Topic 8 Flashcards
To maximize fitness..
an individuals response to these changes must be shorter than a period of change
Responses to environmental change fall into 3 categories
- developmental
- acclimatory
- regulatory
Development response
individuals alters its development to produce a phenotype most suitable to persistent slow change in environmental conditions
European freshwater striders developmental response to environment
eggs hatch, adult lifespan is short, and have 2 morphs long winged and short winged.
Long winged european striders
can fly, move if pond dries up. more energy into survival than reproduction
Short winged european striders
cannot fly, or move if pond dries up. more energy into reproduction than survival
Acclimatory response
changes in response to seasonal variations. (ex: thickening of fur)
acclimatory = habituation of..
an organisms physiological response to environmental conditions
Acclimation
applied to laboratory
Acclimatization
applies to nature. tolerances are not fixed but are preconditioned by recent experience w environmental conditions
Insect in acclimatory response
freeze avoidance strategy. as temp drops they convert glycogen reserves to alcohol which depress the freezing point of the body = freeze avoidance
Freeze tolerance
wood frog. similar to frost hardening in plants. expels fluid interior of cells and controls the ice nucleation process in ICP. (survive up to -50c)
Desiccation tolerance
tardigrades or water bears. allow their tissues to dry up when no available water. revitalized when water is available. but not permanent solution
Regulatory response
rapid changes in behaviour or rates of physiological processes (shivering)
Conformers
allow internal conditions to follow external changes
Regulators
maintain constant internal conditions
Homeostasis
Organisms must maintain an equilibrium between their internal and external environments (negative feedback system)
Negative feedback system
- mechanism that senses internal conditions
- means of comparing the actual with the desired internal conditions
- apparatus that alters internal condition in preferred direction
Poikilothermy (conforming)
cannot maintain constant body temp (varies). amphibians, fish, insects, aquatic organisms. active in narrow range of temp
Homeothermy (regulating)
maintain constant body temp. birds and animals (36-41 C) where biochemical processes in cell are efficient. active under varying temp
Ectotherms
regulate body temp by gaining heat from external sources (poikilotherm)
Advantage and disadvantage of ectotherms
A: energy expenditure can be low
D: growth, reproduction and survival is limited by temp fluctuations
Endotherms
regulate body temp by production of heat (metabolism) homeotherm
Advantage and disadvantage of endotherms
A: growth, reproduction and survival is not affected by temp
D: energy expenditure must be high to maintain metabolic heat production
Heterothermy
both ecto and endothermy , change daily or by seasonal cycle or life stage. most flying insects. high metabolic rates are supported.flight muscles must be between 30-44 C to fly
Many flying insects pump abdomens or shiver wings to generate heat means
ENDO thermic not heterothermy
Limitations of ectotherms
ectotherms generate heat when active.
Every aspect of ecology and behaviour is influenced by..
need to regulate body temp
Limitations of endotherms
endotherm’s ability to maintain constant body temperature is limited under low temperatures
Limitations of endotherms short term
by physiological capacity to generate heat
Limitations of endotherms long term
by ability to gather food (or energy) to satisfy requirements for
metabolic heat production
Animals usually starve to death before they de of
direct causes of cold temps
Reduce energetic costs by ..
altering the loss/gain of heat from environment in a number of ways
1 energy conservation of endotherms
lower regulated temp of portion of body (ex bird feet and legs: counter current heat exchange. heat is minimized by reducing temp gradient between leg and environment)
2 energy conservation of endotherms
Lower the regulated temperature at certain times of the day
Torpor
temp reduction in metabolic activity and lowered body temp
Hibernation
extended reduction of metabolic activity and low body temp
Example of lower the regulated temperature at certain times of the day
hummingbirds, inactive at low temps, 50% less energy consumed, reduces heat loss to environment
3 energy conservation of endotherms
become larger.the importance of body size in energy conservation lies in the surface area to volume ratio
Allometry
surface area to volume ratio
Allometric relationship
a relative increase in a physical or physiological property of an organism in relation to its body size
As body size increases..
volume increases faster than SA
As body size changes..
SA/V ratio changes
As SA/V ratio changes..
heat loss to environmental changes
The larger the volume the great the..
total amount of heat required to keep warm but less heat is lost through outer surface of organism
Small organisms allometry
high SA/V. require less heat but hard to keep warm
Large organisms
low SA/V. require more heat but retained easier
Bermanns rule
A broadly distributed group of species tend to be larger in size in colder environments and smaller in warmer environment (white tailed deer)
