What biological process is responsible for biodiversity?
What biological process is responsible for biodiversity?
All species —from the bacteria on our skin to the birds outside—evolved from a different species at some point. Although it may seem that living things today stay much the same from generation to generation, that is not the case because evolution is ongoing. Evolution is the process through which the characteristics of a species change over time, which can ultimately cause new species to arise.
The theory of evolution is the unifying theory of biology, meaning it is the framework within which biologists ask questions about the living world. Its power is that it provides direction for predictions about living things that are borne out in experiment after experiment. The Ukrainian-born American geneticist Theodosius Dobzhansky famously wrote that “nothing makes sense in biology except in the light of evolution.” He meant that the principle that all life has evolved and diversified from a common ancestor is the foundation from which we understand all other questions in biology.
Discovering How Populations Change
The theory of evolution by natural selection describes a mechanism for how species can change over time. That species change was suggested and debated well before Darwin. The view that species were unchanging was grounded in the writings of Plato, yet there were also ancient Greeks that expressed evolutionary ideas.
In the eighteenth century, ideas about the evolution of animals were reintroduced by various naturalists. At the same time, James Hutton, the Scottish naturalist, proposed that geological change occurred gradually by accumulating small changes from processes (over long periods of time) just like those happening today. This contrasted with the predominant view that the planet’s geology resulted from catastrophic events occurring during a relatively brief past. The geologist Charles Lyell later popularized Hutton’s view in the nineteenth century. Lyell became a friend to Darwin, and his ideas influenced Darwin’s thinking. Lyell argued that the greater age of Earth gave more time for gradual change in species, and the process provided an analogy for gradual change in species.
Charles Darwin and Natural Selection
Natural selection as a mechanism for evolution was independently conceived and described by two naturalists, Charles Darwin and Alfred Russell Wallace, in the mid-nineteenth century. Importantly, each spent years exploring the natural world on tropic expeditions. From 1831 to 1836, Darwin traveled the world on H.M.S. Beagle, visiting South America, Australia, and the southern tip of Africa. Wallace traveled to Brazil to collect insects in the Amazon rainforest from 1848 to 1852 and the Malay Archipelago from 1854 to 1862. Darwin’s journey, like Wallace’s later journeys in the Malay Archipelago, included stops at several island chains, the last being the Galápagos Islands (west of Ecuador). On these islands, Darwin observed species of organisms on different islands that