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A species that exerts an influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.
 
 
Q. Consider the following assumptions: 
1. The food chains/food web in an ecosystem are influenced by keystone species.
2. The presence of keystone species is a specific characteristic of aquatic ecosystems.
3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.
With reference to the passage, which of the above assumptions is/are valid?
  • a)
    1 only
  • b)
    2 and 3 only
  • c)
    1 and 3 only
  • d)
    1, 2 and 3
Correct answer is option 'A'. Can you explain this answer?
Verified Answer
A species that exertsan influence out of proportion to its abundance i...
Solution: a)1 has been mentioned in the passage. 2 is an out of context generalization. 3 is an extreme statement. Ecosystem will suffer a loss, but may not collapse.
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A species that exertsan influence out of proportion to its abundance i...

Assumptions about Keystone Species:

1. The food chains/food web in an ecosystem are influenced by keystone species:
- This assumption is valid based on the example of the sea star Pisaster ochraceus in the rocky intertidal ecosystems. The presence of keystone species like Pisaster can significantly impact the species richness and diversity in an ecosystem by influencing the food chain and interactions between species.

2. The presence of keystone species is a specific characteristic of aquatic ecosystems:
- This assumption is not valid as keystone species can exist in various types of ecosystems, including terrestrial, freshwater, and marine environments. While the passage discusses the sea star as a keystone species in aquatic ecosystems, keystone species can also be found in other types of habitats.

3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem:
- This assumption is not explicitly supported by the passage. While the removal of a keystone species like the sea star Pisaster can have significant impacts on the ecosystem, leading to changes in species composition and diversity, it may not necessarily result in the complete collapse of the ecosystem. Ecosystems have the ability to adapt to changes, although the removal of a keystone species can have cascading effects on other species.

In conclusion, based on the information provided in the passage, the valid assumption is that keystone species play a crucial role in influencing the food chains and food webs in an ecosystem.
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A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. With reference to the passage, consider the following statements : 1. Mussels-are generally the dominant species in intertidal ecosystems. 2. The survival of sea stars is generally determined by the abundance of mussels. Which of the statements given above is /are correct?

A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Which of the following is/are implied by the passage ? 1. Mussels are always hard competitors for sea stars.2. Sea stars of the Pacific coast have reached the climax of their evolution. 3. Sea stars constitute an important component in the energy flow in intertidal ecosystem. Which of the statements given above is/are correct?

Directions for the following 4 (four) items:Read the follouing passage and answer the items that follow. Your answers to these items should be based on the passage only.PassageA species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. What is the crux of the passage ?

Passage 1By going through literature on communalism, certain important aspects that are worth noting arise. First, arbitrary definitions and explanations, often due to the development of opposing schools of thought, have created vagueness around the phenomenon of communalism and its associations with the concept of community. Second, most of the writings on communalism are not on communalism per se. They are on Hindu communalism, Muslim communalism and the Hindu fundamentalism. The connection between communalism and communities is not addressed properly. Third, features of religious communalism - a presumed homogenous community and community consciousness - are also exhibited by sects, cults, castes and linguistic and regional communities. Such communities and their politics are not seen as a part of the restricted idea of communalism. This is why the use of the idea of the ethnic is considered more appropriate, for it can bring under its consideration the full range of such expressions. Fourth, occurrences of communal violence in southern Indian states, its spread to rural and hill areas where tribals and dalits are either involved or attacked, and a range of new subjects for contestation in contemporary times show that communalism is not a peculiar north Indian and urban phenomenon.Writings on communalism, even while highly analytical, consider community in terms of religion. This narrowing of communalism to apply only to religious communities has been uncritically inherited from colonial understandings of communities in India. To begin a discussion on communalism, it is necessary to see how it has been defined and explained, and how it has been associated with the term community. In a crude way, a group of people with some common bonds or notion of common identity can be treated as a community. Apparently, the association of communalism with community looks simplistic. An analysis of the characteristic features of communalism shows that the complex relationship between communalism and community has largely been overlooked. Jones defines communalism as consciously shared religious heritage which becomes the dominant form of identity for a given segment of society.Q. Consider the following statements:I. Most writings on communalism have been charged by religious sentimentII. Colonial understandings of communities in India are less relevant todayWith reference of the passage, which of the following assumptions is/are valid?

