With about colour morphs currently assigned to six nominal species, the genus Tropheus is an ideal model to study evolutionary divergence of populations in allopatry. The morphology of Tropheus has been described as relatively static, but reproductive constraints are sexually dimorphic due to mouthbrooding in females. We analysed phenotypic variation in six populations of T. The mean shapes differed significantly between sexes, populations, and species even though within-sex variation exceeded the divergence among populations. The first principal component of Procrustes shape coordinates revealed differences between populations and species in mouth position and ventral head shape.
Anglerfish - Wikipedia
Sexual Dimorphism. Sexual dimorphism is the systematic difference in form between individuals of different sex in the same species. For example, in some species, including many mammals, the male is larger than the female. In others, such as some spiders, the female is larger than the male. Other sex-specific differences include color most birds , song in birds , size or presence of parts of the body used in struggles for dominance, such as horns, antlers, and tusks; size of the eyes e. Sexual dimorphism in humans is the subject of much controversy. Human male and female appearances are perceived as different, although Homo sapiens has a low level of sexual dimorphism compared with many other species.
9 of the most dramatic examples of sexual dimorphism
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Sexual dimorphism , the differences in appearance between males and females of the same species , such as in colour, shape, size, and structure, that are caused by the inheritance of one or the other sexual pattern in the genetic material. The differences may be extreme, as in the adaptations for sexual selection seen in the exotic plumes and colours of the male bird-of-paradise family Paradisaeidae or in the adaptations for protection exemplified by the great size and huge canine teeth of the male baboon Papio. Many birds show at least some dimorphism in colour, the female being cryptically coloured to remain concealed on the nest while the more-colourful male uses display in courtship and territorial behaviours. The mountain spiny lizard Sceloporus jarrovi is sexually dimorphic in feeding habits: the equal-sized males and females seek out different sizes of prey.