Topic 7: Energy Budgets Flashcards
Energy Demands
reproduction, growth, maintenance, activity
Energy Budgets depend on:
size, activity, environment
Size/Mass effects the way organisms:
- move
- how often they eat
- what they eat
Scaling
study of the effect of size/mass on anatomy/physiology
SA=
l^2
V=
l^3
Increase in size causes a _______ in SA/V
decrease
Advantage of low SA/V in large organisms
heat retention;
heat produced by entire volume & lost through SA
Disadvantage of low SA/V in large organisms
nutrient exchange & energy generation; bigger organisms have highly branched circulatory, digestive, and respiratory systems to increase SA
M=
Scaling Relationships Equation
aW^b
logM=
loga + blogW
Log transformation is used for:
data normalization & to make a power function linear
Allometry
both dimensions do not vary proportionally to size
Y=aM^b
Isometry
both dimensions remain proportional
Y=aX’
logY = loga + (1)logX
Hyperallometry (Positive allometry)
as one dimension increases, the other increases to a greater proportion
Hypoallometry (Negative allometry)
as one dimension increases, the other increases to a lesser proportion
E in =
E rmr + E activity + E production + E excretion
E production =
E growth + E reproduction
E assimilation =
E rmr + E activity + E production
or
E in - E excretion
larger animals have a ____ Ein/unit time because:
Relationship between body size and E in
greater;
- eat less often but more at once
- take in more air w/ each breath and pump more blood per heartbeat but have a low breathing rate and heart rate compared to smaller animals
E excretion
feces, urine, shedding, heat
how long food remains in digestive tract is a phenotypic trait that responds to pressures in the environment
Measure of Evolutionary Fitness
total amount of rate @ which organisms obtain energy from food
Greater retention time =
greater time taken to digest food
High quality food
- easy to digest
- less E lost
- high rate
- plateau’s sooner and higher
Low quality food
harder to digest, more E lost, low rate, plateau’s later and lower
Metabolic Rate
rate of energy consumption when it converts chemical energy to heat & external work
3 reasons for metabolic rate
- helps determine how much food needed
- quantitative measurement of total activity
- ecologically helps determine the pressure on energy supplies in the ecosystem
E rmr
resting metabolic rate - energy expenditure at rest but routine activities/day
E bmr
Basal metabolic rate = metabolism at complete rest
- applies to endotherms
E smr
Standard metabolic rate = metabolic rate measured at a specific temperature
- applies more to ectotherms
E fmr
Field metabolic rate = metabolic rate measured in wild animals
E rmr can be measured through: (2)
Direct or indirect calorimetry
Direct Calorimetry
heat loss - usually an expensive and cumbersome process
Indirect Calorimetry
O2 consumed or CO2 produced - usually the cheaper and easier process
- respirometry
- material balance method
Respirometry
rate of respiratory gas exchange with the environment
Material-balance method
measuring chemical content of organic matter that enters and leaves body
Relation between weight-specific RMR and Body Weight: (equation)
weight-specific MR decreases as body weight increases
M/W = aW^(b-1)
(b-1) = always negative!
E activity
includes most forms of movement above the resting rate
- when the activity increases the heat generated may cover the thermoregulation costs of an energy budget
E production
represents growth & reproduction
What is the E production when the energy budget is balanced?
0
more than enough energy is consumed, E production is:
positive and mass increases
if not enough energy is consumed, E production is:
negative and mass decreases
smaller animals have ______ per gram BMR than larger animals (for endotherms & ectotherms)
greater
______ active animals have __________ metabolic rate
more; higher
