Competition, Selection Pressures, and Survival of the Fittest

Why do most species produce more offspring than can survive?

Resources such as food and space are limited.

What is overproduction of offspring?

Producing more offspring than the environment can support.

What results from overproduction?

Competition for limited resources.

What is intraspecific competition?

Competition between members of the same species.

Why are some individuals more successful in competition?

They possess advantageous characteristics.

What does “fitness” mean in biology?

How well an individual is adapted to survive and reproduce.

What happens to advantageous alleles over generations?

They increase in frequency in the population.

What are selection pressures?

Factors that affect survival and reproduction.

What are biotic selection pressures?

Living factors such as competition, predation, and disease.

Are biotic factors density-dependent?

Yes.

What are abiotic selection pressures?

Non-living environmental factors.

Give examples of abiotic factors.

Temperature extremes, drought, flooding, fire, pollution, earthquakes.

Are abiotic factors density-independent?

Yes.

How do abiotic factors act on populations?

They affect individuals regardless of population density.

Why do better adapted individuals survive?

They are more suited to environmental conditions.

What happens to less adapted individuals?

They have lower survival and reproductive success.

What is evolution by natural selection?

An increase in the proportion of well-adapted individuals over time.