TF阅读真题第779篇The Decline of the Large Blue Butterfly in England

 

The Decline of the Large Blue Butterfly in England

The large blue butterfly undergoes a four-phase life cycle: egg, larva, pupa, and adult. Adults lay eggs on plants that provide food for the larvae, known as caterpillars. When the caterpillar is fully grown, it enters the pupa stage, from which it emerges as a winged adult. The population of the large blue declined greatly in southern England in the late nineteenth century; this was attributed to poor weather. Final extinction of the species in England in 1979 followed two successive hot, dry breeding seasons. Since the beautiful butterfly is highly sought after by collectors, excessive collecting was presumed to have caused the long-term decline that made the species vulnerable to deteriorating climate.

In an attempt to protect the butterfly and its habitat, a reserve was established in the 1930s that excluded both collectors and domestic livestock, but this did not stop the decline. Evidently, habitat had changed through time, including a reduction in wild thyme, which provides the food for the early development period of the large blue’s caterpillar. Moreover, the loss of grass-eating rabbits (through disease) and the exclusion of grass-eating cattle and sheep from the reserve harmed short-turf grasses, which require periodic grazing to flourish. Short woody plants (shrubs) replaced the short-turf grasses that had provided an optimal environment for the large blue. Thyme survived; however, the butterflies continued to decline to extinction in Britain.

A more complex story has since been revealed by research associated with the reintroduction of the large blue to England from continental Europe. The larvae of the large blue butterfly in England and on the European continent prey on colonies of Myrmica ant species. Larval large blues must enter a Myrmica nest to feed on larval ants. Similar predatory behavior and/or tricking ants into feeding them as if they were the ants’ own offspring are features of the natural history of various butterfly groups. After hatching from an egg laid on the larval plant food, the large blue’s caterpillar feeds on thyme flowers until it reaches the final larval phase, around August. At dusk, the caterpillar drops to the ground from its birth plant, where it waits motionless until a Myrmica ant finds it. The worker ant observes the larva for an extended period, perhaps more than an hour, during which the ant eats a sugary substance secreted from the caterpillar’s nectar organs. At some point the caterpillar becomes swollen and adopts a posture that seems to convince the ant that it is dealing with an escaped young ant, and the caterpillar is carried into the ant nest. Until this stage, the caterpillar’s growth has been modest, but in the ant nest the caterpillar becomes predatory on ant eggs and larvae and grows rapidly. The caterpillar spends the winter in the nest and, nine to ten months after entering the nest, pupates (passes through the pupal stage)in early summer of the following year. The caterpillar requires an average of 230 immature ants for successful pupation. It apparently escapes predation by the ants by secreting surface chemicals that mimic those of the ant offspring, and probably receives special treatment in the colony by producing sounds that mimic those of the queen ant. The adult butterfly emerges in the summer and departs rapidly from the nest before the ants can identify it as an intruder.

Adoption and incorporation into the ant colony turns out to be the critical stage in the life history. The complex system involves the ‘correct” ant, Myrmica sabuleti, being present, and this in turn depends on the appropriate microclimate associated with short turf grass. Longer grass causes cooler near-soil microclimate conditions, favoring other Myrmica species, including Myrmica scabrinodes, which may displace Myrmica sabuleti. Although caterpillars associate apparently indiscriminately with any Myrmica species, caterpillar survivorship differs dramatically; with M. sabuleti approximately 15 percent survive, but an unsustainable reduction to less than 2 percent survivorship occurs with M. scabrinodes. For large blue populations to succeed, more than 50 percent of the adoption by ants must be by M. sabuleti. Other factors affecting survivorship are that the ant colony must provide enough larvae to feed the caterpillar well and that it must lie within 2 meters of the birth thyme plant. Such nests are associated with newly burnt grasslands, which are rapidly colonized by M. sabuleti.

 

 

 

 

 

 

 

1

In an attempt to protect the butterfly and its habitat, a reserve was established in the 1930s that excluded both collectors and domestic livestock, but this did not stop the decline. Evidently, habitat had changed through time, including a reduction in wild thyme, which provides the food for the early development period of the large blue’s caterpillar. Moreover, the loss of grass-eating rabbits (through disease) and the exclusion of grass-eating cattle and sheep from the reserve harmed short-turf grasses, which require periodic grazing to flourish. Short woody plants (shrubs) replaced the short-turf grasses that had provided an optimal environment for the large blue. Thyme survived; however, the butterflies continued to decline to extinction in Britain.

