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