Week 3 The Theory of Evolution Douglas J Burks A Complex Theory Ernst Mayr has argued that Darwin s theory of evolution are five interconnected theories If any of the five theories fails they all fail 1 Evolution as such 1 Evolution as such This is the theory that the world is not constant nor recently created nor perpetually cycling but rather is steadily changing and that organisms are transformed in time 2 Common descent 1 3 Multiplication of species 1 1 4 Gradualism This is the theory that every group of organisms descended from a common ancestor and that all groups of organisms including animals plants and microorganisms ultimately go back to a Single origin o f life on earth This theory explains the origin of the enormous organic diversity It postulates that species multiply either by splitting into daughter species or by budding that is by the establishment of geographically isolated founder populations that evolve into new species According to this theory evolutionary change takes place through the gradual change of populations and not by the sudden saltaional production of new individual s that represent a new type A Complex Theory 5 Natural selection 1 According to this theory evolutionary change comes about through the abundant production of genetic variation in every generation The relatively few individuals who survive owing to a particularly well adapted combination of inheritable characters give rise to the next generation Directly quoted from Mayr Ernst 1991 One Long Argument Charles Darwin and the Genesis of Modern Evolutionary Thought Cambridge Massachusetts Harvard University Press Pp 36 37 A Complex Theory The mechanism that leads to change is natural selection It has several distinct components 1 Entails the idea that there is a competition for resources and those best fit give their traits to the next generation 1 Like begets like 1 Parents pass on traits through genes DNA to offspring 1 There are rare mutations or changes in genes that are then passed on 2 3 4 5 Differences occurs in all species Individuals show differences due to mutations Variation 1 Reproductive excess 1 Environmental Selection natural selection 1 more are born than can survive to reproduce With reproductive excess members of species compete for resources and the environment selects those who will succeed in mating and leaving more offspring Obtaining food shelter escaping predators finding mates finding moisture 2 Environmental Change 1 2 The environment changes over time The environment is diverse and selection is different in different areas Ernst Mayr 1991 One Long Argument Evidence for Theory 1 Evolution as such Evolution as such This is the theory that the world is not constant nor recently created nor perpetually cycling but rather is steadily changing and that organisms are transformed in time https www allaboutbirds org news wp content uploads 2018 12 AdaptiveRadiationGraphic jpg Evidence for Theory 2 Common descent This is the theory that every group of organisms descended from a common ancestor and that all groups of organisms including animals plants and microorganisms ultimately go back to a Single origin o f life on earth https biologos org articles whale evolution theory prediction and converging lines of evidence Evidence for Theory 3 Multiplication of species This theory explains the origin of the enormous organic diversity It postulates that species multiply either by splitting into daughter species or by budding that is by the establishment of geographically isolated founder populations that evolve into new species https aminoapps com c science page blog blog 5 charles darwins theory of evolution nNCL u8Wa2d7XllXpB1RZ0mQdmaj7Q Punctuated Equilibrium the hypothesis that evolutionary development is marked by isolated episodes of rapid speciation between long periods of little or no change However the term rapid in evolutionary terms should be understood to mean approximately 500 000 years in some circumstances So for example a species of sea animals lives breeds and dies for thousands of years proposed by Stephen Jay Gould and Niles Eldredge in 1972 Evidence for Theory 4 Gradualism According to this theory evolutionary change takes place through the gradual change of populations and not by the sudden saltaional production of new individual s that represent a new type What do we mean by gradual Evidence for Theory 5 Natural selection According to this theory evolutionary change comes about through the abundant production of genetic variation in every generation The relatively few individuals who survive owing to a particularly well adapted combination of inheritable characters give rise to the next generation https aminoapps com c science page blog blog 5 charles darwins theory of evolution nNCL u8Wa2d7XllXpB1RZ0mQdmaj7Q https www khanacademy org science ap biology gene expression and regulation translation a the genetic code discovery and properties Discussion Do you think the theory of evolution is only a scientific question In the natural world do you see any evidence that contradicts the theory What do you think people find most troubling about this theory What do you think is the strongest evidence presented in favor of the theory Should we trust science That so many individuals must die to lead to change troubles some people Does it trouble you Survival of the fittest entails the fit don t live to reproduce