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Still, it is not unimaginable, within a lake as large as Victoria that they might also divide into separate populations along very subtle lines of variation -- like mating behaviors or feeding preferences.
This sort of interpretation of the situation in Lake Victoria, however, rests upon the notion that the species of cichlid found there evolved from a single ancestral species. Yet, even Meyer acknowledges that this might not be the case: "Within the past decade, however, morphology has increasingly emphasized the view that the flock may be polyphyletic." Put differently, it is possible that the species of cichlid that have evolved in Lake Victoria came from a group of distinct, but closely related, fish that colonized the region several thousand years ago. If this is the case, then the scientific importance of the Victorian cichlids would be somewhat diminished, because a less explosive series of adaptive radiations could explain their modern occurrence. Furthermore, it would bring into question some of the ideas surrounding population isolation with reference to speciation.
Even so, it is difficult to discount the value of the scientific consequences that a better understanding of the mechanisms that brought about the expansion of the haplochromines -- the informal designation of the cichlid groups -- in Lake Victoria would represent. If indeed they did descend from a single species, then it would bring together two major theories within the realm of evolutionary theory: adaptive radiation and punctuated equilibrium. The situation in Lake Victoria could, in fact, validate the underlying notions that Darwin expressed about the Galapagos finches, and the idea that
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Reference:
Goldschmidt, Tijs. 1998. Land-Use Changes and NIS in Lake Victoria. Bright and Lodge, 1998.
Kolar, Cynthia S. And David M. Lodge. 2000. Invasive Species in a Changing World. Washington D.C.: Island Press.
Meyer, Axel et al. 1990. Monophyletic Origin of Lake Victoria Cichlid Fishes Suggested by Mitochondrial DNA Sequences. Nature, 347.
Office of Protected Resources. 2005. Endangered Species Act of 1973. NOAA Fisheries. Available:
http://www.nmfs.noaa.gov/pr/laws/esa.htm.
Wilson, Edward O. 1992. The Diversity of Life. New York W.W. Norton and Company.
Office of Protected Resources. 2005. Endangered Species Act of 1973. NOAA Fisheries. Available: http://www.nmfs.noaa.gov/pr/laws/esa.htm.
Kolar, Cynthia S. And David M. Lodge. 2000. Invasive Species in a Changing World. Washington D.C.: Island Press. Page 15.
Wilson, Edward O. 1992. The Diversity of Life. New York W.W. Norton and Company. Page 108.
Goldschmidt, Tijs. 1998. Land-Use Changes and NIS in Lake Victoria. Bright and Lodge, 1998. Page 8.
Goldschmidt, Tijs.
Wilson 112.
Wilson 110.
Meyer, Axel et al. 1990. Monophyletic Origin of Lake Victoria Cichlid Fishes Suggested by Mitochondrial DNA Sequences. Nature, 347.
Reference:
Goldschmidt, Tijs. 1998. Land-Use Changes and NIS in Lake Victoria. Bright and Lodge, 1998.
Kolar, Cynthia S. And David M. Lodge. 2000. Invasive Species in a Changing World. Washington D.C.: Island Press.
Meyer, Axel et al. 1990. Monophyletic Origin of Lake Victoria Cichlid Fishes Suggested by Mitochondrial DNA Sequences. Nature, 347.
Office of Protected Resources. 2005. Endangered Species Act of 1973. NOAA Fisheries. Available:
http://www.nmfs.noaa.gov/pr/laws/esa.htm.
Office of Protected Resources. 2005. Endangered Species Act of 1973. NOAA Fisheries. Available: http://www.nmfs.noaa.gov/pr/laws/esa.htm.
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