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Hatching rates for North American salamander species have ranged from 19.5% [10] to 30.5%. [11] It is speculated that intergenomic exchanges, like crossing over during meiosis , may play a role. Intergenomic exchanges are often lethal due to the fact that chromosomes in unisexual species are homeologous (similar, but less so than homologous ...
Some documented species, specifically salamanders and geckos, that rely on obligate parthenogenesis as their major method of reproduction. As such, there are over 80 species of unisex reptiles (mostly lizards but including a single snake species), amphibians and fishes in nature for which males are no longer a part of the reproductive process. [41]
Fertilization is the fusion of gametes to produce a new organism. In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization.
Parthenogenesis is a mode of asexual reproduction in which offspring are produced by females without the genetic contribution of a male. Among all the sexual vertebrates, the only examples of true parthenogenesis, in which all-female populations reproduce without the involvement of males, are found in squamate reptiles (snakes and lizards). [1]
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.
The female chooses a site in shallow water among vegetation, and lays a batch of up to 20,000 eggs, and the male simultaneously releases sperm, resulting in external fertilization. [44] The eggs form a thin, floating sheet which may cover an area of 0.5 to 1.0 m 2 (5.4 to 10.8 sq ft). The embryos develop best at water temperatures between 24 ...
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Caecilians are the only order of amphibians to use internal insemination exclusively (although most salamanders have internal fertilization and the tailed frog in the US uses a tail-like appendage for internal insemination in its fast-flowing water environment). [15]