Phylogeography of Haplochromine Fish in the Lake Victoria Region

Engelken, Johannes

Phylogeography of Haplochromine Fish in the Lake Victoria Region

Dateien

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Datum

2002

Open Access-Veröffentlichung

Open Access Green

Sammlungen

Biologie

Publikationstyp

Bachelorarbeit

Publikationsstatus

Published

Zusammenfassung

The three Great East African Lakes are important model systems for evolutionary research. Among other things the massive adaptive radiations of cichlid fish are of interest. The so-called species flock consisting of several hundred endemic cichlid species, which occurs in the region of Lake Victoria, was derived from a single founder population and therefore has a monophyletic origin. It is uncertain, however, when and where this adaptive radiation took place and how the lake was populated. Previous studies were not able to give sufficient answers. Especially, when one considers a recent geological study which suggests the complete desiccation of Lake Victoria about 18.000 to 12 400 years ago. Therefore a characterization of the phylogeography of populations of cichlids of waters nearby was carried out in the present study. Most of these waters were firstly examined in this context. Mitochondrial DNA (D-Loop) of 70 cichlids from the region was sequenced and analyzed, together with unpublished sequences from Lake Kivu and sequences from previous studies. In this way a new picture of the history of Lake Victoria´s cichlid species flock could be drawn. The classification of the cichlids from the different waters could be resolved doubtlessly, whereas interpretation of the data rises new questions. The phylogeographic analyses suggest, that the genetic prerequisites for the adaptive radiation did not necessarily arise in Lake Victoria itself, but possibly in another deep body of water like Lake Kivu. A big founder population could have populated Lake Victoria less than 12.400 years ago. Following that, the special conditions within the lake made possible the astonishingly fast radiation of several hundred species.

Zusammenfassung in einer weiteren Sprache

Die großen Ostafrikanischen Seen sind wichtige Modellsysteme für die Evolutionsforschung. Unter anderem werden hier die massiven adaptiven Radiationen der Buntbarsche (Familie Cichlidae) untersucht. Der sogenannte Artenschwarm aus vielen hundert endemischen Buntbarscharten, der im Gebiet des Viktoriasees vorkommt, ist aus einer einzigen Gründerpopulation hervorgegangen und ist demnach monophyletischen Ursprungs. Wann und wo diese adaptive Radiation allerdings stattgefunden hat und wie der See besiedelt wurde, ist unklar. Bisherige Studien konnten diese Fragen nicht restlos klären. Besonders dann nicht, wenn man eine aktuelle geologische Studie in Betracht zieht, nach welcher der Viktoriasee vor etwa 18 000 bis 12.400 Jahren völlig ausgetrocknet war. Deshalb wurde in der vorliegenden Arbeit eine phylogeographische Charakterisierung der Buntbarschpopulationen einiger in der Region liegender Gewässer vorgenommen. Die meisten dieser Gewässer wurden erstmalig in diesem Zusammenhang untersucht. Mitochondriale DNS (D-Loop) von 70 Buntbarschen der Region wurde sequenziert und mit bisher unveröffentlichte Sequenzen aus dem Kivusee und Sequenzen voriger Studien analysiert. Damit konnte ein verändertes Bild der Geschichte des Buntbarsch-Artenschwarmes des Viktoriasees gezeichnet werden. Die Zugehörigkeit der Buntbarsche der verschiedenen Gewässer konnte zweifelsfrei aufgeklärt werden, wobei ihre Interpretation neue Fragen aufwirft. Die phylogeographischen Analysen geben Hinweise darauf, dass die genetischen Vorraussetzungen für die adaptive Radiation nicht unbedingt im Viktoriasee selbst entstanden, sondern in einem anderen tiefen Gewässer wie dem Kivusee. Eine große Gründerpopulation könnte vor weniger als 12 400 Jahren den Viktoriasee besiedelt haben und dieser ermöglichte mit seinen besonderen Bedingungen dann die erstaunlich schnelle Artaufspaltung in viele hundert verschiedener Arten.

Fachgebiet (DDC)

570 Biowissenschaften, Biologie

Schlagwörter

Phylogeographie, phylogeography, Viktoriasee, Lake Victoria, haplochromines, Buntbarsche, cichlids

Zitieren

ISO 690

ENGELKEN, Johannes, 2002. Phylogeography of Haplochromine Fish in the Lake Victoria Region [Bachelor thesis]

BibTex

@mastersthesis{Engelken2002Phylo-8494,
  year={2002},
  title={Phylogeography of Haplochromine Fish in the Lake Victoria Region},
  author={Engelken, Johannes}
}

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