Final answer:
Fitness is the relative ability of an organism to survive and reproduce, which is influenced by environmental factors and heritable traits. Genetic fitness involves differential reproductive success and influences the prevalence of traits in populations. Selective breeding is an anthropogenic method that can cause genetic changes in offspring.
Step-by-step explanation:
Fitness, in the context of evolution by natural selection, is the relative ability of an organism to survive and produce fertile offspring. In evolutionary theory, traits that contribute to an organism's genetic fitness are determined by its ability to cope with environmental challenges and reproduce effectively. Factors such as variation of traits among individuals, competition for limited resources, and the fact that more offspring are produced than can survive (D), all influence an individual's fitness. In particular, differential reproductive success ensures that certain traits are better represented in the next generation (d).
The good genes hypothesis and the handicap principle are theories of sexual selection explaining why certain traits, such as ornamental features, might signal an individual's fitness and thus be selected for. These theories emphasize the importance of honest signals and the heritability of beneficial traits. Natural selection tends to reproduce individuals with favorable genetic traits over time (d).
In summary, while the environment determines the relative fitness of different phenotypes, such as the black-eyed allele in Drosophila melanogaster studied by Moree, genetic changes, and heritable traits are essential elements that drive the evolution of populations. For instance, selective breeding, which is anthropogenic (B), results in genetic changes in the offspring because it artificially selects for certain traits that humans deem desirable.