Parental care Flashcards
Different ways that parents care for offsrping
1) Preperation of nests, burrows or territories
Example: Nicrophorou burying beetles removes the fur and rolls a carcass into a ball.
2) Pre- birth provisioning
- Multicellular organisms must provide the zygote with provisions so that it can replicate
Example: Egg/ seed
- Males can also provide: resources to mother, provision through gential tract, allowing themselves to be eaten, defend females resources.
3) Post birth provisioning
- Mass provisioning (wasp and certpillar/ sphecids wasps paralize prey and put in seeled pod with egg)
- Continous provisioning (mammals and birds)
4) Care without provisioining
- they can provide (e.g. protecting) without providing resources
Example: Lace bug creche study showed presence of parents increased offsrping survival due to protection rather than provisioning. -> when no predators the absence of mother had no effect
5) social assistance
Parents can provide social assistance to you once they are older
Example: bonobos mothers increase reproductive potential of young by imporving their rank
Social support can also involve teaching offsrping
- e.g. matriarchs provide assistance not only to offsrping but also to other members of the group as they possess knowledge about migration routes, sources of water and food, and other vital information crucial for the survival of the group
A study investigating the evolution of parental care: Peruvian poisonous frogs
These frogs lay their eggs on a leaf and then the yong climb onto the father’s back and are put into lilipad pools.
The male then observes the offsrping and calls to the female when they need food. She lays a trophic eggs.
How did this evolve?
A study compared the survival of offsrping in small (limited resources) and large (predaiton) pools in the presence and absence of parental cares.
The greatest offspring survival is small pools and parental cares.
Pare evolved due to the predation pressure of offsping in large pools pushing eggs to put in small pool but the lack of resources in small pool leading to parental care.
- transition to parental care depends on the size of the pool
- If protected pool with many resources would parental care have evolved?
Optimum parental care
Optimum care is when there is the greatest difference between costs and benefits.
Costs increase linearly and benefits increase with diminishing returns.
This means parental investment depends of the reproductive value of their offspring as this effects the benefits thus the optimum.
Parental investment also depends of other mating opportunities that are availiable
Example: Mouth brooding St peter’s fish
The optimum level of parental care varies depending on whether there is a female or male bias as the benefits of parental care change.
Male bias: Males show parental care more than desertaion due to limitation of mates
female bias: males show desertaion more than female bias to find mates.
Why do females invest more?
Natural selection will favour individuals that leave descendents without paying the cost of looking after them as long as someone else will care. So why do females care more?
Females ensure fitness by ensuring the survival of few large offspring, whereas males would rather have many offspring
This leads to selection acting more strongly on females to provide care, and more strongly on males to compete for mates.
Male care is more common in fish as male show off by caring and there is less of a cost to caring. Females are also more able to abandon care due to external fertilisation.
Cooperative care
In cooperative care, adult help is provided by non-breeding adult helpers. This is relatively rare.
- Occurs when the chance of relatedness is high. e.g. limited dispersal or relies on recognition.
Example: Long tailed tit cooperative breeding
- High predation rate of chicks
- If Mother loses chicks, she will help niehbours.
- More likely to help related neighbours
Occurs based on Hamilton equation
Misdirected care
Parents can manipulate others into caring for their young and paying the costs (host manipulation). Relies on the parent not being able to recongise that they’re not their young. Adapted to create eggs that look similair.
Brood parasites, laying eggs on other nests
Example: Gall wasps
- Waps inject larvae and virus into plants that creates a gall to feed their larvae as they grow and provide a nest.
Example: Cuckoo
Bad care
Parental care does not always lead to the survival of their offsrping.
Abandonement:
If the opportunity arises to gain additional mates then abandonemnet can be beneficial.
Example: St Peter’s fish (sex bias dependent)
Favourtism: Parental care often favours stronger, larger offspring who are more likely to survive and have a reproductive value. In unpredictable environments parents produce optimistic numbers of eggs and end up with a few chick in bad years due to favourtism but lots of chicks in good years due to sufficient resources.
Fillial Cannibailism: Cannibalism can be favoured to divert resources from offsrping with low chance of survival to future broods
Example: commonly seen in fish.
- When egg eating is a male investment into future reproduction, a conflict between female and male interests
emerge
- can lead to discriminating females.
Favouritism
Both abandonment and fillial cannibailism have evolved to improve survival chances of other offspirng. -> methods of parental care
example: HIgh clutch density may increase chance of disease transmission, decreased oxygem, decreased food
- The beaugregory damselfish (Stegastes leucostic), fathers were more likely to eat eggs under low oxygen conditions
Lecture overview
Females tend to show more parental care than males due to anigosamy leading to male male competition and females producing few young which they invest a lot into.
However, there are other parental care dynamics that can evolve.
- Cooperative care (Long tailed tit)
- male care (Female bias mouth brooding st Peter’s fish)
- Female and male care
Key examples of care
- nest building
- pre birth provisions
- Post birth provision
- Care without provisioning
- Social assistance
The evolution of care occurs through different mechanisms (e.g. peruvian frog) and leads to different optimal strategies (St Peter’s fish).
You can also get misdirected care (exploiting others) and bad care (negatively effecting offsrping).
Will care evolve?
Do basic life hisotry characteristics favour parental care?
- High offsrping mortality in the absence
- Slow offsrping developement
- High parental mortality -> multi parental care -> future reproduction chances are low
Do environmental conditions favour parental care?
- VAriable environment
- High resource availiability
Can one or both parents provide care?
- kin recognition
Are the fitness benefits positive?
- Cost of care to parents (remating opportunity? male vs female?)
- Benefits of care to young
- Parent offsrping relatedness
Will a rare mutation for parental care be able to spread in the population?
- Compeititon between those that do and do not privde care
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