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

Temporal Scale

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”

When is Mutant Sickle-cell Gene Desirable?

www.sicklecelldisease-il.org/.../ what/how.html

Natural Selection and Physical Appearance

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

Experimental Evidence for Optimal Foraging

Would ‘field’ observation match experimental results?

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

Natural Selection and Behavior

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

Humans as an Evolutionary Endpoint?

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)