Summary: Conspecific sperm precedence in flour beetles
CLAUDIA FRICKE & GO¨ RAN ARNQVIST
Evolutionary Biology Centre, Department of Animal Ecology, Uppsala University
(Received 9 April 2003; initial acceptance 27 May 2003;
final acceptance 24 August 2003; MS. number 7677)
Two related species may mate readily yet rarely form hybrid zygotes. Such cryptic reproductive isolation
may occur as a result of conspecific sperm precedence, suggesting that postmating sexual selection is a key
process in speciation. However, demonstrating conspecific sperm precedence is nontrivial, and several
methodological problems may confound the results of such studies. By mating females to conspecific and
heterospecific males of varying degree of relatedness, we established the existence of conspecific sperm
precedence in flour beetles, Tribolium spp. Postmating incompatibilities seem to accumulate rapidly in this
group of insects, and we discuss the implications of our findings for the influence of postmating sexual
selection on speciation.
Ó 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
The evolution of reproductive isolation is key in the
formation of new species. In the absence of behavioural
isolation, partial reproductive isolation may be cryptic.
That is, conspecific male gametes are used preferentially
for the fertilization of eggs when females mate with both
conspecific and heterospecific males (Howard 1999; Eady