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BB
Bb bb
Bb bb
Populations: Allele Frequencies
1) Suppose that the frequency of the b allele in the population is .3 .
a) What is the frequency of the B allele in the population?
b) What is the sum of the frequencies of the b and the B alleles?
c) What is the frequency of the bb genotype?
d) What is the frequency of the BB genotype?
e) What is the sum of the frequencies of cats with genotypes BB or bb?
f) What is the frequency of cats with genotype Bb?
g) What is the frequency of cats with genotype bB?
e) What is the frequency of heterozygous cats?
f) What is the sum of the frequencies of cats that are BB, bb and Bb?
If p = frequency of first allele, and q = frequency of second allele
p2 + 2pq + q2 = 1
(Hardy-Weinberg Equation)
Frequency of BB
Frequency of Heterozygotes(Bb or bB)
Frequency of bb
2) Suppose the frequency of B = .2 . What are frequencies of the three possible genotypes?
frequency (BB) =
frequency (bb) =
frequency (Bb/bB) =
Do Allele Frequencies Change Over Time?
p = .2q = .8
Hardy-Weinberg Principle:• In a population, allele frequencies remain constant in the absence of evolutionary forces
Bb
bb
BBbb
Bb
Assumptions of Hardy-Weinberg Principle:
Bb
bb
BBbb
Bb
1) Random Mating
Bb
bb
BBbb
Bb
2) No Mutations
Assumptions of Hardy-Weinberg Principle:
c
Assumptions of Hardy-Weinberg Principle:
Bb
bb
BBbb
Bb
3) Large Population Size
Assumptions of Hardy-Weinberg Principle:
Bb
bb
BBbb
Bb
4) No Immigration
BB
BB
Assumptions of Hardy-Weinberg Principle:
Bb
bb
BB
bb
Bb
5) Genotypes have Equal Fitness(= No Natural Selection)
(2 offspring)(10 offspring)
BB
(6 offspring)
Assumptions of Hardy-Weinberg Principle:1) Random Mating2) No Mutations3) Large Population Size4) No Immigration5) All Genotypes have Equal Fitness
(= No Natural Selection)
? How likely is it that a population meets ALL ASSUMPTIONS?
Natural Selection Case Study: Peppered Moth (Biston betularia)
Biston betularia var. typicaBiston betularia var. carbonaria
DD, Dd dd
1800
1900
England: Industrial Revolution
3
4
Explanation?
Forms of Natural Selection in Populations:DIRECTIONAL SELECTION
20 2122
Genotype: BB Genotype: Bb Genotype: bb
24
Forms of Natural Selection in Populations:DIRECTIONAL SELECTION
Fig. 8.15 in Molles 2006
Forms of Natural Selection in Populations:DISRUPTIVE SELECTION
20 2122
Genotype: BB Genotype: Bb Genotype: bb
2324
Forms of Natural Selection in Populations:DISRUPTIVE SELECTION
Fig. 8.15 in Molles 2006
Forms of Natural Selection in Populations:STABILIZING SELECTION
Fig. 8.15 in Molles 2006
20 2122
Genotype: BB Genotype: Bb Genotype: bb
Fig. 8.15 in Molles 2006
Forms of Natural Selection in Populations:STABILIZING SELECTION
105 6
79
8
Anoles (Anolis): 150 species in the Caribbean Islands
Demonstrating the PROCESS of Adaptation
Observed Relationship of Hind Limb Length to Vegetationin Brown Anoles (Anolis sagrei)
11
Hind Limb Length
1213
14
15 Brown Anole(Anolis sangrei)
Introduction of Brown Anole Populations from Staniel Cay Islandto 14 Caribbean Islands (with no preexisting Anole Populations)
An Experiment to Test for Adaptive Change
Fig. 4.12 in Molles 2008
10-14 Years Later ..
Fig. 4.13 in Molles 2008
10-14 Years Later ..
Question: Phenotypic Plasticity (= Developmental)?
Heritable Trait (with Genetic Basis)?
Possible Lab Experiment to Test for Phenotypic Plasticity versus Heritability of Leg Length
17
Soapberry Bug
18
Species Native to U.S. (3)
Species Introduced to U.S. (3)
19
Soapberry Bugs and Plants inSoapberry Family (Sapindaceae)
Demonstrating HERITABILITY in Natural Selection
Hypothesis: Beak Length Selected to match Distance to Seed in Fruit
16
Fig. 4.15 in Molles 2008
Size of Fruit in Native and Introduced Soapberries
FloridaSouth Central U.S.
Fig. 4.16 in Molles 2008
Observed Relationship between Beak Length and Fruit Radius (Both in FL, TX)
Question: Phenotypic Plasticity (= Developmental)?
Heritable Trait (with Genetic Basis)?
Lab Experiment to Test for Adaptive Change• Rear Juveniles Bugs with Small Beaks on Large Fruited Species• Rear Juvenile Bugs with Large Beaks of Small Fruited Species
Results
Are All Population Changes due to Natural Selection?
Chihuahua Spruce Glanville Fritillary Butterfly
1 http://media-2.web.britannica.com/eb-media/12/59012-004-3F583FEF.jpg
2 http://www.suffolkmothgroup.org.uk/newsletters/40/PB_PepperedMoth.jpg
3 http://media-3.web.britannica.com/eb-media/11/59011-004-F2BFB969.jpg
4 http://www.mlahanas.de/Cyprus/Fauna/image/EuropeanRobin2.jpg
5 http://images.google.com/images?sourceid=navclient&rlz=1T4GGLR_enUS307 US307&q=anolis&hl=en&um=1&ie=UTF-8&sa=N&tab=wi
6 http://www.naturephoto-cz.eu/pic/sevcik/anolis-baracoae--anolis-baracoae.jpg
7 http://www.hlasek.com/foto/anolis_allisoni_4174.jpg
9 http://www.agamen.de/reptilien/leguane/fotos/Anolis5.jpg
10 http://www.thecaribbeanamphibian.com/images/caribbean-islands-map.jpg
11 http://www.cryptomundo.com/wp-content/uploads/0114anolis_datzorum.jpg
12 http://www.ahailey.f9.co.uk/pics5/chrysolepis.jpg
13 http://www.mascotissimo.com/wp-content/uploads/2008/02/anoli_verde_ anolis_carolinensis.jpg
14 http://www.uwgb.edu/biodiversity/herbarium/shrubs/alnrug_xsec01.jpg
15 http://upload.wikimedia.org/wikipedia/commons/thumb/9/94/Anolis_sagrei.jpg /250px-Anolis_sagrei.jpg
16 http://www.biology.duke.edu/rausher/soapber1.JPG
17 http://farm3.static.flickr.com/2226/2523728904_258352f8cd.jpg?v=0
18 http://www.biosurvey.ou.edu/shrub/sasad.jpg
19 http://www.ubcbotanicalgarden.org/potd/cardiospermum_halicacabum2.jpg
20 http://www.bluecross.org.uk/web/MultimediaFiles/BLACKRAB5.JPG
21 http://www.fotosearch.com/comp/PDS/PDS711/white-rabbit-black_~AA028208.jpg
22 http://www.british-giantrabbits.co.uk/images/P7180020.jpg
23 http://i166.photobucket.com/albums/u109/jammyn/070930_Mex9/Mexico380.jpg
24 http://www.natureinstitute.org/pub/ic/ic8/Images/IC8_page10.gif
25 http://pro.corbis.com/images/IH075114.jpg?size=67&uid=%7BB751DF66-D85E- 4E3D-A78C-DC9C3B068766%7D
26 http://www.conifers.org/pi/pic/chihuahuana2.jpg
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