How do environmental changes affect natural selection?

Environmental changes can affect natural selection by altering the survival and reproduction rates of different species.

Natural selection is a fundamental process in evolution, where organisms with traits that enhance survival and reproduction in a particular environment are more likely to pass on these advantageous traits to their offspring. When environmental changes occur, they can significantly impact this process.

For instance, if the environment becomes colder, animals with thicker fur or fat layers may have a survival advantage over those without. These animals are more likely to survive, reproduce, and pass on their genes, leading to a higher prevalence of these traits in future generations. This is an example of directional selection, where one extreme phenotype is favoured over others.

Environmental changes can also lead to disruptive selection, where extreme phenotypes are favoured over intermediate ones. For example, if a forest is replaced by a grassland, tree-dwelling animals may struggle to survive, while ground-dwelling species thrive. Over time, the population may split into two distinct groups adapted to different habitats.

Moreover, environmental changes can cause stabilising selection, where intermediate phenotypes are favoured. For example, in a stable environment, extreme traits may be disadvantageous, and organisms with average traits have the highest survival and reproduction rates.

Lastly, environmental changes can lead to speciation, the formation of new species. If a population is separated by a new river or mountain range, different environmental pressures on each side can lead to the evolution of distinct species.

In conclusion, environmental changes can significantly influence the process of natural selection by altering the survival and reproduction rates of different species. This can lead to changes in the frequency of certain traits, the emergence of new traits, and even the formation of new species.