Evolutionary Trends

Abstract

An evolutionary trend can be defined as a persistent, directional change in a character state, or set of character states, resulting in a significant change through time.

Keywords: evolutionary trends; Cope's rule; macroevolution; microevolution; complexity

Figure 1.

Cladogenetic body‐size evolution via migration and speciation into environments that select for larger sizes. Note the occurrence of anagenetic size change as well. Reproduced with permission from McNamara . Copyright Kenneth J. McNamara, .

Figure 2.

Diagrammatic illustration of the large‐scale evolutionary trend from epifaunal, browsing regular echinoids, through shallow‐burrowing, sand‐dwelling echinoids to deeper‐burrowing, mud‐dwelling echinoids through the Mesozoic and Cenozoic. Persistence of ancestral ecomorphs illustrates increase in variance. Reproduced with permission from McNamara . Copyright Kenneth J. McNamara, .

Figure 3.

Paedomorphocline of species of the brachiopods Tegulorhynchia and Notosaria, illustrating evolutionary trends through the Cenozoic in temporal narrowing of the shell, reduction in number of ribs, decrease in beak angle and increase in relative foramen size by progressive reduction in extent of growth of deltidial plates. These morphological trends are thought to have evolved along an environmental gradient of deep to shallow water. Abbreviations: PS, Pleistocene; R, Recent. Reproduced with permission from McNamara . Copyright Kenneth J. McNamara, .

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References

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Further Reading

Alroy J (1998) Cope's rule and the dynamics of body mass evolution in North American fossil mammals. Science 280: 731–734.

Bales GS (1996) Heterochrony in brontothere horn evolution: allometric interpretations and the effect of life history scaling. Paleobiology 22(4): 481–495.

Bonner JT (1988) The Evolution of Complexity. Princeton: Princeton University..

Conway Morris S (2003) Life's Solution: Inevitable Humans in a Lonely Universe. Cambridge: Cambridge University Press.

Dilcher D (2000) Toward a new synthesis: major evolutionary trends in the angiosperm fossil record. Proceedings of the National Academy of Sciences of the USA 97: 7030–7036.

Jablonski D (1997) Body‐size evolution in Cretaceous molluscs and the status of Cope's rule. Nature 385: 250–252.

Jablonski D, Erwin DH and Lipps JH (eds) (1996) Evolutionary Paleobiology. Chicago: University of Chicago Press.

Maynard Smith J and Szathmáry E (1995) The Major Transitions in Evolution. Oxford: Oxford University Press.

McNamara KJ (1982) Heterochrony and phylogenetic trends. Paleobiology 8: 130–142.

Roopnarine PD, Byars G and Fitzgerald P (1999) Anagenetic evolution, stratophenetic patterns and random walk models. Paleobiology 25: 41–57.

Ross RM and Allmon WD (eds) (1990) Causes of Evolution: A Paleontological Perspective. Chicago: University of Chicago Press.

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How to Cite close
McNamara, Kenneth J(Apr 2006) Evolutionary Trends. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0004136]