The Core Theme: Evolution Accounts for the Unity and Diversity of Life (Campbell Biology)
Evolution is the one idea that makes logical sense of everything we know about living organisms. As the fossil record clearly shows, life has been evolving on Earth for billions of years, resulting in a vast diversity of past and present organisms. But along with the diversity there is also unity, in the form of shared features. For example, while sea horses, jackrabbits, hummingbirds, and giraffes all look very different, their skeletons are organized in the same basic way.
The scientific explanation for the unity and diversity of organisms—as well as for the adaptation of organisms to their particular environments—is evolution: the concept that the organisms living on Earth today are the modified descendants of common ancestors. As a result of descent with modification, two species share certain traits (unity) simply because they have descended from a common ancestor. Furthermore, we can account for differences between two species (diversity) with the idea that certain heritable changes occurred after the two species diverged from their common ancestor. An abundance of evidence of different types supports the occurrence of evolution and the theory that describes how it takes place. To quote one of the founders of modern evolutionary theory, Theodosius Dobzhansky, “Nothing in biology makes sense except in the light of evolution.” To understand Dobzhansky’s statement, we need to discuss how biologists think about the vast diversity of life on the planet.
Urry, Lisa A.. Campbell Biology. Pearson Education. Kindle Edition. https://www.pearson.com/us/higher-education/series/Campbell-Biology-Series/2244849.html
Research Article: Host Life History Strategy, Species Diversity, and Habitat Influence Trypanosoma cruzi Vector Infection in Changing Landscapes
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Date Published: July 3, 2013 Publisher: Public Library of Science Author(s): Marjolein Gysels, Natalie Evans, Arantza Meñaca, Irene J. Higginson, Richard Harding, Robert Pool, Nicholas Jenkins. http://doi.org/10.1371/journal.pone.0068002 Abstract: The terms used to describe care at the end of life (EoL), and its definitions, have evolved over time and reflect the changes in meaning the concept … Continue reading
Date Published: July 13, 2010 Publisher: Public Library of Science Author(s): Ronnie Vernooy, Ejnavarzala Haribabu, Manuel Ruiz Muller, Joseph Henry Vogel, Paul D. N. Hebert, David E. Schindel, Junko Shimura, Gregory A. C. Singer Abstract: Barcoding scientists aspire to adhere to the objectives of the Convention on Biological Diversity by promoting conservation, sustainability, and the … Continue reading
Research Article: Increased Extinction Potential of Insular Fish Populations with Reduced Life History Variation and Low Genetic Diversity
Date Published: November 19, 2014 Publisher: Public Library of Science Author(s): Michael Hellmair, Andrew P. Kinziger, Sofia Consuegra. http://doi.org/10.1371/journal.pone.0113139 Abstract: Theoretical work has shown that reduced phenotypic heterogeneity leads to population instability and can increase extinction potential, yet few examples exist of natural populations that illustrate how varying levels expressed diversity may influence population persistence, … Continue reading