Amphibian sex

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Amphibians employ a genetic mechanism of sex determination, according to all available information on sex chromosomes or breeding tests. Sex reversal allows breeding tests to establish which sex is heterogametic and provides an indication of the mechanism of sex determination. Cases of spontaneous and experimental sex reversal by temperature, hormones or surgery are reviewed and illustrated by previously unpublished studies on crested newts.

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Animals and plants literally throw their semen around in the hope that their genes will be passed on. Some males are targeted in their fertilisation of the females, others are not. And then there are some who choose to be both male and female, and thereby avoid having to pay for expensive dates.

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In the Japanese frog Rana R. Previously we showed that incomplete female-to-male sex-reversal occurred in Z-AR transgenic female frogs. To date, however, there is no report showing that AR with androgens can determine genetically programed male sex fate in any vertebrate species.

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International Journal of Biological Sciences. International Journal of Medical Sciences. Journal of Cancer. Journal of Biomedicine.

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Most animals are one gender throughout their lives, but some species are capable of switching. Amphibians, which exhibit several interesting examples of this phenomenon, sometimes change their sex in response to environmental triggers -- which may be social, climactic or chemical in nature. In some circumstances this appears to be historically natural, while others do so as a result of herbicides or other forms of environmental pollution.

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The chapter is devoted to the consideration of sex determination in vertebrate groups of nonmammalians: fish, amphibians, reptiles, and birds. Attention is drawn to the fact that all these groups of animals, unlike mammals, are implemented hormonal control options for primary sex determination, and there is a possibility of sex reversion. Determination of gonadal development in vertebrates like testis or ovary was initially controlled mainly by sex hormones fish and amphibians.

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Abstract - We review and discuss current knowledge about sex determination in amphibians. The astonishing wide variety of mechanisms of genotypic sex determination is presented and discussed in an evolutionary context. We recall the natural occurrence of transitory juvenile hermaphroditism in some species. Our present knowledge of the mechanisms of sex determination in amphibians is compared to that in mammals.

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Sexual selection in amphibians involves sexual selection processes in amphibiansincluding frogssalamanders and newts. Prolonged breeders, the majority of frog species, have breeding seasons at regular intervals where male-male competition occurs with males arriving at the waters edge first in large number and producing a wide range of vocalizations, with variations in depth of calls the speed of calls [1] and other complex behaviours to attract mates. The fittest males will have the deepest croaks and the best territories, with females known to make their mate choices at least partly based on the males depth of croaking.

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