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Life-History Variation in Poa annua

Richard Law, A. D. Bradshaw and P. D. Putwain
Evolution
Vol. 31, No. 2 (Jun., 1977), pp. 233-246
DOI: 10.2307/2407745
Stable URL: http://www.jstor.org/stable/2407745
Page Count: 14
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Life-History Variation in Poa annua
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Abstract

An experiment is described in which samples of Poa annua from populations experiencing predominantly density-independent regulation are compared with others from populations experiencing predominantly density-dependent regulation. It is found that there are characteristic genetic differences between the life-histories of these populations. Those selected under density-independent regulation have shorter prereproductive periods, higher seed output early in life and shorter lives than those selected under density-dependent regulation. Rates of increase calculated from the life histories of each population are greater in those selected under density-independent regulation. The results help to confirm some recent theoretical predictions of life-history evolution.

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