Final answer:
The correct answer is b. and c. Biologists move individuals between populations to decrease genetic drift and increase heterozygosity, thereby maintaining genetic diversity and reducing the risk of harmful effects like inbreeding depression in small and vulnerable populations.
Step-by-step explanation:
Biologists sometimes move individuals into populations of animals with low population sizes, particularly endangered species, for specific reasons related to genetic drift, genetic variance, and population viability. Among the options provided, the correct answer is option 5) Answers b. and c. Moving individuals between populations can increase the population size and thus decrease genetic drift that can often fix deleterious alleles. This also helps counteract non-random mating and increases heterozygosity, which is essential to maintain a healthy range of genetic diversity within a population.
Small populations are more vulnerable to genetic drift because they have fewer individuals, which means that chance events can more significantly impact the genetic makeup of the population. When a population is small, the gene pool is less stable, making the population more susceptible to the bottleneck effect or the founder effect, both of which can greatly reduce genetic variance. By increasing genetic variance, biologists help mitigate issues like inbreeding depression, which can arise from mating of closely related individuals, potentially bringing together deleterious recessive mutations.