Biogeography is useful because it shows us the geographical distribution of organisms. In other words, it tells us where the plants and animals live, including their ancestors. Most of the time, scientists use biogeography in making connections and patterns about closely related organisms that live in different places and exhibit different characteristics, as well as those distantly related organisms that live in similar environments and exhibit similar characteristics.

Darwin came across fossils that serve as clues to what the Earth was in the past. The fossils of extinct animals resemble some characteristics of the living species. This indicates that modern species have evolved from their extinct ancestors. These fossil form series trace how the evolution took place.

Vestigial structures are the inherited structures or characteristics that do not have an essential function. These structures may show the evolutionary relationship between animal species. An example of a vestigial structure is the pelvic or hip bones of dolphins, which was inherited from their ancestors when they walked on land millions of years ago. Over the years, their ancestors evolved and lost their hind limbs because these structures served no purpose anymore. The hip bones remained and they serve as vestigial structures.

Hox genes are a group of related genes that code proteins and influence the body form or body plan of animals. These genes direct and control the head-to-tail organization of many organisms and they are involved in the developmental processes of embryos. More importantly, they are considered homologous because they are inherited from the ancestors. In this case, scientists study the coding of proteins in the embryo of animals since the hox genes give us clues about the origin and evolution of body plans between organisms.

The study conducted by the Grants tells us that the natural selection in the wild finch population happened within just a couple of years. According to them, the evolution they have observed was frequent and rapid. This opposed the notion of Darwin that evolution has occurred over thousands of years ago from a common ancestor.

The Grants’ worked on Darwin’s hypothesis by using a medium ground finch on one of the islands in Galápagos. They have conducted an observation on the finches’ offspring, beak structure, feeding, and mating behavior. They have discovered that the size of the bird’s beak is related to the way it feeds itself and the way they mate with other birds. In addition, the birds with smaller beaks have a higher chance of surviving when the vegetation is scarce during the hot and dry season. Eventually, finches born on the next generations have possessed smaller beaks than the previous generation after the natural selection.

Most of the investigations done by scientists included the use of new tools and techniques that support the hypotheses of Darwin. These methods include radioactive dating, observation in action, genetics, and molecular biology.

One example is the investigation done by Peter and Rosemary Grant. They both studied and observed natural selection in action. The Grants’ worked on Darwin’s hypothesis by using a medium ground finch on one of the islands in Galápagos. They have discovered that natural selection really occurs and sometimes this may happen quickly within a couple of years.

The experiment of Losos and the Grants both show how competition was involved in the evolution of the native Anoles species and the finches in Galapagos Islands.

Losos conducted an experiment that involved the two Anoles species. He introduced A. sagrei into the natural habitat of A. carolinensis and allowed competition to take place between the two species. As a result, the native species started to move into a new habitat–the higher parts of the tree. Eventually, he saw evolutionary changes among the native Anoles species as they started to develop adaptations, such as sticky toe pads, that are similar to the tree-dwelling species that stay within the higher parts of the tree.

On the other hand, Grants have discovered that the birds with larger beaks have a higher chance of surviving than birds with smaller beaks when the vegetation is scarce during the dry season. Eventually, the size of the finches’ beaks has increased in the next generation. According to the couple, evolution happened within just a span of a couple years.

The experiment of Losos and the Grants both show how competition was involved in the evolution of the native Anoles species and the finches in Galapagos Islands.