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? Evolutionary History • Darwin did not come up with his theories all by himself. • Malthus and others set up a foundation that would allow Darwin to think as he did. • Others came up with the same theory Independently 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? 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 • 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 Microevolution Processes • • • • • Mutation Natural selection Genetic Drift Gene flow Reproductive isolation Mutation • Any heritable change in DNA sequence. • Three types – lethal mutation – neutral mutation – beneficial • The vast majority of mutations are probably invisible or harmful. 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) Genetic drift • Random fluctuation of allele frequencies over time • Works better in small populations • Influenced by who starts a population – 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. 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 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 Evidence for Microevolution • Biogeography • Fossil record • Comparative morphology • Comparative biochemistry 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 – Figure 22.4 (p. 514) A phylogenetic tree The process of fossilizaiton Homologous structures Human evolution We are a class of organisms called Mammals Mammals are vertebrates • Nerve cord • Vertebrae (backbone) • Brain Mammals • Hair • Long infancy (comparatively) • Flexibility in responses due to large brain • Produce milk (mammary glands) Primates • Monkeys & Apes Physically and Biochemical similar Hominoids: • Chimps and Man – Common ancestor about 5 million years ago 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 Origins of primates • 60 mya- nighttime omnivores • 40mya Daytime larger brains • 35mya ancestor to monkeys and apes and humans Humans • Roughly 200,000 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 We are evolving now • Our evolution is cultural not morphological Topic Ecosystems Biosphere: the portion of the earth that supports life: land, air water Ecology: • The study of the interactions of organisms with each other and the environment. More words: • Habitat: The place an organism lives • Community: collections of populations in a habitat. • Niche: physical and biological conditions under which a species can live (an organisms role) • specialist: has very narrow growth conditions • generalist: will grow under a wide range of conditions Relationships in ecology Ecosystem • One or more communities interacting with one another and with the physical environment. Ecosystems will change over time in a process called: • Primary succession: life moves onto an area that previously had no life. Like on a new volcanic island. • Secondary succession: When man, fire, floods disturb a community, a progression of different forms of life inhabit the area for a while A human example of succession The ecosystem organization Energy from the sun passes through the ecosystem The two major classes of life • Autotrophs: (producers) – capture sunlight energy and incorporate it into organic compounds (sugar, Fa, Na, Aa) • Heterotrophs: – feed on the tissue products of autotrophs – Humans and all omnivores and carnivores The major types of consumers • Herbivores eat plants • Carnivores eat animals • Parasites reside in or on living hosts and extract energy • Omnivores eat a variety of organisms • Detritivores: feed on partially decomposed organic mater • Decomposers: reduce waste and dead bodies to their chemical components Players in the Ecosystem A classic food chain Well things are more like a food web. Recycling • Ecosystems require energy and nutrients they lose energy and give off nutrients Recycling of components again • Unlike physical matter energy cannot be recycled – energy that is not passed on to the next tropic level is lost in the form of heat. • Trophic levels: A hierarchy of energy transfers – each level feeds on the lower level. Trophic Levels Energy lost as heat Energy lost as heat Energy lost as heat Pyramids of energy When one group outgrows the supporting group the result is Carniv. Carniv. herbivores herbivores autotrophs autotrophs Biological magnification Biogeochemical cycles • The Hydrologic cycle: How water is moved. • The carbon cycle – Important in global warming and the greenhouse effect • The Nitrogen cycle – An air intermediate moves these atoms across the planet • The Phosphorus cycle – Intense competition of plants and bacteria Impacts of Human Populations • Increasing #’s. The worlds population is still growing. – Birth control programs have not been successful Population dynamics • Population density- individuals per unit area • distribution patterns– clumped, random, uniform SF Bay area Age structure of a population • Preproductive: – before sexual maturity • Reproductive: – 15-44 age when producing young • Post reproductive: – after sexual activity Population growth • (births + immunization) - (death + emigration) • Rate of increase - zero is a balance between births and deaths Population Growth of a population increases over time Time Biotic Potential • Maximum growth rate of a population given low death rates • Depends on – # of offspring per individual – time until sexual maturity – length of sexual maturity Actual rates of population increase • Are influenced by environmental conditions • Usually biotic potential is not reached because of rate limiting conditions • Limits include – – – – disease space pollution predation Carrying capacity • The number of individuals that a given area can support • Mankind has been very effective in increasing the carrying capacity of the earth. Human Population growth • Preindustrial: – Birthrates & deathrates are high population is level over time • Transitional – birth rates are high death rates are low population increases • Postindustrial – birth rates drop & death rates are low population levels off Things that will affect our future Effects of air pollution • • • • Industrial Grey smog Brown automotive smog Acid deposition Damage to ozone Water scarcity and pollution • 1/3 of food is from irrigated fields – irrigation causes salt buildup – increase in human population causes an increase in waste, insecticides, chemicals and pollution Coping with solid waste • Loosing places to store waste (recycle) • Desertification is caused by overusing marginal lands We often times put limits on ourselves Sex hormones and sex hormone mimics Estrogen (Estradiol) DDT Testosterone Diethylstilbestrol Our Future Depends on the Decisions We Make Today Good luck on your final Exam