BIOL3045 Lecture Notes - Lecture 18: Ecological Pyramid, Ontogeny
3 Jul 2018
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Animal Ecological Physiology BIOL3045 460381099
Lecture 18: Individuals to ecosystems.
Growth trajectory S curve seems to be quite universal. Why do we grow like this?
Assimilation rate – what we eat becomes energy in the body some way. Some energy will be
distributed to metabolic rate or new biomass. Metabolic proportion of energy is then distributed
into resting metabolic rate (fuels growth and maintenance), and active metabolic rate. Thus, this
resting metabolic rate is partitioned into energy for maintenance and energy for biosynthesis.
How much energy we consume in a day, part is excreted, and the other part is to ‘do stuff’.
Maintenance allocation, shows how much of the energy is going to growth. This shows that more is
dedicated to growth during younger years, then this starts to decline as we get older.
Stickleback: part of assimilated energy is dedicated to growth. For a second individual he spends
more energy to grow the same amount as the first individual. The first individual is more efficient in
constructing biomass.
Cost of growth Em is defined as respiration/growth. If growth and respiration increase equally, the
cost of growth is independent to temperature. If unequal, the cost of growth increases with
temperature.
Early ontogeny shows alpha = 0.93, nutrients in body is distributed differently and thus they grow
faster. Curves don’t overlap as there is a 20 fold difference between young and adult. However,
when you account for maintenance cost, it reduces to a 5 fold difference.
Em assumes to be independent of temperature and mass. This means that the amount of energy
needed to grow as a baby and as an adult is the same.
This proves true for body mass, where respiration and growth increase the same. But, when you
look at temperature, respiration increases faster than growth.
Can take all energy assimilated throughout lifetime and divide this by how much growth has
occurred, we can calculate efficiency of energy transfer. If you increase energy needed to produce a
gram of biomass, transfer efficiency decreases. This also corresponds to the organisms life, where
overall they have lower efficiency as more energy is dedicated to maintenance then growth.
Ecosystem dynamics, shape of trophic pyramid: Inverted trophic pyramids are present when transfer
efficiency is large, all need to eat something really small and need to have great transfer efficiency.
These inverted pyramids are energetically possible but are unlikely! Young prey are more efficient in
transmitting energy to the next trophic level.
Bigger animals aren’t good at transmitting energy upwards to the pyramid, but they are great at
reproduction. Individuals make more babies as they are growing, consequence of this is that if we
remove them from the system we remove a large chunk of population replenishment. Older
animals are more efficient in reproducing.
Life history + energetics + stochastic processes (chances of going extinct etc.)
Document Summary
Growth trajectory s curve seems to be quite universal. Assimilation rate what we eat becomes energy in the body some way. Some energy will be distributed to metabolic rate or new biomass. Metabolic proportion of energy is then distributed into resting metabolic rate (fuels growth and maintenance), and active metabolic rate. Thus, this resting metabolic rate is partitioned into energy for maintenance and energy for biosynthesis. Ho(cid:449) (cid:373)u(cid:272)h e(cid:374)erg(cid:455) (cid:449)e (cid:272)o(cid:374)su(cid:373)e i(cid:374) a da(cid:455), part is e(cid:454)(cid:272)reted, a(cid:374)d the other part is to (cid:858)do stuff(cid:859). Maintenance allocation, shows how much of the energy is going to growth. This shows that more is dedicated to growth during younger years, then this starts to decline as we get older. Stickleback: part of assimilated energy is dedicated to growth. For a second individual he spends more energy to grow the same amount as the first individual. The first individual is more efficient in constructing biomass. Cost of growth em is defined as respiration/growth.
