STUDY GUIDE: Evolution & Origin of Species Tiffany Fleming & Adan Beltran *Understand the origins of and mechanisms leading to biological diversity* ! DARWINIAN REVOLUTION " Voyage of the HMS Beagle # 1831-1836 # Charles Darwin made his scientific findings of plants, animals, fossils, rocks, etc. " Evolution # Change over time in a populations genetic makeup " Genetic Drift # Random fixation or loss of alleles in a population – due to chance in small populations " Genetic variation # Genetic variation can refer to differences between individuals or to differences between populations. • Mutation is the ultimate source of genetic variation, but mechanisms such as sexual reproduction and genetic drift contribute to it as well " Ideas that came out of the voyage # Descent with Modification • Species evolve and derive over time from common ancestors # Natural Selection • Evolutionary process by which individuals with certain heritable traits leave more offspring than individuals with other traits # Adaptions • Characteristics that evolve organism survival and reproduction in specific environments ! MECHANISMS OF EVOLUTION " Natural Selection # Key Factors • 1.Individuals within species vary. • 2.Some of these variations are heritable. • 3.More offspring are produced than can survive. • 4.Survival and reproduction are nonrandom (i.e., some traits help you survive and reproduce more than others). # Challenges to survival and reproduction + Heritable variation in traits affecting survival and reproduction = The traits that confer survival and reproductive advantages will increase in frequency in the population. " Sexual Selection # " Variation # Variation comes from genetic changes ie: • Mutation (random introduction of alleles) • Recombination (new combinations of alleles, via sexual reproduction)! SPECIATION (how species are formed) " Gene Flow # The transfer of alleles or genes from one population to another. " Hybrids # ! EVOLUTION ≠ NATURAL SELECTION # Evolution is facts # Natural Selection is theory ! Genetic drift ! Differences of genetic drift and natural selection. " Both are methods of genetic change. " Genetic drift happens randomly " Natural selection happens in response to and environmental challenges. " Natural selection: nature selects the genes that can e passed down to the new offspring because those organisms had the traits to survive (survival of the fittest " Genetic Drift: random mutations within a small population that has nothing to do with the environment and whether the genes move onto the offspring or not. ! Evolution as a Theory: " Fossils and the similarities that the fossils had created the theory for Darwin to believe that evolution were real. " Evolution is fact and theory. # Theory: Drawing conclusions based on fragmentary or inconclusive evidence # Fact: Measurable, observable or can create any sort of evidence in the same circumstances it originally occurred in. # Hypothesis: proposed explanation made on the basis of limited evidence as a starting point for further investigation.Ashley Aragon Study Guide History of Life ● Major Events ○ 3 eons ■ Archaea : beginning of the solar system, 4600 million years ago, until 2500 mya (very little diversity) ■ Proterozoic : 2500 mya - 542 mya ■ Phanerozoic : 542 mya - present ○ 3 Eras ■ Paleozoic : (542-251) ends with permian extinction ■ Mesozoic : (251-65.5) ends with cretaceous extinction ■ Cenozoic : (65.5-present) ○ Mass Extinctions ■ Permian Extinction ● Known as the Great Dying ■ Cretaceous Extinction ● Many marine and terrestrial organisms ● Mostly know as dinosaurs ● Thought to have been caused by large meteor. ■ Current ● 25% all species extinct by 2020 ● > 11,000 species endangered ● Continental drift ○ the gradual movement of the continents across the earths surface through time. ○ Pangaea: the world was made up of a single continent through most of geologic time. That continent eventually separated and drifted apart, forming into the seven continents we have today. ● Fossils ○ Any preserved evidence of life from a past geological age, such as the impressions and remains of organisms embedded in stratified rocks. ○ fossils teach us about our planet's past they allow us to see into the past ○ teach us what sort of plants and animals were living hundreds of years ago. Fossils can also can even show us about climate and its change over millions of years. ○ Limitations ■ You are limited by current technology in how to get information out of them ■ you cannot tell when the fossil is from down to the exact year.Shelbi'Odette'Eddie'Garcia''Chapter'20:'Phylogeny'and'the'Tree'of'Life''• Bionomial'Nomenclature'' AWhich'word'is'capitalized?'' AWhich'word'is'called'the'genus?'' ARemember'the'whole'word'italicized.'' '' AKnow'what'the'first'word'and'the'second'word'represent.'• Hierarchical'classification'system'' AAlso'known'as'the'taxonomic'system'' AMemorize'this'from'beginning'to'end'(including'the'domain)'• Phylogenetic'Trees' '' AWhat'are'they'and'how'are'they'built?'' ' Ausing'morphologies'or'molecular'data'' AThey'are'also'a'hypothesis.'This'is'because'trees'are'constructed''' from'physical'or'ch ar a cte ris tic't ra its ,'a nd 'n ot't he ir'a ct ua l 'DN A '' samples.''' ' AAn'example'of'this'would'be'Supergroup'3:'Unikonta.'It'is''' ' apart'of'the'protista.'To'this'day'we'do'not'understand'the''' ' relationships'among'the'protista,'which'me ans'an y'' '' ' phylogenetic'tree'constructed'among'the'protista'group'is''' ' a'hypothesis.''' AWhat'does'a'phylogenetic'tree'show'us?'' ' Awhats'the'difference'between'monophyletic,'paraphyletic,'' '' ' and'polyphyletic'groups'of'organisms?'''''• Monophyletic:'taxon'consists'of'an'ancestral'species'and'all'its'descendants'• Paraphyletic:'consists'of'an' ancestral'species' and'some,'but' not'all,'of'its'descendants.'• Polyphyletic:'most'recent'common'ancestor'is'NOT'part'of'the'group'as'a'whole'' 'AHomology'vs.'Analogy'• Homology:'similarities'that'are'attributable'to'common'ancestry.'' ' Aexample'of'homology:'venus'fly'trap'and'cactus.'Even''' ' though'they'may'have'different'shapes'and'function'today ,''' ' they'originate'from'a'common'ancestor.''' AAnalogy:'Similarities'that'are'attributable'to'convergences.''' '