UCI Bio 94 Emerson-Gaut Midterm 1

Origin of Earth

4.6 billion years ago

Determined through study of radioactive decay of uranium lead in rocks

Earth cools and crust solidifies

4 billion years ago

Origin of life / First evidence of life

3.6 billion years ago

Oldest prokaryotic fossils

3.5 billion years ago

Accumulation of oxygen in the atmosphere

2.3 billion years ago

New prevalence of photosynthetic producers

Origin of eukaryotes

2 billion years ago

Origin of multicellular organisms

1 billion years ago

Oldest animal fossils

700 million years ago

Plants / Fungi colonize land

470 million years ago

Extinction of dinosaurs

60 million years ago

First humans

200,000 years ago

Precambrian Era

4.6 billion - 541 million years ago

Paleozoic Era

541 million - 252 million years ago

Mesozoic Era

252 million - 66 million years ago

Cenozoic

66 million years ago - present

Young Earth Creationism

Earth is around 6,000 years old

Determined through studies of genealogical history of biblical figures

Hadean Eon

Earth = molten rock of hydrogen gasses and lightning

Lack of oxygen major contributor

Took 600 million years for the Earth to cool

Definition of life

1. Uses energy

2. Consists of cells

3. Contains and processes information

4. Capable of self-replication

5. Evolves

The Origin of Life: Process

Step 1: Abiotic synthesis of complex organic molecules

Step 2: The formation of polymers

Step 3: The formation of protobionts

Step 4: The origin of hereditary information

Typological Thinking (Plato)

Idea that there is a true or ideal form of a species that is fixed and unchanging

Lamarck

1. Each species represented a stage in its evolution from a simple ancestor to a more complicated and perfect form

2. Each new species arose from spontaneous generation from non-living matter

3. Characteristics acquired during an organism's lifetime will be passed to its offspring

4. No common ancestry

5. Each species had its own origin and its own evolutionary trajectory

Pasteur

Disproved Lamarck's theory of spontaneous generation

Darwin's Theory of Evolution

1. Steady Change

2. Gradualism

3. Speciation

4. Common Ancestry

5. Natural Selection

Basis of Natural Selection

1. Variation among individuals

2. Variation is heritable

3. Species produce more offspring than can survive

4. Differential reproductive success

Fitness

The ability of an individual to produce fertile offspring relative to other individuals in the population

Adaptation

A heritable trait that increases the fitness of an individual relative to another individual in the population that lacks the trait

Natural Selection Misconceptions

1. It does not change individuals

2. It is not goal directed

3. It does not lead to perfection

Directional Selection

Changes the average value of a trait

Stabilizing Selection

Favors intermediate phenotypes

Disruptive Selection

Extreme phenotypes favored

Sexual Selection

Occurs when there exists a difference in mating success

The Fundamental Asymmetry of Sex

Females are more selective and mate less often

Males must compete either to be noticed by the females or against other males for the opportunity to mate

Intersexual Competition

Female choice

Ex: behavioral signals, attraction

Intrasexual Competition

Male competition

Genetic Drift

Change in the allele frequency of a population due to random chance

Greater effect on smaller populations