•
In reproduction isolation, there will be the emergence of new species.
The basis for Darwin’s evolution was that all organisms can trace their descent to a common ancestor and that, because of natural selection, there becomes a diversity of species. Natural selection proposes that the heritable traits developed by a generation will vary and that some of the traits confer a natural advantage that allows some variations to have a reproductive advantage, perpetuating those particular variations in later descendants, leading to changes in the population. Many of Darwin’s theories came from the study of finches on the Galapagos Islands. He noted specific variations in the bird species, so that those that had certain types of beaks ate seeds and those that had other types of beaks ate insects. He argued that, through natural selection, changes in beak types were self-selected so that there was a reproductive advantage to certain birds in situations of limited resources. Divergences happened, he said, so that more resources (seeds and insects both) could be utilized by the different variations in the species. The Galapagos Island is an isolated island off of Ecuador, containing species similar to those in the mainland but isolated enough that they needed to adapt to local conditions over long periods of time and over multiple generations. The process of the development of new species led to the formation of more than one distinct species of animals, including birds. Darwin proposed that there can be changes of species over time, that new species can originate from pre-existing species, and that there must be a common ancestor to all species. He believed that the diversity of species is because of the inheritance over time of traits that diverged from the ancestor species. He referred to the change in heritable traits over many generations as “descent with modification”. This is now what we call evolution.
NATURAL SELECTION One of the key aspects of Darwin’s theories was that of “natural selection”. It explains how populations evolve over time in certain ways that allow the population to be better suited to their environment over the generations. It is based on the idea that traits are 129
