Population size affects genetic diversity in a number of ways. One way is through genetic drift. Genetic drift is the random process of alleles changing in frequency from one generation to the next due to chance. It is more likely to occur in small populations, where there is less chance of all alleles being represented in the next generation. Over time, genetic drift can lead to the loss of rare alleles and a decrease in overall genetic diversity.

Another way that population size affects genetic diversity is through inbreeding. Inbreeding occurs when two closely related individuals mate. This can lead to the expression of harmful recessive alleles, which can decrease the fitness of individuals and reduce the overall genetic diversity of the population. Inbreeding is more likely to occur in small populations, where there is a higher chance of individuals mating with relatives.

Finally, population size can also affect genetic diversity through gene flow. Gene flow is the movement of alleles between populations. It can increase genetic diversity by introducing new alleles into a population and can reduce genetic diversity by homogenizing the gene pool. Gene flow is more likely to occur in large populations, which are more likely to be in contact with other populations.

Large populations lose genetic diversity more slowly than small populations for a number of reasons. First, large populations have more alleles to begin with. This means that even if some alleles are lost due to genetic drift or inbreeding, there are still a large number of alleles remaining in the population. Second, large populations are more likely to have gene flow from other populations. This can help to introduce new alleles into the population and prevent the loss of genetic diversity.

Here are some examples of how population size affects genetic diversity in the real world:

• Cheetahs: Cheetahs have a very low effective population size, meaning that there is very little genetic variation within the species. This is because cheetahs went through a severe population bottleneck in the past, during which time their population was reduced to just a few hundred individuals. As a result, cheetahs are more susceptible to disease and other threats.
• Giant pandas: Giant pandas are another species with a low effective population size. This is due to a number of factors, including habitat loss and fragmentation, and poaching. Giant pandas are also more susceptible to disease and other threats as a result of their low genetic diversity.
• Humans: Humans have a very large effective population size, meaning that there is a lot of genetic variation within the species. This is because humans have expanded their range throughout the world and have intermixed with other human populations. As a result, humans are more resilient to disease and other threats.

Overall, population size is an important factor that affects genetic diversity. Smaller populations are more likely to lose genetic diversity due to genetic drift, inbreeding, and reduced gene flow. Larger populations are more likely to maintain genetic diversity, which can help them to adapt to change and survive in the long term.

Dr Murtadha Shukur thank you for your contribution to the discussion

Genetic diversity is influenced by population size, with smaller populations having an increased probability of inbreeding, genetic drift, and the potential fixation of deleterious alleles, which decreases genetic diversity and adaptive potential. Higher population genetic diversity in the abundant species is likely due to a combination of demographic factors, including larger local population sizes (and presumably effective population sizes), faster generation times and high rates of gene flow with other populations. Patterns of genetic diversity inform us about population history because each major demographic event leaves an imprint on a population's collective genomic diversity. A reduction in population size reduces genetic diversity, and an increase in population size eventually increases diversity. Maintaining high genetic diversity allows species to adapt to future environmental changes and avoid inbreeding. Inbreeding, which happens when there are small, isolated populations, can reduce a species' ability to survive and reproduce. The interdependence between genetic and species diversity is delicate. Changes in species diversity lead to changes in the environment, leading to adaptation of the remaining species. Changes in genetic diversity, such as in loss of species, leads to a loss of biological diversity. Large populations, on the other hand, are buffered against the effects of chance. If one individual of a population of 10 individuals happens to die at a young age before leaving any offspring to the next generation, all of its genes (1/10 of the population's gene pool) will be suddenly lost. Without genetic variation, a population cannot evolve in response to changing environmental variables and, as a result, may face an increased risk of extinction. As population is exposed to a new disease, selection will act on genes for resistance to the disease if they exist in the population.