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Physiological Ecology

How animals cope with environmental change, and what it means to their distribution and abundance in nature. Physiological Ecology. Steve McCormick USGS, Conte Anadromous Fish Research Center and Dept. of Biology, Dept. of Environmental Conservation, UMASS. Abiotic. Biotic. ?. Food

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Physiological Ecology

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  1. How animals cope with environmental change, and what it means to their distribution and abundance in nature Physiological Ecology Steve McCormick USGS, Conte Anadromous Fish Research Center and Dept. of Biology, Dept. of Environmental Conservation, UMASS

  2. Abiotic Biotic ? Food Predators Disease Conspecifics What environmental factors are important to animals?

  3. Overall strategies for coping: conform or regulate How do animals respond to environmental change? Homeostasis: maintaining a constant internal state in the face of environmental change.

  4. Overall strategies for coping: conform or regulate Sharks Teleost fish How do animals respond to environmental change? External osmotic pressure (mOsm) External osmotic pressure (mOsm) Example: Changes in external salinity.

  5. Overall strategies for coping: conform or regulate Internal heat generation. How do animals respond to environmental change? Variable body temperature. Constant body temperature. No internal heat generation.

  6. Make Believe 101: You’re a fish. How do you respond to increased temperature? Hint: oxygen uptake increases. Fast Slow How do animals respond to temperature change?

  7. Production of enzyme isoforms with different temperature optima. • Trout acclimated to cold water make a different acetylcholinesterasethan trout acclimated to warm water. Physiological Adaptations to Temperature • Abundance of many enzymes will also change.

  8. Homeoviscous 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 Adaptations to Temperature

  9. Environmental change Homeostatic disturbance Target Tissue HYPO- THALAMUS Target Tissue ENDOCRINE GLAND Physiological Response RELEASING HORMONE HORMONE RECEPTOR NEGATIVE FEEDBACK HORMONE (IN BLOOD) [HORMONE BINDING PROTEIN] • Hormones and Acclimation • Provides sensing of enviornment or internal disturbance • highly specific signalling • coordination among tissues • feedback system

  10. Temperature and Acclimation Effects on Performance What are some examples of organismal performance? What are the possible outcomes of acclimation? How would the shape of this curve change after acclimation to high temperature?

  11. 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. How do animals respond to environmental change? (Fry and Hochachka, 1970)

  12. Tolerance of temperature change varies among species Differences in tolerance polygons reflect diversity in thermal capacities Goldfish (1) Salmon (4) Antarctic Rock Perch (5)

  13. 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.

  14. Metabolism = Energy Utilization I = E + M + G I = ingested energy E = excreted energy M = metabolic energy G = growth Ms = standard metabolism Mf = feeding metabolism Ma = active metabolism

  15. Fate of a 100 calorie in fish I = E + M + G

  16. There is an energetic cost to food processing and growth Specific dynamic action (SDA) is a postprandial (after feeding) elevation in metabolic rate

  17. Factors Influencing Metabolic Rate There is a substantial cost to the endothermic strategy. Metabolic rate increases with size… but weight specific metabolic rate decreases with size. - among and within species.

  18. MO2 = rate of O2 consumption Q = cardiac output CaO2 = arterial oxygen content CvO2 = venous oxygen content fH = heart rate Vs = stroke volume

  19. 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.   

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