Ecology Lecture 5-

What is Physiological ecology?

The study of interactions between organisms and their physical environment, and how these interactions influence their survival and determine their geographic range.

How does the physical environment influence an organism’s ecological success?

• availability of energy and resources

• extreme conditions can exceed tolerance limits

what are psychological ecologists trying to understand?

The impact that the physical environment has on defining the geographic distribution of a species

What factors determine aspen distribution, and how is it predicted?

Aspen distribution is limited by low temperatures and drought. A computational approach called environmental niche modeling predicts a potential distribution that is larger than the actual distribution 🌲🌍

What is the difference between potential and actual species distribution?

• Potential distribution: where climate and resources are suitable

• Actual distribution: reduced by biological factors (competition, herbivory, etc.)

• Population abundance is highest where conditions are most favorable 📈

What is a tolerance curve and what does it represent?

A tolerance curve shows how an individual’s physiological rate (e.g., metabolism, photosynthesis) responds to an abiotic factor. It has an optimum, where performance is highest ⚡🌡

Why are tolerance curves important for population persistence?

At the optimal conditions, individuals can survive, grow, and reproduce. For populations to persist, many individuals must experience conditions near this optimum 👥🌱

What is physiological stress?

Stress occurs when environmental conditions deviate from the optimum, causing a decrease in the rate of physiological processes and lowering the potential for survival, growth, or reproduction.

What is acclimatization?

Acclimatization is a short-term, individual-level physiological adjustment that minimizes stress caused by environmental change. It can result in temporary, unregulated changes in homeostasis.

What is hypoxia and how does it affect the body at high altitudes?

Hypoxia occurs at high elevations (typically above 8,000 feet) due to lower partial pressure of oxygen, reducing oxygen delivery to tissues. This can cause altitude sickness, decreased exercise capacity, and impaired cognitive function.

How does the body acclimatize to high elevations?

Acclimatization includes increased breathing rate, increased production of red blood cells and hemoglobin, and increased pulmonary blood pressure to improve oxygen delivery. These changes are reversible when returning to lower elevations.

What is adaptation and how does it occur?

Adaptation is a long-term, genetic response of a population to environmental stress. Natural selection favors individuals with traits that reduce stress, causing those traits to become more common over generations.

What is an example of adaptation to low oxygen conditions?

Andean populations, living at high elevations for ~10,000 years, show adaptations such as higher red blood cell production and greater lung capacity, improving oxygen delivery compared to non-native populations.

How is adaptation different from acclimatization?

• Adaptation: long-term, genetic, population-level change

• Acclimatization: short-term, physiological, individual-level response
  Both reduce stress, but only adaptation increases genetic fitness across generations.

What are ecotypes and how can they lead to speciation?

Ecotypes are populations adapted to specific abiotic or biotic environments. Over time, divergence in physiology and morphology can lead to reproductive isolation and the formation of new species.