Climatic perturbation and speciation of Southern and Eastern African Bulbul/Greenbul species (family Pycnonotidae)

Lokugalappatti, L.G. Sampath (2011-12)

Thesis (PhD (Botany and Zoology))--Stellenbosch University, 2011.

Thesis

ENGLISH ABSTRACT: African greenbuls are an ideal model system with which to explore different hypothesis that may underlie observed patterns of lineage diversification. Among those few hypotheses amenable to falsification by phylogenetic methods concerning the diversification of the southern and east African biota, three can be singled out because of their verifiable predictions: the Plio-Pleistocene refugia, montane speciation and the gradient hypotheses. I used phylogenetic and population genetics methods to reconstruct the diversification history of three African greenbul species/species complexes (Pycnonotidae) in southern and east Africa. My study established that most of the greenbul diversification took place in Plio- Pleistocene and the primary mechanism appears to be climatic cycling, yet dispersal and vicarince too have shaped the population genetic structure. The pattern of diversification observed in the three study taxa/species complexes differs substantially and can mostly be explained by the Pleistocene refuge hypothesis. The study did not support the montane speciation hypothesis as articulated by Roy (1997) for some of the montane Andropadus taxa. Phylogeographic and population genetics analyses on the grey-olive greenbul found a close association between palaeodrainage systems and swampy areas (seeps) as an important habitat configuration for diversification of lineages restructured to these patchy habitats. Historical demographic analysis on Sombre greenbul revealved evidence for putative eastern and southern coastal forest refugia. Further, this study revealed the complex nature of East African biogeography, and two possible routes of dispersal from Albertine Rift refugia to the Eastern Arc and East African coastal forest in the Yellow-streaked greenbul complex.

AFRIKAANSE OPSOMMING: Afrika greenbuls is 'n ideale modelstelsel wat gebruik kan word om verskillende hipotese rakend die waargenome patrone van lyndiversifisering te verken. Onder dié paar hipoteses met betrekking tot die diversifisering van die suidelike en oos Afrika biota wat ontvanklik is vir vervalsing deur filogenetiese metodes, kan drie uitgesonder word as gevolg van hulle verifieerbare voorspellings: die Plio-Pleistoseen toevlugs-, bergspesiasie- en die gradiënt hipoteses. Ek gebruik filogenetiese en bevolkingsgenetiese metodes om die diversifikasiegeskiedenis van die drie Afrikaanse greenbul spesies / spesiekomplekse (Pycnonotidae) te rekonstrueer in die suidelike en oos Afrika. My studie bevind dat meeste van die greenbul diversifikasie plaasgevind het in Plio- Pleistoseen en die primêre meganisme blyk klimaatsverandering te wees alhoewel verspreiding en vikariansie ook bygedra het tot die algemene bevolkingstruktuur. Die waargenome patroon van diversifikasie in die drie studie taxa / spesiekomplekse verskil aansienlik van mekaar maar kan meestal verklaar word deur die Pleistoseen toevlugshipotese. Die studie het egter geen ondersteuning gevind vir die bergspesiasiehipotese soos verwoord deur Roy (1997) vir 'n paar van die berg Andropadus taxa nie. Filogeografiese- en bevolkingsgenetiese ontledings op die grys-olyf greenbul het 'n noue verband gevind tussen palaeodreineringstelsels en moerasgebiede (syferwater) as' n belangrike habitatdrywer vir diversifisering van lyne wat gestruktureer is rondom verbreekte habitatte. Historiese demografiese analises op die Sombre greenbul het moontlike oostelike en suidelike kuswoud heenkomes uitgewys. Hierdie studie het ook die komplekse aard van Oos- Afrika biogeografie ontbloot, asook twee moontlike roetes van verspreiding vanaf die Albertine Rif na die Oostelike Ark asook Oos-Afrika kuswoude in die geel-gestreepte greenbul-kompleks.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/18100
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