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Summary: Natural selection hampers divergence of reproductive traits
in a seed beetle
C. FRICKE1
, C. ANDERSSON & G. ARNQVIST
Evolutionary Biology Centre, Department of Ecology and Evolution, Animal Ecology, Uppsala University, Norbyva¨gen 18D, Uppsala, Sweden
Ever since Darwin (1859) made his case for the
diversifying nature of natural selection, evolutionary
biologists have recognized the crucial role that adaptive
evolution may play in population divergence and
speciation. Although genetic drift can clearly contribute
to the diversification of traits and ultimately the evolu-
tion of reproductive isolation, empirical work during the
last few decades suggests that selection generally plays
the larger role (Schluter, 2000; Coyne & Orr, 2004). In
theory, selection can cause evolutionary diversification
in reproductive traits that result in reproductive isolation
by either direct or indirect selection (Coyne & Orr,
2004). Direct selection on reproductive traits may occur
in sympatric or parapatric populations and will occur
whenever individuals showing greater discriminatory
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