Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/51156
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Type: Journal article
Title: Variation in phenotype, parasite load and male competitive ability across a cryptic hybrid zone
Author: Stuart-Fox, D.
Godinho, R.
de Bellocq, J.
Irwin, N.
Brito, J.
Moussalli, A.
Siroky, P.
Hugall, A.
Baird, S.
Citation: PLoS One, 2009; 4(5):1-10
Publisher: Public Library of Science
Issue Date: 2009
ISSN: 1932-6203
1932-6203
Statement of
Responsibility: 
Devi Stuart-Fox, Raquel Godinho, Joëlle Goüy de Bellocq, Nancy R. Irwin, José Carlos Brito, Adnan Moussalli, Pavel Široký, Andrew F. Hugall and Stuart J. E. Baird
Abstract: <h4>Background</h4>Molecular genetic studies are revealing an increasing number of cryptic lineages or species, which are highly genetically divergent but apparently cannot be distinguished morphologically. This observation gives rise to three important questions: 1) have these cryptic lineages diverged in phenotypic traits that may not be obvious to humans; 2) when cryptic lineages come into secondary contact, what are the evolutionary consequences: stable co-existence, replacement, admixture or differentiation and 3) what processes influence the evolutionary dynamics of these secondary contact zones?<h4>Methodology/principal findings</h4>To address these questions, we first tested whether males of the Iberian lizard Lacerta schreiberi from two highly genetically divergent, yet morphologically cryptic lineages on either side of an east-west secondary contact could be differentiated based on detailed analysis of morphology, coloration and parasite load. Next, we tested whether these differences could be driven by pre-copulatory intra-sexual selection (male-male competition). Compared to eastern males, western males had fewer parasites, were in better body condition and were more intensely coloured. Although subtle environmental variation across the hybrid zone could explain the differences in parasite load and body condition, these were uncorrelated with colour expression, suggesting that the differences in coloration reflect heritable divergence. The lineages did not differ in their aggressive behaviour or competitive ability. However, body size, which predicted male aggressiveness, was positively correlated with the colour traits that differed between genetic backgrounds.<h4>Conclusions/significance</h4>Our study confirms that these cryptic lineages differ in several aspects that are likely to influence fitness. Although there were no clear differences in male competitive ability, our results suggest a potential indirect role for intra-sexual selection. Specifically, if lizards use the colour traits that differ between genetic backgrounds to assess the size of potential rivals or mates, the resulting fitness differential favouring western males could result in net male-mediated gene flow from west to east across the current hybrid zone.
Keywords: Animals; Lizards; Parasites; Body Size; Spectrum Analysis; Discriminant Analysis; Sample Size; Aggression; Competitive Behavior; Phylogeny; Quantitative Trait, Heritable; Phenotype; Geography; Male
Rights: © 2009 Stuart-Fox et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
RMID: 0020091446
DOI: 10.1371/journal.pone.0005677
Appears in Collections:Earth and Environmental Sciences publications

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