Unit 2 - Sex and Behaviour

Question 1

Who has greater parental investment?

Answer 1

Greater investment by females

Question 2

What is female investment?

Answer 2

Female investment in the egg structure in
non-mammals or in the uterus and during
gestation in mammals

Question 3

What is parental investment?

Answer 3

Parental investment is costly but increases
the probability of production and survival of
young

Question 4

What are characteristics of r-selected species?

Answer 4

• smaller,
• have a shorter generation time
• mature more rapidly,
• reproduce earlier in their lifetime, often only once,
• produce a larger number of smaller offspring, each of which receives only a smaller energy input,
• limited parental care,
• most offspring will not reach adulthood

Question 5

What are characteristics of k-selected species?

Answer 5

• larger
• live longer
• mature more slowly,
• can reproduce many times in their lifetime,
• produce relatively few,
• high level of parental care,
• many offspring have a high probability of surviving to adulthood.

Question 6

Where do r-selection take place?

Answer 6

r-selection tends to occur in unstable
environments where the species has not
reached its reproductive capacity

Question 7

Where do k-selection take place?

Answer 7

whereas K-selection tends to occur in stable environments

Question 8

What are the benefits of external fertilisation?

Answer 8

-benefits: very large numbers of offspring
can be produced

Question 9

What are the costs of external fertilisation?

Answer 9

• many gametes predated not fertilised
• no or limited parental care
• few offspring survive

Question 10

What are the benefits of internal fertilisation?

Answer 10

• increased chance of successful fertilisation
• fewer eggs needed
• offspring can be retained internally for protection
  and/or development
• higher offspring survival rate

Question 11

What are the cost of internal fertilisation?

Answer 11

• a mate must be located, which
  requires energy expenditure
• requires direct transfer of gametes from one
  partner to another

Question 12

What are mating systems based on?

Answer 12

Mating systems are based on how many
mates an individual has during one breeding
season

Question 13

What is monogamy?

Answer 13

the mating of a pair of animals to
the exclusion of all others

Question 14

What is polygamy?

Answer 14

individuals of one sex have more
than one mate.

Question 15

What is polygyny?

Answer 15

one male mates exclusively with a
group of females.

Question 16

What is polyandry?

Answer 16

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

Question 17

What is a fixed action pattern (FAP)?

Answer 17

An instinctive behaviour response triggered by a specific stimulus. Once triggered, the FAP behaviour can’t be stopped midstream but must play out to completion.

Question 18

What is a sign stimulus?

Answer 18

A trigger that provokes a behavioural response.

Question 19

What characteristics do sexual selection select?

Answer 19

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

Question 20

What are female species typically?

Answer 20

Females are generally inconspicuous

Question 21

What are male species typically?

Answer 21

usually have more conspicuous markings,
structures and behaviours.

Question 22

Why are females typically more inconspicuous?

Answer 22

To remain concealed, reducing predation and increasing survival chance of her offspring.

Question 23

What does successful courtship behaviour can be as a result of?

Answer 23

species-specific sign
stimuli and fixed action pattern responses

Question 24

What is reversed sexual dimorphism?

Answer 24

When the normally inconspicuous female is larger or more ornate than the male.

Question 25

What can honest signals indicate?

Answer 25

Honest signals can indicate favourable
alleles that increase the chances of survival
of offspring (fitness) or a low parasite burden
suggesting a healthy individual.

Question 26

What does female choice involve?

Answer 26

Female choice involves females assessing
honest signals of the fitness of males

Question 27

What is lekking and what are some animals that do this?

Answer 27

• males gather to display at a lek, where female choice occurs.
• Some bird species exhibit lekking behaviour.

Question 28

What does success in male-male rivalry increase?

Answer 28

Success in male-male rivalry through conflict
(real or ritualised), increases access to
females for mating

Question 29

What is male-male rivalry?

Answer 29

Males will fight for dominance and access to
females, often using elaborate ‘weapons’
such as antlers, tusks, horns.

Question 30

What happens during a lek?

Answer 30

Dominant males occupy the centre of the lek,
with subordinates and juveniles at the fringes
as ‘satellite’ males. During the display,
female choice occurs.