Constancy and change of life in the sea
Abstract Uniformatarianism is the null hypothesis of geology and gradual speciation by natural selection the null hypothesis of evolution. Ecology is the link between the two. The expectation is that gradual changes in earth processes drive gradual shifts in species and communities. Many ecological...
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| Format: | Book Part |
| Language: | English |
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Oxford University PressOxford
1995
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| Online Access: | http://dx.doi.org/10.1093/oso/9780198548294.003.0003 https://academic.oup.com/book/chapter-pdf/52355754/isbn-9780198548294-book-part-3.pdf |
| Summary: | Abstract Uniformatarianism is the null hypothesis of geology and gradual speciation by natural selection the null hypothesis of evolution. Ecology is the link between the two. The expectation is that gradual changes in earth processes drive gradual shifts in species and communities. Many ecological and evolutionary trends are in agreement with this scenario (Overpeck et al. 1992), but much new evidence suggests that changes in climate may be abrupt and unstable, with lasting effects on the subsequent climate and biota (Crowley and North 1988; Kennett and Stott 1991). Sudden environmental change may underlie the nearly universal occurrence of discontinuities in morphology and community composition which mark the age, stage, and epoch boundaries of the geologic timescale which traditionally have been attributed to the imperfections of the fossil record (Darwin 1859; Levinton 1988). Here I review evidence that communities of molluscs, reef corals, and planktonic Foraminifera have changed very little since the end of the Pliocene approximately 2 million years ago (mya). After at least 8 million years (my) of relative faunal stability, turnover of Late Pliocene faunas required only a few hundred thousand years (ky). |
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