evolution by natural selections

Who developed the theory of evolution by natural selection?

Charles Darwin and Alfred Russell Wallace.

What is the pattern of evolution?

Species change through time; species are related by common ancestry.

What is the process that explains the pattern of descent with modification?

Natural selection.

What evidence shows descent from a common ancestor?

The formation of new species, from preexisting species, can be observed today.

What are the criteria for evolution by natural selection?

1. Variation exists among individuals in a population.

2. Some of the trait differences are heritable.

3. Survival and reproductive success is highly variable.

4. Individuals with certain heritable traits are more likely to survive and reproduce.

What does natural selection require?

Heritable variation in a population.

When does natural selection occur?

When individuals with certain heritable traits produce more surviving offspring than individuals without those traits.

What does heritable variation lead to?

Differential reproductive success.

Which mechanism of evolution leads to adaptation?

Natural selection (the only one).

Define fitness.

The ability of an individual to produce surviving, fertile offspring relative to others in the population.

Define adaptation

A heritable trait that increases the fitness of an individual in a particular environment relative to individuals lacking the trait.

Does natural selection lead to perfection?

No.

• Not all traits are adaptive.

• Some traits cannot be optimized due to trade-offs.

• Some traits are limited by genetic, historical, or environmental constraints.

• Natural selection is not the only process of evolution.

Is natural selection goal-directed?

No. Loss of traits can also be adaptive.

About how many Anolis species are in the Caribbean?

About 150 species on more than 700 islands.

What are ecomorphs?

categories of anoles grouped by body characteristics (morphology) and the ecological niches they occupy.

What are the six anole ecomorph groups?

Crown-giant, Trunk-crown, Trunk, Twig, Trunk-ground, Grass-bush.

How are trunk-crown anoles adapted?

Large toe pads allow them to adhere to leaves and move around to catch prey.

How are twig anoles adapted?

Short legs allow them to move easily on twigs to catch prey and avoid predators.

How are trunk-ground anoles adapted?

Long legs allow them to move faster on the ground to catch prey and avoid predators.

How are grass-bush anoles adapted?

Small size, long legs, and very long tails help them balance on thin branches and grass to catch prey.

Apply the criteria of natural selection to twig anoles.

• Variation exists in leg length.

• Leg length is heritable.

• Not all twig anoles survive and reproduce.

• Twig anoles with the shortest legs have the highest survival and reproduction.