Question

Identify two factors that could possibly cause a population to decline to extinction. How might these factors be influenced by population size? Why are small populations more susceptible to extinction from demographic stochasticity than are larger populations?

Answer 1

Ans ) Factors that could cause population extinction are: habitat loss and loss of genetic diversity in the population. Small sized populations are more prone to extinction due to these factors. Habitat loss affects small populations more than the larger ones. In small populations, decrease in genetic diversity is more as compared to larger populations. Number of breeders is less which leads to inbreeding, thus increasing homozygosity and decreasing genetic variability.
Demographic stochasticity is the variation in birth and death rates due to random differences between individuals. It means the birth and death of individuals is probabilistic. It causes extinction more in smaller populations than larger ones because small populations have fewer breeding individuals Since births and deaths are discrete and probabilistic events, there will be less births due to low breeders, leading to the decline of population to extinction.