Living Environment Regents Practice Test 2025 – Complete Exam Prep

Natural selection is a fundamental mechanism of evolution that explains how certain traits become more common in a population over time due to their advantages in survival and reproduction. In the case of icefish, the presence of the antifreeze protein gene provides a significant benefit in their cold, icy habitats.

Individuals with this gene can survive in frigid waters, where their body fluids would otherwise freeze. This adaptation allows them not only to live in environments that others cannot but also to reproduce and pass on this advantageous trait to subsequent generations. As a result, the frequency of the antifreeze protein gene increases within the icefish population because those who possess it have a higher chance of surviving and reproducing compared to those without the gene.

This process highlights the core principle of natural selection, where advantageous traits increase an organism's fitness in a specific environment, leading to a change in the genetic composition of the population over time. Other factors such as predation, food availability, or migration patterns can affect fish populations, but the crucial aspect of the antifreeze protein's increase in frequency is its direct correlation to survival and reproductive success in harsh environmental conditions.