competition; process-based model; simulation model; speciation; species range size; species richness gradients
Funders: Australian Research Council (ARC)
Date Deposited: 18 Mar 2013 02:47
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060299 Ecology not elsewhere classified @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960805 Flora, Fauna and Biodiversity at Regional or Larger Scales @ 100%
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