Ontogenesis Flashcards
What does precocial mean?
Precocial = young are independent and well-developed at birth
PREcocial = PRE-developed in de womb
What does altricial mean?
Altricial = young are helpless at birth and need more maternal care
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Do all species with altricial young carry them constantly?
No, some park their babies in a tree hole e.g. tarsier
What are the 2 nursing styles observed in primates?
- Nursing on demand
2. Nursing on schedule
When do young nurse on schedule?
If they have limited access to their mother, i.e. parked babies
What 3 nutrients are in mother’s milk and what are they for?
- Fat to burn for thermoregulation
- Protein for growth
- Sugar to meet energy demands
Which babies require more fat?
Altricial parked babies; they are not being carried and must await mother’s return for long periods, need to keep warm
Which babies need more protein?
Altricial non-parked babies: do not need as much fat or sugar as are carried by mother, focus on growth
Which babies need more sugar?
Precocial babies as they are running around after their mothers
Non-human ape babies nurse on demand. Do human babies?
No: social convention dictates they sleep separately from the mother and are fed on schedule
Why is it theorised that human babies cry?
Because they are supposed to be on-demand feeders and they are deprived of this due to social convention. This is described as a ‘forced shift in ontogeny’. Humans can adapt although there is a trade-off.
Why is it thought that SID happens?
Because human babies are left alone at night, potential trade-off for ontogeny shift.
Some female monkeys/apes have one nipple longer than the other. True or false?
True, theorised that this may correlate to infant feeding preference.
What is weaning conflict?
When the mother wishes to stop nursing an offspring and the offspring wishes to continue.
When does weaning conflict occur?
When the mother has a new infant that she needs to wean instead. This is a trade-off; a reduction of investment into the first infant in order to invest in the second
What happens to the older infant in weaning conflict?
It regresses to a more helpless state in an effort to gain attention from the mother
There are 2 reproductive strategies, r and K. What are they?
r = fast-breeding K = slow-breeding
Describe r strategy.
List 3 examples of r.
In an unpredictable environment there are seasonal fluctuations of population growth and breakdown correlating to resource availability. Organisms therefore must breed quickly when resources are abundant. As there are fewer organisms surviving, population growth is determined by intrinsic factors (r).
r = age of first repro, litter size, birth intervals
Describe K strategy.
In a predictable environment non-seasonality promotes stable populations and efficient resource use. Therefore population growth is determined by extrinsic factors like K, environmental carrying capacity.
Number of offspring is relative to reproductive strategy. True or false?
True.
If young are altricial, do parents have more or less?
Less because they each require more investment
If young are precocial, do parents have more or less?
More because they require less investment
r and K selection strategies cannot be changed. True or false?
False: humans have adapted around them
If you are r selected, what kind of offspring do you have?
Altricial
