Final answer:
Selection processes like natural selection, genetic drift, and gene flow produce changes in a population's genetic makeup, thereby driving evolutionary change. Natural selection favors traits that improve reproductive success, genetic drift causes random changes in allele frequencies, and gene flow introduces new genetic material.
Step-by-step explanation:
To explain how selection produces changes within a population of a species, we must consider the different selection processes, including genetic drift, gene flow (migration), and artificial selection. These are key mechanisms that drive evolutionary change.
Natural selection acts on the phenotypic variations within a population, favoring those individuals that have traits providing a reproductive advantage under specific environmental conditions. Over generations, these advantageous traits become more common in the population, while less advantageous traits diminish in frequency. This is because individuals with better-suited phenotypes for the environment tend to survive and reproduce more than those with less suited phenotypes, passing on their genes to the next generation.
Genetic drift pertains to random fluctuations in allele frequencies due to chance events. It can have a significant impact on small populations, leading to an evolutionary change that is not necessarily adaptive. Gene flow, or migration, introduces new genetic material into a population, potentially altering allelic frequencies and thus, the population's genetic makeup.
Artificial selection, a process utilized by humans, refers to the intentional breeding for certain traits, which may dramatically change a species' genetic composition over a relatively short timespan.
Mathematical models, such as the Hardy-Weinberg equilibrium, can be applied to predict and analyze these evolutionary effects. Deviations from the model's expectations suggest an ongoing evolutionary process due to factors like natural selection or genetic drift.
In summary, selection, whether natural, artificial, or due to random events like genetic drift, results in changes in allele frequencies, which then drives evolutionary changes within a given population.