Bio 262: Predator Avoidance + Levels of Selection

Predation

eating animals

Herbivory

eating plants

Exploitation

one species benefits & one is harmed

Five non-behavioral anti-predator adaptations

1. Morphological

2. Protective resemblance

3. Aposematism

4. Mimicry

5. Chemical adaptation

Morphological

protective structures like thorns, spines

Protective resemblance

Organism looks like the environment

Aposematism

Prey coloration indicates toxicity/danger

Mimicry

Prey looks like a harmful/dangerous organism.

Chemical adaptations

(plant 'secondary compounds')

Five behavioral antipredator adaptations

1. Passive defense

2. Active defense

3. Active escape

4. Grouping or spacing

5. Alarm calls

Passive defense

do nothing, and hope that predator doesn't notice you

Active defense

predators can be warded off by prey or group of prey

Active escape

prey tries to flee predator

Grouping or spacing

organisms either cluster or spread themselves out depending on their defensive strategy

Alarm calls

call serves as a group-wide predator defense

Why aren't adaptations perfect?

A. Genetic constraints exist to producing perfect adaptations.

B. Not enough time for natural selection to act.

C. Environment changes, requiring new adaptations.

D. Other organisms (predators, parasites, etc.) evolve as well.

Why do maladaptive traits exist?

Both alarm calls and aposematic coloration may endanger bearer to produce signal-what good does it do for individual?

Batesian mimicry

Harmless mimic looks like harmful model

Mullerian mimicry

Harmful mimic looks like harmful model

Group Selection

Selection for traits that benefit individuals of a group that are not necessarily related to one another

True altruism

- trait or behavior that reduces the individual fitness of the bearer or performer while increasing the individual fitness of the recipient(s).

- Kin selection is one mechanism that can produce true altruism

Group Selection Requirements

1. There must be low interchange of individuals among sites

2. There must be rapid extinction in a site once a certain frequency of selfish types occurs

3. A small number of colonists should invade an empty site, on average

4. Colonists of a particular empty site must come from a single other site rather than from several other sites

Kin selection operates to cause an _______ in the frequency of certain genes, especially those which say "help your siblings or relatives."

increase

Fitness that includes the benefits to relatives is sometimes called "_______ fitness."

inclusive

(B)(COR) > C

(benefit to relative)(coefficient of relatedness) > (cost to performer)

Coefficient of Relatedness for diploid organisms

(Fraction of B's genes from father) x (fraction if genes from father shared w/A) + (fraction of B's genes from mother) x (fraction of genes from mother shared w/A)