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Gene conversion is the only method in which gene clusters may become homogenized. Although the size of a gene cluster may vary, it rarely comprises more than 50 genes, making clusters stable in number. Gene clusters change over a long evolutionary time period, which does not result in genetic complexity. [10]
The polar bear (Ursus maritimus) is a large bear native to the Arctic and nearby areas. It is closely related to the brown bear, and the two species can interbreed.The polar bear is the largest extant species of bear and land carnivore, with adult males weighing 300–800 kg (660–1,760 lb).
Also called functionalism. The Darwinian view that many or most physiological and behavioral traits of organisms are adaptations that have evolved for specific functions or for specific reasons (as opposed to being byproducts of the evolution of other traits, consequences of biological constraints, or the result of random variation). adaptive radiation The simultaneous or near-simultaneous ...
The range of the polar bear encircles the North Pole.. A circumpolar distribution is any range of a taxon that occurs over a wide range of longitudes but only at high latitudes; such a range therefore extends all the way around either the North Pole or the South Pole.
A wide range of methods have been developed to assess the structure of human populations with the use of genetic data. Early studies of within and between-group genetic variation used physical phenotypes and blood groups, with modern genetic studies using genetic markers such as Alu sequences, short tandem repeat polymorphisms, and single nucleotide polymorphisms (SNPs), among others. [11]
The naming of hybrid animals depends on the sex and species of the parents. The father giving the first half of his species' name and the mother the second half of hers. (I.e. a pizzly bear has a polar bear father and grizzly bear mother whereas a grolar bear's parents would be reversed.)
This model predicts that the gene clusters must have conserved between species. This is not the case for many operons and gene clusters seen in eukaryotes. [15] According to Eichler and Sankoff the two mean processes in eukaryotic chromosome evolution are 1) rearrangements of chromosomal segments and 2) localized duplication of genes.
An example are tandem clusters of rRNA encoding genes. These genes are transcribed faster than they would be if only a single copy of the gene was available. Additionally, a single RNA gene may not be able to provide enough RNA, but tandem repeats of the gene allow sufficient RNA to be produced.