In population genetics Population genetics is the study of the allele frequency distribution and change under the influence of the four evolutionary processes: natural selection, genetic drift, mutation and gene flow. It also takes account of population subdivision and population structure in space. As such, it attempts to explain such phenomena as adaptation and, a gene pool is the complete set of unique alleles An allele (pronounced /ˈæliːl/ , /əˈliːl/ (US)) (from the Greek αλληλος allelos, meaning each other) is one member of a pair or series of different forms of a gene. In other words, alleles are members of a gene that produces different traits in a gene characteristics. Usually alleles are coding sequences, but sometimes the term is in a species There are many definitions of what kind of unit a species is . A common definition is that of a group of organisms capable of interbreeding and producing fertile offspring, and separated from other such groups with which interbreeding does not (normally) happen. Other definitions may focus on similarity of DNA or morphology. Some species are or population In biology, a population is the collection of inter-breeding organisms of a particular species; in sociology, a collection of human beings. Individuals within a population share a factor may be reduced by statistical means, but such a generalization may be too vague to imply anything. Demography is used extensively in marketing, which relates to.
Description
A large gene pool indicates extensive genetic diversity Genetic diversity is a level of biodiversity that refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary, which is associated with robust populations that can survive bouts of intense selection In the context of evolution, certain traits or alleles of a species may be subject to selection. Under selection, individuals with advantageous or "adaptive" traits tend to be more successful than their peers reproductively—meaning they contribute more offspring to the succeeding generation than others do. When these traits have a. Meanwhile, low genetic diversity (see inbreeding Inbreeding is breeding between close relatives, whether plant or animal. If practiced repeatedly, it can lead to an increase in homozygosity of a population. A higher frequency of recessive, deleterious traits in homozygous form in a population can, over time, result in inbreeding depression. This may occur when inbred individuals exhibit reduced and population bottlenecks Population bottlenecks increase genetic drift, as the rate of drift is inversely proportional to the population size. They also increase inbreeding due to the reduced pool of possible mates) can cause reduced biological fitness Fitness is a central concept in evolutionary theory. It describes the capability of an individual of certain genotype to reproduce, and usually is equal to the proportion of the individual's genes in all the genes of the next generation. If differences in individual genotypes affect fitness, then the frequencies of the genotypes will change over and an increased chance of extinction In biology and ecology, extinction is the death of a species or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species . Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena.
When all individuals in a population are identical with regard to a particular phenotypic A phenotype is any observable characteristic or trait of an organism: such as its morphology, development, biochemical or physiological properties, or behavior. Phenotypes result from the expression of an organism's genes as well as the influence of environmental factors and possible interactions between the two. The genotype of an organism is the trait they are known as monomorphic. When the individuals show several variants of a particular trait they are said to be polymorphic Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph. In order to be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population.
See also
- Biodiversity Biodiversity is the variation of life forms within a given ecosystem, biome, or for the entire Earth. Biodiversity is often used as a measure of the health of biological systems. The biodiversity found on Earth today consists of many millions of distinct biological species, which is the product of nearly 3.5 billion years of evolution
- Conservation biology Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction. It is an interdisciplinary subject drawing on sciences, economics, and the practice of natural resource management. The term conservation biology was
- Founder effect In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1952, using existing theoretical work by those such as Sewall Wright. As a result of the loss of genetic variation,
- Genetic drift Genetic drift or allelic drift is the change in the relative frequency with which a gene variant occurs in a population that results from the fact that alleles in offspring are a random sample of those in the parents, and because of the role of chance in determining whether a given individual survives and reproduces. A population's allele
- Gene flow In population genetics, gene flow is the transfer of alleles of genes from one population to another
- Small population size The influence of stochastic variation in demographic (reproductive and mortality) rates is much higher for small populations than large ones. Stochastic variation in demographic rates causes small populations to fluctuate randomly in size. The smaller the population the greater the probability that fluctuations will lead to extinction. They are
- Cousin couple A cousin couple is a pair of cousins who are involved in a romantic or sexual relationship. In some jurisdictions and cultures, such marriages are legal, accepted, or even actively encouraged, while in others cousin-cousin relationships they are regarded as incest and marriages are prohibited
- Allele An allele (pronounced /ˈæliːl/ , /əˈliːl/ (US)) (from the Greek αλληλος allelos, meaning each other) is one member of a pair or series of different forms of a gene. In other words, alleles are members of a gene that produces different traits in a gene characteristics. Usually alleles are coding sequences, but sometimes the term is
External links
- The Gene Pool and Speciation - from Biology Online, Retrieved August 20, 2008.
Categories: Ecology Ecology is the branch of science that studies the distribution and interactions between living things and the physical environment | Conservation | Selection Categories: Population genetics | Evolutionary processes | Classical genetics | Population genetics Categories: Subfields and areas of study related to evolutionary biology | Population | Genetics | Evolutionary biology |
