1. 5.1 Habitats and Niches 1. Describe the concept of the niche. 2. Examine how interactions between a species and its environment define the species’ niche 3. Infer how removal of an organism at one trophic level can affect another organism in the ecosystem.

2. 5.1 Habitats and Niches Ecosystems can be large places. The environment in one part of an ecosystem is different from the environment in another part. For example, the conditions near a stream may be very different from those on a dry hill above the stream.Ecosystems can be large places. The environment in one part of an ecosystem is different from the environment in another part. For example, the conditions near a stream may be very different from those on a dry hill above the stream. The organisms living in each part of this ecosystem differ from each other.The organisms living in each part of this ecosystem differ from each other.

3. Niches Every organism is adapted to live in its habitat. For example, each organism has special ways of gathering food, reproducing, and avoiding predators. The actions of an organism define its role in the ecosystem.Every organism is adapted to live in its habitat. For example, each organism has special ways of gathering food, reproducing, and avoiding predators. The actions of an organism define its role in the ecosystem. The role of an organism in the ecosystem in called its niche. A niche is more than an organism’s habitat; it is also what the organism does within its habitat.The role of an organism in the ecosystem in called its niche. A niche is more than an organism’s habitat; it is also what the organism does within its habitat.

4. Niches A niche includes both biotic and abiotic factors. Some biotic factors that help define a niche are food sources and predators. Abiotic factors include temperature, amount of sunlight and water.A niche includes both biotic and abiotic factors. Some biotic factors that help define a niche are food sources and predators. Abiotic factors include temperature, amount of sunlight and water. All members of a species are adapted to the same niche. No two species can share the same niche in the same habitat or they will compete for resources.All members of a species are adapted to the same niche. No two species can share the same niche in the same habitat or they will compete for resources. The extinction of a population due to direct competition with another species for a resource is called competitive exclusions.The extinction of a population due to direct competition with another species for a resource is called competitive exclusions.

5. Niche Diversity Niche diversity, the number of different niches in an ecosystem, is often determined by abiotic factors in the environment. In a marsh, for example, there are many organisms. However, there are few different niches because the physical environment in a marsh is fairly constant. By contrast, in a desert ecosystem, there are few organisms but many different niches.Niche diversity, the number of different niches in an ecosystem, is often determined by abiotic factors in the environment. In a marsh, for example, there are many organisms. However, there are few different niches because the physical environment in a marsh is fairly constant. By contrast, in a desert ecosystem, there are few organisms but many different niches.

6. Niche Diversity A predator is an organism that actively hunts other organisms. The organism that is hunted is the prey.A predator is an organism that actively hunts other organisms. The organism that is hunted is the prey. Predators play an important role in increasing niche diversity by decreasing the population size of their prey species.Predators play an important role in increasing niche diversity by decreasing the population size of their prey species.

7. Predators Predators help maintain diversity in ecosystems in many ways. The Great Barrier Reef is one example. A species of sea star called the crown of thorns lives and feeds on the corals that make up the reef. In the past, the crown of thorns was rare because it was eaten by many species of predatory fish, but fishing by people has removed many of the sea star’s predators. The crown of thorns’ numbers increased, and they now consume large stretches of the reef every year. The destruction of the reef results in lost habitat to many species, therefore lover diversity in the ecosystem. Predators help maintain diversity in ecosystems in many ways. The Great Barrier Reef is one example. A species of sea star called the crown of thorns lives and feeds on the corals that make up the reef. In the past, the crown of thorns was rare because it was eaten by many species of predatory fish, but fishing by people has removed many of the sea star’s predators. The crown of thorns’ numbers increased, and they now consume large stretches of the reef every year. The destruction of the reef results in lost habitat to many species, therefore lover diversity in the ecosystem.

8. The Great Barrier Reef

11. Brain CoralBrain Coral

12. The Great Barrier Reef

14. Fire CoralFire Coral

15. The Great Barrier Reef

19. Lesson 6 - Homework 1.How is a niche different from a habitat? 2.What might happen to an ecosystem if all the carnivores were removed? Explain your answer. 3.Explain how the niche of one species might influence the niche of another species. 4.List two examples of biotic factors and abiotic factors that can limit or increase the size of a species’ population.