Ecological Tolerance

Summary

In this video, Mr. Bernard explains ecological tolerance, focusing on the range of abiotic factors species can survive in. He uses a bell curve to illustrate optimal survival zones, zones of stress, and zones of intolerance. He contrasts specialists, with narrow tolerance ranges, to generalists, which adapt to broader conditions. Examples include polar bears and grizzly bears, which diverged evolutionarily but may converge due to changing environments, and koala bears, which are highly specialized to eat eucalyptus leaves. The video highlights how species adapt differently to environmental changes.

Takeaways

• 📊 Ecological tolerance refers to the range of abiotic (non-living) factors under which a species can survive.
• 🌡️ Abiotic factors like moisture, light, pH, salinity, temperature, and soil type influence the survival of species.
• 🔔 Survival can be graphed on a bell curve, with optimal survival in the middle and zones of stress or intolerance at the edges.
• 📉 Species with narrow ranges of tolerance are called specialists, while those with wide ranges are generalists.
• 🐻 Polar bears are specialists, relying on sea ice to hunt seals, but they are being forced to adapt as sea ice melts.
• 🐻‍❄️ Grizzly bears, including the Kodiak bear, are generalists and omnivores, feeding on a variety of food like salmon, berries, and grasses.
• 🔄 Polar bears and grizzly bears are evolutionarily similar, and as polar bears move into grizzly habitats, their interactions may evolve.
• 🐨 The koala is a specialist that eats only eucalyptus leaves, which are toxic to most animals, making them highly dependent on this food source.
• 🌿 Specialists like the koala face greater challenges as environmental conditions change, threatening their narrow food sources.
• ⚖️ Generalists are more adaptable to changing conditions, while specialists are more vulnerable due to their narrow ecological tolerance.

Q & A

What is ecological tolerance?

Ecological tolerance refers to the range of abiotic factors under which a species can survive. Abiotic factors are non-living environmental components such as moisture, light, pH, salinity, temperature, and soil type.

How is ecological tolerance represented on a graph?

Ecological tolerance is graphed with the survival rate on the vertical (y) axis and abiotic factors on the horizontal (x) axis. The graph typically forms a bell curve, where the middle represents the optimal tolerance zone, and the edges indicate zones of stress and intolerance.

What are the different zones in ecological tolerance?

In ecological tolerance, the middle of the bell curve is the optimal tolerance zone, where species have good survival rates. Further out are zones of stress, where survival is more difficult, and at the extreme edges are zones of intolerance, where species cannot survive.

What is the difference between a specialist and a generalist species?

A specialist species has a narrow range of tolerance and is highly adapted to specific environmental conditions. A generalist species has a wide range of tolerance and is more adaptable to a variety of environmental conditions.

Can you give an example of a specialist species?

The koala bear is an example of a specialist species. It feeds only on eucalyptus leaves, which are toxic to most other species, and has developed a specialized digestive system to handle them.

What are some examples of abiotic factors mentioned in the lesson?

The abiotic factors mentioned include moisture, light, pH, salinity, temperature, and soil type.

What might happen to polar bears as their habitat changes due to melting sea ice?

As sea ice melts, polar bears may need to adapt by searching for new food sources. Since they are evolutionarily close to brown bears, they might move into areas where grizzly bears live and compete for food.

How are polar bears and grizzly bears similar?

Polar bears and grizzly bears are evolutionarily similar, with polar bears being more specialized for hunting seals on sea ice, while grizzly bears are more generalist, feeding on fish, berries, and grasses.

What is the impact of being a generalist species?

Generalist species, like grizzly bears, are more adaptable to changes in their environment due to their wide range of tolerance for different abiotic factors. This makes it easier for them to find food and survive in changing conditions.

What are the consequences of being a specialist species?

Specialist species, like the koala, are more vulnerable to environmental changes because they rely on a narrow range of conditions. If those conditions change, it may be difficult for them to survive.