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The XO sex-determination system (sometimes referred to as X0 sex-determination system) is a system that some species of insects, arachnids, and mammals use to determine the sex of offspring. In this system, there is only one sex chromosome, referred to as X. Males only have one X chromosome (XO), while females have two (XX).
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.
In biology, offspring are the young creation of living organisms, produced either by sexual or asexual reproduction. Collective offspring may be known as a brood or progeny . This can refer to a set of simultaneous offspring, such as the chicks hatched from one clutch of eggs , or to all offspring produced over time, as with the honeybee .
Animals with few offspring can devote more resources to the nurturing and protection of each individual offspring, thus reducing the need for many offspring. On the other hand, animals with many offspring may devote fewer resources to each individual offspring; for these types of animals it is common for many offspring to die soon after birth ...
In species that use the XY sex-determination system, parthenogenetic offspring have two X chromosomes and are female. In species that use the ZW sex-determination system the offspring genotype may be one of ZW (female), [28] [29] ZZ (male), or WW (non-viable in most species, [31] but a fertile, [dubious – discuss] viable female in a few, e.g ...
The sex of the green spoonworm, Bonellia viridis, a marine annelid, depends on where the larvae make landfall (female shown). Environmental sex determination is the establishment of sex by a non-genetic cue, such as nutrient availability, experienced within a discrete period after fertilization. [1]
The green turtles is an example of a species that does not receive any possible benefit from polyandry and only uses it to reduce the cost of mating. [19] As for house mice, multiple male mating was observed even when females had the opportunity to select their mate without sexual coercion, showing that it was due to female choice. [ 18 ]
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.