EVOLUTIONARY ECOLOGY (L567), Fall Instructor: Curt Lively, JH 117B; Phone ;

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1 EVOLUTIONARY ECOLOGY (L567), Fall 2015 Instructor: Curt Lively, JH 117B; Phone ; DATE TOPIC (lecture number on web) Aug. 25 Introduction, and some history (1) Aug. 29 Population genetics I: Basic population genetics (2) Sept. 01 Population genetics II (3) Sept. 03 Quantitative genetics I (4) Sept. 08 Quantitative genetics II (5) Sept. 10 Phenotypic models I (6) Sept. 15 Phenotypic models II (7) Sept. 17 Logic of animal conflict, RockPaperScissors and class discussion (8) Sept. 22 Sex-ratio evolution (9) Sept. 24 Local mate competition (diminishing returns I) (10) Sept. 29 Life-history evolution: (11) Oct. 01 Evolution of virulence (diminishing returns III) (new lecture) Oct. 06 Mutation-selection balance, Muller s ratchet (12) Oct. 08 Genetic diversity and sex: the ecological hypotheses (13) Oct. 13 FIRST EXAM 1

2 Oct. 15 Recombination (Burt&Bell paper). Pluralism in models of sex/rec (14) Oct. 20 Synthesis (14) Oct. 22 Epistasis, linkage disequilibrium. Sexual selection I (15) Oct. 27 Sexual selection: II. Oct. 29 Evolution of virulence Nov. 03 Inbreeding, and sickle cell anemia revisited Nov. 05 Kin selection and group selection Nov. 10 Population structure and shifting balance Nov. 12 Speciation I Nov. 17 Speciation II Nov. 19 Macroevolution Nov. 24 Thanksgiving break Nov. 26 Thanksgiving break Dec. 01 TBA Dec. 03 SECOND EXAM Dec. 08 Eco-Evolutionary feedbacks and the Fundamental Theorem Dec. 10 Special topic Material for 1 st exam. Material for 2 nd exam 2

3 L567 Evolution. Lecture 1 Introduction 1. The focus of the course is on the theoretical and conceptual underpinnings of evolution by natural selection and genetic drift. 2. Exploration of the basic models in population genetics, quantitative genetics and evolutionary game theory, with the hope of showing the interface between the approaches and the advantages and disadvantages of each. Emphasis on Evolutionary and Behavioral Ecology. 3. Format is lecture/discussion, with some work in groups. 4. Grades are based on two exams (100pts each), plus several problem sets (about 10pts each). 3

4 Quiz If natural selection is the survival of the fittest (as Herbert Spencer suggested), then we must ask Who survives? A. Then we must ask, who are the most fit? A. Then we must conclude that natural selection is the survival of the A. As such, natural selection is a meaningless tautology*. *True by the virtue of its logical structure alone. 4

5 Quiz If natural selection is the survival of the fittest (as Herbert Spencer suggested), then we must ask Who survives? A. The most fit Then we must ask, who are the most fit? A. The survivors Then we must conclude that natural selection is the survival of the A. survivors As such, natural selection is a meaningless tautology*. *True by the virtue of its logical structure alone. 5

6 See optional reading Peters (1976) from course web page. From Peters (American Naturalist, 1976): In this essay, I argue that the theory of evolution does not make predictions, so far as ecology is concerned, but instead is a logical formula which can only be used to classify empiricisms The essence of the argument is that these theories are actually tautologies and, as such, cannot make empirically testable predictions. For example, if the theory of evolution were summarized as "evolution is the survival of the fittest" and "the fittest are those which survive," this two-axiom statement could be reduced to the single axiom "evolution is the survival of the survivors," a clearly empty phrase. **Warning: I will ask you to formally define fitness in about 30mins 6

7 Following Mayr 1991 ( One long argument ) Darwin s theory had five parts. 1. Evolution as such (not new) 2. Common descent (new) 3. Radiation of species (new) 4. Gradualism (population thinking) (new) 5. Natural selection (new) Page 26. The origin was a superb treatment of a common descent and a great plea for the efficacy of natural selection*, but it was vague and contradictory both on the nature of species and on the mode of speciation 7

8 * Even so, most of Darwin s contemporaries accepted Evolution, but rejected Natural Selection. WHY?? Why accept the result if you reject the mechanism? Reasons for resistance to Natural Selection (from Mayr 1991) 1. Religious grounds (see also Ruse s book) Active association in England between the universities and the church. e.g. some of Darwin s contemporaries were also the authors of the Bridewater Treatises, commission by the Earl of Bridgewater to demonstrate the wisdom and goodness of God as manifested in creation. Rev. William Whewell, Prof. of Geology, Cambridge University Why should the vegetable cycle be exactly the same length as the Earth s cycle? God matched the length of the years. Rev. John Henslow, Prof. of Geology, Cambridge University Rev, Adam Sedwick, Prof. of Geology, Cambridge University 8

9 2. Essentialism (or typological thinking), ingrained since Plato. Things have essences, and they do not change essences. a) rocks do not turn into water b) triangles do not turn into squares Rev. Whewell (1840) Species have real essence in nature, and transition from one to another does not exist John Stuart Mill: Kinds (species) are classes between which there is an impassable barrier. Essentialism was extremely useful in math and physics. Darwin s greatest contribution may have been to get past typological thinking and covert to population thinking. Thinking about variance. (example on board using triangles here.) Note that saltation is a necessary consequence of essentialism. 9

10 3. Strict determinism a) Acceptance of NS requires accepting statistical generalizations b) Reliance on statistical generalizations was considered higgledy piggledy by physicists and philosophers of science. 4. Teleology Rejection of NS because it was not a teleological (goal-orientated) process. Why? 5. No mechanism for heredity. (see also Ruse p ). a) Darwin originally favored blending inheritance, but this clearly could not work since favorable variants would be blended out of existence. Consider a field of white flowers b) There was a need for a mechanism of inheritance that worked, leading Darwin to the Provisional Theory of Pangenesis. 10

11 Darwin s definition of Natural Selection Can it, then, be thought improbable, that variations useful in some way to each being in the great and complex battle of life, should sometime occur in the course of thousands of generations? If such do occur, can we doubt that individuals having any advantage, HOWEVER SLIGHT, would have the best CHANCE of surviving and of procreating their kind? On the other hand we may feel sure that any variation in the LEAST DEGREE injurious would be rigidly destroyed. This preservation of favorable variations and the rejection of injurious variations, I call Natural Selection. 11

12 From Endler s Natural Selection in the Wild NS as a syllogism* 1. If there is heritable variation (h 2 >0), and 2. the variants differ with respect to their abilities to survive and reproduce in the present environment ( S 0 ), then 3. those heritable traits conferring enhanced success should tend to increase in frequency. (there will be an increase in the probability that those traits will increase in frequency.) Is this a testable idea? If so, it becomes science. *Syllogism: a deductive scheme of a formal argument consisting of a major premise, a minor premise and a conclusion. e.g., if A and B are true, then C is true Now, with the ideas in mind, write your definition of fitness. 12

13 More questions for discussion 0. What is Evolution? 1. Is Natural Selection synonymous with Evolution? 2. Is Natural Selection necessary and sufficient for Evolution? 3. Is evolution by natural selection the science of the higgledy piggledy? Is evolution by genetic drift the science of the higgledy piggledy? E(z, z ) first-day quiz 13