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The ZW sex-determination system is a chromosomal system that determines the sex of offspring in birds, some fish and crustaceans such as the giant river prawn, some insects (including butterflies and moths), the schistosome family of flatworms, and some reptiles, e.g. majority of snakes, lacertid lizards and monitors, including Komodo dragons.
Temperature-dependent sex determination (TSD) is a type of environmental sex determination in which the temperatures experienced during embryonic/larval development determine the sex of the offspring. [1] It is observed in reptiles and teleost fish, with some reports of it occurring in species of shrimp.
The sexy son hypothesis explains that females prefer more elaborate males and select against males that are dull in color, independent of the species' vision. [17] Similar sexual dimorphism and mating choice are also observed in many fish species. For example, male guppies have colorful spots and ornamentations, while females are generally grey ...
Some are quite old, meaning that there is some evolutionary force that resists their differentiation. [43] For example, three species of European tree frogs have homologous, homomorphic sex chromosomes, and this homomorphism was maintained for at least 5.4 million years by occasional recombination. [44]
Gibbons, on the other hand, are an example of monogamous primates that can be described as “monomorphic,” meaning males and females appear the same with little to no sexual dimorphism. [2] The correlation between mating system and dimorphism in haplorhines likely indicates sexual selection is the driving force behind dimorphism in species ...
Sexual selection creates colourful differences between sexes in Goldie's bird-of-paradise.Male above; female below. Painting by John Gerrard Keulemans.. Sexual selection is a mechanism of evolution in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex ...
Elephants can use their ears as threat displays in male-to-male competition. Sexual selection in mammals is a process the study of which started with Charles Darwin's observations concerning sexual selection, including sexual selection in humans, and in other mammals, [1] consisting of male–male competition and mate choice that mold the development of future phenotypes in a population for a ...
Insect species make up more than two-thirds of all extant animal species. Most insect species reproduce sexually, though some species are facultatively parthenogenetic. Many insect species have sexual dimorphism, while in others the sexes look nearly identical. Typically they have two sexes with males producing spermatozoa and females ova.