AP Bio Ch 18 Darwin & Evolution

Darwin believed that variations within a population were the building blocks of evolution. These variations, which could be inherited traits or genetic mutations, provided the raw materials for natural selection to act upon. Through the process of natural selection, individuals with advantageous variations were more likely to survive and reproduce, passing on their favorable traits to future generations. This gradual accumulation of beneficial variations over time led to the formation of new species and the diversification of life on Earth. Therefore, it is true that Darwin considered variations in a population to be the raw materials of evolution.

Darwin's observations about changes in species over time and in different environments primarily took place in and near South America. This is evident from his famous expedition on the HMS Beagle, during which he spent a significant amount of time exploring the Galapagos Islands and the South American continent. It was in these locations that Darwin made numerous groundbreaking observations and collected specimens that ultimately led to the development of his theory of evolution by natural selection.

Darwin's theory of natural selection proposes that species evolve over time through the process of descent with modification. This means that new species arise from pre-existing species through gradual changes and adaptations that accumulate over generations. This theory suggests that the characteristics of organisms change over time in response to their environment, leading to the diversity of species we see today. In contrast, inheritance of acquired characteristics, uniformitarianism, and catastrophism are other theories that have been proposed to explain evolution but are not synonymous with Darwin's theory of natural selection.

Darwin's observation that there were Patagonian hares but no rabbits in South America suggests that the distribution of species is influenced by geographical factors, such as isolation and the availability of suitable habitats. This observation aligns with the field of biogeography, which studies the distribution of plants and animals across different regions. Comparative anatomy, the fossil record, comparative embryology, and comparative biochemistry may provide additional evidence to support biogeographical patterns, but they are not directly related to Darwin's observation of the absence of rabbits in South America.

Malthus was not a biologist who suggested that variation provides the means by which populations adapt to their environment. Malthus was actually an economist and demographer who proposed the theory of population growth and its potential consequences. He argued that population growth would eventually outpace the availability of resources, leading to famine and other societal problems. This theory is known as Malthusianism. Therefore, the statement in the question is incorrect.

Both Darwin and Wallace independently proposed the concept of natural selection as a mechanism for evolution. In 1858, Wallace sent a letter to Darwin outlining his own theory of natural selection, which greatly resembled Darwin's own ideas. This prompted Darwin to finally publish his own work on the subject, and both men are now recognized as co-discoverers of the theory of evolution by natural selection.

Charles Darwin was not the first one to consider environment, migration, overcrowding, and isolation of populations as factors that could influence evolution. These factors were actually proposed by other scientists before Darwin. However, Darwin's contribution to the field of evolution was his theory of natural selection, which explained how these factors could lead to the adaptation and evolution of species over time.