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Note Taking Guide – Evolution Development of Evolutionary Thought Isn’t evolution “just” a theory? Scientific theories are explanations that are based on __________________________________, enable __________ predictions, and have been ______________________ in many ways. What is Evolution? Paleontology & Evolution Older layers of sedimentary rock (the layers on the bottom) contain __________ species very dissimilar from modern life. Each layer (stratum) is characterized by a unique group of fossil species. As you move upward through the layers, you find species more and more ______________ to modern life. James Hutton – 1795 A Scottish geologist proposed that it was possible to explain the various landforms by looking at mechanisms currently operating in the world Proposed that the earth was much more than a few thousand years old Jean Baptiste Lamarck Theory of evolution in __________ mechanism: – ________ and _________ - the idea that the parts used the most grow stronger; the parts that don’t get used deteriorate 1 – inheritance of acquired characteristics - the modifications that an organism acquires during its lifetime can be passed along to its offspring recognized adaptation to environment as a primary product of evolution Charles Darwin (1809-1882) Father of modern evolutionary theory Born in England HMS ___________________ ____________________ Islands Darwin’s Observations Darwin noticed that every bird on the Galapagos Islands was a modified finch. The only differences in the birds were their ________ and what they ate. These finches looked very similar to one type on South American continent, but none of these were found in S.A. “How did one species change into a different species?” He wrote On The Origin of Species (1859) after _______ years of study. Darwin’s Four Postulates Individuals within a population _____ in their _________. Some of these traits are heritable. _______ offspring are produced than can survive because of ___________ resources. (remember competition!) Individuals with advantageous traits will _______ and reproduce. What is natural selection? 2 Natural selection - a population of organisms can ________ over generations if individuals having certain heritable traits leave more offspring than others Natural selection is the ___________________by which evolution is proposed to occur What is “artificial selection”? Nature provides the variation among different organisms, and ________ select variations that they find useful. Example: _____________________________________ Darwin used this to help _________________ his case for natural selection. Descent with modification the history of life is like a ________ , with multiple branching and re-branching from a common trunk all the way to the tips of the youngest twigs most branches of evolution are dead ends; about ______of all species that have ever lived are ___________ Survival of the Fittest • Another name for Darwin’s theory of natural selection. • Biologists use the word fitness to describe how good a particular genotype is at leaving offspring in the next generation relative to how good other genotypes are at it. Mechanisms of Evolution 1. ___________ ____________ & Survival of the _____________ (see notes above regarding Darwin) (Modern Ideas) Darwin + Mendel’s work and the work of others, have lead to modern ideas about evolution. 2. Another mechanism of evolution is ____________ ___________ (random changes in genes) which occurs through natural selection. 3. Speciation – formation of new species is due to _________ genetic changes, and that large scale evolution is the result of a lot of small scale evolution. (Variation) ___________________ – process responsible for the variations that exist within a species, or a change in the allele frequency. 3 4. _______________________ – evolution that occurs between species. Examples: the separation of a species to form two distinct species or the development of a new species from many small changes within an existing species 5. Gene Flow -The change in occurrence of genes in a population. This occurs when an individual leaves a population (___________) or new individual joins a population (__________). 6. Genetic Drift ______________changes in the occurrence of genes through chance events. -Examples: can occur when a few individuals of a population break off from the original group and start their own population (founder effect). -Large number of population is killed due to disease, starvation, natural disaster, etc. (bottle necking) Punctuated Equilibrium Darwin felt that biological change was slow and steady as indicated in the____________ __________________. Modern scientists see that this pattern does not always hold. (Darwin’s finches) The term _______________ _________________________ is used to describe a pattern of long, stable periods interrupted by brief periods of more rapid change. This is still controversial today. Evidence of Evolution Fossil Evidence Fossils provided a ____________ ____________ of evolution. Fossils formed in different layers of rock were evidence of gradual change over time. __________________ Body Structures Structures in different species that may perform different functions but are similar because of their common ancestry ______________ organs - structures of no apparent function to an organism; leftover from ancestry; ex - snakes have leg & pelvis bones More homology… 4 Molecular homology - similarity in _______ ____________ between an ancestor and its progeny Embryological homology - similarities only apparent in _________________ development – ex: all vertebrate embryos have “pharyngeal pouches” which later become gills or Eustachian tubes Patterns of Evolution _______________ Radiation When a ___________ species or a small group of species has evolved into several different forms that live in different ways. Example: Darwin’s_________________ (more than a dozen evolved from a single species) ______________ Evolution Explains how unrelated species can develop similar characteristics Porpoise (mammal) & Shark (fish) Unrelated animals, but share similar characteristics to suit their environment Analogous Structures Show similarity in structure based on adaptation for the _______ _____________, not common descent. _______________ Evolution Suggests that many species develop from a _______________ __________________ Penguins (wings for swimming) & vultures (wings for flying) Both are birds, diverged from a common ancestor Co-evolution When two or more organisms in an ecosystem evolve in _________________ to each other. Example: Flowers and their pollinators 5