According to paragraph 2， which of the following is true of the reserve established in the 1930s to protect the large blue butterfly?

AIt helped to stabilize the large blue butterfly population.

BIt contributed to the loss of grass-eating rabbits.

CIts exclusion of livestock made the reserve less suitable for the large blue butterfly.

DIt did not stop the excessive collecting that threatened the large blue butterfly population.

 

2

In an attempt to protect the butterfly and its habitat, a reserve was established in the 1930s that excluded both collectors and domestic livestock, but this did not stop the decline. Evidently, habitat had changed through time, including a reduction in wild thyme, which provides the food for the early development period of the large blue’s caterpillar. Moreover, the loss of grass-eating rabbits (through disease) and the exclusion of grass-eating cattle and sheep from the reserve harmed short-turf grasses, which require periodic grazing to flourish. Short woody plants (shrubs) replaced the short-turf grasses that had provided an optimal environment for the large blue. Thyme survived; however, the butterflies continued to decline to extinction in Britain.

In paragraph 2， which of the following is NOT mentioned as a habitat change that occurred over time in the large blue butterfly reserve?

AWild thyme plants declined.

BShort woody plants spread.

CGrass-eating rabbits died out.

DNew types of short-turf grass appeared.

 

3

A more complex story has since been revealed by research associated with the reintroduction of the large blue to England from continental Europe. The larvae of the large blue butterfly in England and on the European continent prey on colonies of Myrmica ant species. Larval large blues must enter a Myrmica nest to feed on larval ants. Similar predatory behavior and/or tricking ants into feeding them as if they were the ants’ own offspring are features of the natural history of various butterfly groups. After hatching from an egg laid on the larval plant food, the large blue’s caterpillar feeds on thyme flowers until it reaches the final larval phase, around August. At dusk, the caterpillar drops to the ground from its birth plant, where it waits motionless until a Myrmica ant finds it. The worker ant observes the larva for an extended period, perhaps more than an hour, during which the ant eats a sugary substance secreted from the caterpillar’s nectar organs. At some point the caterpillar becomes swollen and adopts a posture that seems to convince the ant that it is dealing with an escaped young ant, and the caterpillar is carried into the ant nest. Until this stage, the caterpillar’s growth has been modest, but in the ant nest the caterpillar becomes predatory on ant eggs and larvae and grows rapidly. The caterpillar spends the winter in the nest and, nine to ten months after entering the nest, pupates (passes through the pupal stage)in early summer of the following year. The caterpillar requires an average of 230 immature ants for successful pupation. It apparently escapes predation by the ants by secreting surface chemicals that mimic those of the ant offspring, and probably receives special treatment in the colony by producing sounds that mimic those of the queen ant. The adult butterfly emerges in the summer and departs rapidly from the nest before the ants can identify it as an intruder.

Which of the following best describes the purpose of paragraph 3 in the passage?

AIt explains a relationship between the large blue butterfly and another type of animal that is important for the butterfly’s survival.

BIt contrasts the history of the large blue butterfly in Britain and in continental Europe to introduce a possible reason for the butterfly’s decline.

CIt challenges the idea that habitat changes played a role in the decline of the large blue butterfly.

DIt identifies a predator species that is a major threat to the survival of the large blue butterfly.

 

