BioEnergetics 1 Flashcards
- Explain the energy budget – including:….
a. Primary inputs? (2)
b. Primary loses? (4)
c. Primary needs? (in order of priority) (4)
The “energy budget” describes the total inputs and outputs of energy for an individual animal. Generally, an animal receives energy inputs that are then either spent on the animal’s needs, or lost through one of the four modes of heat loss.
The inputs are:
- Food
- Solar energy
The losses are:
- Radiation
- Convection
- Conduction
- Evaporation
The needs (in order of priority) are:
- Warmth and maintenance
- Activities (walking, foraging, denning, territory, etc.)
- Growth (storing energy for later)
- Reproduction (and associated activities like mating, courtship, protection, lactation, etc.)
Energy, with respect to an individual’s energy budget, is needed to ‘run the machinery’ and to ‘create the environment’…. What does this mean?
Many internal process in an organism require a specific temperature range in order to function properly, including digestion, respiration, and chemical processes. These processes are the “machinery”. Since the machinery only runs in this specific temperature range, that means that the animal must also “create the environment” in which the “machinery” will operate. With respect to the energy budget, an animal must balance their inputs and outputs to ensure the above conditions are met.
Explain the order in which energy is allocated to the primary needs
- Energy is first used for warmth and maintenance of internal processes.
- If leftovers, goes into Activities like walking, foraging, denning, territory
- Any surplus is stored (growing bigger)
- If there is remaining surplus energy, it can be used for reproduction, which is highly energy demanding
Why do wildlife managers need to know the concept of an individual’s energy budget?
An individual’s energy budget is a BALANCE of the inputs and outputs in their energy system. Wildlife managers need to understand the individual’s energy budget, because these INPUTS AND OUTPUTS are the variables that can be MANIPULATED in order to help the species survive or to reproduce. Any decisions made in the context of wildlife management should account for the NET change to the individual’s energy budget.
What are the 4 modes of heat loss?
Radiation
Convection
Conduction
Evaporation
How is energy gained from the environment by individuals?
- From the environment through radiation (Solar radiation, infrared radiation from the ground or from the veg/environment)
- From food - metabolic processes convert the chemical energy of food into heat
How is heat transferred by radiation?
- Heat transfer resulting from ELECTROMAGNETIC waves entering or leaving an object
- Warm objects radiate heat to cooler objects
- Absorption depends on the properties of the receiving surface
- Thus, radiant heat exchange depends on temperature differential, absorptivity characteristics, surface area, and environmental conditions (weather, TOD, TOY)
What factors influence the rate of energy loss through radiation? (4 factors)
- Temperature Differential - bigger difference equals more exchange
- Absorptivity - color, molt or pelage change
- Surface area - more surface area = more loss or gain
- Environment - more radiation during the day, some absorbed, some bounced back.
How can an individual influence the heat gain/lost by radiation? (3 ways)
- Changing which parts of the body are exposed via posture (surface and absorption)
- Varying when they are active (environment)
- Varying where they are active (Vegetation reduces radiation coming in during the day (shade) & reduces radiation leaving the system at night)
In an effort to increase/decrease energy change from radiation, when and where should deer forage:
a. In cold winters?
b. In warm summers?
In cold winters, deer should forage during the day in clear areas, to maximize incoming radiation.
In hot summers, deer should forage at night (also in clear areas) to maximize outgoing radiation
How is energy gained/lost through convection?
- Is heat transfer due to mass movement of heated molecules in a fluid (air or water)
- Air next to the body is heated, moves away, and is replaced by cooler air
What influences the rate of energy lost through convection? Explain?
- Temperature differential
- Surface area can be modified via behaviour (posture & orientation to wind and sun)
How does energy lost through convection vary with body size? Why?
Losses due to convection are greater for smaller bodies than larger bodies.
This is because the smaller the body of the animal is, the larger its surface area is in relation to its volume. This means that PROPORTIONALLY, more of the animal is EXPOSED to the effects of convection
How does subnivean spaces influence energy lost through convection
Subnivean species (like northern small mammals) spend lots of time under the snow to minimize convection energy loss. Under the snow, there is no wind, and thus less energy loss due to convection
How is heat lost through conduction and what influences the rate of this heat lost?
- Conduction is the exchange of energy by direct MOLECULAR CONTACT
- Conduction refers to the transfer of heat through direct contact of two objects with different temperatures. Heat will go from the highest concentration to a lower concentration.
Influenced by whether the objects are insulators or conductors. Insulators prevent conduction, conductors facilitate it. Also, contact must be firm and devoid of air and water
