Gene flow is the transfer of genetic material from one population to another. Gene flow between two populations of the same species is mediated through reproduction and vertical gene transfer from parent to child. Horizontal gene transfer (HGT, also known as lateral gene transfer) allows gene flow between two distinct species, such as gene transfer from bacteria or viruses to a higher creature or gene transfer from an endosymbiont to the host.
Factors affecting gene flow-
Now we will study more about genes, gene flow, how gene flow happens and lastly at what factors affect gene flow.
Gene-
The gene is the fundamental, physical, and functional unit of heredity. Genes are the building blocks of DNA sequences (genotypes). An organism’s phenotypic characteristic is defined by its genotypes in conjunction with other factors (such as environmental effects). Changes in the DNA drive evolution and natural selection.
Gene flow-
The transfer of genes or alleles between interbreeding populations of a species is referred to as gene flow in population genetics. When individuals of one gene pool mate with members of another gene pool, the allele frequencies of the offspring might change (which pertains to the proportion of members in a population carrying a specific variant of a gene). As a result, the genetic diversity within a population may be influenced by the gene pool. Members of a population of a given species moving to a new environment, for example, may generate gene flow when they mate with members of an existing population in the ecosystem. As a result, highly mobile animals are more likely to change allele frequency as a result of gene flow.
How does gene flow happen-
Process starts with the transfer of genetic material from one population of a species to another by interbreeding, consequently altering the makeup of the recipient population’s gene pool. The introduction of novel alleles via gene flow enhances population diversity and allows for new trait combinations. Gene flow occurs in humans mostly as a result of voluntary or forced movement of human groups.
Although gene flow does not affect allele frequencies throughout a species, it may affect allele frequencies in specific populations. In the case of migration, the bigger the difference in allele frequencies between resident and migrant individuals, as well as the larger the number of migrants, the greater the impact of migrants on the resident population’s genetic makeup.
What factors affect gene flow-
Certain variables operate as stumbling blocks to gene flow. Physical barriers, geologic events, and geographical barriers are all variables that influence the pace of gene flow. The roadway dividing the populations of blooming plant species on different sides is an example of a geographical barrier. This species may recombine gene pools if pollen from one plant can fertilise the other and finally create viable offspring. If, on the other hand, the plant is unable to reach the population of plants of the same species on the other side due to this barrier, gene flow between the two populations may be limited.
1.Speciation in allopatric species- Speciation and gene flow are two examples of how speciation affects gene flow. When physical barriers prevent gene flow, Allopatric speciation, or geographical isolation, occurs, preventing groups of the same species from exchanging genetic material. Natural, but not necessarily, physical impediments to gene flow exist. Impassable mountain ranges, seas, and enormous deserts are examples. Artificial, man-made barriers, such as the Great Wall of China, have hampered the gene flow of natural plant populations in certain circumstances. Ulmus pumila, one of these native species, has a lower prevalence of genetic differentiation than Vitex negundo, Ziziphus jujuba, Heteropappus, Prunus armeniaca which grow on the other side of the Great Wall of China from Ulmus pumila. This is because Ulmus pumila relies on wind pollination for reproduction, while the latter-plants rely on insect pollination.
2.Speciation in Sympatrics- Physical barriers to gene flow aren’t always necessary. When new species from the same ancestor species emerge along the same range, this is known as sympatric speciation. This is often caused by a reproductive barrier. Two Howea palm species located on Lord Howe Island, for example, were shown to have significantly different blooming periods that were connected with soil preference, resulting in a reproductive barrier that inhibited gene flow. Due to reproductive hurdles, fragmentation, specialised pollinators, or restricted hybridisation or hybridisation creating unsuitable hybrids, species may coexist in the same habitat but have extremely little gene flow. A cryptic species is one in which people cannot discern the difference between it and other species without using genetics.
Conclusion-
In this article we have read about what is meant by gene, gene flow, how it happens and lastly at what factors affect gene flow. Natural, but not necessarily, physical obstacles to gene flow exist. Impassable mountain ranges, seas, and enormous deserts are examples. They may be artificial, man-made barriers in certain circumstances. In the absence of the four causes that may modify allele frequencies, the Hardy-Weinberg equilibrium principle states that allele frequencies in a population will stay constant. Natural selection, mutation, genetic drift, and migration are the causes.