BIOL3045 Study Guide - Final Guide: Ecological Pyramid, Species Richness, Ontogeny
3 Jul 2018
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Part 2
Individuals: Influences fitness by constraining how quickly an organism reaches maturity and
produces offspring.
• The metabolic rate of an individual is dependent on the mass and temperature: metabolic
rate increases infinitely with mass and reaches an optimum curve with temperature.
• Mass
o Isometry: true linear relationship on a natural scale (using log scale it is a linear
relationship). Allometry: for every unit of body mass, the growth is smaller. Shows
that a bigger organism has smaller metabolic rate per unit gram. If your system
shows this, then the society needs varying amounts of energy to sustain all
individuals.
o Rubner shows that as body mass becomes bigger, the volume increases more than
the surface area at a rate proportional to 2/3. However, Kleiber believed that the
scaling relationship was much closer to ¾. Other scientists explained Kleiber’s
findings through fluid dynamics. However, this does not account for all organisms
(such as sea sponges) and what happens during exercise. Still looking for
information to explain deviations from ¾.
o Applications of this scaling proportion is important in:
▪ Determining how much anticancer drug to administer.
▪ Fisheries determining greatest profit though yield.
▪ How much carbon is being recycled per year in a particular ecosystem.
• Temperature
o Endotherms have very sophisticated mechanisms to cope with temperature, to
maintain homeostasis (i.e. goose bumps, vasoconstriction, shaking).
o Other endotherms may undergo hibernation, or decreased heartbeat, to live off the
fat they gained from the feeding season.
o There is a tendency for organisms to get bigger as latitude increases. Allows for
greater insulation of the body: more mass, less surface area, better at maintaining
better constant body temperature.
o This can also be seen for ectotherms as developmental rates are faster in the
warmer temperatures, those in warmer temperatures have smaller eggs, those in
the colder temperatures have larger eggs.
o When metabolic rate vs. body mass:
o When b0 vs. temperature (exponential increase):
o This is explained by the Boltzmann and Arrhenius distribution of temperature
dependence.
o The effect of size and temperature on metabolic rate:
▪ As temperature increases, there will be a greater number of smaller species,
populations will become younger and individuals will mature faster.
Populations: It constrains the intrinsic rate of population increase and density.
• Heterotrophic metabolism < net photosynthetic production: net photosynthetic production
is a primary restraint.
• Gives us predictability power to see how much carbon will be output to the system.
Document Summary
Isometry: true linear relationship on a natural scale (using log scale it is a linear relationship). Allometry: for every unit of body mass, the growth is smaller. Shows that a bigger organism has smaller metabolic rate per unit gram. However, kleiber believed that the scaling relationship was much closer to . Other s(cid:272)ientists explained klei(cid:271)er"s findings through fluid dynamics. However, this does not account for all organisms (such as sea sponges) and what happens during exercise. The higher to the top, the less energy available: energetic limits should be manifested most strongly for the most abundant species. Community: constrains how much energy and materials can flow through to the next trophic level: growth trajectory s curve seems to be universal. Quick exponential phase, transition phase, followed by plateau phase: the energy we eat is either excreted or assimilated. Assimilated energy is distributed to metabolic rate, or new biomass.
