Ancient forest fragmentation or recent radiation? Testing refugial speciation models in chameleons within an African biodiversity hotspot

Simple item page
dc.contributor.authorTolley K.A.
dc.contributor.authorTilbury C.R.
dc.contributor.authorMeasey G.J.
dc.contributor.authorMenegon M.
dc.contributor.authorBranch W.R.
dc.contributor.authorMatthee C.A.
dc.date.accessioned2011-10-13T16:58:19Z
dc.date.available2011-10-13T16:58:19Z
dc.date.issued2011
dc.description.abstractAim East Africa is one of the most biologically diverse regions, especially in terms of endemism and species richness. Hypotheses put forward to explain this high diversity invoke a role for forest refugia through: (1) accumulation of new species due to radiation within refugial habitats, or (2) retention of older palaeoendemic species in stable refugia. We tested these alternative hypotheses using data for a diverse genus of East African forest chameleons, Kinyongia. Location East Africa. Methods We constructed a dated phylogeny for Kinyongia using one nuclear and two mitochondrial markers. We identified areas of high phylogenetic diversity (PD) and evolutionary diversity (ED), and mapped ancestral areas to ascertain whether lineage diversification could best be explained by vicariance or dispersal. Results Vicariance best explains the present biogeographic patterns, with divergence between three major Kinyongia clades (Albertine Rift, southern Eastern Arc, northern Eastern Arc) in the early Miocene/Oligocene (>20Ma). Lineage diversification within these clades pre-dates the Pliocene (>6Ma). These dates are much older than the Plio-Pleistocene climatic shifts associated with cladogenesis in other East African taxa (e.g. birds), and instead point to a scenario whereby palaeoendemics are retained in refugia, rather than more recent radiations within refugia. Estimates of PD show that diversity was highest in the Uluguru, Nguru and East Usambara Mountains and several lineages (from Mount Kenya, South Pare and the Uluguru Mountains) stand out as being evolutionarily distinct as a result of isolation in forest refugia. PD was lower than expected by chance, suggesting that the phylogenetic signal is influenced by an unusually low number of extant lineages with long branch lengths, which is probably due to the retention of palaeoendemic lineages. Main conclusions The biogeographic patterns associated with Kinyongia are the result of long evolutionary histories in isolation. The phylogeny is dominated by ancient lineages whose origins date back to the early Miocene/Oligocene as a result of continental wide forest fragmentation and contraction due to long term climatic changes in Africa. The maintenance of palaeoendemic lineages in refugia has contributed substantially to the remarkably high biodiversity of East Africa. © 2011 Blackwell Publishing Ltd.
dc.description.versionArticle
dc.identifier.citationJournal of Biogeography
dc.identifier.citation38
dc.identifier.citation9
dc.identifier.citationhttp://www.scopus.com/inward/record.url?eid=2-s2.0-80051663651&partnerID=40&md5=40cb13f546005da4c12c23b140ab0333
dc.identifier.issn3050270
dc.identifier.other10.1111/j.1365-2699.2011.02529.x
dc.identifier.urihttp://hdl.handle.net/10019.1/16681
dc.subjectBiodiversity hotspots
dc.subjectBiogeography
dc.subjectChamaeleonidae
dc.subjectClimate shifts
dc.subjectEast Africa
dc.subjectKinyongia
dc.subjectLizards
dc.subjectPhylogeny
dc.subjectRefugia
dc.subjectReptiles
dc.subjectclimate change
dc.subjectendemism
dc.subjectevolutionary biology
dc.subjecthabitat fragmentation
dc.subjecthot spot
dc.subjecthypothesis testing
dc.subjectlizard
dc.subjectMiocene
dc.subjectOligocene
dc.subjectphylogenetics
dc.subjectphylogeny
dc.subjectrefugium
dc.subjectspecies diversity
dc.subjectEast Africa
dc.subjectAves
dc.subjectChamaeleonidae
dc.subjectReptilia
dc.subjectSquamata
dc.titleAncient forest fragmentation or recent radiation? Testing refugial speciation models in chameleons within an African biodiversity hotspot
dc.typeArticle
Files
Collections
Stellenbosch University - Scopus Publications