evolutionmutations.notebook may 13,...
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EvolutionMutations.notebook
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May 13, 2011
Apr 2710:03 AM
Aim: What factors contribute to evolution?
Do Now: What is the explanation for this fruit? Is it evolved?
HomeworkComplete the reading &questions on HIV mutation & Evolution
4/27/10
Take out Fact/ Inference Worksheet
Bird beak Lab Quiz Friday
8
Apr 2710:05 AM
Mutations are random.Not all mutations matter to evolution.
Somatic mutations occur in nonreproductive cells and won’t be passed onto offspring.
For example, the golden color on half of this Red Delicious apple was caused by a somatic mutation. The seeds of this apple do not carry the mutation.
Apr 2710:14 AM
The only mutations that matter to largescale evolution are those that can be passed on to offspring.
These occur in reproductive cells like eggs and sperm and are called germ line mutations
Mutations & Evolution
A single germ line mutation can have a range of effects:• No change occurs in phenotype
• Small change occurs in phenotype Example1 small change can cause a cats ear to curl backwards
• Big change occurs in phenotype.Example DDT resistance in insects are sometimes caused by single mutations
Apr 2810:34 AM
Aim: What are some other factors that effect evolution?
Do Now: Why is it so difficult to develop a vaccine for HIV
Apr 2811:34 AM
LE5 4/28/10
Apr 286:31 AM
Factors that Influence Evolution
• Descent and the genetic differences that are heritable and passed on to the next generation
• Mechanisms of change : Mutation, migration (gene flow), genetic drift, and natural selection
• The importance of genetic variation
• The random nature of genetic drift and the effects of a reduction in genetic variation
• How variation, differential reproduction, and heredity result in evolution by natural selection
• Coevolution: How different species can affect each other’s evolution
EvolutionMutations.notebook
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May 13, 2011
Apr 287:04 AM
Descent with ModificationEvolution only occurs when there is a change in gene frequency within a population over time.
These genetic differences are heritable and can be passed on to the next generation— which is what really matters in evolution: long term change
Several generation Later.....
What happened to the beetles?
*Environmental changes
Apr 2711:47 AM
Gene FlowGene flow—also called migration—is any movement of genes from one population to another.
Lower rate of gene flow:Corn, which is windpollinated, may be unlikely to fertilize individuals more than 50 feet away
Higher rate of gene flow:However, other organisms are able to distribute their genes much further. For example, fruit flies released in Death Valley were recaptured almost 15 kilometers away from the site of release
• It can introduce or reintroduce genes to a population, increasing the genetic variation of that population
• By moving genes around, it can make distant populations genetically similar to one another, reducing the chance of speciation. • The less gene flow between two populations, the more likely that two populations will evolve into two species
Apr 286:50 AM
Genetic DriftDefinition• In each generation, some individuals may, just by chance, leave behind a few more descendents than other individuals• The genes of the next generation will be the genes of the “lucky” individuals, not necessarily the healthier or “better” individuals.
Apr 286:54 AM
CoevolutionDefinition• Cases where two (or more) species affect each other’s evolution
Example: an evolutionary change in the morphology of a plant, might affect the morphology of an herbivore that eats the plant, which in turn might affect the evolution of the plant, which might affect the evolution of the herbivore...and so on.
Likely to happen when different species have close ecological interactions with one another:
• Predator/prey and parasite/host • Competitive species• Mutualistic species
Apr 286:59 AM
CoevolutionSome Central American Acacia species have hollow thorns and pores at the bases of their leaves that secrete nectar. These hollow thorns are the exclusive nestsite of some species of ant that drink the nectar. But the ants are not just taking advantage of the plant—they also defend their acacia plant against herbivores.
The plants would not have evolved hollow thorns or nectar pores unless their evolution had been affected by the ants, and the ants would not have evolved herbivore defense behaviors unless their evolution had been affected by the plant
Apr 299:33 AM
Aim: What is the other evidence for evolution?
Do Now: What are the difficulties in developing an HIV vaccine?
Homework:
Read the Beaks of Finches Lab for tonight!
Text: Read pp.382385 p. 385 2,3
Barron's Regents Review $7.99Red
44/29/10LE3
EvolutionMutations.notebook
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May 13, 2011
Apr 2910:06 AM Apr 2911:12 AM
Beaks That Were Number of Beak Types
Characteristics of Beaks(Size & Shape)
Present at the bebinning of Activity
Successful at feeding in round 1 small seeds, no need to migrate
Not Successful at feeding in Round 1 fed on sml seeds, had to migrate
Successful at feeding at Round 2 on original island small seeds
Successful at feeding in round 2 on new island large seeds
Not successful at feeding in Round 2 on either island species dies out
Successful at feeding in Round 3 on original island small seeds
Sucessful at feeding in Round 3
Successful at feeding in Round 3 on new island large seeds
Not Successful at feeding in Round 3 on either island
Beaks Of Finches Class Results
Apr 3011:10 AM
Aim: What is the other evidence of Evolution?
