Gene flow

The introduction and establishment of genes from one breeding population into another’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 the voluntary or forced movement of human groups. 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.

Now we will take an in-depth look at gene flow, gene flow examples and lastly at gene flow diagram.

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.

Types-

• Vertical gene transmission- Parent to offspring and may occur between two populations of the same species. The genetic material is transferred from parents to children via vertical gene transfer. It might be done either sexually or asexually. Horizontal gene transfer, on the other hand, is the transfer of genetic material from a donor organism to an organism that is not its offspring.
• Horizontal gene transfer (HGT, also known as lateral gene transfer)- Occurs 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.
• HGT without symbiosis is also prevalent; the majority of recorded examples include the presence of genes from bacteria in the nucleus. Their popularity maybe because they are more visible than genes from other eukaryotes, yet bacteria may be the primary source of new genes due to their number.

Barriers-

• Allopatric speciation- When physical barriers hinder gene flow, this leads to Allopatric speciation or a remoteness that prevents groups of the same species from exchanging genetic material. Natural, but not necessarily, physical limitations to gene flow exist. Impassable mountain ranges, seas, and enormous deserts are examples. 
• Artificial, man-made boundaries, like the Great Wall of China, have restricted the gene flow of natural plant populations in certain circumstances. As there is little to no gene flow to facilitate recombination of the gene pools, samples of the same species growing on separate sides have evolved genetic variations.
• Sympatric speciation- Gene flow barriers may not necessarily have to be physical. When life forms from the same ancestor species emerge along with the same range, this is known as sympatric speciation. This is often caused by a reproductive barrier. Due to reproductive hurdles, fragmentation, specialised pollinators, or restricted hybridization or hybridization creating unsuitable hybrids, species may coexist in the same habitat but have relatively little gene flow. 
• A breed is one in which people cannot discern the difference between it and other species without using genetics.  genetic pollution, assortative mating, and outbreeding may all arise from gene flow between hybrid and wild populations, resulting in a loss of genetic diversity. Endogamy can cause genetic distance in human groups owing to differences in caste, ethnicity, culture, and religion.

Gene flow examples-

• Dogs- Dogs come in many shapes and sizes across the globe. A wild wolf is dwarfed by the biggest domestic dogs. Even as an adult, the tiniest domestic dog may be mistaken for a baby wolf. Dogs have altered practically every element of their look since they were werewolves in one community or another. Dogs are one of the most well-known instances of artificial selection, which is the process of establishing features via selective breeding.

All werewolves about 15,000 years ago. However, some of these pre-dogs were much more prone to scavenge from the burgeoning human settlements. The wolves retreated away from civilisation, whilst the pre-dogs grew closer to people. The humans and the dogs eventually figured out a “social compact” of sorts.

• Bacteria- Bacteria and other asexual organisms may occasionally transmit genetic diversity through non-sexual means. Horizontal gene transfer, for example, allows DNA to be passed across species without the necessity for sexual reproduction. In reality, these gene exchanges millions of years ago are responsible for most of today’s variety. This is one of many gene flow biology examples.

Gene flow diagram-

The probable consequences of increasing genetic exchange are summarised in this diagram. The black highlights cases of gene flow affecting the number of taxa, whereas the grey highlights examples of gene flow affecting population fitness. The dotted lines represent examples where gene flow has a detrimental impact on biodiversity, whereas the continuous lines represent cases where gene flow has a beneficial impact on biodiversity.

Conclusion-

In this article we have read about gene flow, gene flow types, barriers to gene flow, examples of gene flow and lastly, we tried to understand the gene flow with the help of a flow diagram. The transfer of genes from one group to another may also result in evolution. This gene flow occurs as organisms move. Even if no other evolutionary processes are at work, the removal or addition of species may easily influence gene pool frequencies. While there are certain drawbacks to gene flow, the benefits have outweighed the drawbacks in the long term.