Biodiversity refers to the amount species variation. Species are defined by the genes present in the individual members of their group. Genes are the most basic unit of heredity (passing characteristics from parent to offspring); genes carry the information that determine the traits of an individual. A species is understood in terms of the individual organisms that carry genes which will allow them to interbreed and successfully reproduce with one another. If two organisms can not create offspring with one another, then chances are, they do not belong to the same species because there genes are incompatible.
Compatible sets of individuals produce offspring that have portions of both of their genetic material. Because offspring carries a random combination of genes from both its parents, it will have traits that neither one of its parents possesses alone, giving it a slightly different chance of survival than either of them. However, the offspring will belong to the same species. We have just contrived a hypothetical scenario consisting of three distinct individuals of the same species. To breeders (the parents), who have distinct sets of genes and thus differing odds of survival, and their single child. The child, taking both parts of its genetic material from its parents, of course also has a different chance of survival than either of its parents.
Because no two members, (except for sets of twins) have all of their genetic material in common, then adding more members to this family trees grants increasing chances of at least one of them surviving some disease outbreak, predator or severe storm. All it takes is a few lone survivors that has traits which allows it to live long enough to reproduce with another member belonging to the same species. Understandably, if there are fewer members of a species, then the chances for our lone survivors living long enough to reproduce are consequently slimmer.
Genetic Diversity Protects Against Extinction
The species that populate Earth’s environments require a diverse population of genes in order to survive. The greater the number of distinct gene variations within a species, the greater the species’ chances of survival are. Differing gene combinations give differential odds of survival.- but more variations mean more opportunities to have surviving combinations.
Genes define an organism’s physiological (and perhaps psychological) characteristics, which help the organism survive the local environment. If survival characteristics are multiplistic, then survivors will be more common. Reduced diversity within the gene pool will decrease the variance between members of the same species. With less variance, members of the same species have similar chances of survival- a species is likely to die out if they all have homogenous chances of survival. Without significant diversity in genes, extinction becomes an eminent possibility.