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  2. Hermaphrodite - Wikipedia

    en.wikipedia.org/wiki/Hermaphrodite

    A rough estimate of the number of hermaphroditic animal species is 65,000, about 5% of all animal species, or 33% excluding insects. Insects are almost exclusively gonochoric, and no definitive cases of hermaphroditism have been demonstrated in this group. [4] There are no known hermaphroditic species among mammals [5] or birds. [6]

  3. Sex-determination system - Wikipedia

    en.wikipedia.org/wiki/Sex-determination_system

    Different populations of the Japanese frog Rana rugosa uses different systems. Two use homomorphic male heterogamety, one uses XX/XY, one uses ZZ/ZW. Remarkably, the X and Z chromosomes are homologous, and the Y and W as well. Dmrt1 is on autosome 1 and not sex-linked. This means that an XX female individual is genetically similar to a ZZ male ...

  4. XY sex-determination system - Wikipedia

    en.wikipedia.org/wiki/XY_sex-determination_system

    The idea is instead of having a simplistic mechanism by which you have pro-male genes going all the way to make a male, in fact there is a solid balance between pro-male genes and anti-male genes and if there is a little too much of anti-male genes, there may be a female born and if there is a little too much of pro-male genes then there will ...

  5. Parthenogenesis - Wikipedia

    en.wikipedia.org/wiki/Parthenogenesis

    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 ...

  6. Mammalian reproduction - Wikipedia

    en.wikipedia.org/wiki/Mammalian_reproduction

    Most mammals are viviparous, giving birth to live young. [1] However, the five species of monotreme, the platypuses and the echidnas, lay eggs. The monotremes have a sex determination system different from that of most other mammals. [2] In particular, the sex chromosomes of a platypus are more like those of a chicken than those of a therian ...

  7. Gonochorism - Wikipedia

    en.wikipedia.org/wiki/Gonochorism

    Gonochorism has evolved independently multiple times. [8] It is very evolutionarily stable in animals. [9] Its stability and advantages have received little attention. [10]: 46 Gonochorism owes its origin to the evolution of anisogamy, [11] but it is unclear if the evolution of anisogamy first led to hermaphroditism or gonochorism.

  8. List of mammals of Japan - Wikipedia

    en.wikipedia.org/wiki/List_of_mammals_of_Japan

    This is a list of mammal species recorded in Japan (excluding domesticated and captive populations). Of the 172 [1] species of mammal found—112 native terrestrial mammals (those that are endemic are identified below; this number includes 37 species of bat), 19 introduced species, 40 species of Cetacea, and the dugong—161 are listed for the Japan region on the IUCN Red List of Threatened ...

  9. Sexual differentiation - Wikipedia

    en.wikipedia.org/wiki/Sexual_differentiation

    Sexual differentiation is the process of development of the sex differences between males and females from an undifferentiated zygote. [1] [2] Sex determination is often distinct from sex differentiation; sex determination is the designation for the development stage towards either male or female, while sex differentiation is the pathway towards the development of the phenotype.