Female-biased sex ratio is a common phenomenon in parasites; however, the cause and consequence of the skewed sex ratio is less well known. Here, we studied the difference in sex ratio, a possible mechanism responsible for the development of unbalanced proportion of sexes and its consequences on sexual size dimorphism, between 3 louse species parasitizing the house sparrow Passer domesticus. Philopterus fringillae was more prevalent than Sturnidoecus refractariolus and Brueelia cyclothorax. As expected, the most common species, which was probably least affected by isolation and, hence, inbreeding, was characterized by a balanced sex ratio, whereas the 2 other species with low prevalence were significantly more female biased than expected on the basis of the local mate competition hypothesis. Further, in support of this notion, we found that P. fringillae infrapopulation size significantly, and positively, correlated with the sex ratio. Finally, we found significant differences in sexual dimorphism among the 3 louse species and, as expected, the relative size of males was smallest in species with a more female-biased sex ratio.
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1 February 2013
Sex Ratio and Sexual Dimorphism of Three Lice Species with Contrasting Prevalence Parasitizing the House Sparrow
Péter László Pap,
Costică Adam,
Csongor István Vágási,
Zoltán Benkő,
Orsolya Vincze
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Journal of Parasitology
Vol. 99 • No. 1
February 2013
Vol. 99 • No. 1
February 2013