Unit 1a. Natural Selection

What is evolution?

Descent with modification; populations change over time.

What is the difference between pattern and process in evolution?

Pattern is observed change; process is the mechanism causing change.

Do individuals evolve?

No, populations evolve over time.

Why is Lamarck important?

He suggested species change over time.

What are the two principles of Lamarckian Evolution?

Use & disuse; inheritance of acquired characteristics.

What is use and disuse?

Used traits strengthen; unused traits weaken.

What is inheritance of acquired characteristics?

An organism that acquired a trait during its lifetime could pass that trait onto its offspring.

What is adaptation in the context of evolution?

An inherited trait that increases survival and reproduction.

How is adaptation related to speciation?

Adaptations can lead to new species over time.

Who developed natural selection?

Charles Darwin.

What is natural selection?

Individuals with favorable inherited traits survive and reproduce more.

How did Darwin explain adaptation?

Through natural selection, where individuals with certain inherited traits tend to survive and reproduce at higher rates.

What are the three broad observations in nature according to Darwin?

Unity of life, diversity of life, and the match between organisms and their environment.

How did Darwin describe the history of life?

As a branching tree.

What does Darwin's tree of life represent?

The history of life with multiple branches (species) stemming from a common trunk (common ancestors).

Why is variation important in natural selection?

It allows some individuals to survive better than others.

What is the significance of variation in inherited traits within a population?

Individuals with favored traits tend to leave more offspring than those without them.

Why doesn't every offspring survive?

More offspring are produced than the environment can support.

What happens to favorable traits over time?

They become more common in a population.

What is the main takeaway regarding evolution in populations?

Individuals do not evolve; populations evolve over time.

Can natural selection remove traits?

Yes, harmful traits can decrease.

What are the four lines of evidence for evolution?

Direct observations, homology, the fossil record, and biogeography.

What is direct observation of evolution?

Seeing evolutionary change happen in real time.

What is an example of direct observation of evolutionary change?

Antibiotic resistance in MRSA, arising through mutation and horizontal gene transfer.

How does antibiotic resistance arise?

Mutation and horizontal gene transfer.

What is homology?

Similar traits due to common ancestry.

What are homologous structures?

Similar structures from a shared ancestor.

What are vestigial structures?

Reduced traits that had a function in ancestors.

What is convergent evolution?

Independent evolution of similar traits.

What are analogous structures?

Similar function, different ancestry.

Example of analogous structures?

Sugar gliders and flying squirrels.

What does the fossil record document?

Patterns of evolution over time.

What can fossils document?

New species and major evolutionary groups.

What is biogeography?

The geographic distribution of species, which helps predict when and where different groups evolved.

What factors affect species distribution?

Continental drift and environment.

What was Pangaea?

The single, large supercontinent that existed in Earth's history.