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An inversion is a chromosome rearrangement in which a segment of a chromosome becomes inverted within its original position. An inversion occurs when a chromosome undergoes a two breaks within the chromosomal arm, and the segment between the two breaks inserts itself in the opposite direction in the same chromosome arm.
Inversion was first noted in 1822 by the French zoologist Étienne Geoffroy Saint-Hilaire, when he dissected a crayfish (an arthropod) and compared it with the vertebrate body plan. The idea was heavily criticised, but periodically resurfaced, and is now supported by some molecular embryologists.
This theory is lacking in theoretical support because mutations that cause a large reduction in fitness can only be fixed through genetic drift in small, inbred populations, and the effects of chromosomal rearrangements on fitness are unpredictable and vary greatly in plant and animal species.
The increased strength of the face inversion effect over time supports the perceptual learning hypothesis, since more experience with faces results in increased susceptibility to the effect. [20] The more familiar a particular type of face (e.g. human or dog) is, the more susceptible one is to the face inversion effect for that face.
Human walking is about 75% less costly than both quadrupedal and bipedal walking in chimpanzees. Some hypotheses have supported that bipedalism increased the energetic efficiency of travel and that this was an important factor in the origin of bipedal locomotion. Humans save more energy than quadrupeds when walking but not when running.
Inversion (evolutionary biology), a hypothesis about the evolution of the dorsoventral axis in animals Inversion (kinesiology) , movement of the sole towards the median plane Chromosomal inversion , where a segment of a chromosome is reversed end-to-end
Anthrozoology, also known as human–animal studies (HAS), is the subset of ethnobiology that deals with interactions between humans and other animals. It is an interdisciplinary field that overlaps with other disciplines including anthropology , ethnology , medicine , psychology , social work , veterinary medicine , and zoology .
Position effect is the effect on the expression of a gene when its location in a chromosome is changed, often by translocation. This has been well described in Drosophila with respect to eye color and is known as position effect variegation (PEV). [1] The phenotype is well characterised by unstable expression of a gene that results in the red ...