Genetic Diversity in Species

Hannah Phillips

The genes that make up an organism alter characteristics, physical build, and abilities. In more scientific terms, the entire collection of an animal’s DNA, also known as a genome, breaks down into two categories: genotype and phenotype. Genotype refers to “the set of genes in its DNA responsible for a particular trait,” whereas phenotype is the physical attributes or observable characteristics that result from the formation of all genes. Measured differences in these genes account for genetic diversity, which plays an essential role in the evolution of species’.

Reasons for Genetic Variation

Variations among genomes of the general population or same species can occur for a number of reasons, namely, mutations, sexual reproduction and gene flow. Mutations occur when there is a change in the DNA sequence, thus leading to evolutionary changes. Reproduction results in a new blend of genes, introduced from two organisms. The transfer of genes between differing populations or organism groups from interbreeding is called gene flow, another source of genetic variation.

Genetic Variation and Evolution

The ability of genes to change allows species to survive their constantly changing environments. Natural selection comes into play as organisms that are ‘better-adapted’ to their environments reproduce and generate more organisms that share those thriving traits. The natural selection of organisms and their adaptable traits, results in species’ evolution.

Species with Low Genetic Diversity

A lack of variation in genes can be harmful to a species because it hinders their ability to evolve as environmental factors change. Surviving diseases or overcoming endangerment threats become a much more daunting task when a species doesn’t have the genes that will allow for population persistence. Wild cheetahs and island foxes are a couple of species that have a low genetic diversity.

Wild Cheetahs 

Wild Cheetahs are a species that face issues spawning from low genetic diversity, making them more vulnerable to extinction. As a result of what is believed to have been a collapse of population during severe climate changes over 10,000 years ago, cheetahs resorted to inbreeding. By breeding amongst its closely related organisms, the cheetahs’ genetic diversity has lessened their level of diversity. A specific side effect wild cheetahs face is decreased sperm quality, which makes reproduction a struggle.

California Channel Island Foxes

Living on the California Channel Islands, this fox species has been deemed one of the least, if not the least, genetically diverse animal. Scientists have found that island foxes are 99.9 percent alike in relation to each other. The small islands they inhabit make inbreeding more accessible and common, which is a contributor to the low variation of genetics. The U.S. Fish and Wildlife Service assisted in helping this species out of endangerment in the early 2000s by introducing predators to the mainland. While the population is now exceling scientists are hesitant to celebrate its increased numbers because they still have very low genetic variation.The mere introduction of a disease could wipe out a species that is not genetically equipped.

Human Impact

As the human population continues to expand rapidly, large habitats for species are being broken up and separated. Large land swaths that house various organisms and grounds for interbreeding are rapidly being depleted as mankind encroaches. Trash pollutes habitats, rapidly changing climates make for drastic ecosystem shifts, and the hunger for status and money drive poaching. While genetic variation is not the sole reason for species extinction, these humanistic changes make it increasingly difficult for species to allow natural selection to pick the strongest genes and persist. 

Species that experienced high biodiversity, like birds, have lost variation over time. Traveling constantly to various locations and introducing differing populations, birds as a whole actively interbreed. Through the use of pesticides and habitat loss the bird populations in North America have plummeted. These smaller populations mean that there are less opportunities for interbreeding and less variation of genetic makeup.

In an effort to boost genetic variation in species, zoos have attempted to assist with interbreeding through breeding programs. Their hopes are to boost populations and their biodiversity for future generations. Biologists study the impact of introducing new blood to species who are struggling to attain diversity naturally. Cautious in their approach, biologists aim to avoid completely eliminating pure breeds through rapid integration of hybrid organisms. 

Sources: Berkeley, Center for Biological Diversity, Hoedspruit Endangered Species Centre (HESC), Medline Plus, National Geographic, Pacific Standard, Proceedings of the National Academy of Sciences, Science, Smithsonian, The Wall Street Journal, The Washington Post, Your Dictionary