The Holocene History of Lake Victoria

Johnson, Thomas C.; Kelts, Kerry; Odada, Eric O.

doi:10.1579/0044-7447-29.1.2

Cited by 180 publications

(128 citation statements)

References 49 publications

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“…We dated divergence within the Lake Victoria catchment to 0.120 (±0.110 SD) and 0.089 (±0.074 SD) MYA using the Gondwanan fragmentation and cichlid fossil calibrations, respectively. Both estimates are within the age of the Lake Victoria catchment formation, approximately 400,000 years ago (Johnson et al 2000).…”

Section: Accumulation Of Genetic Diversity Within African Radiationsmentioning

confidence: 51%

Age of Cichlids: New Dates for Ancient Lake Fish Radiations

Genner

Seehausen

Lunt

et al. 2007

Molecular Biology and Evolution

265

344

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Timing divergence events allow us to infer the conditions under which biodiversity has evolved and gain important insights into the mechanisms driving evolution. Cichlid fishes are a model system for studying speciation and adaptive radiation, yet, we have lacked reliable timescales for their evolution. Phylogenetic reconstructions are consistent with cichlid origins prior to Gondwanan landmass fragmentation 121-165 MYA, considerably earlier than the first known fossil cichlids (Eocene). We examined the timing of cichlid evolution using a relaxed molecular clock calibrated with geological estimates for the ages of 1) Gondwanan fragmentation and 2) cichlid fossils. Timescales of cichlid evolution derived from fossil-dated phylogenies of other bony fishes most closely matched those suggested by Gondwanan breakup calibrations, suggesting the Eocene origins and marine dispersal implied by the cichlid fossil record may be due to its incompleteness. Using Gondwanan calibrations, we found accumulation of genetic diversity within the radiating lineages of the African Lakes Malawi, Victoria and Barombi Mbo, and Palaeolake Makgadikgadi began around or after the time of lake basin formation. These calibrations also suggest Lake Tanganyika was colonized independently by the major radiating cichlid tribes that then began to accumulate genetic diversity thereafter. These results contrast with the widely accepted theory that diversification into major lineages took place within the Tanganyika basin. Together, this evidence suggests that ancient lake habitats have played a key role in generating and maintaining diversity within radiating lineages and also that lakes may have captured preexisting cichlid diversity from multiple sources from which adaptive radiations have evolved.

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Section: Accumulation Of Genetic Diversity Within African Radiationsmentioning

confidence: 51%

Age of Cichlids: New Dates for Ancient Lake Fish Radiations

Genner

Seehausen

Lunt

et al. 2007

Molecular Biology and Evolution

265

344

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“…In some small lakes, the proxies may have very simple explanations, because they consist of simple sedimentary processes [4], but these environmental conditions might only have local representations. Proxies from large lakes are indicators of the regional environment, but development of proper understanding and explanation of these factors is always difficult because large lakes have complicated sedimentary processes [5].…”

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confidence: 99%

The spatial distribution and sedimentary processes of organic matter in surface sediments of Nam Co, Central Tibetan Plateau

et al. 2012

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In this study, 67 surface sediment samples collected from Nam Co in central Tibet were analyzed for total carbon, total organic carbon and total nitrogen, and 51 of these samples were also analyzed for n-alkanes. The origin and spatial distribution of organic matter were then investigated using these proxies, and the control factors responsible for the spatial distribution patterns and paleolimnological significance were discussed. The results indicated that the origin of organic matter in surface sediment of Nam Co is consistent with the sources of n-alkanes, which were primarily submerged plants, followed by terrestrial plants, and then aquatic algae and bacteria. The organic matter in surface sediments of the lake showed typical spatial variability. Because of the great influence of underwater topography, river inputs and water quality, the spatial distribution of organic matter is enriched from the source to the deposit center. This spatial variability of organic matter in the lake indicates that the sediments in different areas have different sensitivities to environmental changes, which is important to reconstruction of paleoenvironments and paleoclimate using lake sediment cores.Tibetan Plateau, Nam Co, surface sediments, spatial distribution, sedimentary processes Citation:Wang Y, Zhu L P, Wang J B, et al. The spatial distribution and sedimentary processes of organic matter in surface sediments

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“…It is shared by Kenya, Uganda and Tanzania in the ratios 6%, 45% and 49% of the surface area (Johnson et al, 2000). It stretches 412 km from North to South between 0°30'N and 3°12'S and 355 km from West to East between 31°37'W and 34°53'E, and lies across the equator at an altitude of 1135 m above sea level (Johnson et al, 2000).The lake is relatively shallow, with a maximum depth of 80 m and an average depth of 40 m. Nyanza gulf is a large inlet from Lake Victoria that extends into Kenya, and it is comparatively shallow, with maximum and average depth of 68 m and 6 m respectively.…”

Section: Materials and Methods:-mentioning

confidence: 99%