Charles Darwin and the Theory of Natural Selection

Unity and diversity among birds. These four birds are variations on a common body plan. For example, each has feathers, a beak, and wings. However, these common features are highly specialized for the birds’ diverse lifestyles.
Source: Urry, Lisa A.. Campbell Biology (p. 14). Pearson Education. Kindle Edition.

Charles Darwin and the Theory of Natural Selection (Campbell Biology)

An evolutionary view of life came into sharp focus in November 1859, when Charles Darwin published one of the most important and influential books ever written, On the Origin of Species by Means of Natural Selection. The Origin of Species articulated two main points. The first point was that contemporary species arose from a succession of ancestors that differed from them. Darwin called this process “descent with modification.” This insightful phrase captured the duality of life’s unity and diversity—unity in the kinship among species that descended from common ancestors and diversity in the modifications that evolved as species branched from their common ancestors. Darwin’s second main point was his proposal that “natural selection” is a primary cause of descent with modification.

Darwin developed his theory of natural selection from observations that by themselves were neither new nor profound. However, although others had described the pieces of the puzzle, it was Darwin who saw how they fit together. He started with the following three observations from nature: First, individuals in a population vary in their traits, many of which seem to be heritable (passed on from parents to offspring). Second, a population can produce far more offspring than can survive to produce offspring of their own. With more individuals than the environment is able to support, competition is inevitable. Third, species generally are suited to their environments—in other words, they are adapted to their circumstances. For instance, a common adaptation among birds that eat mostly hard seeds is an especially strong beak.

By making inferences from these three observations, Darwin arrived at his theory of evolution. He reasoned that individuals with inherited traits that are better suited to the local environment are more likely to survive and reproduce than less wellsuited individuals. Over many generations, a higher and higher proportion of individuals in a population will have the advantageous traits. Evolution occurs as the unequal reproductive success of individuals ultimately leads to adaptation to their environment, as long as the environment remains the same.

Darwin called this mechanism of evolutionary adaptation natural selection because the natural environment consistently “selects” for the propagation of certain traits among naturally occurring variant traits in the population. We see the products of natural selection in the exquisite adaptations of various organisms to the special circumstances of their way of life and their environment. The wings of the bat are an excellent example of adaptation.


Urry, Lisa A.. Campbell Biology. Pearson Education. Kindle Edition.


Related Research

Research Article: Charles Darwin’s Reception in Germany and What Followed

Date Published: July 28, 2009 Publisher: Public Library of Science Author(s): Axel Meyer Abstract: 150 years ago, Heinrich Bronn provided in the first German translation of Charles Darwin’s Origin of Species a rather liberal interpretation, even adding his own view of Darwin’s ideas in an additional 15th chapter. Ernst Haeckel widely popularized his view of … Continue reading

Research Article: Reappraising Sexual Coevolution and the Sex Roles

Date Published: December 8, 2009 Publisher: Public Library of Science Author(s): Russell Bonduriansky Abstract: Over recent decades, new ideas have radically altered how we see sex and reproduction. The implications of these ideas are still being explored, yielding intriguing discoveries. Partial Text: The history of evolutionary biology illustrates how theory shapes what we see and … Continue reading

Research Article: Sorcerer II: The Search for Microbial Diversity Roils the Waters

Date Published: March 13, 2007 Publisher: Public Library of Science Author(s): Henry Nicholls Abstract: This feature explores bioprospecting and the legal issues related to collecting and cataloging microbial diversity from oceanic locations around the world. Partial Text: Craig Venter is not short of ambition. With the human genome fresh off the sequencing machines, he set … Continue reading