On the Age and Origin of Lake Ejagham, Cameroon, and Its Endemic Fishes
| Autor: | Kenneth Alton, Jay Curt Stager, Brendan Wiltse, D. A. Livingstone, David T. King, Christopher Martin, Lucille W. Petruny |
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| Rok vydání: | 2017 |
| Předmět: |
0106 biological sciences
Evolution Speciation media_common.quotation_subject 010502 geochemistry & geophysics 010603 evolutionary biology 01 natural sciences Physical Geography and Environmental Geoscience law.invention West African monsoon Arts and Humanities (miscellaneous) Cichlid law parasitic diseases Paleoclimatology Cameroon Radiocarbon dating Endemism 0105 earth and related environmental sciences Earth-Surface Processes media_common geography geography.geographical_feature_category biology Ecology Lake Ejagham Paleontology Sediment Diatom Geology biology.organism_classification Archaeology Volcano Africa General Earth and Planetary Sciences |
| Zdroj: | Quaternary Research, vol 89, iss 1 Quaternary Research (United States), vol 89, iss 1 |
| ISSN: | 1096-0287 0033-5894 |
| DOI: | 10.1017/qua.2017.37 |
| Popis: | Lake Ejagham is a small, shallow lake in Cameroon, West Africa, which supports five endemic species of cichlid fishes in two distinct lineages. Genetic evidence suggests a relatively young age for the species flocks, but supporting geologic evidence has thus far been unavailable. Here we present diatom, geochemical, mineralogical, and radiocarbon data from two sediment cores that provide new insights into the age and origin of Lake Ejagham and its endemic fishes. Radiocarbon ages at the base of the longer core indicate that the lake formed approximately 9 ka ago, and the diatom record of the shorter core suggests that hydroclimate variability during the last 3 millennia was similar to that of other lakes in Cameroon and Ghana. These findings establish a maximum age of ca. 9 cal ka BP for the lake and its endemic species and suggest that repeated cichlid speciation in two distinct lineages occurred rapidly within the lake. Local geology and West African paleoclimate records argue against a volcanic, chemical, or climatic origin for Lake Ejagham. Although not conclusive, the morphometry of the lake and possible signs of impact-induced effects on quartz grains are instead more suggestive of a bolide impact. |
| Databáze: | OpenAIRE |
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