Diversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africa

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dc.contributor.authorFuchs, Jérômeen_ZA
dc.contributor.authorFjeldså, Jonen_ZA
dc.contributor.authorBowie, Raurien_ZA
dc.date.accessioned2015-10-28T07:03:01Z
dc.date.available2015-10-28T07:03:01Z
dc.date.issued2011en_ZA
dc.description.abstractBACKGROUND:The Eastern Arc Mountains of Africa have become one of the focal systems with which to explore the patterns and mechanisms of diversification among montane species and populations. One unresolved question is the extent to which populations inhabiting montane forest interact with those of adjacent lowland forest abutting the coast of eastern Africa. The Tiny Greenbul (Phyllastephus debilis) represents the only described bird species within the Eastern Arc/coastal forest mosaic, which is polytypic across an altitudinal gradient: the subspecies albigula (green head) is distributed in the montane Usambara and Nguru Mountains whereas the subspecies rabai (grey head) is found in Tanzanian lowland and foothill forest. Using a combination of morphological and genetic data, we aim to establish if the pattern of morphological differentiation in the Tiny Greenbul (Phyllastrephus debilis) is the result of disruptive selection along an altitudinal gradient or a consequence of secondary contact following population expansion of two differentiated lineages. RESULTS: We found significant biometric differences between the lowland (rabai) and montane (albigula) populations in Tanzania. The differences in shape are coupled with discrete differences in the coloration of the underparts. Using multi-locus data gathered from 124 individuals, we show that lowland and montane birds form two distinct genetic lineages. The divergence between the two forms occurred between 2.4 and 3.1 Myrs ago.Our coalescent analyses suggest that limited gene flow, mostly from the subspecies rabai to albigula, is taking place at three mid-altitude localities, where lowland and montane rainforest directly abut. The extent of this introgression appears to be limited and is likely a consequence of the recent expansion of rabai further inland. CONCLUSION: The clear altitudinal segregation in morphology found within the Tiny Greenbul is the result of secondary contact of two highly differentiated lineages rather than disruptive selection in plumage pattern across an altitudinal gradient. Based on our results, we recommend albigula be elevated to species rank.en_ZA
dc.identifier.apacitationFuchs, J., Fjeldså, J., & Bowie, R. (2011). Diversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africa. <i>BMC Evolutionary Biology</i>, http://hdl.handle.net/11427/14462en_ZA
dc.identifier.chicagocitationFuchs, Jérôme, Jon Fjeldså, and Rauri Bowie "Diversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africa." <i>BMC Evolutionary Biology</i> (2011) http://hdl.handle.net/11427/14462en_ZA
dc.identifier.citationFuchs, J., Fjeldså, J., & Bowie, R. C. (2011). Diversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africa. BMC evolutionary biology, 11(1), 117.en_ZA
dc.identifier.ris TY - Journal Article AU - Fuchs, Jérôme AU - Fjeldså, Jon AU - Bowie, Rauri AB - BACKGROUND:The Eastern Arc Mountains of Africa have become one of the focal systems with which to explore the patterns and mechanisms of diversification among montane species and populations. One unresolved question is the extent to which populations inhabiting montane forest interact with those of adjacent lowland forest abutting the coast of eastern Africa. The Tiny Greenbul (Phyllastephus debilis) represents the only described bird species within the Eastern Arc/coastal forest mosaic, which is polytypic across an altitudinal gradient: the subspecies albigula (green head) is distributed in the montane Usambara and Nguru Mountains whereas the subspecies rabai (grey head) is found in Tanzanian lowland and foothill forest. Using a combination of morphological and genetic data, we aim to establish if the pattern of morphological differentiation in the Tiny Greenbul (Phyllastrephus debilis) is the result of disruptive selection along an altitudinal gradient or a consequence of secondary contact following population expansion of two differentiated lineages. RESULTS: We found significant biometric differences between the lowland (rabai) and montane (albigula) populations in Tanzania. The differences in shape are coupled with discrete differences in the coloration of the underparts. Using multi-locus data gathered from 124 individuals, we show that lowland and montane birds form two distinct genetic lineages. The divergence between the two forms occurred between 2.4 and 3.1 Myrs ago.Our coalescent analyses suggest that limited gene flow, mostly from the subspecies rabai to albigula, is taking place at three mid-altitude localities, where lowland and montane rainforest directly abut. The extent of this introgression appears to be limited and is likely a consequence of the recent expansion of rabai further inland. CONCLUSION: The clear altitudinal segregation in morphology found within the Tiny Greenbul is the result of secondary contact of two highly differentiated lineages rather than disruptive selection in plumage pattern across an altitudinal gradient. Based on our results, we recommend albigula be elevated to species rank. DA - 2011 DB - OpenUCT DO - 10.1186/1471-2148-11-117 DP - University of Cape Town J1 - BMC Evolutionary Biology LK - https://open.uct.ac.za PB - University of Cape Town PY - 2011 T1 - Diversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africa TI - Diversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africa UR - http://hdl.handle.net/11427/14462 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/14462
dc.identifier.urihttp://dx.doi.org/10.1186/1471-2148-11-117
dc.identifier.vancouvercitationFuchs J, Fjeldså J, Bowie R. Diversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africa. BMC Evolutionary Biology. 2011; http://hdl.handle.net/11427/14462.en_ZA
dc.language.isoengen_ZA
dc.publisherBioMed Central Ltden_ZA
dc.publisher.departmentPercy FitzPatrick Institute of African Ornithologyen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an Open Access article distributed under the terms of the Creative Commons Attribution Licenseen_ZA
dc.rights.holder2011 Fuchs et al; licensee BioMed Central Ltd.en_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/2.0en_ZA
dc.sourceBMC Evolutionary Biologyen_ZA
dc.source.urihttp://www.biomedcentral.com/bmcevolbiol/en_ZA
dc.subject.otherBiodiversityen_ZA
dc.subject.otherGenetic Speciationen_ZA
dc.subject.otherPasseriformesen_ZA
dc.subject.otherPhylogeographyen_ZA
dc.subject.otherPigmentationen_ZA
dc.subject.otherSelection, Geneticen_ZA
dc.titleDiversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africaen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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