Welcome to Evolution
Biol 4208
Dr. Julie R. Etterson
Ada
Tse GTA
Three objectives for
today
- General
introduction to the course
- Overview
of the syllabus
- Introduction
of EvoBeaker computer simulations
The earth is incredibly diverse
- True
at all levels of biological organization
- Biomes
- Communities
within biomes
- Species
within communities
- Populations
of a given species
- Physiological
tolerances
- Nutritional
requirements
- Life
span
- Reproductive
system
- Capacity
for behavior
- Gene
sequences of an individual
- Catalytic
abilities of enzymes
- Structure
of cells and organisms
People have struggled to understand earth’s complexity
- Where
did living things come from?
- Why
are there so many different kinds?
- Why
are they so apparently well-designed for living where they live?
- Why
are they so apparently well structured for doing what they do?
- Most
cultures of the world have creation stories
a) Genesis
b) Native
American
c) African
Western scientific thought on creation
- Essentialism
a) Originated
with Plato and Aristotle
b) Every
form and idea has a perfect immutable essence that is imperfectly imitated on
earth
c) Creation
follows “Great Chain of Being” that grades from inanimate objects to lower
forms of life (i.e. bacteria, plants, insects) to the higher forms of life.
d) Because
humans are both physical and spiritual, we are a link between animals and
angels.
- The
Great Chain of Being
a)
The chain of being, from Charles Bonnet, Œuvres d'histoire naturelle et de philosophie, 1779-83
- Until
the 18th century, the role of science was to catalogue nature to appreciate
the wisdom of the creator
- Exhaustive
categorization of plants and animals in Systema Naturae (1735) was
undertaken to discover the pattern of creation
- “Relatedness”
meant closeness to the Creator’s design
- Uniformitarianism
a) New
theories emerged for origin of the stars and planets
b) Evidence
was found that the Earth had undergone extensive changes over time
c) Evidence
of extinct species was found by geologists
d) New
theory was proposed that the same processes that have happened in the past are
continuing to happen in the present
- First
coherent theory of evolution
a) Each
species arose from nonliving mater by spontaneous generation
b) “nervous
fluid” causes progress up the “Great Chain of Being” according to inner needs
c) Acquired
characteristics are inherited
d) Species
differ for two reasons:
e) different ages
f)
different needs
Darwin’s
inspiration
- Trained
as clergyman but passionately interested in natural history
- Invited
to be a naturalist on 5-year voyage on British naval ship, the Beagle,
charting South American waters
- Galapagos
island collections particularly important
- Collected
enormous numbers plants and animals
- Ornithologist
examining his collections pointed out similarities and differences between
mainland and island races
- Birds
on islands shared a common ancestor
- Species
that arrived from the mainland had diverged into many forms
- Differences
in tortoises on different islands also observed
Darwin’s
theory of variational evolution
- Species
diverged from one family tree
- Characters
of lineages change over time
- Radical
change results from many generations of gradual and incremental change
- Evolution
occurs by changing the proportion of individuals within certain
characteristics within populations
- Proportions
change because certain characteristics allow greater survival and/or
reproduction of individuals that expression them
- One
very serious problem Darwin
could not address.
- Mechanism
of inheritance
- Prevailing
idea of blending inheritance didn’t work
- All
individual become more alike over time
- Amassed
evidence for evolution for 20 years until Wallace sent him a manuscript
outlining the theory of natural selection
Is evolution a theory, a hypothesis, or a fact?
- “Theory” in everyday language means
unsupported speculation
- A scientific theory is coherent body of
interconnected statements based on reasoning and evidence that explain a
variety of observations
- A hypothesis is an informed statement of
what might be true
- A strongly supported hypothesis is
considered a fact
- A fact is something that we observe to
be true
- Most “truths” cannot be proven
What is a scientific truth?
1.
Plate
tectonics was a new theory when I was a kid
2.
Extensive
support has accumulated in the last decades
3.
Considered
a scientific fact
4.
New
ideas refine the theory
5.
Novel
that explores mathematical truths and great existential questions
6.
Follows
the lives of two 20th century mathematicians, Turing & Gödel
7.
1931
"incompleteness theorems"
8.
Some
mathematical truths can never be proven
9.
Unsettling
scientific and human implications
10.
Posited
hard limits to what we can ever logically, definitively know
What constitutes evidence in evolution?
1.
Form a
hypothesis based on observation
2.
Make a
prediction based on theory
3.
Test the
hypothesis in an experiment
Compelling evidence supports the theory of evolution to
the extent that it is consider “fact” by most scientists
Evolution of antibiotic resistance
- 25-30% people are colonized without
adverse effects
- Originally all susceptible to penicillin
- 50 % resistant to stronger drug,
Methicillin
- Vanocomycin that was used to treat
methicillin-resistant hospital strains - now resistant
- MRSA more prevalent in hospitals
Evidence in Evolutionary Biology
- Where do guppies originate?
- Tropical streams
Evolutionary thinking
- Make one or more observations (facts)
- Develop a hypothesis to explain the
pattern your observe
- Think of experiments to distinguish
between your hypothesis and the null hypothesis
- Evaluate which hypothesis is supported
by your data
- Guppy coloration differs in different
ponds
- Guppies cannot cross waterfalls