4

A more complex story has since been revealed by research associated with the reintroduction of the large blue to England from continental Europe. The larvae of the large blue butterfly in England and on the European continent prey on colonies of Myrmica ant species. Larval large blues must enter a Myrmica nest to feed on larval ants. Similar predatory behavior and/or tricking ants into feeding them as if they were the ants’ own offspring are features of the natural history of various butterfly groups. After hatching from an egg laid on the larval plant food, the large blue’s caterpillar feeds on thyme flowers until it reaches the final larval phase, around August. At dusk, the caterpillar drops to the ground from its birth plant, where it waits motionless until a Myrmica ant finds it. The worker ant observes the larva for an extended period, perhaps more than an hour, during which the ant eats a sugary substance secreted from the caterpillar’s nectar organs. At some point the caterpillar becomes swollen and adopts a posture that seems to convince the ant that it is dealing with an escaped young ant, and the caterpillar is carried into the ant nest. Until this stage, the caterpillar’s growth has been modest, but in the ant nest the caterpillar becomes predatory on ant eggs and larvae and grows rapidly. The caterpillar spends the winter in the nest and, nine to ten months after entering the nest, pupates (passes through the pupal stage)in early summer of the following year. The caterpillar requires an average of 230 immature ants for successful pupation. It apparently escapes predation by the ants by secreting surface chemicals that mimic those of the ant offspring, and probably receives special treatment in the colony by producing sounds that mimic those of the queen ant. The adult butterfly emerges in the summer and departs rapidly from the nest before the ants can identify it as an intruder.

Paragraph 3 suggests that a worker ant is attracted to a large blue caterpillar because the caterpillar

Asecretes food for the worker ant

Blooks similar to a thyme flower

Clooks like food for ant larvae

Dis the same color as worker ants

 

5

A more complex story has since been revealed by research associated with the reintroduction of the large blue to England from continental Europe. The larvae of the large blue butterfly in England and on the European continent prey on colonies of Myrmica ant species. Larval large blues must enter a Myrmica nest to feed on larval ants. Similar predatory behavior and/or tricking ants into feeding them as if they were the ants’ own offspring are features of the natural history of various butterfly groups. After hatching from an egg laid on the larval plant food, the large blue’s caterpillar feeds on thyme flowers until it reaches the final larval phase, around August. At dusk, the caterpillar drops to the ground from its birth plant, where it waits motionless until a Myrmica ant finds it. The worker ant observes the larva for an extended period, perhaps more than an hour, during which the ant eats a sugary substance secreted from the caterpillar’s nectar organs. At some point the caterpillar becomes swollen and adopts a posture that seems to convince the ant that it is dealing with an escaped young ant, and the caterpillar is carried into the ant nest. Until this stage, the caterpillar’s growth has been modest, but in the ant nest the caterpillar becomes predatory on ant eggs and larvae and grows rapidly. The caterpillar spends the winter in the nest and, nine to ten months after entering the nest, pupates (passes through the pupal stage)in early summer of the following year. The caterpillar requires an average of 230 immature ants for successful pupation. It apparently escapes predation by the ants by secreting surface chemicals that mimic those of the ant offspring, and probably receives special treatment in the colony by producing sounds that mimic those of the queen ant. The adult butterfly emerges in the summer and departs rapidly from the nest before the ants can identify it as an intruder.

According to paragraph 3， in which TWO of the following ways does the large blue caterpillar seem to trick Myrmica ants while inside the ants’ nest? To receive credit, you must select TWO answer choices.

ABy remaining motionless so that it escapes the attention of the worker ants

BBy changing its growth rate to match that of a maturing ant larva

CBy secreting chemicals that are similar to those produced by young Myrmica ants

DBy making sounds that are similar to those produced by the queen ant

 

6

Adoption and incorporation into the ant colony turns out to be the critical stage in the life history. The complex system involves the ‘correct” ant, Myrmica sabuleti, being present, and this in turn depends on the appropriate microclimate associated with short turf grass. Longer grass causes cooler near-soil microclimate conditions, favoring other Myrmica species, including Myrmica scabrinodes, which may displace Myrmica sabuleti. Although caterpillars associate apparently indiscriminately with any Myrmica species, caterpillar survivorship differs dramatically; with M. sabuleti approximately 15 percent survive, but an unsustainable reduction to less than 2 percent survivorship occurs with M. scabrinodes. For large blue populations to succeed, more than 50 percent of the adoption by ants must be by M. sabuleti. Other factors affecting survivorship are that the ant colony must provide enough larvae to feed the caterpillar well and that it must lie within 2 meters of the birth thyme plant. Such nests are associated with newly burnt grasslands, which are rapidly colonized by M. sabuleti.

