Lecture 22

Question 1

True or False: both animals and plants have a variety of mechanisms that determines an individuals sex

Answer 1

true (ex. XY, XX, hermaphrodite, etc)

Question 2

do most plants have sex chromosomes?

Answer 2

some have evolved that ability, but most of them do not have sex chromosomes. Rather they make two different sizes gametes large and small but does not have to do anything with sex differentiation

Question 3

What are four various sexual strategies?

Answer 3

1. parthenogenesis
2. hermaphroditism
3. haplodiploidy
4. environmental sex determination

Question 4

what is parthenogenesis?

Answer 4

• can be both miotic and sexual forms
• organisms develop from unfertilized eggs
• females can either make eggs that are fully viable or need to be fertilized by sperm

Question 5

what is hermaphroditism?

Answer 5

• organisms possess both male and femae reproductive organs (obligate)
• or they can change sex at some point in their lives (sequential)

Question 6

what type of sexaual strategies are plants mainly?

Answer 6

• hermaphroditic
• capable of self fertilization but they can also have factors that allow them to not do self fertilization to prevent selfing, instead doing male and female things

Question 7

what is haplodiploidy?

Answer 7

• haploid males develop from unfertilized eggs
• diploid females develop from fertilized eggs
• this leads to differences in relatedness between parents, daughters, sons, etc

Question 8

what is environmental sex determination?

Answer 8

• the early developmental environment determines whether individual will be female or male
• ex. temperature dependent sex determination

Question 9

what happens once there is sex?

Answer 9

• females invest in few large gametes (egg)
• males invest in many small gametes (sperm)

Question 10

what is anisogamy?

Answer 10

differences in. gamete size

Question 11

what does anisogamy cayse in terms of investment?

Answer 11

• due to anisogamy there is an initial sex difference in parental investment, cost of gamete is different right away
• can cause amplification of assymetry in parental investment

Question 12

what does selection favor?

Answer 12

selection favors phenotypes that get more genes into the next generation

Question 13

how can sexual selection actually be harmful in terms of survival?

Answer 13

• sexual selection can produce costly, conspicous traits that compromise survival (they can produce traits that make you more present to predators which causes a sex disadvantage)

Question 14

In sexual selection how is fitness measured?

Answer 14

in sexual selection, fitness is measured relatbive to members of the same sex

Question 15

what is the difference in terms of surival evolution between natural selection and sexual selection?

Answer 15

in natural selection is it harder for traits that decrease survival to evolve, but this is not seen in some certaine examples for sexual selection (ex. having very bright feathers)

Question 16

what is sexual selection?

Answer 16

differences in reproductive success (fitness) due to variance in mating success (via the competition for access to mates and non random choice of mates)

Question 17

what happens to the sex that invests more in offspring production?

Answer 17

the sex that invests more in offspring production and care has fewer reproductive opportunties

Question 18

what is a result of sexual selection if they invest more in offspring production?

Answer 18

• they should be choosier and more discrimination
• then they should become a limiting resource for the opposite sex as a result of becoming more choosier

Question 19

how do females tend to invest in their gametes?

Answer 19

• generally invest in few, large, costly gametes
• certain of offspring parentage (knows who the father is)
• limited by fecundity (how many offspring it can produce)

Question 20

how do males invest in their gametes

Answer 20

• generally invest in many small and cheap gametes
• uncertain of paternity (who it fathered)
• limited by number of mates available

Question 21

what do sexual dimporphisms result from?

Answer 21

• result from sexual selection
• the asymmetric nature of investment in sexual reproduction often leads to dramatic sexual dimorphisms in characters directly related to intrasexual compeition and/or intersexual choice

Question 22

what is sexual dimorphisms?

Answer 22

the two sexes look different

Question 23

what are ornaments?

Answer 23

attractive traits that increase mating success (ex. peacock tail- just there to look pretty no function)

Question 24

what are arnaments?

Answer 24

weaponry used to outcompete other individuals (ex. antlers in deer)

Question 25

# w what are the two kinds of sexual selection?

Answer 25

* intrasexual selection * intersexual selection

Question 26

what is intrasexual selection?

Answer 26

* mating success determined by within sex-sex interactions * usually male-male compeition (female-female is possible just not as common)

Question 27

what is intersexual selection?

Answer 27

* mating success determined by between sex interactions * female choice of mates

Question 28

what is bateman's principle?

Answer 28

* the greater variance in reproductive success among males than females * since male gametes are not as limiting, male reproductive success increases lniearly with increasing number of mates (male just keeps on increasing if he can get mates)

Question 29

what happens when bateman's principle is true?

Answer 29

sexual selection is higher on males

Question 30

what does more mating for males mean?

Answer 30

more offspring

Question 31

what is mating like for females- the general trend?

Answer 31

* just a few matings saturate the number of offspring (becuase it is limited by resources) * female number of mates flatten out over time with reproductive success because even if she keeps on mating her resources run out to produce more offspring * resources include time, etc

Question 32

what can male-male compeititon lead to?

Answer 32

* male-male compeition leads to extreme variance in reproductive success for males * in general, bigger/healthier/stronger males win, but may come at a cost for longevity

Question 33

what does high variance in male reproductive success lead to?

Answer 33

intense sexual selection

Question 34

what are some manifestations of intrasexual competition?

Answer 34

* direct physical combat * fighting ability * early arrival at breeding sites * territory defense

Question 35

what are direct benefits of female choice?

Answer 35

females may benefit from increased nutrition, provisioning, or paternal care that increases their reproductive output or the quality of their offspring

Question 36

what are indirect benefits of female choice?

Answer 36

* the benefit affects the genetic quality of the female's offspring (so does not benefit the female directly) * showy ornaments often serve as indicators of high quality males

Question 37

what traits can females rely upon as indicators of quality in males>

Answer 37

* good genes process: genetically superior mates produce fitter offspring * arbitrary choice process: females that mate with preferred fathers produce sons that will have high mating sucess