CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry Cain Wasserman Minorsky Jackson Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 21 The Evolution of Populations
© 2014 Pearson Education, Inc. Overview: The Smallest Unit of Evolution _________________________________________ _________________________________________ _________________________________________ ___
© 2014 Pearson Education, Inc. Figure 21.1
© 2014 Pearson Education, Inc. Figure (after drought) (similar to the prior 3 years) Average beak depth (mm) 9 8 0
© 2014 Pearson Education, Inc. Microevolution _________________________________________ _________________________________________ __ 3 mechanisms __________________________________________ _________________________________________ _________________________________________ __
© 2014 Pearson Education, Inc. Figure 21.3
© 2014 Pearson Education, Inc. __________________________________________ __________________________________________ Genetic Variation
© 2014 Pearson Education, Inc. Figure 21.5 (a) Caterpillars raised on a diet of oak flowers (b) Caterpillars raised on a diet of oak leaves
© 2014 Pearson Education, Inc. Altering Gene Number or Position __________________________________________ __________________________________________ __________________________________________ __________________________________________ __________________________________________ __________________________________________
© 2014 Pearson Education, Inc. Concept 21.2: The Hardy-Weinberg equation can be used to test whether a population is evolving population __________________________________________ __________________________________________ A gene pool __________________________________________ __________________________________________ __________________________________________ __________________________________________ __________________________________________
© 2014 Pearson Education, Inc. Figure 21.6 Porcupine herd Beaufort Sea Fortymile herd Porcupine herd range Fortymile herd range MAP AREA ALASKA CANADA NORTHWEST TERRITORIES YUKON ALASKA
© 2014 Pearson Education, Inc. __________________________________________ __________________________________________ __________________________________________ The Hardy-Weinberg; Calculating Allele Frequencies
© 2014 Pearson Education, Inc. Conditions for Hardy-Weinberg Equilibrium ___________________________________________ ___________________________________________ ___________________________________________ ___________________________________________ ___________________________________________
© 2014 Pearson Education, Inc. ________________________________________ ________________________________________ 1.__________________________________ 2.__________________________________ 3.__________________________________ 4.__________________________________ 5.__________________________________
© 2014 Pearson Education, Inc. __________________________________________ __________________________________________ __________________________________________
© 2014 Pearson Education, Inc. p 2 2pq q 2 1 _________________________________________ _________________________________________ _________________________________________ _________________________________________ ____ The Hardy-Weinberg equation
© 2014 Pearson Education, Inc. ___________________________________________ Factors that change allele frequencies
© 2014 Pearson Education, Inc. Genetic Drift Genetic drift __________________________________________ __________________________________________ __________________________________________ ___ Animation: Causes of Evolutionary Changes Animation: Mechanisms of Evolution
© 2014 Pearson Education, Inc. Figure CWCWCWCW CRCRCRCR CRCWCRCW CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCWCRCW CRCWCRCW CRCWCRCW p (frequency of C R ) 0.7 q (frequency of C W ) 0.3 Generation 1
© 2014 Pearson Education, Inc. Figure CWCWCWCW CRCRCRCR CRCWCRCW CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCWCRCW CRCWCRCW CRCWCRCW CWCWCWCW CRCRCRCR CRCWCRCW CRCRCRCR CRCRCRCR CRCWCRCW CRCWCRCW CRCWCRCW CWCWCWCW CWCWCWCW 5 plants leave offspring p (frequency of C R ) 0.7 q (frequency of C W ) 0.3 p 0.5 q 0.5 Generation 2Generation 1
© 2014 Pearson Education, Inc. Figure CWCWCWCW CRCRCRCR CRCWCRCW CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCWCRCW CRCWCRCW CRCWCRCW CWCWCWCW CRCRCRCR CRCWCRCW CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCWCRCW CRCWCRCW CRCWCRCW CWCWCWCW CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CWCWCWCW 5 plants leave offspring 2 plants leave offspring p (frequency of C R ) 0.7 q (frequency of C W ) 0.3 p 0.5 q 0.5 p 1.0 q 0.0 Generation 2Generation 3Generation 1
© 2014 Pearson Education, Inc. The Founder Effect founder effect - _________________________________________ _________________________________________ _________________________________________ _________________________________________ _________________________________________ _________________________________________
© 2014 Pearson Education, Inc. The Bottleneck Effect __________________________________________ __________________________________________ __________________________________________ __________________________________________
© 2014 Pearson Education, Inc. Figure Original population Surviving population Bottlenecking event (a) By chance, blue marbles are overrepresented in the surviving population. (b) Florida panther (Puma concolor coryi)
© 2014 Pearson Education, Inc. Figure 21.10a-1 Original population (a) By chance, blue marbles are overrepresented in the surviving population.
