Physiological Ecology Flashcards
All individuals must ‘solve’ some basic problems:
- Acquire energy, nutrients, or resources necessary to grow and develop
- Must survive to reproductive age
- Acquire energy, resources, or mates necessary to reproduce and rear offspring
Solutions are difficult because of:
- Large number of environment factors affecting survivorship, growth, and reproduction
- Enormous variation in these factors in time and space
One approach to explaining the distribution and abundance of organisms is to understand:
How individuals cope with environmental factors.
- How are organisms physiologically adapted to their environments?
- What happens when an organism’s environment changes?
Physiological Ecology
Study of the biophysical, biochemical, and physiological processes used by plants and animals to cope with factors of their physical environment, or employed during ecological interactions with other organisms.
Two Types of Abiotic Factors:
- Resource: abiotic factor that is consumed by an organism or made less available to others (food, water, space, etc)
- condition: abiotic factor that varies in time and space and to which organisms respond differently (temperature, salinity, humidity, etc)
Poikilotherms:
Body temperature fluctuates with ambient temperature of environment
Homeotherms:
Maintain relatively constant body temperature despite changes in environmental temperature
Heterotherms:
poikilotherm + homeotherm
Ectotherms:
Regulate body temperature by selecting appropriate thermal environmentals
Endotherms:
Regulate body temperature by using internal metabolic processes
(many endothermic animals also select appropriate thermal environments to aid in regulation of body temp)
Torpor:
Animals that normally maintain a high body temperature that permit it to drop under certain conditions
How do we measure a Thermal Performance Curve?
Performance: correlates to fitness
Limits:
- Dynamic: using CTmax and CTmin (critical temp)
- Static: using upper and lower LT50 (lethal temp, 50 = 50% of organisms that die at that temp)
Why do we see thermal performance curves?
- Lower critical thermal limits mean that at some point an organism will freeze to death, but some can recover!
- Cellular fluids freeze and cells burst
Earlier: - slowed muscle contractions
- slowed ATP production
- decline in nervous function
- High temperatures = reduction in metabolic efficiency
Lower performance due to: - O2 limitation and fermentative metabolism: O2 supply = maximized, fermentation ATP production doesn’t require O2 but is less efficient
- Cellular stress: heat shock, heat shock proteins
Ecological Implications of the thermal performance curve
Very narrow range of temperatures over which species perform optimally
- Distribution Limits
- Implications of Climate Change
- Performance curves and distribution limits can change
Temperature can affect an organism in a number of different ways:
- How fast they grow
- How many offspring they can have
- How fast they run/swim/fly
- How weel they avoid predators
Distribution Limits
Where an organism is found spatially and temporally either on a small scale or wide geographic scale
- Intertidal zones offer the perfect place to study distribution limits bc we see a wide range of environment conditions over a small region
Implications of Climate Change
Important for predicting how an organism will respond to climate change
Organisms will a larger range of tolerance can withstand change better vs tropical organisms who have a narrow tolerance range and cannot withstand change as well
Many changes have been observed:
- Poleward or altitudinal shifts in geographical distribution
- Population collapse, local extinctions
- Failure of large scale migrations
- Changes in timing of biological events
- Change in food availability and food web structure
Performance curves and distribution limits can change
Acclimation: changes in physiology or morphology resulting from exposure to environmental stress
- shift term shift
- usually reversible
- similar to acquired characteristics, but temporary
Adaption: genetically-based changes in physiology or morphology via natural selection
- permanent shift
Acclimation
Physiological NOT genetic changes in response to temperature, is generally reversible with changes in the environmental conditions
What limits might be put on the ability of an organism to acclimatize to climate change?
If a species is already close to the upper critical limit of their temperature range
- Species that evolved to the greatest tolerance to high temperatures tend to be less able to acclimate to high temperatures, putting species located in regions of high temperatures (tropics) at particular risk
Adaption
Evolutionary differences in performance
- Different adaptions to local climate
Limits to adaptive responses
Physiological limits:
- laws of chemistry and physics set ultimate limits
Homeostasis has energetic costs:
- no organism has unlimited time, energy, or other resources
- Extra resources can be allocated to one function only by reducing allocation to others
