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Bayesian island biogeography in a continental setting: the Rand Flora case
Isabel Sanmartín1, Cajsa Lisa Anderson, Marisa Alarcon
1Real Jardin Botanico, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain. isanmartin@rjb.csic.es
Biology Letters
|March 26, 2010
Summary
This study uses Bayesian island biogeography to explain the Rand Flora, a disjunct plant distribution. Results show limited exchange between southern and northern Africa, with distinct origins for floras in Northwest Africa-Macaronesia and southern Africa.
Area of Science:
- Ecology
- Evolutionary Biology
- Biogeography
Background:
- The 'Rand Flora' describes a disjunct distribution pattern observed in numerous plant lineages across Macaronesia-northwest Africa, Horn of Africa-southern Arabia, and east-south Africa.
- Understanding the evolutionary origins of this continental-scale floristic pattern has been a long-standing challenge in botany due to the lack of robust analytical frameworks.
Purpose of the Study:
- To apply a Bayesian approach to island biogeography for disentangling the evolutionary origins of the Rand Flora.
- To statistically analyze phylogenetic and distributional data to estimate historical biotic exchange rates and area carrying capacities.
Main Methods:
- Phylogenetic and distributional data from 13 plant lineages exhibiting the disjunct distribution were analyzed.
- A Bayesian statistical framework was employed to model island biogeography principles on a continental scale.
- Estimates of area carrying capacities and historical rates of biotic exchange between regions were calculated.
Main Results:
- Little biotic exchange was detected between southern Africa and the northern African region, with any exchange occurring via East Africa.
- Northwest Africa-Macaronesia exhibited the lowest carrying capacity but the highest dispersal rate, suggesting flora establishment through immigration.
- Southern Africa displayed the highest carrying capacity and lowest dispersal rate, indicating a flora primarily shaped by in situ diversification.
Conclusions:
- The study provides statistical evidence for distinct evolutionary histories shaping the Rand Flora across different regions.
- The findings suggest that floristic patterns can be explained by varying rates of dispersal and in situ diversification.
- Further methodological improvements are discussed for analyzing complex hypotheses like asymmetric dispersal and cyclical events.
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