=Inbreeding= '''Inbreeding occurs when closely related individuals produce offspring together''' ==Inbreeding Depression== [image:] Inbreeding usually reduces the biological fitness (the ability to survive and reproduce) of a population. When related individuals reproduce there is an increased chance that their offspring will be affected by a recessive disorder. This is because most individuals carry some mutant alleles (versions of a gene). However, they aren't affected by this because they normally carry another, functioning, version of each gene too. Essentially this means that most mutant / non-functional alleles are recessive. When two closely related individuals reproduce it is more likely that they both carry recessive alleles for the same gene / trait (as they will have inherited them from the same parent or grandparent). Therefore, their offspring are much more likely to inherit two non-functional recessive alleles for the same trait. This will most likely result in some disorder that reduces their biological fitness (the ability to survive and reproduce). When unrelated individuals breed (called outbreeding) they are much less likely to pass on recessive alleles for the same disorders. Therefore their offspring are less likely to be affected by these disorders (they will simply be carriers).