Final answer:
True, evolution cannot occur without genetic changes in populations. Evolution manifests as changes in a population's gene pool and allele frequencies over time due to mutation, natural selection, genetic drift, and gene flow. It is the population that evolves, not the individuals within it.
Step-by-step explanation:
Evolution cannot occur without genetic changes in populations. This statement is true. Evolution refers to the change in the genetic composition of a population over time, which can only happen through alterations in the population's allele frequencies or gene pool.
A population's genes change through processes such as mutation, natural selection, genetic drift, and gene flow. Mutations introduce new genetic variation, while natural selection enhances the frequency of beneficial alleles that improve survival and reproductive success. It is essential to note that natural selection can only act upon existing genetic variation; it cannot create new traits from nothing.
For natural selection to lead to evolution, the variation within a population must be heritable, meaning it has a genetic basis. Non-genetic variation, such as differences caused by environmental factors like nutrition, will not lead to evolution because these traits are not passed down to the next generation.
Another aspect to understand is that individuals do not evolve. Instead, evolution is observed at the population level as the average traits within a population change over generations. For example, if a population of finches experiences a change in average bill size due to selective pressures, individual finches do not change their bill sizes; the population's average bill size changes over time because the genetic composition shifts with the selective pressures.
Evolution and speciation are related but not synonymous. Evolution can lead to speciation, which is the formation of new species, but changes within a species may not constantly lead to the creation of a new species.