Sex and Behaviour 2.4

Question 1

Parental investment is costly but increases what?

Answer 1

the probability of production and survival of young

Question 2

what is classified based on the level of parental investment in offspring and number of offspring produced?

Answer 2

r-selected (r-strategists) and K-selected (K-strategists) organisms

Question 3

where do r-selection tend to occur?

Answer 3

occurs in unstable environments where the species has not reached its reproductive capacity

Question 4

where do K-selection tend to occur ?

Answer 4

stable environments

Question 5

what are mating systems based on and what do these range from?

Answer 5

how many mates an individual has during one breeding season

these range from polygamy (polygyny and polyandry) to monogamy

Question 6

what do many animals have?

Answer 6

mate-selection courtship rituals

Question 7

what can successful courtship behaviour in birds and fish be a result of?

Answer 7

species-specific sign stimuli and fixed action pattern responses

Question 8

many species exhibit sexual dimorphism as a product of what?

Answer 8

sexual selection

Question 9

what type of sexual dimorphism occurs in some species?

Answer 9

Reversed sexual dimorphism

Question 10

what does female choice involve?

Answer 10

females assessing honest signals of the fitness of males

Question 11

what happens in lekking species?

Answer 11

males gather to display at a lek, where female choice occurs

Question 12

what does success in male-male rivalry through conflict (real or ritualised) increase?

Answer 12

access to females for mating

Question 13

what does sexual selection select for?

Answer 13

characteristics that have little survival benefit for the individual, but increase their chances of mating

Question 14

what is the difference between egg and sperm?

Answer 14

sperm are produced in much larger quantity than eggs
an egg has a larger energy store

Question 15

what does external fertilisation allow and what are the disadvantages?

Answer 15

• allows very large numbers of offspring to be produced
• many gametes are predated or not fertilised, no or limited parental care, leads to few offspring surviving

Question 16

what does internal fertilisation allow and what are the disadvantages?

Answer 16

• allows increased chance of successful fertilisation and fewer eggs are needed.
  Offspring can be retained internally for protection and/or development - higher offspring survival rate
• energy is used in locating a mate and requires difficult direct transfer of gametes for one partner to another

Question 17

what happens in polygyny?

Answer 17

one male mates exclusively with a group of females

Question 18

what happens in polyandry?

Answer 18

one female mates with a number of males in the same breeding season

Question 19

why do many species exhibit sexual dimorphism?

Answer 19

as a product of sexual selection

Question 20

what happens in sexual dimorphism?

Answer 20

females are generally inconspicuous
males usually have more conspicuous markings, structures and behaviours

Question 21

what happens in reversed sexual dimorphism?

Answer 21

females are more conspicuous than males

Question 22

what are r-selected species?

Answer 22

they are:
- smaller
- have a shorter generation time
- mature more rapidly
- reproduce earlier in their lifetime (often only once)
- produce larger numbers of smaller offspring (which receive a smaller energy input)
- they give limited parental care so most offspring will not reach adulthood

Question 23

what are k-selected species?

Answer 23

they are:
- larger
- live longer
- mature more slowly
- reproduce many times in the lifetime
- produce relatively few, larger offspring
- they give high level of parental care so many offspring have a high probability of surviving to adulthood

Question 24

what can honest signals indicate?

Answer 24

• favourable alleles that increase the chances of survival of offspring (fitness)
• low parasite burden - suggests healthy individual

Question 25

what happens in a monogamy mating system?

Answer 25

individuals have only one mate

Question 26

what happens at a lek?

Answer 26

• dominant males occupy the centre of a lek, with subordinates and juveniles at the fringes as ‘satellite’ males
• female choice occurs during the display