SEXUAL DIMORPHISM AND SPECIATION ON TWO ECOLOGICAL COINS: PATTERNS FROM NATURE AND THEORETICAL PREDICTIONS

Adaptive divergence of phenotypes, such as sexual dimorphism or adaptive speciation, can result from disruptive selection via competition for limited resources. Theory indicates that speciation and sexual dimorphism can result from identical ecological conditions, but co-occurrence is unlikely becau...

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Bibliographic Details
Published in:Evolution 2011-09, Vol.65 (9), p.2553-2571
Main Authors: Cooper, Idelle A., Gilman, R. Tucker, Boughman, Janette Wenrick
Format: Article
Language:English
Subjects:
Adaptation, Biological
Adaptive radiation
adaptive splitting
Animal behavior
Animal populations
Animals
Biological Evolution
Body Size
British Columbia
Computer simulation
disruptive selection
Ecological competition
ecological dimorphism
Ecological disturbance
Ecological genetics
Ecological modeling
Ecological selection
Evolution
Female
Fish
Genetic Speciation
Head - anatomy & histology
Lakes
Male
Models, Biological
Multivariate Analysis
Phenotypes
Polymorphism
Population ecology
Selection, Genetic
Sex Characteristics
Sexual dimorphism
Smegmamorpha - anatomy & histology
Smegmamorpha - genetics
Speciation
stickleback species pair
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Summary:Adaptive divergence of phenotypes, such as sexual dimorphism or adaptive speciation, can result from disruptive selection via competition for limited resources. Theory indicates that speciation and sexual dimorphism can result from identical ecological conditions, but co-occurrence is unlikely because whichever evolves first should dissipate the disruptive selection necessary to drive evolution of the other. Here, we consider ecological conditions in which disruptive selection can act along multiple ecological axes. Speciation in lake populations of threespine sticklebacks (Gasterosteus aculeatus) has been attributed to disruptive selection due to competition for resources. Head shape in sticklebacks is thought to reflect adaptation to different resource acquisition strategies. We measure sexual dimorphism and species variation in head shape and body size in stickleback populations in two lakes in British Columbia, Canada. We find that sexual dimorphism in head shape is greater than interspecific differences. Using a numerical simulation model that contains two axes of ecological variation, we show that speciation and sexual dimorphism can readily co-occur when the effects of loci underlying sexually dimorphic traits are orthogonal to those underlying sexually selected traits.
ISSN:0014-3820
1558-5646
DOI:10.1111/j.1558-5646.2011.01332.x