Final answer:
When addressing natural selection in exams, use the acronym VISTA: Variation, Inheritance, Selection, Time, and Adaptation. These principles describe how natural selection shapes populations over time through different types of selection forces. Remember that natural selection acts on phenotypes and can maintain alleles in the population if they offer survival advantages.
Step-by-step explanation:
When answering exam questions on natural selection, it's helpful to use the acronym VISTA, which stands for Variation, Inheritance, Selection, Time, and Adaptation.
These principles come together to shape populations through natural selection. Various forces of natural selection can lead to different outcomes such as stabilizing, directional, or disruptive changes within a population.
Variation within a population is essential for natural selection because it provides the raw material upon which selection can act. Inherited traits that are advantageous for survival and reproduction can be passed down to offspring, known as Inheritance.
Selection pressures then determine which variations are more advantageous, thus affecting which traits become more common in the population over Time. As a result, populations can develop new Adaptations that enhance their survival and reproduction in specific environments.
Natural Selection and Population Variation
Natural selection operates on the phenotype, not the genotype, and can result in allele frequencies changing over generations. An adaptation is a trait shaped by natural selection to increase the likelihood of survival and reproduction.
The recessive sickle-cell allele remains in the gene pool because carriers have an advantage against malaria, illustrating how natural selection can maintain harmful alleles if there is an associated benefit.