Search results
Results from the WOW.Com Content Network
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.
Over time amphibians have been found evolving to increasing internal fertilization. [citation needed] Within amphibians, it is common for high vertebrates to internally fertilize because of the transition from water to land during vertebrate evolution. There is an advantage for the amphibians who are internally fertilizing allowing for the ...
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]
Oviparity occurs in all birds, most reptiles, some fishes, and most arthropods. Among mammals , monotremes (four species of echidna , and the platypus ) are uniquely oviparous. In all but special cases of both ovuliparity and oviparity, the overwhelming source of nourishment for the embryo is the nutrients stored in the yolk, pre-deposited in ...
In amphibians, the development of the animal-vegetal axis occurs prior to fertilization. [1] Sperm entry can occur anywhere in the animal hemisphere. [ 2 ] The point of sperm entry defines the dorso-ventral axis - cells opposite the region of sperm entry will eventually form the dorsal portion of the body.
This is an accepted version of this page This is the latest accepted revision, reviewed on 23 December 2024. Group of animals including lepidosaurs, testudines, and archosaurs This article is about the animal class. For other uses, see Reptile (disambiguation). Reptiles Temporal range: Late Carboniferous–Present Pre๊ ๊ O S D C P T J K Pg N Tuatara Saltwater crocodile Common box turtle ...
Parthenogenesis is a form of reproduction where eggs develop without fertilization, resulting in unisexual species. This phenomenon is closely related with reproductive modes such as hybridogenesis, where fertilization occurs, but the paternal DNA is not passed on.