Final answer:
Populations with reduced genetic diversity face an increased risk of extinction due to the vulnerability to recessive lethal alleles, reduced adaptability to changing environmental conditions, the phenomenon of inbreeding depression, and limited adaptive potential.
Step-by-step explanation:
Populations with reduced genetic diversity face an increased risk of extinction due to several factors. Firstly, a decline in genetic diversity makes a population more vulnerable to recessive lethal alleles, which can cause abnormalities and increase the susceptibility to diseases. Additionally, reduced genetic diversity makes a population less adaptable to changing environmental conditions. If a population lacks genetic diversity, it may not have the necessary variations to survive and reproduce successfully in new or challenging environments.
Another reason for increased extinction risk is the phenomenon known as inbreeding depression, which occurs when closely related individuals mate and bring together deleterious recessive mutations. In small populations, there is a higher chance of inbreeding occurring, leading to a higher prevalence of harmful mutations and reduced fitness. This can result in decreased reproductive success and ultimately, population decline or extinction.
Furthermore, populations with low genetic diversity may have limited adaptive potential. Genetic diversity is crucial for natural selection to act upon and for populations to evolve in response to environmental changes. If a population lacks genetic diversity, it may struggle to adapt to new predators, diseases, or habitat alterations, increasing the risk of extinction.