Passage 1By going through literature on communalism, certain important aspects that are worth noting arise. First, arbitrary definitions and explanations, often due to the development of opposing schools of thought, have created vagueness around the phenomenon of communalism and its associations with the concept of community. Second, most of the writings on communalism are not on communalism per se. They are on Hindu communalism, Muslim communalism and the Hindu fundamentalism. The connection between communalism and communities is not addressed properly. Third, features of religious communalism - a presumed homogenous community and community consciousness - are also exhibited by sects, cults, castes and linguistic and regional communities. Such communities and their politics are not seen as a part of the restricted idea of communalism. This is why the use of the idea of the ethnic is considered more appropriate, for it can bring under its consideration the full range of such expressions. Fourth, occurrences of communal violence in southern Indian states, its spread to rural and hill areas where tribals and dalits are either involved or attacked, and a range of new subjects for contestation in contemporary times show that communalism is not a peculiar north Indian and urban phenomenon.Writings on communalism, even while highly analytical, consider community in terms of religion. This narrowing of communalism to apply only to religious communities has been uncritically inherited from colonial understandings of communities in India. To begin a discussion on communalism, it is necessary to see how it has been defined and explained, and how it has been associated with the term community. In a crude way, a group of people with some common bonds or notion of common identity can be treated as a community. Apparently, the association of communalism with community looks simplistic. An analysis of the characteristic features of communalism shows that the complex relationship between communalism and community has largely been overlooked. Jones defines communalism as consciously shared religious heritage which becomes the dominant form of identity for a given segment of society.Q. What is the reason that communalism has come to be identified only with religion?

A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer?
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A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer? for UPSC 2024 is part of UPSC preparation. The Question and answers have been prepared according to the UPSC exam syllabus. Information about A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for UPSC 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer?.
Solutions for A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for UPSC. Download more important topics, notes, lectures and mock test series for UPSC Exam by signing up for free.
Here you can find the meaning of A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer?, a detailed solution for A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer? has been provided alongside types of A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice A species that exertsan influence out of proportion to its abundance in an ecosystem is called a keystone species. The keystone species may influence both the species richness of communities and the flow of energy and materials through ecosystems. The sea star Pisaster the flow of energy and materials through ecosystems. The sea star Pisaster ochraceus, which lives in rocky intertidal ecosystems on the Pacific coast of North America, is also an example of a keystone species. Its preferred prey is the mussel Mytilus californianus . In the absence of sea- stars, these mussels crowd out other competitors in a broad belt of the intertidal zone. By consuming mussels, sea star creates bare spaces that are taken over by a variety of other species. A study at the University of washington demonstrated the influence of Pisaster on species richness by removing sea stars from selected parts of the intertidal zone repeatedly over a period of five years. Two major changes occured in the areas from which sea stars were removed. First, the lower edge of the 46. mussel bed extended farther down into the intertidal zone, showing that sea stars are able to eliminate mussels completely where they are covered with water most of the time. Second, and more dramatically, 28 species of animals and algae disappeared from the sea star removal zone. Eventually only Mytilus, the dominant competitor, occupied the entire substratum. Through its effect on competitive relationships, predation by Pisaster largely determines which species live in these rocky intertidal ecosystems.Q. Consider the following assumptions:1. The food chains/food web in an ecosystem are influenced by keystone species.2. The presence of keystone species is a specific characteristic of aquatic ecosystems.3. If the keystone species is completely removed from an ecosystem, it will lead to the collapse of the ecosystem.With reference to the passage, which of the above assumptions is/are valid?a)1 onlyb)2 and 3 onlyc)1 and 3 onlyd)1, 2 and 3Correct answer is option 'A'. Can you explain this answer? tests, examples and also practice UPSC tests.
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