Multivariate and geometric morphometrics in the analysis of sexual dimorphism variation in Podarcis lizards

Abstract

Podarcis bocagei and P. carbonelli are two closely related lacertid species, very similar morphologically and ecologically. We investigated sexual dimorphism patterns presented by both species in allopatry and in sympatry. Sexual size and shape dimorphism patterns were analyzed using both multivariate and geometric morphometric techniques. Multivariate morphometrics revealed a marked sexual dimorphism in both species-males being larger with more robust habitus and females presenting a longer trunk. General patterns of sexual size dimorphism are not modified in sympatry, although there is evidence for some morphological change in male head size. The application of geometric morphometrics offered a more detailed image of head shape and revealed that males present a more developed tympanic area than do females, while females have a more rounded head. Differences in the degree of sexual shape dimorphism were detected in sympatry, but no consistent patterns were observed. From the results of the study, and based on previous knowledge on the populations studied, we conclude that the morphological differences observed are probably not caused by exploitative competition between the species, but rather appear attributable to the modification of the relative influence of sexual and natural selection on both sexes. J. Morphol. 268:152-165, 2007 2007 Wiley-Liss, Inc.

Altitudinal effects on the life history of the Anatolian lizard(Apathya cappadocica, Werner 1902) from southeastern Anatolia, Turkey

“…Most species of lacertid lizards are male-biased in terms of body size and head dimensions (Kaliontzopoulou et al, 2007). Our study points out the life history traits of A. cappadocica across altitudinal gradients from 3 populations in southeastern Anatolia, Turkey, and the results of this study showed that the males of this species were larger than females in 3 populations (male-biased SSD).…”

Analyzing Fluctuating Asymmetry with Geometric Morphometrics: Concepts, Methods, and Applications

“…Therefore, the consensus shape from this Procrustes fit yields an estimate of the median axis or plane that takes into account the information from all the landmarks. This approach avoids the need for any ad-hoc assumptions that some landmarks, for instance those at anterior and posterior extremes of the midline, are more "reliable" than others and are therefore better suited for identifying the median line or plane [215][216][217][218][219][220][221].…”

“…Alternative approaches, such as using various ad-hoc procedures for identifying a median axis from just some landmarks [215][216][217][218][219][220][221] or ignoring the symmetry of the structure altogether [227][228][229][230], seem clearly inferior to the Procrustes approach for object symmetry. Using only half of a symmetric structure, which was a reasonable recommendation before methods to deal with object symmetry were available [34], is still sometimes used [231][232][233][234], but also has a number or disadvantages because it offers no principled way of removing potentially confounding asymmetry in the structure [13,235].…”

Traditional and geometric morphometrics detect morphological variation of lower pharyngeal jaw inCoris julis(Teleostei, Labridae)

“…Statistical analyses were performed on symmetrized half-configurations and not on whole configurations, because if whole configurations were used the very high correlations between members of each pair of symmetric semilandmarks would potentially lead to the within-group covariance matrix being nearly singular and statistical analyses, such as CVA, that require within-group covariance matrix inversion would not be possible (Corti et al 2001;Klingenberg et al 2002). For visualization purposes the sizestandardized half-configurations were regressed on the canonical scores using tpsRegr (Rohlf 2007b), a procedure previously used for landmark data Cavalcanti 2004;Kaliontzopoulou et al 2007). The estimated extreme shapes of such regressions were then back-reflected using the program LMEdit of the IMP package and the two resulting extreme shapes were visualized using the 'wireframe graph' option of the software MorphoJ (Klingenberg 2011).…”