lecture 8

Question 1

what are secondary sexual characteristics?

Answer 1

characteristics of males and females not directly involved in the process of reproduction

Question 2

what is intrasexual selection?

Answer 2

when individuals of one sex compete among themselves for mates

Question 3

what is intersexual selection?

Answer 3

when individuals choose mates of the opposite sex based on some particular trait

Question 4

why do individuals make choices based on characteristics?

Answer 4

they are honest signals of good genes

Question 5

what is reproductive investment?

Answer 5

the time and resources expended on each offspring

Question 6

does males or females have higher reproductive investment?

Answer 6

females

Question 7

why do females have a higher reproductive investement?

Answer 7

• females produce larger gametes
• females have to raise the offspring

Question 8

what is reproductive success?

Answer 8

an individual’s production of offspring per breeding event or lifetime

Question 9

how are females limited for reproductive sucess?

Answer 9

limited primarily by availiabilty of resources for production of gametes or offspring (low variability)

Question 10

how are males limited in reproductive success?

Answer 10

limited primarily by mating oppurtunities (high variability)

Question 11

what is the “main” reproductive strategy for females?

Answer 11

invest in high quality mate to obtain high quality offspring

Question 12

why do females need to choose high quality mates?

Answer 12

because they have high investment and lower variability

Question 13

what type of sexual selection is going to be important for high investment females?

Answer 13

intersexual selection and mate choice

Question 14

what is the “main” reproductive strategy for males?

Answer 14

increase the quantity of mating opportunities

Question 15

why should males increase the quantity of mating opportunities instead of quality?

Answer 15

because they are the low investment sex with high variability

Question 16

what type of sexual selection is going to be important for low investment males?

Answer 16

intrasexual selection

Question 17

what are some exceptions to these rules for females?

Answer 17

can be promiscuous
- genetic compatibility
- reduced risk of interbreeding
-protection against infanticide

Question 18

what are some exception to these rules for males?

Answer 18

can be choosey
- sperm is not always cheap
- copulation can be demanding
- sex-role reversal

Question 19

what is sexual selection?

Answer 19

selection that depends on the advantage which certain individuals have over others of the same sex and species soley in the respect of reproduction

Question 20

what are the sources of fitness differences?

Answer 20

1. survival (viability selection)
2. gamete production (fecundity)
3. mating ability (gamete exchange)
4. fertilizing ability (gamete fusions)

Question 21

what conditions are secondary sexual characteristics important under?

Answer 21

1. when individuals of one sex compete among themselves for mates (intrasexual selection)
2. when individuals choose mates of the opposite sex on the basis of a particular trait (intersexual selection)

Question 22

what is batemans principle?

Answer 22

1. reduce investment in gamete and parental care by males increases their potential rate of reproduction biasing the relative numbers of sexually active males to receptive females at any one time
2. this leads to increased intensity of intrasexual competition, greater variance in breeding success and stronger selection for traits affecting competitive ability in males than in females
3. this leads to greater selectivity in choice of mating partners by females
4. which generates selection pressure in males for traits that display their quality as breeding partners