Sexual Selection

Question 1

What are hidden conflicts between males and females in animals?

Answer 1

Gamete investment
Number of mating partners/offspring each can have
Parenting efforts of each

Question 2

Describe conflict of differences in number of mating partners of offspring

Answer 2

Mammals often polygynous
Males often mate with as many females as possible, low resource utilization
Females: less benefit from mating with multiple males, limited number of eggs and pregnant during specific times of year, unable to get pregnant while lactating

Question 3

Describe differences in parenting efforts between

Answer 3

Polygyny

Females: provide most or all of parental care(major source of taking energy)
Males invest little to no resources
Overall, male offspring have higher number of offspring than females

Overall, female provide more valuable resources than male for offspring

Question 4

How can offspring tell you about the maternal conditions in deer?

Answer 4

male - good maternal conditions, means can handle larger offspring
female - maternal conditions poor, only handle smaller offspring

Driving what sex SHOULD be; males best under conditions with plentiful resources and healthy maternal conditions; females best under conditions with less positive and more limited resources

Question 5

Intra-sexual compeition

Answer 5

more active fighting, competition for limited resources

Question 6

Inter-sexual competition

Answer 6

all about being chosen, animals picky

Question 7

Dimorphisms

Answer 7

Physical characteristics between males and females

such as being best chosen or better male competitor for resources

Question 8

Describe examples of influences of sex ratio on offspring

Answer 8

Examples:

Bees, wasps: female can control whether egg is fertilized or not; fertilized can make males and females while unfertilized can make males

Reptiles: temperature of egg incubation determines sex ratio, females can control this by the depth at which she buries her eggs

Question 9

Describe examples of influences of sex ratio in mammal offspring

Answer 9

Resources associated with food availability
Resources associated with female maternal condition
good = male, not so good = female

Question 10

Describe the ant mandible in sexual selection

Answer 10

the ant mandibles are only there to take out other ants/competition

Question 11

Factors of Intrasexual competition

Answer 11

Fighting
Strength competitions
Visual or auditory displays
Repellant odors
Mate guarding
Increase number of sperm delivered
Sperm plug (why)
Sperm competition

Question 12

Give an example of intrasexual competition of mate guarding

Answer 12

orb weaving spider

Males and females different size (dimorphism, so either competition or pickiness)
Female bigger than male
Male will insert pedipalps for sperm transfer into female
Peidpalps swell and male locked into place
Does not allow for other mates to come along
Male will die and female consumes them

Question 13

Describe sperm plug (r u kidding)

Answer 13

a literal block; temporary block to prevent other sperm from entering canal

Question 14

Describe Sperm competition

Answer 14

males and females both use this, use of spermatheca important

males can clean out spermatheca to increase chance offspring are his

Question 15

What do females choose in Inter-sexual competition

Answer 15

Females:
Choose who
choose how much time to mate with males
Choose material resources males provide
Choose gifts received from male
Choose genetic benefits received from male

Question 16

Describe 2 example2 of sperm competition

Answer 16

Dunnock bird/Intra-sexual competiton

Males peck cloaca, so female releases sperm from spermatotheca
Birds then put cloacas together to reproduce

Pirate bug:
Stronger male injects weaker male with their sperm, so when weaker male mates it will actually inject stronger male’s sperm into female

Question 17

Describe an example of sperm plugs

Answer 17

Use sperm plugs on each other
Males use sperm plugs on other males to prevent competition….okay I guess

Moniliformes dubius

Question 18

Describe sperm competition in salamanders

Answer 18

Males lay down spermatophore for female to walk over and pick up
Competitor male will lay their spermatophore on top of another one in order to be the one picked up by the female

Question 19

Describe how frogs use inter-sexual competition

Answer 19

Lots of female choices
Depth of water (material); shallow water is warmer while deep water is colder which affects when eggs hatch
Amount of vegetation(material); needs right amount to allow appropriate development
Quality of habitat important to female

Question 20

Describe how Satin Bowerbird will attempt to get chosen by females

Answer 20

Male wants to be chosen by females
Males attracted to anything blue, so will create a bower to attract females with lots of blue objects
Blue objects can be anything (trash, caps, etc.)

Males will sabotage other males
Female does not always choose the first male

Question 21

Describe inter-sexual relationship of scorpion fly

Answer 21

male provides female nuptial gift (food)

In other cases, Males approach with action without approaching only first; forced copulation
- Some do this due to not having the best quality traits based from other males

Question 22

Describe intersexual relationship of Common Tern (bird)

Answer 22

Females will choose male depending on how they are provided for (food, etc.) through reproduction stages
This means male can provide well for family

Question 23

How do male guppies become desirable for females in intersexual competition?

Answer 23

Copying mate choice theory
- Males hanging out with older females let the younger females know they have good traits that the younger females want

Question 24

Good genes theory

Answer 24

Females looking for the best traits they can get from males
Males may fall under too much pressure to give those traits, and it leads to traits with negative impacts

Question 25

Give an example and experiment of the good genes theory

Answer 25

Long-tailed Widowbird
- Polygynous
Male tails about 50cm in length
Female tails about 7cm in length
Males said to have long tail in order to be desirable to females

Experiment:
Group with untouched tail, Group with cut tail feathers to 14cm, Group with cut tail feathers and glued back on, Group with elongated tails (85cm)

Experiment favored 85cm tail, BUT not favorable to live like this; Handicap theory  tail too long and too much to handle

Question 26

Describe how male Moorhen (bird) are chosen

Answer 26

¾ of time related to incubation
- Males chosen based on how chunky they are; more plump, more desirable

Question 27

For what reason(s) might forced copulations exist?

Answer 27

happens when organism does not have the most valuable traits

Question 28

What factors can influence the sex ratio of offspring?

Question 29

In the context of sexual selection, why are males with a handicap perceived to have a benefit?

Answer 29

• it could be taken as a sign they are healthy and can provide resources the female needs, when in reality it creates difficulty for the male to go about daily activities