| Popis: |
Fossil fauna at paleoanthropological sites provides evidence for speciation and extinction events throughout the Plio-Pleistocene. Regarding fauna, first and last appearance dates are temporally clustered around time periods that correlate with climatic shift. The Turnover-Pulse Hypothesis asserts climate change as the cause of punctuated speciation and extinction events. Contending that climate is the cause of first and last appearance of species may be spurious due to inherent sampling biases in the fossil record. Species divergence and extinction may be influenced by climate, but the ultimate cause of species turnover is unclear. This research project required compilation of datasets of first and last appearance dates from South Africa and east Africa. These datasets were used to derive rates of species turnover in order to program a model to simulate the fossil record. Development of a species turnover simulation was undertaken utilizing mathematical modeling software (Matlab). Continuous speciation and extinction was simulated over 3.2 million years for South African fauna and 4.4 million years for east African fauna. Simulated continuous speciation and extinction produces peaks of turnover similar to turnover-pulses. Therefore, the fossil record is unable to support the Turnover-Pulse Hypothesis’s reliance on climate change as a causal mechanism for speciation and extinction. Rather, patterns of first and last appearance dates that indicate peaks of species turnover are a product of biased sampling. |
