Final answer:
Evolution is more noticeable in mosquitoes than in squirrels due to their shorter life cycles and higher reproductive rates. Microevolution, like pesticide resistance, changes population genetics without creating new species and can spread rapidly through mosquito populations.
Step-by-step explanation:
The most important reason that one can see evolution in a population of mosquitoes more easily than in a population of squirrels is that mosquitoes have a much shorter life cycle and higher reproduction rates, allowing for more generations and a faster accumulation of genetic changes. Additionally, mosquitoes can undergo microevolution, such as the development of pesticide resistance, which does not create a new species but does change the genetic composition of the population. This resistance occurs when there's a mutation that some mosquitoes have, making them resist the pesticide, and as these survive and reproduce, the trait becomes more prevalent in the population. Female mosquitoes may choose mates with this resistance, enhancing the fitness of their offspring.
For instance, widespread use of a pesticide may kill most mosquitoes, but those with a random mutation conferring resistance will survive. When they reproduce, they pass on the resistant trait, resulting in a higher proportion of resistant mosquitoes in the following generations. Various factors, like genetic modifications to produce mosquitoes that die in the larval stage or environmental changes affecting mosquito reproduction, can influence these evolutionary patterns.