On the meaning and existence of an effective population size.
We investigate conditions under which a model with stochastic demography or population structure converges to the coalescent with a linear change in timescale. We argue that this is a necessary condition for the existence of a meaningful effective population size. We find that such a linear timescale change is obtained when demographic fluctuations and coalescence events occur on different timescales. Simple models of population structure and randomly fluctuating population size are used to exemplify the ideas and provide an intuitive feel for the meaning of the conditions.
Department of Conservation Biology and Genetics, Evolutionary Biology Center, Uppsala University, S-752 36, Uppsala, Sweden. per.sjodin@ebc.uu.se
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P
Sjödin
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I
Kaj
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S
Krone
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M
Lascoux
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M
Nordborg
D003198:Computer Simulation; D003710:Demography; D005828:Genetics, Population; D008390:Markov Chains; D008957:Models, Genetic; D008962:Models, Theoretical; D011156:Population Density; D011157:Population Dynamics; D013269:Stochastic Processes; D013997:Time Factors