The word “indiscriminately”in the passage is closest in meaning to

Awithout delaying

Bwithout preference

Cwithout danger

Dwithout being noticed

 

7

Adoption and incorporation into the ant colony turns out to be the critical stage in the life history. The complex system involves the ‘correct” ant, Myrmica sabuleti, being present, and this in turn depends on the appropriate microclimate associated with short turf grass. Longer grass causes cooler near-soil microclimate conditions, favoring other Myrmica species, including Myrmica scabrinodes, which may displace Myrmica sabuleti. Although caterpillars associate apparently indiscriminately with any Myrmica species, caterpillar survivorship differs dramatically; with M. sabuleti approximately 15 percent survive, but an unsustainable reduction to less than 2 percent survivorship occurs with M. scabrinodes. For large blue populations to succeed, more than 50 percent of the adoption by ants must be by M. sabuleti. Other factors affecting survivorship are that the ant colony must provide enough larvae to feed the caterpillar well and that it must lie within 2 meters of the birth thyme plant. Such nests are associated with newly burnt grasslands, which are rapidly colonized by M. sabuleti.

In paragraph 4， which of the following is NOT mentioned as a factor affecting survivorship of the large blue caterpillar?

AThe stage of development of the ant larvae that the caterpillar feeds on

BThe species of Myrmica ant that adopts the caterpillar

CThe number of larvae available in the ant colony

DThe distance of the ant colony from the thyme plant where the caterpillar hatched

 

8

Adoption and incorporation into the ant colony turns out to be the critical stage in the life history. The complex system involves the ‘correct” ant, Myrmica sabuleti, being present, and this in turn depends on the appropriate microclimate associated with short turf grass. Longer grass causes cooler near-soil microclimate conditions, favoring other Myrmica species, including Myrmica scabrinodes, which may displace Myrmica sabuleti. Although caterpillars associate apparently indiscriminately with any Myrmica species, caterpillar survivorship differs dramatically; with M. sabuleti approximately 15 percent survive, but an unsustainable reduction to less than 2 percent survivorship occurs with M. scabrinodes. For large blue populations to succeed, more than 50 percent of the adoption by ants must be by M. sabuleti. Other factors affecting survivorship are that the ant colony must provide enough larvae to feed the caterpillar well and that it must lie within 2 meters of the birth thyme plant. Such nests are associated with newly burnt grasslands, which are rapidly colonized by M. sabuleti.

According to paragraph 4， which of the following types of grass environments provides the best chance of survival for large blue caterpillars?

ALonger grasses

BGrasses with cool near-soil microclimate conditions

CNewly planted grasses

DNewly burnt grasses

 

9

The large blue butterfly undergoes a four-phase life cycle: egg, larva, pupa, and adult. Adults lay eggs on plants that provide food for the larvae, known as caterpillars. When the caterpillar is fully grown, it enters the pupa stage, from which it emerges as a winged adult. [■]The population of the large blue declined greatly in southern England in the late nineteenth century; this was attributed to poor weather. [■]Final extinction of the species in England in 1979 followed two successive hot, dry breeding seasons.[■] Since the beautiful butterfly is highly sought after by collectors, excessive collecting was presumed to have caused the long-term decline that made the species vulnerable to deteriorating climate.[■]

Look at the four squaresthat indicate where the following sentence could be added to the passage

However, climate was not the only factor believed to have played a role.

Where would the sentence best fit？Click on a square  sentence to the passage.

10

Greater understanding of the large blue butterfly has shed light on its decline in England.

AExcessive collecting may have made large blue butterflies more vulnerable to changes in weather, and changes in vegetation over time resulted in a less suitable habitat.

BLarge blue butterflies in Continental Europe experienced similar declines to those living in England, leading scientists to assume that there must be a common cause.

CDuring its final larval stage, a large blue caterpillar is carried into a Myrmica ants’ nest, where it spends up to ten months growing rapidly by feeding on immature ants.

DThe growth of cattle and sheep populations in Britain reduced the number of wild thyme plants, forcing large blue butterflies to lay their eggs on short woody plants.

EOver time, Myrmica ant species have evolved to recognize the large blue caterpillar’s attempts to trick them and are much less likely to take the caterpillar into their nests.

FLarge blue caterpillars have the best chance of survival when adopted primarily by members of the M. sabuleti ant species, which can be affected by changes in grassland habitat.