Question: Intraguild Predation — ecological significance, dynamics, and implications for biological control
Introduction
Intraguild Predation (IGP) represents a complex ecological interaction where a top predator simultaneously eliminates a competitor and a shared prey, complicating classical predator-prey models and carrying significant implications for ecosystem management.
Body
1. Defining the IGP Structure
IGP occurs when a top predator consumes an intermediate predator that also feeds on a common prey species. This creates a three-species module combining competition and predation simultaneously. The intermediate predator thus occupies a dual role — predator to the basal prey and prey to the top predator.
2. Population Dynamics and Coexistence
Contrary to the assumption that IGP always drives competitive exclusion, ecological theory and empirical evidence show coexistence is possible under specific productivity conditions. When basal prey is abundant, the intermediate predator can sustain itself despite predation pressure from the top predator. Coexistence depends critically on the relative efficiencies of both predators in exploiting shared prey.
3. Prevalence in Arthropod Communities
IGP is extensively documented in arthropod systems, including predatory mites, beetles, and parasitoids. These communities frequently exhibit overlapping trophic roles, making IGP structurally common rather than exceptional in terrestrial invertebrate food webs.
4. Implications for Biological Control
In agricultural biological control programmes, IGP poses a practical challenge — introducing multiple natural enemies to suppress pest populations can backfire if the introduced agents engage in mutual predation. This undermines pest suppression efficacy and demands careful selection of compatible biocontrol agents.
Conclusion
IGP reveals that trophic interactions are rarely linear; managing them requires understanding community-level dynamics. Effective biological control and conservation strategies must account for IGP to avoid unintended destabilisation of target ecosystems.
Word count: 239
PYQ 2024
Consider the following:
1. Carabid beetles
2. Centipedes
3. Flies
4. Termites
5. Wasps
Parasitoid species are found in how many of the above kind of organisms?
PYQ
Which of the following correctly describes 'Amensalism' as a biological interaction?
1. Both interacting species suffer a negative fitness consequence.
2. One species is harmed while the other is unaffected.
3. The harmed species always gets excluded from the habitat.
4. Allelopathy in plants is a form of amensalism.
Select the correct answer using the code given below:
PYQ
Consider the following statements about 'Janzen-Connell Hypothesis':
1. It proposes that specialist herbivores and pathogens accumulate near parent trees, reducing seedling survival close to the parent.
2. It provides a mechanism for the maintenance of high tropical tree diversity.
3. It predicts that the probability of seedling establishment is highest directly beneath the parent tree.
4. Evidence for the hypothesis has been found in both tropical and temperate forests.
Which of the above statements are correct?
PYQ
The phenomenon of 'Müllerian Mimicry' differs from 'Batesian Mimicry' in which fundamental aspect?
(a) In Müllerian mimicry, both model and mimic are unpalatable, while in Batesian mimicry the mimic is palatable
(b) In Müllerian mimicry, the model is always a vertebrate, while in Batesian mimicry both are invertebrates
(c) Müllerian mimicry evolves only in insects, while Batesian mimicry occurs across all animal groups
(d) In Müllerian mimicry, the mimic benefits at the expense of the model, while in Batesian mimicry both benefit
PYQ
With reference to the phenomenon of 'Mycoheterotrophy', consider the following:
1. Mycoheterotrophic plants obtain carbon from mycorrhizal fungi rather than through photosynthesis.
2. All mycoheterotrophic plants are completely achlorophyllous.
3. Monotropa uniflora (Indian Pipe) is a classic example of a mycoheterotrophic plant.
4. Mycoheterotrophy is an exclusive feature of angiosperms.
Which of the above statements are correct?