Unit 2.4 - Sex and Behaviour

Question 1

What is parental investment?

Answer 1

Use of resources by a parent to benefit future or existing offspring

Question 2

What are the benefits of parental investment?

Answer 2

Increased number of offspring, improved chance of survival, increasing the evolutionary fitness of the parent

Question 3

What can parental investment be in terms of?

Answer 3

• Resources used in production in gametes
• Resources used to provide an environment suitable for fertilisation
• Resources used for parental care

Question 4

What takes more parental investment, production of an egg or a sperm?

Answer 4

Egg

Question 5

Why is there a bigger investment in the production of an egg?

Answer 5

Larger eggs

Need to contain an energy source

Question 6

What is the selection pressure for eggs?

Answer 6

Larger eggs

Question 7

What is the selection pressure for sperm?

Answer 7

Contain no excess mass so they can be fast moving

Question 8

Describe polygamy

Answer 8

Each individual may mate with several others in the same reproductive season

Question 9

Describe monogamy

Answer 9

Each individual only shares gametes with one other individual

Question 10

What are the two type of parental care strategists?

Answer 10

r and K strategists

Question 11

Describe characteristics of ‘r’ selected strategists

Answer 11

Unstable Environment
Short Maturation Span
Short Lifespan
Usually high death rate
Small size of offspring
No/Little Parental Care

Question 12

An organism has a high level of parental care, lives in a stable environment and has a long life span, what type of strategist are they?

Answer 12

K selected Strategists

Question 13

What is a sessile organism?

Answer 13

Organisms that are fixed in one space or very slow moving

Question 14

State examples of solutions by sessile organisms for reproduction

Answer 14

Being self fertile
Synchronised release of gametes
Use of other organisms to carry gametes

Question 15

State some costs of external fertilization

Answer 15

Low success rate
Relies on environment
Little selection over mate

Question 16

Give some benefits of internal fertilization

Answer 16

Fewer gametes need to be produced

Greater control in choosing a mate

Question 17

Give some costs of internal fertilization

Answer 17

Greater exposure to predators whilst finding a mate

Increased risk of parasitism

Question 18

What does courtship involve?

Answer 18

Behaviours and Characteristics associated with attracting a mate

Question 19

What results in the evolution of elaborate and intricate courtship displays and sexual dimorphism?

Answer 19

Sexual selection

Question 20

What is a sign stimuli?

Answer 20

Stimuli capable of triggering a fixed action pattern response in another member of the species

Question 21

What is a fixed action pattern response?

Answer 21

Series of acts that occur behaviorally and instinctively in animals when triggered by a sign stimuli

Question 22

Give an example of a sign stimuli/fixed action pattern response pathway

Answer 22

The swollen belly of a female stickleback acts as a sign stimuli for the male to commence his zig-zag courtship dance

Question 23

What is imprinting?

Answer 23

Irreversible developmental process that occurs during a critical time period in young animals

Question 24

How does imprinting increase fitness?

Answer 24

Through natural selection

Forming an attachment to a parent that provides care increases survival chance

Question 25

How can imprinting affect an organism in later life?

Answer 25

Influence mate choice

Pick mate that resembles parental phenotypes

Question 26

What is Sexual Dimorphism?

Answer 26

Differences in characteristics between two sexes of the same species

Question 27

What leads to sexual dimorphism?

Answer 27

Sexual selection

Question 28

What are differences typically in, in relation to sexual dimorphism?

Answer 28

Size and colouration

Question 29

What is reverse sexual dimorphism?

Answer 29

Differences in characteristics between two sexes of the same species resulting in a more conspicuous female

Question 30

Give an example of a group of species with reverse sexual dimorphism

Answer 30

Birds of Prey

Question 31

What is a sneaker male?

Answer 31

A male that is not the strongest or biggest so superficially resembles a female in order to avoid male to male rivalry and sneak in a mate with females

Question 32

Give an example of a species that has sneaker males

Answer 32

Blue gill sunfish

Question 33

What characteristics are likely to make a male successful in male to male rivalry?

Answer 33

Large in size
Greater weaponry
Stronger

Question 34

What is a ‘honest signal’?

Answer 34

Characteristics that allow potential mates to assess the genetic quality of the males

Question 35

Good phenotypic quality is an indicator of what in males?

Answer 35

Good genes

Low parasitic burden

Question 36

What is a lek?

Answer 36

Area where birds gather during mating season for community courtship displays

Question 37

Describe lekking

Answer 37

Communal displaying by groups of males, females visit the lek area to assess males and select a suitable mate
Dominant males tend to win females and satellite males attempt to intercept females at the peripheral of the lek area

Question 38

Explain what is meant by a lekking species

Answer 38

Males gather in communal area to display and females assess the males

Question 39

Explain why lekking is often given as an example of sexual selection

Answer 39

Displaying increases male’s chances of passing on genes

Question 40

State a benefit to females in receiving honest signals

Answer 40

Offspring of the female will have more favorable characteristics