bellringer -march 12, 2014
DESCRIPTION
Bellringer -March 12, 2014. Imagine a population of 200 birds, some red and some yellow. The red allele, R, is dominant over the yellow allele, r . There are 72 RR birds, 96 Rr birds, and 32 rr birds in the population. What are the genotypic frequencies in the population ? - PowerPoint PPT PresentationTRANSCRIPT
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Bellringer-March 12, 2014 Imagine a population of 200 birds, some red and some
yellow. The red allele, R, is dominant over the yellow allele, r. There are 72 RR birds, 96 Rr birds, and 32 rr birds in the population.
◦ What are the genotypic frequencies in the population?
◦ What are the allelic frequencies in the population?
◦ Using the frequencies you calculated in b, what would Hardy-Weinberg predict the genotypic frequencies should be? What about allelic frequencies? Is this population in Hardy Weinberg equilibrium?
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ANSWER KEY RR = 72/200 = 0.36; Rr=96/200 = 0.48 ; rr= 32/200
= 0.16 R=72 + 72 + 96 = 240/400 = 0.6; r = 32 + 32 + 96 = 160/400 = 0.4 P=R= Red q= r = yellow 32/200= 0.16 = yellow = rr= q2
√0.16=√q2
q = 0.4 then p = 0.6 RR = p2 = (0.6)2 = 0.36 = 36.00% Rr = 2pq = 2(0.6)(0.4) = 0.48= 48.00% rr = q2 = (0.4)2 = 0.16 = 16.00%
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Evolution and Speciation
(Macroevolution part 1)
Ms. KimH. Biology
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Evolution on a small scaleChange in allele frequencies from one
generation to the nextA process that leads to a change in a
speciesNatural selectionGenetic DriftGene Flow MutationSexual Selection
Microevolution explains how populations evolve
What is microevolution?
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What is Macroevolution?Origin of different species
SPECIATIONExtinction of speciesEvolution of major features
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Protective Coloring◦ Camouflage and Mimicry
Physiological Adaptations◦ Reproductive/Hormonal Changes◦ Color changes
Behavioral Adaptations◦ Courtship dances/ songs◦ “Fighting” tactics
Also arise in response to environmental pressures◦ Temperature, Antibiotic/pesticide resistance
Types of Adaptations
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Animals who have greater fitness survive in environment and live to reproduce
Random changes in DNA (mutations) can lead to greater or less fitness ◦ Produced by Sexual Reproduction◦ Allow for DIVERSITY in a Population
Adaptations allow an organism to survive better in their environment
Mechanism for change in a population of organisms
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Directional◦Extreme form favored by natural selection
Stabilizing◦Middle form most successful
Disruptive◦Two extreme forms successful in separate environments
RECALL: 3 Types of Natural Selection
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Types of Evolution1. Convergent evolution organisms that are NOT closely related
independently evolve similar traits as a result of having to adapt to similar environments.
2 species acquiring same characteristics from 2 different ancestral species
Ex: Dolphins & fishesEx: Wings of bees & bats
Analogous Structures
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2. Divergent evolution 2 species gradually become different Often occurs when closely related species
diversify to new habitatsFormation of 2 descendent species from an ancestral speciesEx: Darwin’s finchesType: Adaptive radiation
Homologous structures
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Adaptive Radiation Example of divergent
evolution Appearance of numerous species
over a short period of time Adapted species from a common
ancestor when they are introduced to new environmental opportunities
Typically occurs when a few organisms make their way to new, usually distant areas OR mass extinctions occur, which open up new niches
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KAUAI5.1
millionyears OAHU
3.7millionyears
HAWAII0.4
millionyears
1.3millionyears
MAUIMOLOKAI
LANAI Argyroxiphium sandwicense
Dubautia linearisDubautia scabra
Dubautia waialealae
Dubautia laxa
N
Hawaiian archipelago Example of adaptive radiation
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What type of evolution?
A.Divergent B.ConvergentC.Coevolution
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What type of evolution?
A. Divergent B. ConvergentC. Coevolution
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3. Coevolution 2 organisms evolve (change) in
response to each other Insects and the flowers (ex: orchids)
they pollinate
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4. Parallel Evolution 2 species evolve independently of
each other, maintaining similar traits
Usually occurs between unrelated species (but similar ancestors) that do NOT occupy the same or similar habitats◦Ex: Eutherians (placental) and
Marsupial mammals
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What type of evolution?
A. Divergent B. ConvergentC. Parallel Evolution
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What is Speciation?Origin of new
species
How would we identify if a species is “new”?
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Anagenesis (phyletic evolution) ◦transforms one species into another
Cladogenesis (branching evolution)◦ the splitting of a gene pool, giving rise to one or more new species
Two Basic Patterns of Evolutionary Change
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LE 24-2
Anagenesis Cladogenesis
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Gradualism◦Species change slowly (gradually) over time
Punctuated Equilibrium◦Species can make rapid “leaps” in evolution
How fast does evolution occur?
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TimeGradualism model Punctuated equilibrium model
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What is a Species? Species is a Latin word meaning “kind” or “appearance”◦A population of organisms that produces viable fertile offspring in nature.
◦They can NOT interbreed with other populations
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Example 1CASE 1A mule is the offspring of a female horse
and a male donkey. In contrast, the hinney is the offspring of a male horse and female donkey. The mule is easier to breed and larger in size than the hinney. For these reasons, the mule became an important domesticated animal. Horses have 64 chromosomes, donkeys have 62. The mule has 63 and cannot evenly divide, that is why the animal is sterile.
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Example 2CASE 2A liger is a cross between a female tiger
and a male lion. In contrast, the tigon is a cross between a male tiger and a female lion. These two species do not breed in nature because their habitats are so different. Lions live in open grasslands while tigers live in forests. In captivity, it is possible to produce ligers and tigons. Male ligors are sterile, but female ligers are fertile and may reproduce with either tigers or lions.
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Example 3CASE 3E.coli is a bacterium normally found in
the intestines. It is harmless and may actually be beneficial to the human digestive system. There is a pathogenic strain of E.coli that produces a toxin that can kill its human host. The two strains look very similar under a microscope. Comparison of their genomes reveals that the pathogenic strain lacks 528 genes found in the normal strain and has 1,387 genes not found in the normal strain.
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What are other species concepts?
5 Types:Morphological
Group of individuals sharing similar characteristicsRecognition
Behavior/chemical recognition between individualsGenetic
Range of variation in DNA- similar in individualsCladistic
Species defined as a branch in a cladogramBiological
Group of individuals capable of interbreeding
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Similarity between different species different behaviors and songs
Diversity within a species defined by capacity to interbreed.
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Speciation = the origin of new species◦ Must explain how new species originate and how
populations evolve Microevolution (genotype evolution)
◦ adaptations that evolve within a population’s gene pool
Macroevolution (phenotype evolution)◦ refers to evolutionary change at the population
level◦ Major biological changes evident in the fossil
record
Speciation