Extinction of populations due to inbreeding depression with demographic disturbances |
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Authors: | Yoshinari Tanaka |
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Institution: | (1) Laboratory of Theoretical Ecology, Institute of Environmental Science and Technology, Yokohama National University, Tokiwadai 79-7, Hodogaya-ku, Yokohama 240, Japan |
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Abstract: | The process of population extinction due to inbreeding depression with constant demographic disturbances every generation
is analysed using a population genetic and demographic model. The demographic disturbances introduced into the model represent
loss of population size that is induced by any kind of human activities, e.g. through hunting and destruction of habitats.
The genetic heterozygosity among recessive deleterious genes and the population size are assumed to be in equilibrium before
the demographic disturbances start. The effects of deleterious mutations are represented by decreases in the growth rate and
carrying capacity of a population. Numerical simulations indicate rapid extinction due to synergistic interaction between
inbreeding depression and declining population size for realistic ranges of per-locus mutation rate, equilibrium population
size, intrinsic rate of population growth, and strength of demographic disturbances. Large populations at equilibrium are
more liable to extinction when disturbed due to inbreeding depression than small populations. This is a consequence of the
fact that large populations maintain more recessive deleterious mutations than small populations. The rapid extinction predicted
in the present study indicates the importance of the demographic history of a population in relation to extinction due to
inbreeding depression. |
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Keywords: | extinction inbreeding depression deleterious mutation genetic load conservation biology |
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