sexual selection

Question 1

how does behaviour affect reproductive success both pre and post copulation

Answer 1

pre copulatory behaviour of competing to both access and attract mates and post copulatory behaviours such as nurturing

Question 2

what is the sexual selection paradox and how is it explained

Answer 2

complex courtship displays evolve despite the fact that they reduce the chance of survival for the individual. these must have evolved as a result of sexual selection as opposed to natural

Question 3

what is anisogamy

Answer 3

fertilisation which involves two dissimilar gametes, possible explaining differences in parental investment

Question 4

what is sex ratio

Answer 4

the ratio of males to females. there is often more males due to females not always being available to mate eg gestation/ lactation periods

Question 5

what are the results of anisogamy, other than investment differences (2)

Answer 5

variation in male reproductive success (some are very successful some not at all) and the creation of different territory types due to female distribution being based on resource density to support high energy cost eggs

Question 6

what factors determine the intensity of sexual selection (2)

Answer 6

the amount of parental effort (therefore free time) and the sex ratio (ability to prevent females mating with other males)

Question 7

what is intrasexual selection

Answer 7

the competition within a sex (usually male) for fertilisations

Question 8

what is intersexual selection

Answer 8

the selection for traits attractive to the opposite sex eg feathers, colour

Question 9

what are the two subclasses of intrasexual selection

Answer 9

pre copulatory which is competition based on competitor asymmetry, and post copulatory which is competition of sperm

Question 10

what are the two subclasses of post copulatory competition, which is a subclass of intrasexual selection

Answer 10

defensive eg mate guarding, scooping sperm, penis length etc or offensive eg more efficient sperm (usually found in polygamous species)

Question 11

what ae examples of pre and post copulatory traits invested in by males,, and why don’t they invest in both

Answer 11

pre eg size, weaponry, post eg tested mass. they usually don’t invest in both due to the energy investment

Question 12

what is Fisher’s runaway effect

Answer 12

traits persist due to their ability to increase reproductive success despite having no real meaning. sons inherit them and daughters inherit an attraction to them

Question 13

what are indirect or genetic indicator mechanisms

Answer 13

indicators of good traits eg health, immunocompetence, developmental stability

Question 14

what are direct or non genetic indicator mechanisms

Answer 14

indicators of good traits which are not genetic eg ability to hold territory, gifts

Question 15

when do females benefit from choosing a mate

Answer 15

when the ‘meaningless’ attractive traits actually have some correlation with the quality of the mate

Question 16

what is the morphological result of sexual selection

Answer 16

females and males become different- dimorphism, dichromatism, physiological regulation etc

Question 17

where do signals originate

Answer 17

everyday actions which were inadvertently conveyed to others and impacted their behaviour

Question 18

what is sensory exploitation

Answer 18

exploiting existing behaviours of the receiver eg mimicking prey movement to attract a female

Question 19

what is arms race of sexual selection

Answer 19

males to manipulate the females into mating and females to determine the deceptive males from those who are actually good quality

Question 20

what are the two arms by which signals are designed

Answer 20

strategically (what the message conveys eg health) and tactically (efficiency of transmission, detectability, and exploitation of the receiver CNS and psychological landscape

Question 21

what does receiver psychology depend on (3)

Answer 21

detectability, discriminability and memorability

Question 22

when do signals have negative consequences

Answer 22

when there are eavesdroppers eg predators

Question 23

what drives signal honesty

Answer 23

sexual selection, intrasexual by probing and punishment from other males and intersexual by females choosing dishonest males being punished by poor fitness

Question 24

what is the handicap principle

Answer 24

high energy signals can only be borne by high quality individuals

Question 25

what does the handicap model show

Answer 25

that high energy is needed to produce testosterone to produce high quality secondary sexual characteristics, whilst also maintaining a strong immune system

Question 26

what are the different types of handicap (4)

Answer 26

qualifying (inhabited regardless so only quality individuals will survive), condition-dependent (will only develop if the individual can afford them), revealing (costly and developed to show an otherwise hidden quality) or strategic choice (only traits which will be ‘believed’ by the female are developed)

Question 27

how do bad phenotypes survive in the population

Answer 27

they may reduce sexual attractiveness but increase chance of survival- it is a trade off between sexual and natural selection