Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Principles of evolution, our heritage and the Origins of Life What was life like a long time ago? How did we come into being? How do we know this? What is the process? Evolutionary History Darwin did not come up with his theories all by himself. Many others set up a foundation that would allow Darwin to think as he did. Others came up with the same theory Independently Bio 130 Human Biology The “species problem” Why do populations of organisms change over time? If an organism is present in a particular area, it must be perfect for that area, so why then do exotic species pose a threat? Bio 130 Human Biology Evolution vocabulary words Evolution: Change in lines of descent over time. Microevolution: series of changes that give rise to a new species (population). Macroevolution: major large scale patterns of change in groups of living organisms. Population: a group of individuals of the same species Bio 130 Human Biology Populations evolve not individuals. Populations exhibit great variability. When this variability changes over time is when we get new species. (micro evolution) Sources of variation within a population mutations create new alleles crossing over during meiosis leads to new combinations of alleles independent assortment mixes alleles Bio 130 Human Biology Microevolution Processes Mutation Natural selection Genetic Drift Gene flow Reproductive isolation Bio 130 Human Biology Mutation Any heritable change in DNA sequence. Three types lethal mutation neutral mutation beneficial The vast majority of mutations are probably invisible or harmful. Bio 130 Human Biology Natural selection: Is the major process to produce populations that have different characteristics. First described by Darwin If a trait is more adaptive it improves the chances of producing offspring (adaptation) It gives more of its alleles to the following generation (greater fitness) Bio 130 Human Biology Genetic drift: Random fluctuation of allele frequencies over time Works better in small populations Influenced by who starts a population Inhabitants of Pitcairn island, descendants of the 7 Bounty Mutineers Bio 130 Human Biology Bottleneck effect Founder effect Gene Flow: Genes flow with the individuals of a population Physical flow tends to minimize genetic variation, like shuffling the deck. Bio 130 Human Biology Reproductive Isolation and speciation Species: are populations of individuals that can interbreed. When separated by 10,000 or more generations many species can no longer interbreed. Types of isolation geographic, behavioral, biochemical Bio 130 Human Biology Rates of evolutionary change Gradualism: Evolution is a slow and methodical process Punctuated equilibrium: Evolution occurs in rapid bursts followed by long periods without change Adaptive radiation: numerous branches from a single point on an evolutionary tree. Typically follows periods of change (a big dieoff) Bio 130 Human Biology Evidence for Microevolution Fossil record Comparative morphology Comparative biochemistry Biogeography Bio 130 Human Biology How Fossils are formed Fig 22.1 The process of fossilization Homologous structures share a common origin Fig 22.4 Early developmental similarity among vertebrate embryos Fig 22.5 Bio 130 Human Biology We do not go through evolution during embryogenesis, we just share homologous structures and vestigial structures Comparative biochemistry Human Birth control works in Chimpanzees Cytochrome C a protein of 104 AA length Exactly the same in Humans and Chimps 1 AA difference in rhesus monkeys 16AA difference in Chickens 50AA difference in Yeast Insulin Bio 130 Human Biology / biogeography Fig 22.7 Bio 130 Human Biology Life Evolved on the Earth about 3.8 Billion Years Ago Small organic molecules joined to form larger molecules Genetic material originated Organic molecules aggregated into droplets Bio 130 Human Biology Major Milesones in evolution, starting with chemistry and ending with more recognizable things Photosynthesis and Oxygen atmosphere Multicellular organisms are 1.3 billion years old Aerobic metabolism How do we arrange life? Making an evolutionary tree A phylogenetic tree Sim to fig 22.11 Human evolution We are a class of organisms called Mammals (Mammalia) (120mya) Mammals are vertebrates Phylum (550 MYA) Nerve cord Vertebrae (backbone) Brain Bio 130 Human Biology Mammals Hair Long infancy (comparatively) Flexibility in responses due to large brain Produce milk (mammary glands) Bio 130 Human Biology How biologist classify man Bio 130 Human Biology Primates Monkeys & Apes Physically and Biochemically similar Bio 130 Human Biology Hominoids: Chimps and Man Common ancestor about 4-5 million years ago Bio 130 Human Biology Bio 130 Human Biology Evolutionary Trends from primate to human Upright walking Precision and Power grip Daytime color vision w/ depth perception More generalized teeth for omnivore diet Increase in brain size allows for new and abstract behavior Bio 130 Human Biology Another way to list the family tree of primates hominoids Bio 130 Human Biology Origins of primates 60 mya- nighttime omnivores 40mya Daytime larger brains 35mya ancestor to monkeys and apes and humans 25mya hominoids Humans and our like are hominid’s Bio 130 Human Biology Bio 130 Human Biology Humans Roughly 100,000 years old (from H. erectus) 15,000 years in the Americas 35,000 years in Asia decline of Neanderthal 2 modes Multiregional hypothesis (humans from independent evolution in Europe, Asia, Africa and Australia Out of Africa, one ancestor Bio 130 Human Biology We are evolving now Our evolution is cultural not morphological Bio 130 Human Biology 0 Millions of years ago 10 Hominid Hominoids 20 30 Primates 40 50 Common primate ancestor 60 Figure 22.11 Bio 130 Human Biology Differences Within the Human Species Racial differences are slight differences in phenotypes between subgroups of a common species Differences helped populations adapt to environments Dark skin: provides protection from ultraviolet (UV) damage in intense sunlight Light skin: allows adequate UV radiation for vitamin D production in less intense sunlight Racial differences are no more significant than individual differences Figure 22.16 Is natural selection always natural? What effect does Mass extinction have? What effect will global travel and communication have on our phenotypic and cultural differences? Bio 130 Human Biology