Evolutionary Biology BIOL 3350 Dr Lisa Rapaport Lecture 3 Notes I Early Ideas about Species A Plato s thoughts History of Evolutionary Thought 1 Believed that God created an ideal form eidos Visible world was a manifestation of that form with imperfections 2 Fixity of species Ideal form does not change Plato believed that each species had an ideal form Things that we see in the world are manifestations of that perfect form with some imperfections We would not expect forms to change if they were God s B European Thought During the Renaissance perfect creations 1 Stasis The earth was full as it should be because God created it so it must be perfect already no need for change C Scala Naturae or the Great Chain of Being Aristotle 1 Progression from most complex to least complex Humans are at the top of the hierarchy pyramid 2 Organisms are unchanging they are prefect If change occurred that would mean that the original creations that God set on Earth were not perfect this is impossible because everything that God creates is perfect Look at life as a pyramid lesser forms at the bottom greater forms at the top humans Aristotle saw life as being this progression Old forms would not go extinct New forms would not appear Everything would stay the same because everything was perfect since God made it all D The Scientific Revolution 1 Expansionism Discovered new places South America North America Central southern Africa 2 Advances in Science Technology Astronomers Copernicus Galileo and Kepler 1 o Copernicus The first astronomer to posit the idea of a heliocentric solar system a system in which the planets and planetary objects orbit the sun o Galileo Discovered the four most massive moons of Jupiter which were the first moons ever known to orbit a planet other than Earth o Kepler Discovered the ovoid oval egg shaped movements of the planets around the sun first astronomer to state the fundamental laws of planetary motion defended Copernicus s theory Mathematicians Descartes and Newton o Descartes Developed geometry made an important connection between geometry and algebra which allowed for the solving of geometrical problems by way of algebraic equations promoted a new concept of matter o Newton Explained how gravity works Printing Press Gutenberg Invented the printing press Printing press allowed things to be copied more easily and more efficiently The Bible was basically the only thing that was copied prior to the invention of the printing press each page had to be copied one at a time E Focus on cataloging and describing species 1 Carolus Linnaeus published Systema Naturae in 1735 We still use his classification method today Believed in the fixity of forms no change needed because everything is already perfectly created by God He was cataloging the diversity of the Creator Noticed physical similarities II Discovering a World in Flux A Comparative Biology Georges Cuvier 1 Late 18th Century 2 Unity of Structure the parts of each species are in harmony together 3 Groups of species share the same harmonies He was very methodical about comparing differences between species living Each species could be described by its harmony of parts Extinct species were very similar often times to species that were He was the first to acknowledge that the extinction of species is a regular occurrence and it is a part of nature There is a continuity between the species that are extinct and the species that are alive 2 B Organic Mutability 1 Plants and animals were not constant in form Change was possible through artificial selection Individuals within species were not exactly constant in form necessarily 2 Gilbert White 1780 Studied different breeds of pigeons Discovered that many different forms can arise from a single stock Some consider Gilbert White to be Europe s first ecologist First to realize the importance of all of the different parts of the ecosystem C Principles of Geology Lyell in 1834 1 Calculated extinction rates using fossil record Extinction rates were relatively constant from layer to layer We should have more species at the beginning with some that have gone extinct but we do not see that Concept that nature selects certain species to survive 2 Periods of major extinctions occurred at the same time as periods of environmental change Layers of rock associated with periods of environmental change D Early Ideas of Evolutionary Change Inheritance of acquired characteristics 1 Jean Baptiste de Lamarck 1744 1829 Use and disuse alter body form during an individual s lifetime When the environment changes organisms change as well in response Believed in change within species Organisms become better adapted to their environment through selection against unadvantageous traits E Species selection vs individual selection 1 More fit species survived less fit species died 2 Evolution sorted variations by chance 3 Selection of the individual rather than on the whole species level III Darwin s Theory of Adaptation Charles Darwin 1809 1882 A Observations made in the Gal pagos Islands 1 Mockingbirds from different islands were so different that they did not even look like the same species tortoises and finches also differed greatly from island to island 2 The shapes of the finches bills reflected their food source smaller thinner bills softer food larger thicker bills harder food their bill sizes just depended on what kind of food they had readily available to them on their specific island 3 Gal pagos Islands Giant Tortoises The tortoises on the different islands had different shell shapes he could tell which islands the tortoises came from based on their shell shapes 3 4 Finches 14 species The finches on the Gal pagos islands are all derived from a common ancestor finch Explains why they do have many similarities they are different in ways due to their different habitats they adapted to their specific environment 5 Variation according to local conditions Fewer species more generalized beak shapes More species less variation within a given species Some of the variation was really driven by the competition that the birds were experiencing B Darwin s Postulates Individuals within species are variable 1 2 Certain of these variants are passed on to offspring 3 More offspring are produced than can survive 4 Differential survival and reproduction C The Natural History of Fur Color in Beach Mice 1 Fur Color Gradient from light to dark 5 primary types within that gradient 2 The Spatial Distribution of Fur Color