9/30/16-BASIS OF BIOLOGICAL VARIATION-Divinity, Catastrophism, and Evolution9/30/16-BASIS OF BIOLOGICAL VARIATION-Divinity, Catastrophism, and Evolution- Divine Creationo Through the 14th century the Genesis version of Divine creation accepted as explanation for biological diversityo Included following beliefs: Earth was young (Archbishop Usher-10/22/4004 BC) Species were unchanging (“fixity of species”) Species arranged in hierarchy, with humans at the top (“Great Chain of Being”)o Challenges to Doctrine Discovery of New World and circumnavigation of glove exposed Europeans to diversity never before seen In 1514, Copernicus challenged Aristotle’s notion that the Earth was fixed at center of the universe; later elaborated by Galileo Other discoveries in physics and biology suggested that phenomena were governed by natural laws (e.g., gravity) Through the 18th century most still attributed creation to Divine forces, but now phenomena were investigated, not accepted as unknowable- Making Sense of Biological Variationo Carolus Linnaeus (1707-1778) By 16th century, interest in biological diversity was great Linnaean classification system formed the basis for taxonomy still used today With some controversy, Linnaeus included humans in his scheme First to propose a process of biological changeo Jean Baptiste Lamarck (1744-1829) Hypothesized a dynamic interplay between organic forms and the environment- As environment changed, organic forms changed dueto increased or decreased use- These “acquired” traits would then be passed on to offspring- Catastrophismo Georges Cuvier (1769-1832) Opposition to Lamarck came to Cuvier, who believed in thefixity of species Suggested that extinction in fossil record came as a result of regional catastrophes such as the biblical flood Locations of catastrophe were then repopulated from nearby, unaffected regions- The Darwinian Breakthrougho Charles Darwin (1809-1882) In 1831, Charles Darwin set sail on a 5-year global expedition aboard the H.M.S. Beagle He left believing in the fixity of species and shortly later grew doubtfulo Influencing Darwin’s Thinking Charles Lyell (1797-1875)- Principal of uniformitarianism (if gravity is around now, it has always been around)- Implied slow, gradual change (not catastrophism)- Required deep geological time Thomas Malthus (1766-1834)- Essay on the Principle of Population- Populations increase faster than the rate of resources- Life is full of competition, a struggle to survive Darwinian Natural Selection- Variation exists in a given population species2- Under given set of environmental conditions, certain members possess traits that allow them to survive and reproduce more often than those lacking such traits (some selected for, others against)- With each generation, population evolves, adapts- To Darwin, evolution was simply “descent with modification”; it had no particular direction, no