Final answer:
The inbreeding coefficient increases with each generation of inbreeding because it measures the likelihood that alleles are identical by descent, which can lead to inbreeding depression as harmful recessive alleles become more common, thereby reducing a population's fitness and genetic diversity.
Step-by-step explanation:
The inbreeding coefficient, denoted as F, tends to increase in every generation where there is inbreeding because it measures the probability that two alleles are identical by descent. The process of mating between closely related individuals, or inbreeding, brings together similar genotypes, which often include deleterious or harmful recessive alleles that can lead to an increase in abnormalities and diseases, a phenomenon known as inbreeding depression. As the amount of gene flow is reduced, and less genetic diversity is present within a population, harmful alleles can become more common, resulting in a decline in population fitness over time.
Populations with higher genetic diversity have more resources to adapt when environments change because they have a wider variety of genetic material to work with. But when inbreeding occurs, it decreases genetic diversity, increases homozygosity, and can cause rare, recessive diseases to manifest more frequently. Over generations, if inbreeding continues, the population can suffer from a loss of fitness and adaptability due to this reduced genetic diversity.