Parental Care Flashcards
What is parental care?
Any form of care that increases fitness & reproductive potential of an offspring
Under what conditions might you expect to find parental care?
When young face conditions that could affect survival:
1. Physically harsh environments
2. High predation pressure
3. Intense competition with conspecifics
Give 2 examples of species that provide no parental care.
- Fish
- Turtles
Give 2 examples of species that provide parental care.
- Whales
- Primates
What 5 things may parental care involve?
- Care of fertilised eggs
- Providing protected environment
- Protection from predators & disease
- Provision of food for young
- Care or defence of young until
independence
What are the costs & benefits to providing parental care?
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
The willingness of a parent to invest in any offspring should be influenced by what?
- Parents’ future prospects of reproducing
- Relative value of current offspring
Which type of species are less willing to risk their lives to protect young: short- or long-lived species?
Give an example.
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
What would encourage parental care to evolve?
If it increases the parents’ lifetime reproductive success
Does benefit/cost ratio increase or decrease with offspring age?
Decreases
When does selection favour parents stopping care?
When cost:benefit = 1
When costs in terms of being unable to produce another offspring exceed benefits to the current one
When does selection favour an offspring soliciting care?
When costs:benefits = 0.5
Would be more Benicia for parent to produce + start investing in sibling
Give an example of unusual parent-offspring conflict?
- 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%
What is siblicide?
Whereby some young kill their brothers & sisters
What species exhibit siblicide?
- Some amphibians
- Some sharks
Why may siblicide occur?
- Insurance against failure
- Environmental uncertainty
What are the 4 evolutionary stable strategies to decide who should care for young?
- Neither parent cares
- Male cares for young, female deserts (‘stickleback strategy’) - will only become ESS if presence/absence of females makes no difference to offspring survival
- Female cares for young, male deserts (‘duck strategy’)
- Both partners care - reproductive success must be greater than if either female deserts
Single parent care provided by makes is generally only found in what type of animal?
- Ectotherms with external fertilisation
- Males are more sure of paternity
- Frequent only in fish, e,g. Sticklebacks
Why is male only care so uncommon?
- Uncertainty about paternity
- Have the potential to mate with many females
- Would only be selected if benefits outweigh costs
Why may species alloparent?
May involve:
- Inclusive fitness
- Obtaining parenting experience
- Reciprocal altruism
When does alloparental care occur?
Give an example.
- 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
Should parents adjust their parental behaviour to maximise their fitness in the short term?
No. They should maximise fitness or lifetime reproductive success long term
What is an evolutionary stable strategy?
One which is stable within a population and which is resistant to evolutionary change though natural selection.
Under what circumstances would one expect a female to desert her young to be cared for by the male only?
When her presence or absence makes no difference to the survival of the offspring
