Final answer:
Darwin and Wallace observed patterns in nature leading to the theory of natural selection, which posits that inherited variations benefiting survival and reproduction will become more prevalent. This process adapts populations to their environments and is considered the mechanism of adaptive evolution.
Step-by-step explanation:
Darwin convincingly argues that natural selection could be the mechanism of selection. This mechanism stemmed from the observation of certain patterns within various organisms by both Darwin and Alfred Russel Wallace. These patterns led them to independently conceive an explanation for how and why these changes could take place in nature. In the concept of natural selection, also known as survival of the fittest, individuals with favorable inherited traits are more likely to survive and reproduce. Therefore, these traits become more prevalent in subsequent generations, leading to evolutionary change.
The principle of natural selection can be broken down into three main points: variation in traits among individuals is inherited; more offspring are produced than can survive, due to limited resources, which leads to competition; and those traits that provide an advantage in this competition are more likely to be passed on to the next generation. Darwin's ideas were influenced by reading the work of economist Thomas Malthus and elaborated in his landmark publication, On the Origin of Species.
Natural selection results in the adaptation of a population to its local environment and is the sole mechanism known for adaptive evolution. Despite not understanding the mechanics of inheritance at the time, which would later be explained by Gregor Mendel's work on genetics, natural selection remained a robust theory. Over time, the modern synthesis integrated Darwin's principles of natural selection with Mendel's genetic discoveries, creating a comprehensive understanding of evolution.