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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.
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Principles of evolution , our heritageand 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)
Human evolution We are a class of organisms called Mammals
Nerve cord Vertebrae (backbone) Brain Mammals are vertebrates
Hair Long infancy (comparatively) Flexibility in responses due to large brain Produce milk (mammary glands) Mammals
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 theenvironment.
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
Biology Major Undeclared liberal arts Relationships in ecology habitat community specialist niche generalist