KA2.4 - Sex and Behaviour

Question 1

Define ‘parental investment’

Answer 1

the use of resources (time or energy) to benefit future or existing offspring

Question 2

Compare sperm and eggs in animals.

Answer 2

• Sperm = high number produced
• Egg = Low number produced and larger due to energy store

Question 3

Why is female parental investment often greater in animals?

Answer 3

Development of egg structure (non-mammals) and uterus/gestation (mammals)

Question 4

What is the benefit of parental investment?

Answer 4

Increases the probability of production and survival of young

Question 5

Compare r-selected and K-selected organisms based on offspring number and environment.

Answer 5

r-selected = Many offspring, unstable environments
K-selected = Few offspring, stable environments

Question 6

Describe the key features of a r-selected species?

Answer 6

• 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 7

Describe the key features of a k-selected species?

Answer 7

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

Question 8

What is a typical physical characteristic and generation time for r-selected species?

Answer 8

• Smaller size
• Shorter generation time

Question 9

Describe the maturation and reproduction timing of r-selected species.

Answer 9

• Mature more rapidly
• Reproduce earlier in life, often only once

Question 10

Describe the offspring of r-selected species (number, size, energy input)

Answer 10

Produce a large number of smaller offspring, each receiving a smaller energy input

Question 11

What level of parental care do r-selected species typically exhibit, and what is the survival rate of offspring?

Answer 11

• Limited parental care
• Most offspring do not reach adulthood

Question 12

What is a typical physical characteristic and lifespan for K-selected species?

Answer 12

Larger size
Live longer

Question 13

Describe the maturation and reproduction timing/frequency of K-selected species.

Answer 13

• Mature more slowly
• Can reproduce many times in their lifetime

Question 14

Describe the offspring of K-selected species (number, size).

Answer 14

Produce relatively few, larger offspring

Question 15

What level of parental care do K-selected species typically exhibit, and what is the survival rate of offspring?

Answer 15

• High level of parental care
• Many offspring likely survive to adulthood

Question 16

What are the benefits of external fertilisation

Answer 16

Very large numbers of offspring can be produced

Question 17

What are the costs of external fertilisation

Answer 17

• Many gametes predated or not fertilised
• No or limited parental care
• Few offspring survive

Question 18

What are the benefits of internal fertilisation

Answer 18

• Increased chance of successful fertilisation.
• Fewer eggs needed.
• Offspring can be retained internally for protection and/or development.
• Higher offspring survival rate.

Question 19

What are the costs of internal fertilisation

Answer 19

• A mate must be located (requires energy)
• Requires direct transfer of gametes between partners

Question 20

Define ‘external fertilisation’

Answer 20

Gametes release directly into the environment

Question 21

Define ‘internal fertilisation’

Answer 21

Gametes released into the reproductive tract of females

Question 22

What determines an organism’s mating system?

Answer 22

The number of mates an individual has during one breeding season.

Question 23

Define ‘monogamy’

Answer 23

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

Question 24

Define ‘polygamy’

Answer 24

individuals of one sex have more than one mate

Question 25

Define 'polygyny'

Answer 25

one male mates exclusively with a group of females

Question 26

Define 'polyandry'

Answer 26

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

Question 27

Polygyny and polyandry are both types of?

Answer 27

Polygamy

Question 28

What is the purpose of courtship rituals in animals?

Answer 28

To facilitate mate selection

Question 29

What does successful courtship behaviour in animals like birds and fish involve? | These are **not** types of courtship behaviour

Answer 29

* Species-specific sign stimuli * Fixed action pattern responses

Question 30

Define 'species-specific sign stimuli'

Answer 30

An external stimulus (e.g., chemicals, sound, displays/dances) that causes a predictable response in members of the same species | Not actually required knowledge, but helps understand what it is.

Question 31

Define 'fixed action pattern responses'

Answer 31

A predictable (innate) series of actions triggered by the species-specific sign stimuli. | Not actually required knowledge, but helps understand what it is.

Question 32

What is sexual selection, and what is its primary outcome for an individual?

Answer 32

It selects for characteristics with little survival benefit but that increase mating chances.

Question 33

Define 'sexual dimorphism'

Answer 33

Opposite sexes exhibit different morphological characteristics (look quite different)

Question 34

In sexually dimorphic species, what is the typical difference in conspicuousness between males and females?

Answer 34

* **Females**: Generally inconspicuous. * **Males**: Usually have more conspicuous markings, structures, and behaviors

Question 35

Define 'reversed sexual dimorphism'

Answer 35

When the female is more conspicuous | conspicuous = visible

Question 36

Which species is reversed sexual dimorphism most common?

Answer 36

Insects, spiders, fish, reptiles and birds of prey

Question 37

State three examples of courtship behaviour?

Answer 37

1. Female choice 2. Male-male rivalry 3. Lekking behaviour

Question 38

Define 'female choice' in the context of courtship behaviour?

Answer 38

Females **choose** a male partner | Females can only reproduce with one male so choosing correctly is key

Question 39

Explain what a female is assessing during female choice?

Answer 39

The **fitness of males** using honest signals to choose a partner that will give her offspring a better chance of survival

Question 40

Explain what 'honest signals' indicate in the context of female choice?

Answer 40

* Favourable alleles that increase the chances of survival of offspring * A low parasite burden suggesting a healthy individual

Question 41

Define 'male to male rivalry' in the context of courtship behaviours?

Answer 41

When males compete for access to females for mating

Question 42

Describe male-male rivalry in courtship

Answer 42

* Males compete (real or ritualised conflict) for dominance * Success in rivalry increases access to females for mating * Often involves elaborate "weapons" (e.g., antlers)

Question 43

Describe lekking behaviour

Answer 43

Males gather to display at a lek where female choice occurs | Lek = a grouping of males 'showing off'

Question 44

Explain how a dominance hierarchy affects lekking behaviour?

Answer 44

Some bird species exhibit lekking behaviour. Dominant males occupy the centre of the lek, with subordinates and juveniles at the fringes as “satellite” males.