Tolerance - SS2 Biology Lesson Note

Biological tolerance refers to an organism's ability to endure or withstand certain environmental conditions or stress factors without experiencing significant harm or adverse effects. Each species has a specific range of tolerance for various environmental factors, such as temperature, humidity, pH, salinity, and pollution levels. These tolerances can vary widely among different organisms and are often key determinants of their distribution and abundance.

 

The concept of tolerance is closely related to an organism's physiological and ecological adaptations. Organisms that are well adapted to specific environmental conditions typically have a higher tolerance for those conditions, while others may be more sensitive or intolerant.

 

Here are a few examples of biological tolerance:

1.       Temperature Tolerance: Organisms have a range of temperatures within which they can function optimally. Some species, known as thermophilic organisms, thrive in high-temperature environments like hot springs, while others, called cryophilic organisms, are adapted to extremely cold habitats like polar regions. Temperature tolerance also influences the distribution of species across latitudes and altitudes.

2.       Salinity Tolerance: Marine organisms have varying degrees of tolerance to salinity levels. Euryhaline species can tolerate a wide range of salinity, allowing them to inhabit both marine and freshwater environments. In contrast, stenohaline species have a narrow tolerance range and are restricted to either marine or freshwater habitats.

3.       pH Tolerance: Different organisms have different pH tolerances. Some species, such as acidophilic bacteria, can survive and even thrive in highly acidic environments, while others, like alkaliphilic organisms, can tolerate high alkalinity. pH tolerance is important for organisms living in habitats with extreme acidity or alkalinity, such as acidic mine drainage or alkaline lakes.

4.       Pollution Tolerance: Some organisms exhibit a higher tolerance for pollution or toxic substances than others. Certain bacteria and fungi, for example, are capable of breaking down and metabolizing pollutants, making them tolerant to contaminated environments. On the other hand, pollution-sensitive species may experience adverse effects or population declines in polluted areas.

 

Understanding the tolerance ranges of organisms is crucial in ecological studies, environmental monitoring, and conservation efforts. Changes in environmental conditions, such as climate change or pollution, can influence the distribution and abundance of species by exceeding their tolerance limits. Assessing tolerance levels helps identify vulnerable species, predict ecosystem responses to environmental changes, and inform management strategies to mitigate impacts and protect biodiversity.