Do Now: Do your bodies contain an organ that you rarely or never use? What is it? Why do we have it?
Apr 299:39 AM
Other Evidence for Evolution
Evolutionary theory predicts that related organisms will share similarities that are derived from common ancestors.
Homologous Structures Similar characteristics due to relatedness. Several ways to look at homologous structures: 1. by comparing the anatomies of different living things, 2. looking at cellular similarities and differences, 3. studying embryological development, 4. studying vestigial (Unused) structures within individual organisms.
Each leaf has a very different shape and function, yet all are homologous structures, derived from a common ancestral form. The pitcher plant and Venus' flytrap use leaves to trap and digest insects. The bright red leaves of the poinsettia look like flower petals. The cactus leaves are modified into small spines which reduce water loss and can protect the cactus from herbivory.
vestigial organ is any part of an organism that has diminished in size during its evolution because the function it served decreased in importance or became totally unnecessary.
Apr 3011:03 AM
Each leaf has a very different shape and function, yet all are homologous structures, derived from a common ancestral form. The pitcher plant and Venus' flytrap use leaves to trap and digest insects. The bright red leaves of the poinsettia look like flower petals. The cactus leaves are modified into small spines which reduce water loss and can protect the cactus from herbivory.
What do you notice about the leaves of these plants?
Apr 3011:05 AM
Another example of homology is the forelimb of tetrapods (vertebrates with legs).
All Share same three bones: Radius, Ulna & humurus, Also seen in extinct species, Eustenopteron
EvolutionMutations.notebook
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May 13, 2011
Apr 3011:09 AM
Hoatzin chicks have claws on their wings, as do some chickens and ostriches. This reflects the fact that bird ancestors had clawed hands
May 39:18 AM
Aim: How fast does evolution take place?
Do Now: What are some important factors in determining how fast evolution occurs?
HomeworkAll assignments Due Friday 5/7 Take Home Evolution QuizVocabulary:Population genetics, Hardy Weinberg Principle, Gene flow,
Nonrandom mating, genetic drift, Species, speciation, isolation, subspecies, Extinction2. Read pp.399401, 404406, 411 4143. P.403 # 1,34. P.409 # 2,3,55. P. 414 # 2,3, 6
LE3 5/3/10Discussion on Oil spill/ impact on populations/Human impact on EnvironmentGlobal warming???
May 39:18 AM
Aim: How fast does evolution take place?
Do Now: What are some important factors in determining how fast evolution occurs?
HomeworkAll assignments Due Friday 5/71. Take Home Evolution Quiz2. Vocabulary:Population genetics, Hardy Weinberg Principle, Gene flow, Nonrandom mating, genetic drift, Species, speciation, isolation, subspecies, Extinction2. Read pp.399401, 404406, 411 4143. P.403 # 1,34. P.409 # 2,3,55. P. 414 # 2,3, 6
May 38:32 AM
Darwin realized in 1835 that all the finch species arose from one ancestral form that had adapted to a variety of feeding conditions.
Adaptive radiation- in which one species diversifies into many to exploit a wide range of habitats.
May 38:35 AM
Aim: How fast Does Evolution Take Place?
Two models explain the speed of Evolution
a. Gradualism describes evolution as a slow, ongoing process (Darwin, 1835)
b. Punctuated Equilibrium says that gene mutation can result in a new species in a relatively short period of time leaving few fossils ( Stephen Jay Gould, 1972)
LE3 5/4/2010Copy Now
May 38:37 AM
Stasis: A population of mollusks is experiencing stasis: living, dying, and getting fossilized every few hundred thousand years. Little observable evolution seems to be occurring judging from these fossils.
Isolation: A drop in sea level forms a lake and isolates a small number of mollusks from the rest of the population.
Strong selection and rapid change: The small, isolated population experiences strong selection and rapid change because of the novel environment and small population size
What do you think happens to the snail gene pools in both populations?
Speciation is more likely at the edge of a population a small group can easily become separated geographically from the main body undergo changes that can create a survival advantage produces a new, noninterbreeding species.
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May 13, 2011
May 39:07 AM
Variations & AdaptationsVariation an inherited trait that makes an individual different from other members of the species.
Adaptations any variation that makes an organism better suited to its environment
http://www.uen.org/utahlink/activities/view_activity.cgi?activity_id=4750
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