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In 1973, M. J. D. White, then at the end of a long career investigating karyotypes, gave an interesting summary of the distribution of chromosome polymorphism. "It is extremely difficult to get an adequate idea as to what fraction of the species of eukaryote organisms actually are polymorphic for structural rearrangements of the chromosomes.
For example, crocodiles possess a temperature-dependent sex determining polyphenism, where sex is the trait influenced by variations in nest temperature. [ 3 ] When polyphenic forms exist at the same time in the same panmictic (interbreeding) population they can be compared to genetic polymorphism . [ 4 ]
It operates on polymorphic species, species which have different forms. In apostatic selection, the common forms of a species are preyed on more than the rarer forms, giving the rare forms a selective advantage in the population. [1] It has also been discussed that apostatic selection acts to stabilize prey polymorphisms.
In biology, polymorphism [1] is the occurrence of two or more clearly different morphs or forms, also referred to as alternative phenotypes, in the population of a species. To be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating).
This condition has been detected in many species. Trichomycterus davisi, for example, is an extreme case where the polymorphism was present within a single chimeric individual. [1] It has also been studied in alfalfa, [2] shrews, [3] Brazilian rodents, [4] and an enormous variety of other animals and plants. [5] In one instance it has been ...
Genetic polymorphism and natural selection give rise to otherwise edible species (the mimic) gaining a survival advantage by resembling inedible species (the model). Such a mimicry complex is referred to as Batesian and is most commonly known by the mimicry by the limenitidine viceroy butterfly of the inedible danaine monarch. Later research ...
Delta smelt, once an important part of the local California ecosystem, are now effectively extinct — meaning they still exist, but their numbers are so few that they no longer have any impact on ...
Breeding in a number of animal and plant species has been revolutionized by the emergence of SNP arrays. The method is based on the prediction of genetic merit by incorporating relationships among individuals based on SNP array data. [13] This process is known as genomic selection. Crop-specific arrays find use in agriculture. [14] [15]