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San Miguel de Tucumán, Argentina

Vanhooydonck B.,University of Antwerp | Cruz F.B.,CONICET | Abdala C.S.,Institute Herpetologia FML | Azocar D.L.M.,CONICET | And 2 more authors.
Biological Journal of the Linnean Society | Year: 2010

Although differential selective pressures on males and females of the same species may result in sex-specific evolutionary trajectories, comparative studies of adaptive radiations have largely neglected within-species variation. In this study, we explore the potential effects of natural selection, sexual selection, or a combination of both, on bite performance in males and females of 19 species of Liolaemus lizards. More specifically, we study the evolution of bite performance, and compare evolutionary relationships between the variation in head morphology, bite performance, ecological variation and sexual dimorphism between males and females. Our results suggest that in male Liolaemus, the variation in bite force is at least partly explained by the variation in the degree of sexual dimorphism in head width (i.e. our estimate of the intensity of sexual selection), and neither bite force nor the morphological variables were correlated with diet (i.e. our proxy for natural selection). On the contrary, in females, the variation in bite force and head size can, to a certain extent, be explained by variation in diet. These results suggest that whereas in males, sexual selection seems to be operating on bite performance, in the case of females, natural selection seems to be the most likely and most important selective pressure driving the variation in head size. © 2010 The Linnean Society of London.

Szumik C.,CONICET | Aagesen L.,CONICET | Casagranda D.,CONICET | Arzamendia V.,CONICET | And 20 more authors.
Cladistics | Year: 2012

The idea of an area of endemism implies that different groups of plants and animals should have largely coincident distributions. This paper analyses an area of 1152000km 2, between parallels 21 and 32°S and meridians 70 and 53°W to examine whether a large and taxonomically diverse data set actually displays areas supported by different groups. The data set includes the distribution of 805 species of plants (45 families), mammals (25 families), reptiles (six families), amphibians (five families), birds (18 families), and insects (30 families), and is analysed with the optimality criterion (based on the notion of endemism) implemented in the program NDM/VNDM. Almost 50% of the areas obtained are supported by three or more major groups; areas supported by fewer major groups generally contain species from different genera, families, or orders. © 2011 The Willi Hennig Society.

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