Apes unit 2 slide show 3

What is a natural disturbance in an ecosystem?

A natural event that disrupts the structure and/or function of an ecosystem, causing organisms to respond.

Give examples of natural disturbances.

Tornadoes, hurricanes, asteroids, forest fires, droughts.

Why can natural disturbances be greater than human-caused ones?

Because they can occur over much larger time frames.

What are the three categories of natural disturbances?

Periodic (regular frequency), Episodic (occasional irregular events), Random (no frequency).

What causes Earth’s climate to vary over geologic time?

Slight changes in Earth’s orbit and tilt.

What are examples of natural climate changes caused by orbital shifts?

Mini-ice ages and warmer periods.

How has sea level varied over geologic time?

It rises and falls as glacial ice melts and reforms.

Give an example of environmental change caused by rising sea levels.

Flooding of coastal and estuary habitats.

Why might wildlife migrate?

To find new habitats in response to natural disruptions.

Give an example of migration in land animals.

Wildebeests following rainfall patterns in the African savanna.

Give an example of migration in marine species.

Ocean species moving north as water warms.

How does climate change affect bird migrations?

Birds migrate and breed earlier as insect hatching shifts earlier.

What is evolution?

The change in genetic composition of a population over time.

What are the two main categories of evolution?

Microevolution (population-level changes) and Macroevolution (changes across species groups).

What are the five random processes that can cause microevolution?

Mutations, gene flow, genetic drift, bottleneck effect, founder effect.

What are the two main causes of genetic diversity in populations?

Mutations and crossing over.

What is an adaptation?

A trait that increases an organism’s fitness.

What is natural selection?

Evolution through natural mechanisms, often described as 'survival of the fittest.'

What are Darwin’s four key ideas of natural selection?

Excess offspring, not all survive, traits are inherited, favorable traits increase survival/reproduction.

What are the three possible outcomes for organisms under environmental change?

Adapt, move, or die.

What is selective pressure?

Environmental conditions that kill individuals without the adaptation.

How can drought affect finch populations?

Small-beaked finches may die, while large-beaked finches survive due to harder seeds.

How does macroevolution occur?

Through accumulated small changes (microevolution).

What are the two types of speciation?

Allopatric (geographic separation) and Sympatric (genetic isolation without geographic separation).

What often causes sympatric speciation in plants?

Self-fertilization or behavioral/temporal isolation.

How does the pace of environmental change affect species survival?

Faster change reduces the likelihood of adaptation, leading to migration or extinction.

Why might fish die if oceans warm too quickly?

Dissolved oxygen becomes less available, and migration may be impossible.

How does genetic diversity affect adaptation?

Higher diversity increases chances of adapting to change.

How does lifespan affect evolution rate?

Shorter lifespans evolve quickly; longer lifespans evolve slowly.