Final answer:
Inbreeding depression can worsen due to increased expression of deleterious mutations, leading to higher offspring mortality, decreased lifespans, and reduced fertility. This can result in an Allee effect, reducing a population's survivability, especially after a bottleneck event, and potentially leading to extinction. Conservation efforts aim to maintain genetic diversity and prevent these outcomes.
Step-by-step explanation:
Inbreeding Depression and Population Extinction
Inbreeding depression is an increase in abnormalities and diseases in populations that result from the mating of closely related individuals. This genetic phenomenon can lead to detrimental impacts on a population's health and vitality, potentially worsening over time. When inbreeding occurs, there is a higher chance of deleterious mutations being expressed because related individuals are more likely to carry the same harmful alleles. This can result in increased offspring mortality, decreased lifespans, and lower fertility rates.
In extreme cases, inbreeding depression can reduce a population's genetic diversity so significantly that the population may not be able to adapt to environmental changes or resist diseases, leading to an Allee effect. This effect exacerbates the reduction in individual fitness as population size becomes small, which can spiral into an extinction vortex. Additionally, after a disaster that causes a bottleneck effect, the survivors' genetic structure may lack the genetic diversity needed to ensure the population's long-term survival.
Conservation genetics tools measure inbreeding depression alongside gene flow and genetic diversity loss. These indicate how a population's reduced genetic variance might affect its ability to continue thriving. Breeders, therefore, avoid inbreeding to maintain necessary genetic diversity and prevent diversifying selection from diluting desired genes.