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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 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.
Since carotenoid-based ornamentation suggests mate quality, female two-spotted guppies that develop colorful orange bellies during breeding season are considered favorable to males. [60] The males invest heavily in offspring during incubation, which leads to the sexual preference in colorful females due to higher egg quality.
Some chromosomal sex determination systems in animals. A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. [1] Most organisms that create their offspring using sexual reproduction have two common sexes and a few less common intersex variations.
Environmental cues that often trigger the development of males or females include temperature, nutrient (or food in the case of animals) and water availability, photoperiod, competitive stress, and pheromones from conspecific individuals. [7] [8] Specific mechanisms and cues vary between species.
This is because mammals have imprinted genetic regions, where either the maternal or the paternal chromosome is inactivated in the offspring for development to proceed normally. A mammal developing from parthenogenesis would have double doses of maternally imprinted genes and lack paternally imprinted genes, leading to developmental abnormalities.
Moon wrasse, Thalassoma lunare, a protogynous animal species. Protogynous hermaphrodites are animals that are born female and at some point in their lifespan change sex to male. [27] Protogyny is a more common form of sequential hermaphroditism in fish, especially when compared to protandry. [28]
Based on the Trivers-Willard model, Clutton-Brock hypothesized that the sex ratio of mammalian offspring may change according to maternal condition, where high-ranked females should produce more male offspring and low-ranked females should produce more female offspring. [19] This is based on the assumption that high-ranked females are in better ...