Parental Care

Question 1

What is parental care?

Answer 1

Any form of care that increases fitness & reproductive potential of an offspring

Question 2

Under what conditions might you expect to find parental care?

Answer 2

When young face conditions that could affect survival:
1. Physically harsh environments
2. High predation pressure
3. Intense competition with conspecifics

Question 3

Give 2 examples of species that provide no parental care.

Answer 3

1. Fish
2. Turtles

Question 4

Give 2 examples of species that provide parental care.

Answer 4

1. Whales
2. Primates

Question 5

What 5 things may parental care involve?

Answer 5

1. Care of fertilised eggs
2. Providing protected environment
3. Protection from predators & disease
4. Provision of food for young
5. Care or defence of young until
   independence

Question 6

What are the costs & benefits to providing parental care?

Answer 6

Costs:
- Parents devote time & energy to provide resources at high energy cost
- May reduce parent’s chance of surviving
Benefits:
- Enhance chance of offspring surviving to adulthood

Question 7

The willingness of a parent to invest in any offspring should be influenced by what?

Answer 7

• Parents’ future prospects of reproducing
• Relative value of current offspring

Question 8

Which type of species are less willing to risk their lives to protect young: short- or long-lived species?
Give an example.

Answer 8

Long-lived
E.g. American robin (short-lived) vs Argentinian rufous-bellied thrush (long-lived)
Both exposed to tape calls of jays (predators)
Thrush were less willing to risk their lives to feed current brood

Question 9

What would encourage parental care to evolve?

Answer 9

If it increases the parents’ lifetime reproductive success

Question 10

Does benefit/cost ratio increase or decrease with offspring age?

Answer 10

Decreases

Question 11

When does selection favour parents stopping care?

Answer 11

When cost:benefit = 1
When costs in terms of being unable to produce another offspring exceed benefits to the current one

Question 12

When does selection favour an offspring soliciting care?

Answer 12

When costs:benefits = 0.5
Would be more Benicia for parent to produce + start investing in sibling

Question 13

Give an example of unusual parent-offspring conflict?

Answer 13

• Killer whales
• Mothers provide more support for sons after weaning than daughters, whose care ceases after reaching adulthood
• Additional investment in sons = cost to mom
• Each additional surviving son that a mother
  supports cuts a female’s chances of having a
  new calf in any given year by more than 50%

Question 14

What is siblicide?

Answer 14

Whereby some young kill their brothers & sisters

Question 15

What species exhibit siblicide?

Answer 15

• Some amphibians
• Some sharks

Question 16

Why may siblicide occur?

Answer 16

• Insurance against failure
• Environmental uncertainty

Question 17

What are the 4 evolutionary stable strategies to decide who should care for young?

Answer 17

1. Neither parent cares
2. Male cares for young, female deserts (‘stickleback strategy’) - will only become ESS if presence/absence of females makes no difference to offspring survival
3. Female cares for young, male deserts (‘duck strategy’)
4. Both partners care - reproductive success must be greater than if either female deserts

Question 18

Single parent care provided by makes is generally only found in what type of animal?

Answer 18

• Ectotherms with external fertilisation
• Males are more sure of paternity
• Frequent only in fish, e,g. Sticklebacks

Question 19

Why is male only care so uncommon?

Answer 19

• Uncertainty about paternity
• Have the potential to mate with many females
• Would only be selected if benefits outweigh costs

Question 20

Why may species alloparent?

Answer 20

May involve:
- Inclusive fitness
- Obtaining parenting experience
- Reciprocal altruism

Question 21

When does alloparental care occur?
Give an example.

Answer 21

• When genetic parents are aided in caring for young by older offspring or unrelated individuals
• E.g. ostriches, several females will lay eggs in 1 nest & major female incubates all eggs

Question 22

Should parents adjust their parental behaviour to maximise their fitness in the short term?

Answer 22

No. They should maximise fitness or lifetime reproductive success long term

Question 23

What is an evolutionary stable strategy?

Answer 23

One which is stable within a population and which is resistant to evolutionary change though natural selection.

Question 24

Under what circumstances would one expect a female to desert her young to be cared for by the male only?

Answer 24

When her presence or absence makes no difference to the survival of the offspring

Question 25

What is the dilution effect?

Answer 25

Animals will adopt other offspring in the hope that the chance of predation on their own offspring is reduced.