Species Interactions - worksheet + Answers PDF

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Species Interactions 

Question 1: Focal species

Focal species: sparrow (secondary consumer; omnivore) 4 interacting species: -

Grass (primary producer; autotrophy)

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Grasshoppers (primary consumer; herbivore)

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Toads (secondary consumers; carnivore)

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Snakes (tertiary consumers; carnivore)

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Question 2: Interactions o Sparrow and snake: predator and prey. The snakes will eat the sparrow for food. So, the existence of the snakes is harmful to the survival of the sparrows. But their interaction is beneficial to the snakes. o Sparrow and grasshopper: predator and prey. The sparrows eat the grasshoppers for food. So, this interaction is beneficial to the sparrows but harmful to the grasshoppers. o Sparrow and toad: competing relationships. Both the sparrows and the toads eat the grasshoppers. So, the existence of toads is harmful to the sparrows because the toads bring competition for the sparrows’ food resources.

o Sparrow and grass: no direct interaction, but have potential benefit. Since the sparrow eats the grasshopper, and the grasshopper eats the grass, the existence of the sparrows is beneficial to the grass because they help eliminate the grass’s predator.

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Question 3: Effects of change on focal o My choice: option 1 (“high water temperatures, reducing soil moisture…”) o Direct effects: unseasonable weather will make the sparrows’ living environment become less comfortable. It may cause the sparrow get sick or disordered behavior. This could influence its quality of life. So, the population of sparrows may be reduced by strange weather.

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Question 4: Effects of change on interactions o Since the temperatures get higher and the moisture levels of soil reduce, the grass won’t be able to grow well. So, the amount of grass will decline. This results in the less food resources of grasshoppers. Some grasshoppers may die due to lack of food. So, the number of grasshoppers will also go down. And since the water temperature raised, the toads won’t have comfortable living environment. Their number will go down as well. The less number of competitor will cause the increasing number of the sparrows. But since their food is limited now, and their living environment is uncomfortable, their population won’t increase significantly. Since the

population of toads declines, the snakes will have less food resources as well. So, the snakes will become less. 

Question 5: Effects on humans. o Since all the population declined, the diversity of the natural system will decrease. This is bad for human to conduct research in studying natural species and protect them. o The reducing population of these species could also disturb the balance of the natural system. Human is also part of this system, so we may lose some positive regulation brought by these species. o Reduction of these species will cause the human spend more money conducting research to save their life because we always devote to maintain the balance of the nature.

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Question 6: Wolf reintroduction o Direct consequences: the population of wolves will decline very fast. o Indirect consequences: 

The wolves’ preys, such as deer and goats will have increasing population because their predators become less and less.

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The food of deer and goats will decrease because increasing population cause higher competition of the food resources.

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The destruction of natural system. Most preys of wolves are herbivores. So, when their population increases, they will consume more natural resources such as leaves, grasses or trees.

o Factors to consider: decision should depend on the number of wolves and its preys. When the number of wolves far more than its preys, hunting should be allowed to control the wolves’ population. But when the natural system is totally balance. To be specific, the population of wolves and its preys are balance, the park should not allow hunting because it will disrupt the balance. When the wolves’ population are far less than its preys, the park should allow the people to hunt goats or deer in order to keep the balance. o Unexpected consequences happened because it’s hard to control how many wolves will be hunted. If the hunted wolves were limited, it won’t have big effects to the overall natural system. But the natural system will be disrupted if people hunted too many wolves. Also, we don’t know if there’s any other natural factors influence the population of wolves’ preys. So this often have unintended consequences....