Functional incompatability between the fertilization systems of two allopatric populations of Callosobruchus maculatus (Coleoptera: bruchidae)

Brown, Denise V. and Eady, Paul E. (2001) Functional incompatability between the fertilization systems of two allopatric populations of Callosobruchus maculatus (Coleoptera: bruchidae). Evolution: International Journal of Organic Evolution, 55 (11). pp. 2257-2262. ISSN 22572262

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Functional incompatability between the fertilization systems of two allopatric populations of Callosobruchus maculatus (Coleoptera: bruchidae)
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Official URL: http://dx.doi.org/10.1111/j.0014-3820.2001.tb00740...

Abstract

Recent studies indicate that postcopulatory sexual selection may represent an important component of the speciation process by initiating reproductive isolation via the evolutionary divergence of fertilization systems. Using two geographically isolated populations of the polyandrous beetle Callosobruchus maculatus, we investigated divergence in fertilization systems by determining the extent of postcopulatory functional incompatibility. Through reciprocal, cross-population matings we were able to separately estimate the effects of male and female population origin and their interaction on the extent of last-male sperm precedence, female receptivity to further copulation and female oviposition. Our results indicate partial incompatibility between the fertilization systems of the two populations at all three functional levels. Males derived from the same population as females outcompete rival, allopatric males with respect to sperm preemption, sperm protection, and ability to stimulate female oviposition. This pattern is reciprocated in both populations indicating that postcopulatory, prezygotic events represent important mechanisms by which between-population gene flow is reduced. We suggest the partial gametic isolation observed is a by-product of the coevolution of male and female fertilization systems by a process of cryptic female choice. Our results are consistent with a mechanism akin to conventional mate choice models although they do not allow us to reject antagonistic sexual coevolution as the mechanism of cryptic female choice.

Item Type:Article
Additional Information:Recent studies indicate that postcopulatory sexual selection may represent an important component of the speciation process by initiating reproductive isolation via the evolutionary divergence of fertilization systems. Using two geographically isolated populations of the polyandrous beetle Callosobruchus maculatus, we investigated divergence in fertilization systems by determining the extent of postcopulatory functional incompatibility. Through reciprocal, cross-population matings we were able to separately estimate the effects of male and female population origin and their interaction on the extent of last-male sperm precedence, female receptivity to further copulation and female oviposition. Our results indicate partial incompatibility between the fertilization systems of the two populations at all three functional levels. Males derived from the same population as females outcompete rival, allopatric males with respect to sperm preemption, sperm protection, and ability to stimulate female oviposition. This pattern is reciprocated in both populations indicating that postcopulatory, prezygotic events represent important mechanisms by which between-population gene flow is reduced. We suggest the partial gametic isolation observed is a by-product of the coevolution of male and female fertilization systems by a process of cryptic female choice. Our results are consistent with a mechanism akin to conventional mate choice models although they do not allow us to reject antagonistic sexual coevolution as the mechanism of cryptic female choice.
Keywords:Reproduction, Selection, Callosobruchus, sperm competition, Reproductive incompatibility, Gametic isolation, Cryptic female choice
Subjects:C Biological Sciences > C142 Reproductive Biology
C Biological Sciences > C170 Population Biology
C Biological Sciences > C710 Applied Molecular Biology, Biophysics and Biochemistry
Divisions:College of Science > School of Life Sciences
ID Code:898
Deposited By: Bev Jones
Deposited On:28 Jun 2007
Last Modified:13 Mar 2013 08:24

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