The ZO sex-determination system is a system that determines the sex of offspring in
caddisflies
The caddisflies (order Trichoptera) are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the basis ...
and several
moth
Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...
s. In those species, there is one sex chromosome, Z. Males have two Z chromosomes, whereas females have one Z. Males are ZZ, while females are ZO.
The ancestor of
Lepidoptera
Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...
and Trichoptera had ZO sex determination, which became a
ZW sex-determination system
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 flatwor ...
in the largest clade,
Ditrysia
Ditrysia is a clade of lepidopterans that contains both butterflies and a majority of moth species. They are named for the fact that the female has two distinct sexual openings: one for mating, and the other for laying eggs.
About 98% of know ...
, as well as in
Tischerioidea
Tischerioidea is the superfamily of "trumpet" leaf miner moths. The superfamily contains just one family, Tischeriidae, and traditionally one genus, ''Tischeria'', but currently three genera are recognised, widespread around the world including ...
. Some of the ZW species later reverted to the ZO system.
See also
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Y-chromosomal Adam
In human genetics, the Y-chromosomal Adam (more technically known as the Y-chromosomal most recent common ancestor, shortened to Y-MRCA), is the patrilineal most recent common ancestor (MRCA) from whom all currently living humans are descended. ...
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Sex Determination in ''Silene''
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Sex-determination system
A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. Most organisms that create their offspring using sexual reproduction have two common sexes, males and females, and in ...
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Sexual differentiation
Sexual differentiation is the process of development of the sex differences between males and females from an undifferentiated zygote. Sex differentiation is usually distinct from sex determination; sex determination is the designation of the de ...
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Haplodiploid sex-determination system
Haplodiploidy is a sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid. Haplodiploidy is sometimes called arrhenotoky.
Haplodiploidy determines the se ...
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XY sex-determination system
The XY sex-determination system is a sex-determination system present in many mammals (including humans), some insects (''Drosophila''), some snakes, some fish (guppy, guppies), and some plants (''Ginkgo'' tree).
In this system, the sex of an ...
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XO sex-determination system
The XO sex-determination system (sometimes referred to as X0 sex-determination system) is a system that some species of insects, arachnids, and mammals (not including humans) use to determine the sex of offspring. In this system, there is only o ...
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Temperature-dependent sex determination
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. It is observed in reptiles and teleost fish, ...
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X chromosome
The X chromosome is one of the two sex chromosomes in many organisms, including mammals, and is found in both males and females. It is a part of the XY sex-determination system and XO sex-determination system. The X chromosome was named for its u ...
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Y chromosome
The Y chromosome is one of two sex chromosomes in therian mammals and other organisms. Along with the X chromosome, it is part of the XY sex-determination system, in which the Y is the sex-determining chromosome because the presence of the ...
References
Sex-determination systems
Lepidopterology
Chromosomes
Insects
Moths
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