Lab 3: The Mating Game (Celine)

In this activity, what did we attempt to simulate?

The selective pressures on males and females that influence sexual behavior

Sexual selection

A special case of natural selection that acts on an organism's ability to obtain or successfully copulate with a mate

(Copulate means to have sex)

What does sexual selection "select" for?

Animals that go to extreme lengths for sex

Ex. Peacocks maintain elaborate tails

Ex. Elephant seals fight over territories

Ex. Fruit flies perform dances

Ex. Some species deliver persuasive gifts

What are two types of selections that characteristics can undergo?

Intersexual and intrasexual selection

Intersexual selection

The sexually selected trait is designed to attract the opposite sex

Ex. Male peacocks have beautiful tails to attract the females

Intrasexual selection

The sexually selected trait is designed to repel rivals of the same sex

Ex. Elephant seals compete for females by physically fighting each other (it often gets really bloody!)

T/F Sexual selection can be powerful enough to produce features that are harmful to the individual's survival

True

Give an example in which sexual selection produces features that are harmful to the individual's survival

Ex. While extravagant and colorful tail feathers or fins attract interested members of the opposite sex, they also attract predators!

There are inherent biological asymmetries between the sexes. By definition, what are males known for?

Males produce many small, relatively cheap gametes (sperm).

They generally provide little or no care to their offspring.

There are inherent biological asymmetries between the sexes. By definition, what are females known for?

Females produce fewer, larger, relatively expensive gametes (egg).

When an offspring receives parental care, it is typically provided by the mother.

Why do females usually have a lower potential reproductive rate than males?

Females generally invest more resources per offspring and can produce a limited number of gametes

How is the operational sex ratio biased, and why?

The operational sex ratio is male-biased.

Due to female's lower potential reproductive rate, more males than females are available to mate at any given time.

What is the adult sex ratio (typically)?

1:1 (male:female)

Remember, however, that the ratio is male-biased

Which gender tends to complete for the opposite gender, and which gender tends to choose among the opposite gender?

Males tend to compete for sexually receptive females

Females can choose among males

What criteria can be used when females are choosing among males?

Criteria such as external signals of male quality (e.g. color or song) or material donation (e.g. nuptial/wedding gifts)

What happens in sex role reversal?

Exactly in the name: The roles are reversed!

- Males provide more parental care

- Females compete for mates

- Males become the choosier sex

In our simulation, what was each student assigned (hint: it was 3 things)?

1) A sex (male or female)

2) An identification letter (A-I for females, R-Z for males)

3) Quality score (1 being the lowest, 5 being the highest)

In exercise 1, we simulated a typical mating dynamic. What was considered a successful mating?

When a female takes a sperm from a male and brings the pair of gametes to the instructor

Note: The female going alone simulated the idea that males tended to not care for their offspring

In exercise 1, we simulated a typical mating dynamic. What were additional rules in the simulation other than what counted as successful mating?*

*I doubt this will be on the exam, but just in case!

1) A male and female must agree to mate

2) Only one egg may be fertilized at a time (i.e. a female can only accept one sperm at a time, and each time she accepts a sperm she must bring the sperm and egg to the front of the classroom)

3) You can mate with the same partner multiple times

4) When mating season is over, no more fertilizations can take place

5) Males must remain in "breeding area"

In exercise 2, we simulated an anthro-simulated mating dynamic. What does this mean?

"Anthro-simulated" basically means that this exercise (better) simulates the dynamics of human reproductive behavior.

In exercise 2, we simulated an anthro-simulated mating dynamic. What was considered a successful mating?

When a female and male BOTH mate and carry their gametes to the instructors.

Note: Both mom and dad typically have involvement in their child's life. Men are expected to care for their offspring.