Lab 3: The Mating Game (Sarah)

In this activity, we will work through three exercises to simulate the ______on males and females that influence sexual behavior.

selective pressures

what type of selection is sexual selection?

special case of natural selection

what does sexual selection act on? (2 things)

1. organism's ability to obtain (often by any means necessary) a mate

2. organism's ability to successfully copulate (have sexual intercourse) with a mate

What type of animals do sexual selection select for?

animals that go to extreme lengths for sex

3 examples of animals that go to extreme lengths for sex

1. peacocks maintain elaborate tails

2. elephant seals fight over territories

3. fruit flies perform dances

what are the two types of sexual selection and their functions?

intersexual selection (sexually selected trait is designed to attract the opposite sex)

intrasexual selection (sexually selected trait is designed to repel rivals of the same sex)

what can sexual selection do besides obtaining / copulating a mate?

It can be powerful enough to produce features that are harmful to the individual's survival

extravagant and colorful tail feathers or fins are likely to attract ________, as well as interested members of the opposite sex

predators

what type of asymmetries exist between the sexes?

biological asymmetries

what type of gametes do males typically produce?

many small, relatively cheap sperm

what type of gametes do females typically produce?

fewer, larger, relatively expensive eggs

when offspring receive parental care, who is it typically provided by?

the mother

when males provide more parental care, what is it called?

sex role reversal

why do females usually have a lower potential reproductive rate? (2 reasons)

1. Females generally invest more resources per offspring than males

2. females produce a limited number of gametes

If females have a lower potential reproductive rate, how does it affect the operational sex ratio?

more males than females are available to mate at any given time --> operational sex ratio is male-biased

the operational sex ratio can be male-biased even though the adult sex ratio may be ______

1:1 (male: female)

what type of females do males tend to compete for?

Males tend to compete for sexually receptive females

when males compete for females, females can choose among males using what criteria? (2 examples)

1. external signs of male quality

2. material donations/nupital gifts

what are examples of mate quality?

color or song

in cases of "sex role reversal" (when males provide more parental care), females compete for mates, and males become the _____ sex

choosier

what is each student assigned in the activity? (3 things)

1. a sex (male or female)

2. an identification letter

3. a quality score

what are identification letters represented with?

letters of the alphabet

what is the range of quality (from lowest to highest?)

1 to 5

what two things are evident to your classmates by the headband that you wear during the activity?

sex and quality

Males and females have which color headbands?

Males - blue

females - pink

how is the quality of the individual determined?

by the number of spots (more spots = better quality)

what mating dynamic is the first exercise?

typical mating dynamic

when indicated by the instructor, where will you mingle?

in a designated area of the room

who will you mate with?

your classmates

when will you mate?

during mating season

what indicates a "successful mating"?

when a FEMALE takes a sperm from a male and brings the pair of gametes to the instructor

what will the instructor record? (two things)

1. The identity of the female and male (alphabet)

2. the reproductive success points of each offspring

how is the reproductive success rate determined?

sum the point values of male and female gametes (determined for each offspring)

How long is the duration of the mating season?

Unpredictable (instructor can call an end to the season at any time)

What is your objective in this activity?

to maximize your reproductive success

How is reproductive success different from reproductive success points?

reproductive success = sum of all the reproductive points of all your offspring

A female can force a male to mate, and vice versa (T/F)

False (must agree to mate)

How many eggs can be fertilized at one time?

only one

what must a female do each time she accepts a sperm?

she must bring the sperm and egg to the front of the classroom

You can only mate with the same partner once (T/F)

False (You can mate with the same partner multiple times)

when does no more fertilization take place?

When the instructor declares "mating season is over"

what type of mating dynamic is excercise 2?

anthro-simulated mating dynamic

The rules of the anthro-simulated mating dynamic is identical to that of exercise 1 with only ONE exception (T/F)

True

what is the one exception made to the rules in the anthro-simulated mating dynamic?

After a successful mating, BOTH parents (not just the female) must carry their gametes to the instructor.

What does the second exercise better simulate?

the dynamics of human reproductive behavior

What is the third exercise?

changing a different rule from exercise 1

What two things will be graphed for each gender in this lab?

1. the number of matings

2. total reproductive success

Females tend to produce fewer gametes. Therefore, they are more likely to invest more heavily into parental care (T/F)

True

How have males adapted to a relatively high number of rivals?

Evolved any number of ways to "win" at mating by advertising their quality (= sexual selection)

Increased risk of predation or parasitism is part of costs to sexually selected traits (T/F)

True

Why are there costs to sexually selected traits?

Building weapons or ornaments requires resources