Download Basic Principles

Vertebrate Adaptations
Lecture 1:
Overview of Course.
Lecture 2:
Natural Selection and Evolution.
1.
Evolution is defined as changes in allele frequencies over time.
a. It is a law, not a theory, and not an hypothesis.
b. The definition says nothing about men coming from monkeys, or chickens
coming from tuna.
c. The law is falsifiable.
d. Those people who argue against the idea of evolution usually do not
understand what it is. It is safe to say that their objections to evolution
concern the consequences of evolution and the proposed history of life, not
the mechanics of evolution itself.
2.
A note about science
a. Science is a process of conjecture and refutation.
b. Why do we attempt to falsify hypotheses, and not support them?
c. What are the consequences of a wrong decision?
d. Some important definitions:
i. Fact
ii. Truth
iii. Reality
iv. Belief
v. Proof
3.
What are the fundamental principles of biology?
a. The laws of physics and chemistry
i. Law of gravity
ii. Laws of thermodynamics
iii. Law of evolution via natural selection
4.
The observations of Charles Darwin.
a. There is variation amongst organisms.
b. That variation is heritable.
c. Some forms of variation are better than others.
d. Populations tend to grow exponentially.
e. Populations can not grow exponentially for very long.
5.
Darwin’s conclusion.
a. Those organisms with the better forms of variation will survive longer and
produce more offspring. This is effectively, natural selection.
b. Notice – this says nothing about survival of the fittest.
c. Notice also, Darwin was religious. He agonized over how people would react
to his work, and in fact, this lead to the very delayed publication of his work.
6.
Natural Selection
a. Defined as the differential reproduction and survival of organisms.
b. There are a variety of forms of natural selection.
i. Directional selection
ii. Stabilizing selection
iii. Disruptive selection
c. Natural selection can be broken down further into:
i. Sexual selection
1. Secondary sexual characters
2. Size
ii. Kin selection
1. Prairie dogs
2. Green Woodhoopoes
iii. Group selection
1. Suicide in lemmings?
d. Does altruism exist?
e. What is the unit of selection?
i. Allele
ii. Chromosome
iii. Cell
iv. Organism
v. Population
vi. Species
7.
Some Examples of evolution.
a. The peppered moth in England
b. Domestic dogs
c. People
i. Diabetes
ii. Skin color
iii. Height?
d. Notice in each of these cases, there is no speciation.
e. Isolating mechanisms
i. Behavioral
ii. Temporal
iii. Morphological
iv. Social
v. Geographic
f. RasenKreise of Salamanders and pocket mice.
g. K-rate in California
h. Humans
i. A note about heterochrony & chimps.
i. Convergence in design
i. Hedgehogs, porcupines, and echidnas
ii. Whales, dolphins, penguins, and tuna
8.
Hardy-Weinberg Equilibrium
a. This is the null hypothesis against which evolution is tested.
b. A population can either be in HW equilibrium for a particular trait, or not.
There is no in-between.
c. Within HW equilibrium, allele frequencies do not change, although genotype
frequencies may change over time.
9.
A consideration of Homology and Analogy.
a. Homology is defined as similarity in structure that results from a common
ancestry.
b. Analogy can be defined as similarity in structure that results from functional
or structural necessity.
10.
Evolution: the 4 biases.
a. Adaptationism
i. The idea that all characteristics of an organism represent adaptations to
its environment.
ii. Consider thePanda’s thumb.
iii. Consider your little toe, your pinkie, or your earlobe.
b. Progressivism
i. The idea that all evolution has led to the development of mankind, that
mankind represents the pinnacle of evolution, that life can be arranged
on a ladder of life.
ii. More appropriate view is probably one that characterizes life on earth
as a developing bush with many branches.
c. Determinism.
i. The idea that we are constrained by our evolution, that we are limited
by our genes.
ii. Consider ‘mongolism’, and IQ tests.
d. Gradualism
i. The idea that all evolution is slow and gradual.
ii. Contrast with punctuated equilibrium and the idea of the ‘missing
link.’