Download L567 Evolution 2006 - Indiana University Bloomington

EVOLUTIONARY ECOLOGY (L567), Fall 2015
Instructor: Curt Lively, JH 117B; Phone 5-1842; email ([email protected]).
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Introduction, and some history (1)
Population genetics I: Basic population genetics (2)
Population genetics II (3)
Quantitative genetics I (4)
Quantitative genetics II (5)
Phenotypic models I (6)
Phenotypic models II (7)
Logic of animal conflict, RockPaperScissors and class discussion (8)
Sex-ratio evolution (9)
Local mate competition (diminishing returns I) (10)
Life-history evolution: (11)
Evolution of virulence (diminishing returns III) (new lecture)
Mutation-selection balance, Muller’s ratchet (12)
Genetic diversity and sex: the ecological hypotheses (13)
FIRST EXAM
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Recombination (Burt&Bell paper). Pluralism in models of sex/rec (14)
Synthesis (14)
Epistasis, linkage disequilibrium. Sexual selection I (15)
Sexual selection: II.
Evolution of virulence
Inbreeding, and sickle cell anemia revisited
Kin selection and group selection
Population structure and shifting balance
Speciation I
Speciation II
Macroevolution
Thanksgiving break
Thanksgiving break
TBA
SECOND EXAM
Eco-Evolutionary feedbacks and the Fundamental Theorem
Special topic
Material for 1st exam. Material for 2nd exam
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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).
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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.
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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.
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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
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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”
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* 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
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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.
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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 p210-214).
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.
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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.
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From Endler’s “Natural Selection in the Wild”
NS as a syllogism*
1. If there is heritable variation (h2>0), and
2. the variants differ with respect to their abilities to survive and reproduce in
the present environment ( S ¹ 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.
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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
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