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Variation in the populations gene pool allows natural selection to act upon traits that allow the population to adapt to changing environments. Selection for or against a trait can occur with changing environment – resulting in an increase in genetic diversity (if a new mutation is selected for and maintained) or a decrease in genetic ...
The distribution of many physical traits resembles the distribution of genetic variation within and between human populations (American Association of Physical Anthropologists 1996; Keita and Kittles 1997). For example, ~90% of the variation in human head shapes occurs within continental groups, and ~10% separates groups, with a greater ...
In his 1930 book The Genetical Theory of Natural Selection, Fisher postulates that the rate of change of biological fitness can be calculated by the genetic variance of the fitness itself. [1] Fisher tried to give a statistical formula about how the change of fitness in a population can be attributed to changes in the allele frequency.
Genetic variation can be identified at many levels. Identifying genetic variation is possible from observations of phenotypic variation in either quantitative traits (traits that vary continuously and are coded for by many genes, e.g., leg length in dogs) or discrete traits (traits that fall into discrete categories and are coded for by one or a few genes, e.g., white, pink, or red petal color ...
This leads to copy-number variation within a population. Duplications are a major source of raw material for evolving new genes. [25] Other types of mutation occasionally create new genes from previously noncoding DNA. [26] [27] In the distribution of fitness effects (DFE) for new mutations, only a minority of mutations are beneficial ...
A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection.Meanwhile, low genetic diversity (see inbreeding and population bottlenecks) can cause reduced biological fitness and an increased chance of extinction, although as explained by genetic drift new genetic variants, that may cause an increase in the ...
Climate change is a drastic and enduring change in weather patterns. By driving species out of their fundamental niche, climate change can lower population size and consequently lower genetic variation. The founder effect, which occurs when a population is founded by few individuals.
Neutral events can radically reduce genetic variation through population bottlenecks. [108] which among other things can cause the founder effect in initially small new populations. [109] When genetic variation does not result in differences in fitness, selection cannot directly affect the frequency of such variation.