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Genetic drift in range expansions is very sensitive to density dependence in dispersal and growth
Author(s) -
Birzu Gabriel,
Matin Sakib,
Hallatschek Oskar,
Korolev Kirill S.
Publication year - 2019
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/ele.13364
Subject(s) - biological dispersal , density dependence , range (aeronautics) , sublinear function , population , population density , ecology , biology , statistical physics , physics , mathematics , materials science , demography , mathematical analysis , sociology , composite material
Abstract Theory predicts rapid genetic drift during invasions, yet many expanding populations maintain high genetic diversity. We find that genetic drift is dramatically suppressed when dispersal rates increase with the population density because many more migrants from the diverse, high‐density regions arrive at the expansion edge. When density dependence is weak or negative, the effective population size of the front scales only logarithmically with the carrying capacity. The dependence, however, switches to a sublinear power law and then to a linear increase as the density dependence becomes strongly positive. We develop a unified framework revealing that the transitions between different regimes of diversity loss are controlled by a single, universal quantity: the ratio of the expansion velocity to the geometric mean of dispersal and growth rates at expansion edge. Our results suggest that positive density dependence could dramatically alter evolution in expanding populations even when its contribution to the expansion velocity is small.