Sequential fragmentation of Pleistocene forests in an East Africa biodiversity hotspot : chameleons as a model to track forest history

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dc.contributor.authorMeasey, G. Johnen_ZA
dc.contributor.authorTolley, Krystal A.en_ZA
dc.date.accessioned2012-01-18T08:06:37Z
dc.date.available2012-01-18T08:06:37Z
dc.date.issued2011-10-28
dc.descriptionCITATION: Measey, G. J. & Tolley, K. A. 2011. Sequential fragmentation of Pleistocene forests in an East Africa biodiversity hotspot : chameleons as a model to track forest history. PLoS ONE, 6(10): e26606, doi:10.1371/journal.pone.0026606.
dc.descriptionThe original publication is available at http://journals.plos.org/plosone
dc.description.abstractBackground The Eastern Arc Mountains (EAM) is an example of naturally fragmented tropical forests, which contain one of the highest known concentrations of endemic plants and vertebrates. Numerous paleo-climatic studies have not provided direct evidence for ancient presence of Pleistocene forests, particularly in the regions in which savannah presently occurs. Knowledge of the last period when forests connected EAM would provide a sound basis for hypothesis testing of vicariance and dispersal models of speciation. Dated phylogenies have revealed complex patterns throughout EAM, so we investigated divergence times of forest fauna on four montane isolates in close proximity to determine whether forest break-up was most likely to have been simultaneous or sequential, using population genetics of a forest restricted arboreal chameleon, Kinyongia boehmei. Methodology/Principal Findings We used mitochondrial and nuclear genetic sequence data and mutation rates from a fossil-calibrated phylogeny to estimate divergence times between montane isolates using a coalescent approach. We found that chameleons on all mountains are most likely to have diverged sequentially within the Pleistocene from 0.93–0.59 Ma (95% HPD 0.22–1.84 Ma). In addition, post-hoc tests on chameleons on the largest montane isolate suggest a population expansion ∼182 Ka. Conclusions/Significance Sequential divergence is most likely to have occurred after the last of three wet periods within the arid Plio-Pleistocene era, but was not correlated with inter-montane distance. We speculate that forest connection persisted due to riparian corridors regardless of proximity, highlighting their importance in the region's historic dispersal events. The population expansion coincides with nearby volcanic activity, which may also explain the relative paucity of the Taita's endemic fauna. Our study shows that forest chameleons are an apposite group to track forest fragmentation, with the inference that forest extended between some EAM during the Pleistocene 1.1–0.9 Ma.
dc.description.urihttp://journals.plos.org/plosone/article?id=10.1371/journal.pone.0026606
dc.description.versionPublisher's version
dc.format.extent9 pages
dc.identifier.citationMeasey, G. J. & Tolley, K. A. 2011. Sequential fragmentation of Pleistocene forests in an East Africa biodiversity hotspot : chameleons as a model to track forest history. PLoS ONE, 6(10): e26606, doi:10.1371/journal.pone.0026606.
dc.identifier.issn1932-6203 (online)
dc.identifier.otherdoi:10.1371/journal.pone.0026606
dc.identifier.urihttp://hdl.handle.net/10019.1/19187
dc.language.isoen
dc.publisherPublic Library of Science
dc.rights.holderAuthors retain copyright
dc.subjectKinyongia boehmeien_ZA
dc.subjectChameleonsen_ZA
dc.subjectPaleobotany -- Pleistoceneen_ZA
dc.subjectForest ecology -- Africa, Easten_ZA
dc.subjectBiodiversity -- Africaen_ZA
dc.titleSequential fragmentation of Pleistocene forests in an East Africa biodiversity hotspot : chameleons as a model to track forest historyen_ZA
dc.typeArticle
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