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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).
All the flies look alike whatever inversions they carry: this is an example of a cryptic polymorphism. Accordingly, Dobzhansky favoured the idea that the morphs became fixed in the population by means of Sewall Wright's drift. [54] However, evidence rapidly accumulated to show that natural selection was responsible: Drosophila polytene ...
A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 [ 3 ] and then again in his 1982 book The Extended Phenotype suggested that one can regard bird nests and other built structures such as ...
Heterostyly is a unique form of polymorphism and herkogamy in flowers. In a heterostylous species, two or three morphological types of flowers, termed "morphs", exist in the population. On each individual plant, all flowers share the same morph. The flower morphs differ in the lengths of the pistil and stamens, and these traits are not continuous.
Examples of such traits include flowering time, drought tolerance, polymorphism, mimicry, and avoidance of attacks by predators. [2] [citation needed] Research usually involves a mixture of field and laboratory studies. [3] Samples of natural populations may be taken back to the laboratory for their genetic variation to be analyzed.
Polymorphisms can be identified in the laboratory using a variety of methods. Many methods employ PCR to amplify the sequence of a gene. Once amplified, polymorphisms and mutations in the sequence can be detected by DNA sequencing, either directly or after screening for variation with a method such as single strand conformation polymorphism analysis.
Incomplete lineage sorting (ILS) [1] [2] [3] (also referred to as hemiplasy, deep coalescence, retention of ancestral polymorphism, or trans-species polymorphism) is a phenomenon in evolutionary biology and population genetics that results in discordance between species and gene trees.
Polymorphism is a general concept in biology where more than one version of a trait is present in a population. In some cases of differing counts, the difference in chromosome counts is the result of a single chromosome undergoing fission , where it splits into two smaller chromosomes, or two undergoing fusion, where two chromosomes join to ...