Sexual selection molds the morphology, physiology and behavior of males in many animals. At first glance, it seems reasonable to assume that females would use the same male traits and signals in mate choice as males do during male-male competition. However, intra- and intersexual competition may affect traits in the same or the opposite direction, with differing strength. We investigated which ...

In polyandrous species, sperm morphometry and sperm velocity are under strong sexual selection. Although several hypotheses have been proposed to explain the role of sperm competition in sperm trait variation, this aspect is still poorly understood. It has been suggested that an increase in sperm competition pressure could reduce sperm size variation or produce a diversity of sperm to maximize ...

Content The use of sub-talar joint positioning to describe intrinsic foot ‘deformity’ is principally used by podiatrists attempting to rationalise lower limb symptoms and the use of foot orthoses. In order to have evolved the physical structures that we exhibit, natural variation of form must exist, along with the conservation of common functional attributes. Results from molecular genetics res...

Variation in squamate foot morphology is likely relevant during evolutionary processes of habitat colonization because distinct surfaces differ in energetic and functional demands for locomotion. We combined new foot morphological data with published information of limb and tail lengths to investigate evolutionary changes possibly associated with the differential usage of ecological settings by...

A new entomopathogenic nematode, Steinernema tophus n. sp. is described from South Africa. Morphological, molecular (ribosomal gene sequence data) together with cross-hybridization studies were used for diagnostics and identification purposes. Both molecular and morphological data indicate the new species belongs to the 'glaseri-group' of Steinernema spp. Key morphological diagnostic traits for...

Increased phylogenetic information (often based on analyses of DNA sequences) has revolutionized comparative biology. Phylogenies are used to guide the choice of species for comparisons and to identify traits that are homologous versus analogous. They are also used to perform “phylogenetically correct” statistical analyses that attempt to account for the fact that related species tend to resemb...

Pati ducks are recently registered indigenous non-descript duck variety of Assam mainly used for meat, egg and ritual sacrifices. In the present study, some important phenotypic morphometric traits were studied under field conditions. Morphometric measurement both Drake Ducks recorded plumage colour patterns all body parts noted by visual observation. The mean length (cm) Body, Shank, Bill, Nec...

The relative importance of ancient demography and climate in determining worldwide patterns of human within-population phenotypic diversity is still open to debate. Several morphometric traits have been argued to be under selection by climatic factors, but it is unclear whether climate affects the global decline in morphological diversity with increasing geographical distance from sub-Saharan A...

INTRODUCTlON ,. . The foundation of most evolutionary theory rests upon inferences drawn from geographic variation or upon the verification of predictions made about it. The study of geographic variation occupies a central position in evolutionary biology. .. because geographic variation is ordinarily the smallest amount of evolution that can be detected in nature and because evolutionary theor...