BSU IN AFS meeting Tue Aug 23TONIGHT! 5:00 pm CL 167 Electrofishing demonstration.
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Transcript of BSU IN AFS meeting Tue Aug 23TONIGHT! 5:00 pm CL 167 Electrofishing demonstration.
Chapter 5 Temperature relations
Probably the most limiting factor in organism’s distributions
Active animal life limited between ~ 0˚ C and 50˚ C
Dilemma of life
• Organisms need energy + nutrients
• Enzymes function under narrow ranges of T
• Internal environment differs from external = gradient
• = dilemma
T varies in time + space
• Temporal (daily, seasonal, multi-year, long-term changes)
• Spatial (latitude, elevation, aspect, microclimate)
T varies in time + space
• Temporal (daily, seasonal, multi-year, long-term changes)
• Spatial (latitude, elevation, aspect, microclimate)
• Less variable in aquatic habitats
Dealing With It: ADAPTATION
• Optimum conditions for physiological activity match the prevailing environmental conditions
• Downside: Species can only survive in specific environments
<<<<<<<<<< Range of Tolerance >>>>>>>>>>
Optimum
Range of Limitation ProteinDenaturation
Temperature
O2
Upt
ake
Met
abo
l ic R
ate
CO
2 U
ptak
eH
eart
Ra t
e
Temperature Response Curve
Adaptations to deal with extreme T
• Mechanisms to regulate body T– Control radiative heat gain/loss– Control convective heat gain/loss– Evaporative heat dissipation– Metabolic heat gain– Control T of critical tissues only
Adaptations to deal with extreme T
• Mechanisms to avoid extreme T– Seasonal migration– Daily/hourly movements– Physiological dormancy
Definitions:
• Acclimation = short-term change in morphology or physiology
• Adaptation = evolutionary change in morphology or physiology
Acclimation example:
• Desert shrubs– A. glabriuscula saltbrush from cool coastal CA– T. oblongifolia from Death Valley
Acclimation T
Le
tha
l T
10 40
10
40
Solid line = range of thermal toleranceDash = acclimation T
E.g., fish kept at 30 C has upper lethal limit of 38 C and lower lethal limit of 9 C
Trade-offs for T regulationTrade-offs for T regulation
• Poikilotherms: Poikilotherms: – Inactive when T is not optimumInactive when T is not optimum
• Result:Result:– Low energy needs for homeostasisLow energy needs for homeostasis
Poikilotherms can regulate T Poikilotherms can regulate T with behavior (ectothermic)with behavior (ectothermic)
• In deserts, shade under shrub can be 25˚CIn deserts, shade under shrub can be 25˚C
• Ground exposed to sun can be > 60˚ CGround exposed to sun can be > 60˚ C
• Desert iguana maintains body T 39 - 43˚C by Desert iguana maintains body T 39 - 43˚C by changing microhabitatschanging microhabitats
Trade-offs for T regulation• Homeotherms:
– Metabolic rate to heat– Evaporative water to cool
• Result:– Loss of resources for repro, growth, etc.
Cost-Benefit ofMetabolic Thermo-Regulation• Benefit: Species can be active in cold
environments (increases opportunity to acquire resources)
• Cost: Energy expended to generate heat is not available for growth or reproduction
• Most advantageous in environments where energy (food) is abundant
Minimizing Cost ofMetabolic Thermo-Regulation
• Increase RESISTANCE to heat loss / gain b/t body and environment.
– Fur, Feathers, Fat Layer (Insulation)– Low body surface-to-volume ratio
• Large body size• Shorter / Fewer appendages and
elongation