Final answer:
Darwin's understanding of artificial selection, where desirable traits in domesticated animals and plants are selectively bred by humans, helped inform his theory of natural selection, in which the environment acts as a selector for traits that improve survival and reproduction. This process leads to changes in species over time, eventually culminating in new species.
Step-by-step explanation:
Understanding the mechanisms of artificial selection was pivotal in shaping Charles Darwin's conception of natural selection and the theory of evolution. By observing how humans selectively bred domesticated animals and plants to enhance desirable traits, Darwin recognized parallel processes could occur in nature. In artificial selection, humans consciously choose which organisms to breed based on specific traits, leading to changes in the phenotypes of species over time.
Darwin extrapolated that in the natural world, the environment serves a similar role to human breeders, selecting for traits that enhance an organism's chances of survival and reproduction.
Natural selection thus acts on the natural variations within a population, where individuals with advantageous traits are more likely to survive the 'struggle for existence.' Over generations, these traits become more common, as they are inherited by the next generation. This process, which Darwin labeled 'descent with modification,' results in populations adapting to their environments and, potentially, the formation of new species.
Although Darwin and Wallace didn't have a comprehensive understanding of genetics, which led to initial doubts about how natural selection could bring about gradual evolutionary changes, the integration of genetics into evolutionary theory during the modern synthesis resolved these questions. It clarified that natural selection affects a population's genetic makeup and thereby facilitates both microevolution and macroevolution.