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Evolution by Natural SelectionEvolution by Natural Selection
10/2/06 ES 100: Environmental Ecology10/2/06 ES 100: Environmental Ecology
http://home.comcast.net/~fsteiger/cartoon2.gif
A few more logistics…
• From Eric Zimmerman: if you are a double major in ES and EEMB, you may not need to take this class.
• Field Trip (Wed. before Thanksgiving)• Will take about 2 hours (8-9:50).
• Transportation provided, but self-guided field exploration
• You can do it BEFORE-hand, on your own, if you prefer
• Midterm #2 (aka Final Exam)• Add codes: I actually have them now, come see me.• Section assignment this week: check course website!
Recap of Intro. Lecture
• Definition of ecology• Ecology vs. Environmentalism• Reductionism vs. Systems Thinking• Scientific Method: Case study of Lake Apopka
Alligators– Hypotheses must be testable– A hypothesis can be disproved, yielding support for the
‘alternative’ hypothesis.– A theory is the highest level of scientific understanding
Ecosystem Ecology
Community Ecology
Population Ecology
Physiological Ecology
Organization within Ecology
The Classification of Living Things
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primata
Family: Hominidae
Genus: Homo
Species: Sapiens
Roots of Ecology• Carl von Linné (mid 1700’s)
• classification of living things
• Alexander von Humboldt (early 1800’s) • botanical geography
• Charles Darwin and Alfred Wallace 1850• animal geography• theory of evolution by natural selection
• Ernst Haeckel 1866• coined the term “ecology”
• Edward Suess 1875• “biosphere” as the condition that promotes life: it includes plants, animals,
and non-living things
• Arthur Tansley 1935• “ecosystem” concept: interaction between living and non-living entities in
the biosphere
Theory of Evolution by Natural Selection
• Natural selection is the mechanism that explains evolution• Natural Selection: scale = individual• Evolution: scale = many generations
Theory of Evolution by Natural Selection
• Natural selection is the mechanism that explains evolution• Natural Selection: scale = individual• Evolution: scale = many generations
• Darwin’s observations:• Organisms produce more young than can survive.• All species exhibit genetic variability (from mutation and
random combination of parent’s genes).• Individuals with traits most suited to environment most
likely to survive.• Only survivors contribute to the gene pool.
• Theory: Lineages with most appropriate biological programming (genes) for current environmental conditions will leave the most descendants.
Bush, page 7:
“Sickle-cell anemia, Down’s syndrome, and color blindness are heritable, and each would reduce an individual’s chance of survival in a wild human population”
Optimal Foraging Theory
• Organisms that ‘forage’ most efficiently will be more likely to reproduce (improve fitness)– Thus, natural selection favors optimal foraging.
– Cost/benefit analysis
• What is foraging?
• What do plants and animals forage for?
police.ucsb.edu/ crime_prevent.html
Natural Selection and Biochemical Traits
Testing Hypotheses:Observation vs. Experimentation
• Observation: • See patterns in the field• Strength:
grounded in reality• Weakness:
mechanistically weak
• Experimentation: Manipulate system by creating experiments
• Strength: control variables
• Weakness: not realistic
Are Human’s Exempt from Natural Selection?
http://www.pbs.org/wgbh/evolution/library/01/6/l_016_08.htmlSWEATY T-SHIRT EXPERIMENT:
Defining ‘evolution’Scientific Definitions:• All the changes that have transformed life on earth from its earliest beginnings
to the diversity that characterizes it today –Neil Campbell
• The origination of species of animals and plants … –O.E.D.
Common Usage:• A process of continuous change from a lower, simpler, or worse to a higher,
more complex, or better state –Merriam-Webster’s Dictionary
From a scientific point of view, evolution is just how new species come about
Theory of Evolution: Criticisms
• Microevolution is generally accepted, but macroevolution is hotly debated
– How does evolution add information to a genome to create progressively more complicated organisms?
– How is evolution able to bring about drastic changes so quickly?
– How could the first living cell arise spontaneously to get evolution started?
Basilosaurus Ambulocetus Pakicetus Humpback
Section this Week
Internet assignment for Internet assignment for sectionsection this week: this week:– Visit course websiteVisit course website– Follow “Evolutionary Feast” linkFollow “Evolutionary Feast” link– Prepare (typed) assignment and bring to sectionPrepare (typed) assignment and bring to section– Bring food to section Bring food to section (can bring a form of the (can bring a form of the
fruit/vegetable- chocolate instead of cocoa beans)fruit/vegetable- chocolate instead of cocoa beans)
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