living organisms is what enables us to survive and thrive in this world. The capacity of species to adapt to new circumstances, whether this is resource scarcity, a changing environment or other disturbances to their natural environment, depends on genetic diversity. Essentially, genetic diversity is the total number of characteristics in the genetic makeup of a species¹. The greater the variation in genes, the more likely is that individuals in a population will possess the differentiated genes which are needed to adapt to an environment. In scientific literature, these differentiated genes are called “alleles” and their presence is what will help species survive. The theory of natural selection suggests that it is this variety of genes that allows species to evolve, adapt and propagate successfully.
More specifically, genetic diversity can be a species natural defence system against disease and survival even under extreme weather conditions but more importantly, genetic diversity can help weed out unfavourable traits in species which maximises opportunities for thriving in any environment². When a species can only reproduce within a small or isolated population of organisms, individuals of that species may be forced to breed with close relatives which simply creates a more uniform and smaller gene pool for the species. Inbreeding, as the phenomenon is called, makes species weaker and more susceptible to diseases. Apart from humans, where incest is considered illegal in most countries and where even marriage among cousins is often prohibited, the concerns related to inbreeding are very well illustrated in the case of some of our favourite pets. For example, in the case of many dog breeds, in order to preserve their pedigree, inbreeding is regularly conducted. This has meant that a lot of hereditary conditions, such as hip dysplasia, and illnesses are more easily passed on to a pup³.
The absence of genetic diversity was the reason behind one of history’s biggest famines¹. The causes of the Potato Famine in Ireland which took place in the 19th century can be traced back to the susceptibility of the specific type of potato, the new potato plant, to a specific disease. Because new potato plants are not a result of reproduction – they are instead created from one parent plant – they exhibit very low genetic diversity. The potato’s low genetic diversity meant that the virus spread to the vast majority of the potato crop which was a staple food for the Irish population leaving one million people to starve to death. Absence or low genetic diversity is also in part what makes agricultural monocultures more susceptible to disease.
Many studies have also highlighted how species diversity (i.e. biodiversity) and genetic diversity are inter-linked, inter-dependent and equally important. Lead researcher Dr. Richard Lankau, whose team illustrated how genetic diversity and species diversity depend on each other, has highlighted that “Diversity within a species is necessary to maintain diversity among species, and at the same time, diversity among species is necessary to maintain diversity within a species. And if any one type is removed from the system, the cycle can break down, and the community becomes dominated by a single species”⁴.