Colour Polymorphism and Alternative Breeding Strategies: Effects of Parent’s Colour Morph on Fitness Traits in the Common Wall Lizard
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Colour polymorphism (CP) is widespread in animals, but mechanisms underlying morph evolution and maintenance are not completely resolved. In reptiles, CP is often genetically based and associated with alternative behavioural strategies, mainly in males for most cases. However, female colour morphs also display alternative reproductive strategies associated with behavioural and physiological traits, which may contribute to maintain CP in the population. Both sexes of the common wall lizard (Podarcis muralis) show three pure colour morphs, white, yellow and red. Here, we looked for the effects of male and female colour morphs on fitness traits of captive-breeding pairs. All yellow-throated females laid clutches of many small eggs and produced many light offspring, behaving as r-strategists, whereas white-throated females laid clutches of few large eggs and produced few heavy offspring, behaving as K-strategists. Red-throated females adopted a conditional Kr-strategy depending on their size/age. These basic female strategies were modulated in relation to mate morph: white females had the best fitness gain in terms of viable offspring when mated to red males; mating between yellow morphs yielded a greater breeding success than all other morph crosses, but also lighter offspring; finally, red females produced heavy progeny when paired with red or white males, and light offspring in pair with yellow males. Thus, correlation between CP and traits relevant to fitness combined with non-random mating, either assortative or disassortative, could increase the potential for CP to contribute to divergent evolution in the common wall lizard.
KeywordsClutch size Colour polymorphism Breeding strategies Breeding success Egg size Morph combination Kr-strategy Podarcis muralis
We wish to thank Drs. F. Pupin, M. Melpignano, and M. Teofilo Pignati for their help with field and laboratory work. Many thanks are also due to Prof. M. B. Rasotto for her useful comments on an early draft of the paper. Research was supported by PhD grants (Doctorate in Experimental Ecology and Geobotany) from the University of Pavia to D. P.-R. and A. B. The study was carried out in conformity with the Italian current laws for lizard collection and detention.
The study was carried out with the agreement of the Ministero dell’Ambiente Italiano (Aut. Prot. DPN no. 2009-0016034, validity 2009–2011).
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