© 2014 Pearson Education, Inc. Figure 21.10a-2 Original population Bottlenecking event (a) By chance, blue marbles are overrepresented in the surviving population.
© 2014 Pearson Education, Inc. Figure 21.10a-3 Original population Surviving population Bottlenecking event (a) By chance, blue marbles are overrepresented in the surviving population.
© 2014 Pearson Education, Inc. Case Study: Impact of Genetic Drift on the Greater Prairie Chicken _________________________________________ _________________________________________ _________________________________________ ___
© 2014 Pearson Education, Inc. Figure 21.11a Pre-bottleneck (Illinois, 1820) Post-bottleneck (Illinois, 1993) Range of greater prairie chicken Greater prairie chicken (a)
© 2014 Pearson Education, Inc. Figure 21.11b Illinois 1930–1960s 1993 Kansas, 1998 (no bottleneck) Nebraska, 1998 (no bottleneck) 1,000–25,000 50 75,000– 200, Location Population size 750,000 Number of alleles per locus Percentage of eggs hatched 93 (b)
© 2014 Pearson Education, Inc. _________________________________________ _________________________________________ _________________________________________ ___ _________________________________________ _________________________________________ _________________________________________ _________________________________________ ____
© 2014 Pearson Education, Inc. Gene Flow Gene flow - __________________________________________ __________________________________________ __________________________________________ __________________________________________ __________________________________________
© 2014 Pearson Education, Inc. __________________________________________ __________________________________________ __________________________________________ __________________________________________ Concept 21.4: Natural selection is the only mechanism that consistently causes adaptive evolution
© 2014 Pearson Education, Inc. Directional, Disruptive, and Stabilizing Selection 3 modes of natural selection _________________________________________ _________________________________________ _________________________________________ _________________________________________ _________________________________________
© 2014 Pearson Education, Inc. Figure Original population Evolved population Original population Frequency of individuals Phenotypes (fur color) (a) Directional selection (b) Disruptive selection(c) Stabilizing selection
© 2014 Pearson Education, Inc. Figure Bones shown in green are movable. Ligament
© 2014 Pearson Education, Inc. Figure 21.14a
© 2014 Pearson Education, Inc. Sexual Selection __________________________________________ ________________________________________
© 2014 Pearson Education, Inc. Figure 21.15
© 2014 Pearson Education, Inc. The Preservation of Genetic Variation _________________________________________ _________________________________________
© 2014 Pearson Education, Inc. Balancing Selection _________________________________________ _________________________________________ ___________________________________________ _________________________________________
© 2014 Pearson Education, Inc. __________________________________________ __________________________________________ __________________________________________ ______________________________________
© 2014 Pearson Education, Inc. Figure Distribution of malaria caused by Plasmodium falciparum (a parasitic unicellular eukaryote) Key Frequencies of the sickle-cell allele 10.0–12.5% 12.5% 7.5–10.0% 5.0–7.5% 2.5–5.0% 0–2.5%
© 2014 Pearson Education, Inc. _________________________________________ _________________________________________ ___________________________________________ _______________________________________ example, frequency-dependent selection selects for equal numbers of “right-mouthed” and “left-mouthed” scale-eating fish
© 2014 Pearson Education, Inc. Figure “Left-mouthed” P. microlepis “Right-mouthed” P. microlepis Sample year Frequency of “left-mouthed” individuals 1981 ’83 ’85’87’
© 2014 Pearson Education, Inc. Figure 21.19