Bio 101: Evolution

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Terms

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Precambrian: Earliest, oldest

Simple, single-celled organisms
Paleozoic: Presence of Trilobites
Mesozoic: Age of reptiles, dinosaurs, vertebrates
Cenozoic: Age of Mammals

Current Age
Index Fossils: Help compare organisms from different areas
Theory of Superposition: The deeper you go in rock layers, the further back you go.

Deeper is older.

Higher is younger.
Theory of Uniformity: Things happening today occurred in the past.

Mountains rose from the sea and eroded back down.

These take a long time.

Thus, the earth must be very old.
Theory of Evolution: Individuals vary: These are inheritable.

Variation is good/bad/neutral: determined by natural conditions.

Those with good live longer and reproduce more.

Compete for limited resources.

Over time, species change.
"Survival of the Fittest": Fitness: health and reproduction

Those who survive best and reproduce best leave more offspring.
"Natural Selection": Conditions of nature determines which variations contribute to health.
"Descent with Modification": Species will change over time.

Due to Natural Selection, Competition & Survival of the Fittest

Individuals vary - these are inheritable.
Unaltered Fossils: real bone, teeth, amber, mummification
Altered Fossils: carbonization, cast, mold, petrification
Trace Fossils: worm tubes, internal cast, gastrolith
Transitional Fossils: Show changes in species over time.
Radiometric Dating (Purpose): Actual age to the fossils.

Actual age of Geologic Eras.
Radiometric Dating (Process): Isotopes are taken in and used like the original element.

Unstable, so decay over periods of time.

By determining how much has decayed, we see how old it is.
Biogeography: Explains why organisms are found where they are.
Continental Drift: Continent moves from Equator to Mid-Latitudes.

Land areas separate into two and move.

Two separate land masses come together --> Climate Changes, Predator/Prey Changes, Natural Selection may change, Species may change

(Marsupials predominate in Australia... Similarity between ostrich, emu, and rhea.
Embryological Similarities: Longer they resemble one another, more closely related they are.
Adolescent Similarities: Longer they continue to be alike, more closely related they are.
DNA/DNA Hybridization: Take DNA from two different species.

Combine to make one DNA molecule.

Heat to break bonds.

More heat needed means more bonds had formed.

Most heat equals most similar.
Agents of Evolutionary Change: Mutations
Gene Pool
Genetic Drift
Gene Flow
Mutations: Changes occur in individuals.
If beneficial, will spread.
Allow the individual to benefit from Natural Selection.
Gene Pool: The total of all the genes posible in the population.

A population is limited to the possibilities in its gene pool.
Gene Flow: Changes occur in individuals.

If beneficial, will spread.

Movement of genes within a population.
Non-Random Mating: Mates chosen based on beneficial trails.

Natural Selection is basis for whether a trait is beneficial.

Specials are capable of change due to non-random mating.
Stabilizing Selection: Birth Weight
Directional Selection: Giraffe Neck
Disruptive Selection: Snails
Isolation Mechanisms: Things that spearate populations so that genetic drift can occur.

(Pre-mating & Post-mating)
Pre-mating: 1. Geographic
2. Ecological (habitat)
3. Behavioral
4. Temporal
5. Mechanical
Post-mating: 1. Gamete (chemical)
2. Zygote Mortality
3. Hybrid Sterility
4. Second Generation Fitness
Geographic: Some aspect of geography separates the group.
Ecological: where they live prevents interaction
Behavioral: actions keep them separate
Temporal: Reproductive Timing is off
Mechanical: Reproductive apparatus does not fit
Gamete: Sperm cannot penetrate egg
Zygote Mortality: Fertilization occurs -> zygote does not develop properly -> death results
Hybrid Sterility: Mule example
Second Generation Fitness: Two species mate, produce offspring.

Offspring mates. Second generation is less fit.

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