10 percent rule ecology

Summary

In this video, the presenter explains key concepts related to food webs and energy transfer. They discuss how energy moves through different trophic levels and introduce the '10% rule,' which highlights the energy loss as you move up the food chain. The presenter also addresses competition within food webs, pointing out how animals, like hawks and snakes, may compete for resources such as rabbits. By using V-shaped diagrams, they illustrate the competition between species. Additionally, they examine how energy decreases at each level, using specific examples like grass, rabbits, and hawks.

Takeaways

• 🌿 A food web illustrates how energy is transferred from one organism to another in an ecosystem.
• 🦅 Competition in a food web can be identified by looking for a 'V' shape, which represents multiple predators targeting the same prey.
• 🐍 The hawk and the snake compete for the rabbit as a food source, forming a 'V' pattern of competition.
• 🐇 The rabbit and the mouse also face competition from predators like snakes and hawks.
• ⚡ The 10% rule states that only 10% of the energy from one trophic level is transferred to the next.
• 🌾 Producers such as wildflowers and grass are at the base of the food web, providing 100,000 kilocalories of energy.
• 🔢 Moving from grass to rabbit (one trophic level) transfers 10% of the energy, resulting in 10,000 kilocalories.
• 🦅 Moving from rabbit to hawk (another trophic level) transfers another 10%, leaving 1,000 kilocalories available for the hawk.
• 🔥 A large amount of energy is lost as heat during energy transfer between trophic levels.
• 🐟 In another example, multiple organisms such as small fish, newts, and diving beetles compete for water fleas, again forming a 'V' pattern of competition.

Q & A

What is the main concept behind a food web?

A food web shows how energy is transferred from one individual to another in an ecosystem. It illustrates the feeding relationships between different organisms, from producers to consumers.

How does competition manifest in a food web?

Competition in a food web can be identified by looking for a 'V' shape. This indicates that two or more species are competing for the same resource. For example, the hawk and the snake are competing for the rabbit.

What does the 'V for victory' concept refer to?

'V for victory' is a visual aid used to spot competition in food webs. When you see a 'V' shape, it indicates that the species at the points of the 'V' are competing for a common resource.

How does the 10% energy rule apply to food webs?

The 10% rule in food webs states that only 10% of the energy at one trophic level is transferred to the next level. For example, if producers (wildflowers and grass) have 100,000 kilocalories of energy, only 10,000 kilocalories are transferred to the rabbit, and only 1,000 kilocalories are transferred to the hawk.

What is the significance of trophic levels in energy transfer?

Trophic levels represent the different stages in a food chain. As you move from one level to the next, only 10% of the energy from the previous level is transferred, with the rest lost, primarily as heat.

What does a trophic level represent in an ecosystem?

A trophic level represents an organism's position in the food chain. Producers like plants are at the first level, herbivores are at the second level, and carnivores are at higher levels.

How do you calculate energy transfer across trophic levels?

To calculate energy transfer, multiply the energy available at one trophic level by 10% for each subsequent level. For example, starting with 100,000 kilocalories, the energy transferred to the rabbit is 10,000 kilocalories, and the energy transferred to the hawk is 1,000 kilocalories.

In the competition problem with the water fleas, which animals are competing?

The animals competing for the water fleas are the small fish, newt, and diving beetle. This forms a competition triangle, with all three species vying for the same resource.

What is the role of producers like wildflowers and grass in a food web?

Producers like wildflowers and grass form the base of a food web. They capture solar energy and convert it into chemical energy, which is then transferred up the food chain to herbivores and carnivores.

Why is energy loss an important concept in food webs?

Energy loss is crucial to understanding food webs because it explains why higher trophic levels contain fewer individuals. Only 10% of the energy moves up the food chain, so less energy is available for organisms at higher levels, resulting in smaller populations.