Physiological Ecology How animals cope with environmental change, and what it means to their distribution and abundance in nature Steve McCormick USGS,

Physiological Ecology

How animals cope with environmental change,

and what it means to their distribution and abundance in nature

Steve McCormickUSGS, Conte Anadromous Fish Research CenterandDept. of Biology, Dept. of Environmental Conservation, UMASS

What environmental factors are important to animals?

?

Abiotic Biotic

FoodPredatorsDisease Conspecifics

How do animals respond to environmental change?

Overall strategies for coping: conform or regulate

Homeostasis: maintaining a constant internal state in the face of environmental change.

How do animals respond to environmental change?

Overall strategies for coping: conform or regulate

Example: Changes in external salinity.

External osmotic pressure (mOsm)External osmotic pressure (mOsm)

Sharks Teleost fish

How do animals respond to environmental change?Overall strategies for coping: conform or regulate

No internal heat generation.

Internal heat generation.

Constant body temperature.

Variable body temperature.

How do animals respond to temperature change?Make Believe 101:

You’re a fish. How do you respond to increased temperature?

Hint: oxygen uptake increases.

Fast

Slow

Physiological Adaptations to TemperatureProduction of enzyme isoforms with different temperature optima.

Trout acclimated to cold water make a different acetylcholinesterase than trout acclimated to warm water.

Abundance of many enzymes will also change.

Physiological Adaptations to TemperatureHomeoviscous adaptation

Maintaining a constant membrane fluidity (“liquid crystal state”) is essential to normal function of cells.

Temperature strongly influences the fluidity of membranes.

Animals increase the ratio of saturated:unfaturated fatty acids in cell membranes in response to increased temperature increase in order to maintain membrane fluidity.

Physiological Response

HYPO-THALAMUS

ENDOCRINEGLAND

TargetTissue

HORMONE (IN BLOOD)

Environmental changeHomeostatic disturbance

RELEASINGHORMONE

[HORMONE BINDING PROTEIN]

HORMONERECEPTOR

NEGATIVE FEEDBACK

TargetTissue

Hormones and Acclimation

Provides sensing of enviornment or internal disturbancehighly specific signallingcoordination among tissuesfeedback system

Temperature and Acclimation Effects on Performance

What are the possible outcomes of acclimation? How would the shape of this curve change after acclimation to high temperature?

What are some examples of organismal performance?

How do animals respond to environmental change?

Acclimation (often) results in a greater capacity near the acclimation temperature. - but there are usually trade-offs Survival has the widest capacities. Activity, growth, and reproduction are usually more constrained.

No universal pattern of life history sensitivity to temperature.

(Fry and Hochachka, 1970)

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Tolerance of temperature change varies among species

Differences in tolerance polygons reflect diversity in thermal capacities

Antarctic RockPerch (5)

Salmon (4)

Goldfish (1)

Most animals have thermal preferences

For example, most fish will precisely select position in a thermal gradient

The “fundamental niche” (determined by physiological ability) may be different from the “realized niche” (what occurs in nature). The latter may be driven by behavior and ecological constraints such as presence of predators and prey.

Metabolism = Energy Utilization

I = E + M + GI = ingested energyE = excreted energyM = metabolic

energyG = growth

Ms = standard metabolism

Mf = feeding metabolism

Ma = active metabolism

Fate of a 100 calorie in fish

I = E + M + G

There is an energetic cost to food processing and growth

Specific dynamic action (SDA) is a postprandial (after feeding) elevation in metabolic rate

Factors Influencing Metabolic Rate

Metabolic rate increases with size…

but weight specific metabolic rate decreases with size. - among and within species.

There is a substantial cost to the endothermic strategy.

MO2 = rate of O2 consumptionQ = cardiac outputCaO2 = arterial oxygen contentCvO2 = venous oxygen contentfH = heart rateVs = stroke volume

Class exercise

Can animals adapt (evolve) in response to climate change? What are the physiological mechanism involved? How will their capacity to adapt affect their geographic distribution?

Pick one example of climate change impacts, such as temperature, rainfall, sea level, ocean acidification, etc. You can choose one or several papers to bolster your arguments, but an exhaustive literature review is not necessary.