2.4 Ecological Tolerance

Summary

Ecological tolerance refers to the range of environmental conditions in which an organism can survive, such as temperature, salinity, and sunlight. The script explains that organisms thrive within an optimal range, depicted as the peak of a bell curve, where most survive. As conditions move toward extremes, fewer organisms can endure, leading to zones of physiological stress and, ultimately, death. The tolerance range varies by species and can change over time, as seen with salmon, which adapt to both freshwater and seawater throughout their life cycle.

Takeaways

• 🌱 Ecological tolerance refers to the range of conditions that an organism can survive in.
• 🌡️ Going beyond an organism's tolerance range leads to stress, and eventually, death.
• 💧 Ecological tolerance includes factors like temperature, salinity, flow rate, and sunlight.
• 🌍 Tolerance can apply to both individual organisms and species as a whole.
• 📈 A bell curve represents the number of organisms that can survive under varying conditions, with most thriving in the optimal range.
• ⚠️ As conditions approach extremes, organisms experience physiological stress, leading to a decline in survival.
• 🚫 At the extremes of the tolerance range, no organisms survive, marking the zone of intolerance.
• 💡 The optimal range, where most organisms thrive, is referred to as the preferred niche.
• 🐻 Different organisms have different tolerance ranges, such as bears thriving in cold temperatures.
• 🐟 Tolerance ranges can change over an organism’s lifetime, as seen with salmon that shift from freshwater to saltwater environments.

Q & A

What is ecological tolerance?

Ecological tolerance refers to the range of environmental conditions that an organism can endure without experiencing injury or death.

What happens when an organism goes outside of its ecological tolerance range?

If an organism goes outside its tolerance range, it can experience injury, and prolonged exposure can lead to death.

What are some examples of environmental factors that affect ecological tolerance?

Examples include temperature, salinity, flow rate, and the amount of sunlight.

Can ecological tolerance be applied to both individual organisms and species?

Yes, ecological tolerance can be applied to both individuals and entire species.

What is the 'optimum range' in ecological tolerance?

The optimum range is the range of conditions where most organisms within a species thrive, represented by the top of the bell curve in a graph.

What is the 'zone of physiological stress' in ecological tolerance?

The zone of physiological stress is where organisms begin to struggle due to environmental conditions approaching the extremes, leading to a decrease in survival rates.

What is the 'zone of intolerance' in ecological tolerance?

The zone of intolerance is the point beyond which no organisms can survive due to extreme environmental conditions.

How does ecological tolerance vary between species?

Different species have different ranges of tolerance based on environmental factors. For example, bears have an optimal range in colder temperatures, whereas giraffes are adapted to warmer conditions.

Can an organism's tolerance range change over its lifetime?

Yes, some organisms, like salmon, exhibit varying tolerance ranges throughout their lifetime, as they shift between freshwater and saltwater environments.

How does the graph discussed in the transcript represent ecological tolerance?

The graph represents the number of organisms surviving under different environmental conditions, with a bell curve showing the optimum range, zones of physiological stress, and zones of intolerance.