How do gene pools change over time in response to environmental pressures?

Gene pools change over time in response to environmental pressures through the process of natural selection.

Natural selection is a key mechanism of evolution, first articulated by Charles Darwin. It is the process by which traits become more or less common in a population due to consistent effects upon the survival or reproduction of their bearers. In other words, it is the differential survival and reproduction of individuals due to differences in phenotype, or observable traits.

When environmental pressures such as climate change, predation or disease occur, they can affect the survival and reproduction of individuals within a population. Those individuals with traits that enable them to survive and reproduce more effectively in the new environment will pass these advantageous traits on to their offspring. Over time, these traits become more common within the population, leading to a change in the gene pool. This is known as adaptive evolution.

For example, consider a population of beetles living in a forest. If the forest becomes darker due to increased growth of vegetation, beetles with darker colouration may be better camouflaged from predators and therefore more likely to survive and reproduce. Over time, the gene for dark colouration will become more common in the beetle population, leading to a change in the gene pool.

However, it's important to note that not all changes in gene pools are due to natural selection. Other factors such as genetic drift, gene flow and mutation can also cause changes in gene pools. Genetic drift is a random change in allele frequencies that occurs in small populations. Gene flow is the transfer of genetic variation from one population to another. And mutation is a change in a DNA sequence, usually occurring because of errors in replication or repair.

In conclusion, gene pools change over time in response to environmental pressures primarily through the process of natural selection. However, other factors such as genetic drift, gene flow and mutation can also play a role.