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Patterns of Evolution Chapter 17 Section 4
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Macroevolution/Microevolution family large long Macroevolution- One genus or family evolves into another….due to large scale changes that take place over long periods of time. Small species short Microevolution- Small scale changes within a species to produce new varieties or species in a relatively short amount of time.
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Macroevolution/Microevolution allele gene Both involve changes in allele frequencies in gene pools same basic Both work through the same basic processes differenceapproach scale The difference is largely one of approach and scale
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Macroevolution/Microevolution Macroevolution 1. L arge-scale changes in gene frequencies 2. Occurs over a l ll longer (geological) t tt time period 3. Occurs at or above the l ll level of species in separated gene pools 4. Consists of e ee extended microevolution Microevolution 1. S mall-scale changes in gene frequencies 2. Occurs over a f ff few generations 3. Occurs w ww within a species or population in s ss same gene pool 4. Refers to s ss smaller evolutionary changes
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Macroevolution/Microevolution Macroevolution 5. Has n nn not been directly o oo observed 6. Evidence based on r emnants of the past 7. M M M More controversial 8. Example: Birds from reptiles Microevolution 5. O bservable 6. Evidence produced by e ee experimentation 7. Less controversial 8. Example: Bacterial resistance to antibiotics
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Macroevolution/Microevolution
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DDog Variability When bred for certain traits, dogs become different and distinctive. This is a common example of microevolution— changes in size, shape, and color—or minor genetic alterations. It is not macroevolution: an upward, beneficial increase in complexity. Macroevolution/Microevolution
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Macroevolution has never been observed in any breeding experiment. Theories…? The controversy still exists http://evolution-facts.org/New- material/Microevolution.pdf http://evolution-facts.org/New- material/Microevolution.pdf Macroevolution/Microevolution
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29+ Evidences for Macroevolution "Evidences"? Copyright © 1999-2003 by Douglas Theobald, Ph.D.Douglas Theobald, Ph.D. http://www.talkorigins.org/faqs/comdesc/evide nces.html http://www.talkorigins.org/faqs/comdesc/evide nces.html Patterns of Macroevolution
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Much written in the support of macroevolution
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A. Mass Extinctions B. Adaptive Radiation C. Convergent Evolution D. Coevolution E. Gradualism F. Punctuated Equilibrium G. Developmental Genes These are theories/models of evolution
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Mass Extinctions EEvent in which m mm many types of living things became extinct a aa at the same time. PPeriod in which huge numbers of s ss species disappeared. WWhole e ee ecosystems were w ww wiped out LLeft h hh habitats/niches o oo open BBelieved to result in b bb burst of evolution of new species in new habitat DDisrupted e ee energy flow throughout the biosphere and caused f ff food webs to collapse
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PPossible causes –A–A–A–Asteroids hitting earth –V–V–V–Volcanic eruptions –C–Continental d dd drift –S–S–S–Sea levels changing
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Believed to be an on-going process
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Adaptive Radiation TThe evolution of an a aa ancestral species, which was a aa adapted to a particular way of life, into m mm many diverse species, each adapted to a d dd different habitat MMany new s ss species diversify from a common ancestor. TThe b bb branching out of a population through variation. TThe new species l ll live in d dd different ways than the o oo original species did.
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Diversity in anoles is most striking in the Caribbean islands
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Adaptive Radiation Hawaiian honeycreepers Variation in color and bill shape is related to their habitat and diet
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Convergent Evolution OOOOpposite of d dd divergent evolution (adaptive radiation) UUUUnrelated o oo organisms independently e ee evolve similarities when adapting to s ss similar environments, or ecological n nn niches AAAAnalogous structures are a result of this process EExample: penguin limb/whale f ff flipper/fish f ff fin TThe wings of insects, birds, pterosaurs, and bats all serve the s ss same function and are s ss similar in structure, but each evolved independently AAll are believed to descend from a common ancestor…Totally theoretical!!
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ocotillo (left) from the American Southwest, and in the allauidia (right) from Madagascar
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Convergent Evolution Similar body shapes and structures have evolved in the North American cacti...and in the euphorbias in Southern Africa
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Coevolution TThe m mm mutual evolutionary i ii influence between two species WWhen t tt two species e ee evolve in r rr response to changes in e ee each other TThey are closely connected to one another by ecological interactions (have a symbiotic relationship) including: –P–Predator/prey –P–P–P–Parasite/host –P–P–P–Plant/pollinator EEEEach party exerts selective p pp pressures on the other, thereby affecting each others' evolution TTotally theoretical
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Coevolution
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Coevolution Coevolution between the yucca moth and the yucca plant. (right) A female yucca moth pushing pollen into the stigma tube of the yucca flower while visiting the flower to deposit her eggs. Yucca moth larvae (left) feeding on seeds in the yucca fruit. Theoretical!!
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Coevolution Clown Fish and Sea anemone
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Gradualism TThe evolution of new species by gradual accumulation of s ss small genetic changes over l ll long periods of time EEmphasizing s ss slow and s ss steady change in an organism OOccurs at a slow but c cc constant rate OOver a short period of time it is h hh hard to notice
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(Theoretical) Gradualism
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Gradualism
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Gradualism
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Punctuated Equilibrium SSSStable periods of no change (genetic equilibrium) i ii interrupted by r rr rapid changes involving many different lines of descent OOpposite of g gg gradualism IIt is rare, rapid events of b bb branching speciation CCharacterized by long periods of v vv virtual standstill ("equilibrium"), " "" "punctuated" by episodes of very f ff fast development of new forms
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Horseshoe crabs have change little since their first appearance in the fossil record. They are in a state of equilibrium
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Punctuated Equilibrium
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Developmental Genes DDevelopment is a p pp progressive process TThere are a variety of certain developmental genes that regulate the timing of certain events
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HHox genes – are m mm master control genes SSome a aa alter the p pp position of an organ OOthers a aa alter when things happen Lamb born with seven legs
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Hox Genes body plans Determine body plans patterning Function in patterning the body axis body regions Provide the identity of particular body regions
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Hox Genes SSSSmall changes in such powerful regulatory genes, or changes i ii in genes turned on by them, are thought to be a m mm major source of evolutionary c cc change (a) normal fruit fly (b) Antennapedia mutation Fruit fly head showing the effects of the Antennapedia gene. This fly has legs where its antennae should be.
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Hox Genes Hox Genes control development of central nervous system and are common to most organisms. Four groups of similar Hox Genes, shown in color, appear to control related regions of the human body and the fly. Each box represents a single Hox Gene. Illustration by Lydia Kibiuk, Copyright © 1994 Lydia Kibiuk.
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Patterns of Macroevolution that are Does this equal can undergo Do they undergo inunder formin Species UnrelatedRelated Inter- relationships Similar environments Intense environmental pressure Small populations Different environments Coevolution Convergent evolution Extinction Punctuated equilibrium Adaptive radiation Flow Chart
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