Prey predator coexistence
In microbial communities, competitive interactions are common, which can lead to rapid exclusion
of community members under standard conditions. However coexistence and escape from
competitive exclusion is facilitated by evolutionary change in between-species interactions,
resulting in, cross-feeding or a niche shift to underexploited resources. It is a fact that two bacterial
species, Escherichia coli and Pseudomonas fluorescens, compete for shared resources and are
consumed by a keystone predator, the ciliate Tetrahymena thermophila. When genetically diverse
strains of E. coli and P. fluorescens were coinhabited with one strain of Tetrahymena thermophila,
over time the ciliate perished leading to increased competition between the two bacterial species.
However, when genetically diverse population of Tetrahymena was added to the bacterial mixed
cultures, all the three species thrived.
The prudence of predation has been extensively exploited by farmers for pest control.
4
(i) The key to coexistence is:
a. Predating on more than one species.
b. Having a large population of prey against a small population of predator.
c. Evolution of predators synchronized with that of their preys.
d. Removing the competition between species in a particular niche.
(ii) If genetic diversity in E.coli and P.fluorescens in a niche lead to their co-existence in the absence
of the ciliate, the possible reason would be:
a. resource partitioning
b. increased competition
c. change in environment
d. they are flagellated
(iii) E.coli are used an indicators of sewage polluted water as
a. The presence of E.coli indicates its genetic diversity.
b. E.coli is a normal inhabitant in large intestines of humans.
c. It causes urogenital diseases.
d. E.coli does not cause any harm to humans.
(iv) The ciliate can predate on both the bacterial species because it shows
a. Cross-feeding
b. Competitive exclusion
c. It is large in size
d. It has a gullet
(v) Assertion: Tetrahymena can be used to treat sewage.
Reason: Tetrahymena can degrade the E.coli populations in sewage.
a. Both assertion and reason are true, and the reason is the correct explanation of the assertion.
b. Both assertion and reason are true, but the reason is not the correct explanation of the
assertion.
c. Assertion is true but reason is false.
d. Both assertion and reason are false
Answers
Answer:
Prey predator coexistence
In microbial communities, competitive interactions are common, which can lead to rapid exclusion
of community members under standard conditions. However coexistence and escape from
competitive exclusion is facilitated by evolutionary change in between-species interactions,
resulting in, cross-feeding or a niche shift to underexploited resources. It is a fact that two bacterial
species, Escherichia coli and Pseudomonas fluorescens, compete for shared resources and are
consumed by a keystone predator, the ciliate Tetrahymena thermophila. When genetically diverse
strains of E. coli and P. fluorescens were coinhabited with one strain of Tetrahymena thermophila,
over time the ciliate perished leading to increased competition between the two bacterial species.
However, when genetically diverse population of Tetrahymena was added to the bacterial mixed
cultures, all the three species thrived.
The prudence of predation has been extensively exploited by farmers for pest control.
4
(i) The key to coexistence is:
a. Predating on more than one species.
b. Having a large population of prey against a small population of predator.
c. Evolution of predators synchronized with that of their preys.
d. Removing the competition between species in a particular niche.
(ii) If genetic diversity in E.coli and P.fluorescens in a niche lead to their co-existence in the absence
of the ciliate, the possible reason would be:
a. resource partitioning
b. increased competition
c. change in environment
d. they are flagellated
(iii) E.coli are used an indicators of sewage polluted water as
a. The presence of E.coli indicates its genetic diversity.
b. E.coli is a normal inhabitant in large intestines of humans.
c. It causes urogenital diseases.
d. E.coli does not cause any harm to humans.
(iv) The ciliate can predate on both the bacterial species because it shows
a. Cross-feeding
b. Competitive exclusion
c. It is large in size
d. It has a gullet
(v) Assertion: Tetrahymena can be used to treat sewage.
Reason: Tetrahymena can degrade the E.coli populations in sewage.
a. Both assertion and reason are true, and the reason is the correct explanation of the assertion.
b. Both assertion and reason are true, but the reason is not the correct explanation of the
assertion.
c. Assertion is true but reason is false.
d. Both assertion and reason are false