Sexual dimorphism in the ratio of digit lengths has been correlated to behavioral, physiological, and morphological traits in a variety of taxa. While sexual dimorphism in the second-to-fourth digit length ratio (2D:4D) is a well-established indicator of prenatal androgen exposure in mammals, investigations into the patterns of 2D:4D and the drivers of such variation in other taxa are lacking. ...

Numerous studies have examined sexual dimorphism in the morphology and behavior of vertebrates; very few, however, have explicitly investigated the possibility of gender differences in physiological performance, despite the observations of such differences in humans. In this study, I investigated physiological sexual dimorphism in the lizard genus Cnemidophorus by measuring five whole-animal tr...

Teeth are well preserved after death and they exhibit remarkable sexual dimorphism. Hence, they provide excellent materials for forensic investigations intended for identification of sex. Present study was undertaken on permanent mandibular canines of 90 male and 90 female subjects of age group 17-23 years. The mesiodistal width for right and left mandibular canines and intercanine distance wer...

Plants of Lycium californicum, L. exsertum, and L. fremontii produce flowers that are either male-sterile (female) or hermaphroditic, and populations are morphologically gynodioecious. As is commonly found in gynodioecious species, flowers on female plants are smaller than those on hermaphrodites for a number of floral traits. Floral size dimorphism has often been hypothesized to be the result ...

Some species have potential for intense mate competition yet exhibit little or no sexual size dimorphism, despite predictions from sexual selection theory. Using a conceptual model, we show the conditions for which passive mate guarding with copulatory plugs can be an alternative and more successful strategy to active (direct) guarding, reducing selection pressure on large male size. The model ...

Some monogamous primates are characterized by biparental care, territoriality, and a reduced level of physical dimorphism. In others, the relationship between those behavioral patterns and dimorphism is less clear. I tested Bergmann's and Rensch's rules using Aotus spp. body mass data and I characterized the extent of sexual dimorphism in body mass, dental and physical measurements in a sociall...

Conditions favoring population divergence in trophic features, such as the low levels of species richness and interspecific competition found on islands, can be similar to conditions that increase their sexual dimorphism or overall variance. Male emberizid sparrows of tidal marshes have undergone parallel evolution of large bills. We tested for parallel increases between dimorphism and overall ...

Body size of many animals varies with latitude: body size is either larger at higher latitudes (Bergmann's rule) or smaller at higher latitudes (converse Bergmann's rule). However, the causes underlying these patterns are poorly understood. Also, studies rarely explore how sexual size dimorphism varies with latitude. Here we investigate geographic variation in body size and sexual size dimorphi...

1. The evolution of sexual dimorphism presents a challenge because males and females must express two phenotypes from the same underlying genome. In vertebrates, one solution to this challenge is to link the expression of shared traits to sex steroids. However, even ‘male-biased’ steroids such as testosterone (T) circulate at biologically significant levels in females, raising the question of w...

RATIONALE Abdominal aortic aneurysms (AAAs) exhibit marked sexual dimorphism with higher prevalence in men. Similarly, AAAs induced by angiotensin II (AngII) infusion into mice exhibit a higher prevalence in males. Testosterone promotes AAA pathology in adult male mice through regulation of angiotensin type 1A receptors (AT1aR) in abdominal aortas. However, mechanisms for sexual dimorphism of r...