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Polydactyly also occurs in modern extant reptiles [82] and amphibians. [83] Polydactyly was a non-pathological, reacquired condition in extinct marine reptiles such as ichthyosaurs and hupehsuchians, some of which containing upwards of ten digits within their flippers. [84]
Polydactyly (from Greek πολυ-poly-'many') is when a limb has more than the usual number of digits. This can be: As a result of congenital abnormality in a normally pentadactyl animal. Polydactyly is very common among domestic cats. For more information, see polydactyly.
One of the polydactyl cats at the Ernest Hemingway House in Key West, Florida.This particular cat has seven (two extra) toes on each paw. A polydactyl cat is a cat with a congenital physical anomaly called polydactyly (also known as polydactylism or hyperdactyly), which causes the cat to be born with more than the usual number of toes on one or more of its paws.
Oligodactyly is therefore the opposite of polydactyly. [2] [3] Very rare, this medical condition usually has a genetic or familial cause. [3] [4] Oligodactyly is sometimes a sign or symptom of several syndromes including Poland syndrome and Weyer Ulnar Ray Syndrome. [5] It is a type of dysmelia.
In late 2003, a new specimen of hupehsuchian called SSTM 5025, found from the same area as Hupehsuchus and Eretmorhipis, was briefly mentioned in the journal Nature. [7] It is most notable for exhibiting polydactyly, in which more than the usual maximum of five digits per limb were seen as in most advanced tetrapods. Polydactyly is also seen in ...
In parapatric speciation, there is only partial separation of the zones of two diverging populations afforded by geography; individuals of each species may come in contact or cross habitats from time to time, but reduced fitness of the heterozygote leads to selection for behaviours or mechanisms that prevent their interbreeding. Parapatric ...
Waddington called the effect he had seen "genetic assimilation". His explanation was that it was caused by a process he called "canalization".He compared embryonic development to a ball rolling down a slope in what he called an epigenetic landscape, where each point on the landscape is a possible state of the organism (involving many variables).
Paternal gametes (sperm for example) do not have cytoplasmic mitochondria [citation needed]. Thus, the phenotype of traits linked to genes found in either chloroplasts or mitochondria are determined exclusively by the maternal parent. In humans, mitochondrial diseases are a class of diseases, many of which affect the muscles and the eye ...