Zoology 2024 Paper I 50 marks Explain

Q6

(a) What is ecological succession ? Explain the different types and theories of ecological succession. (20 marks) (b) Explain Aggressive and Territorial behaviour in animals, with suitable examples. (15 marks) (c) What are the major carps of India ? Describe the polyculture methods of rearing the major carps. (15 marks)

हिंदी में प्रश्न पढ़ें

(a) पारिस्थितिक अनुक्रम क्या है ? पारिस्थितिक अनुक्रम के विभिन्न प्रकारों और सिद्धांतों की व्याख्या कीजिए। (20 अंक) (b) जानवरों में आक्रामक एवं क्षेत्रीय व्यवहार की उपयुक्त उदाहरणों सहित व्याख्या कीजिए। (15 अंक) (c) भारत की प्रमुख कार्प कौन-सी हैं ? प्रमुख कार्पों के पालन की पॉलीकल्चर विधियों का वर्णन कीजिए। (15 अंक)

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Directive word: Explain

This question asks you to explain. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.

See our UPSC directive words guide for a full breakdown of how to respond to each command word.

How this answer will be evaluated

Approach

The directive 'explain' demands clear exposition of concepts with causal reasoning. Allocate approximately 40% of time/words to part (a) given its 20 marks, and 30% each to parts (b) and (c). Structure with a brief introduction defining succession, then three dedicated sections for each sub-part, using diagrams for (a) and (c), and concluding with integrated applied significance of succession theory and aquaculture.

Key points expected

Part (a): Definition of ecological succession; distinction between primary and secondary succession; seral stages and climax community; Clements' monoclimax vs. Gleason's polyclimax vs. Tansley's climax pattern hypothesis
Part (a): Mechanisms—facilitation, tolerance, inhibition; relay floristics vs. initial floristics composition
Part (b): Aggressive behaviour—types (offensive/defensive, ritualized), functions, examples (stags, Siamese fighting fish, rhesus macaques); Territoriality—types (Type A-D), costs/benefits, examples (songbirds, coral reef fish, langurs)
Part (c): Indian major carps—Labeo rohita (rohu), Catla catla (catla), Cirrhinus mrigala (mrigal); exotic carps distinction
Part (c): Polyculture rationale—compatible feeding niches; surface, column, and bottom feeders; stocking ratios; composite culture with Cyprinus carpio; yield advantages and disease management

Evaluation rubric

Dimension	Weight	Max marks	Excellent	Average	Poor
Concept correctness	20%	10	Precise definitions across all parts: succession as directional change in community structure over time; accurate distinction between Clementsian superorganism concept and Gleason's individualistic hypothesis; correct classification of aggressive vs. territorial behaviours; accurate identification of three Indian major carps with scientific names	Basic definitions correct but conflates primary/secondary succession or misattributes theories; mixes aggressive and territorial concepts; lists carps but may miss one species or use common names only	Fundamental errors like defining succession as evolution, confusing inhibition with facilitation, or identifying wrong fish species as Indian major carps
Diagram / labelling	20%	10	Two clear diagrams: (a) seral stages from pioneer to climax with abiotic changes (soil depth, N-content) and biotic replacement; (c) pond profile showing vertical stratification of carp feeding zones with species positioning; proper labelling with arrows indicating succession direction	One relevant diagram with partial labelling; or two diagrams with missing components like abiotic gradients or feeding zone boundaries	No diagrams, or irrelevant sketches; poorly labelled diagrams that confuse primary and secondary succession axes
Examples & nomenclature	20%	10	Specific Indian examples: for (a) succession in Sambhar Lake or deforested Western Ghats; for (b) Nilgiri langur territoriality, Indian bullfrog aggression; for (c) exact scientific names Labeo rohita, Catla catla, Cirrhinus mrigala with their feeding habits	Generic examples (lichens, ferns) without Indian context; common names for fish; behavioural examples from textbooks without specificity	No examples, or invented examples; wrong scientific names (e.g., Cyprinus for Indian major carps); confused aggressive displays with courtship
Process explanation	20%	10	Clear mechanistic explanations: for (a) how facilitation alters environment for subsequent species; for (b) how costs of aggression shape ritualization and territorial defense strategies; for (c) step-by-step polyculture methodology from pond preparation to harvesting with species interaction logic	Lists processes sequentially but weak causal links; describes polyculture steps without explaining niche complementarity; mentions aggression costs without elaborating energy trade-offs	Descriptive only, no process logic; confuses polyculture with monoculture; cannot explain why aggression is ritualized
Evolutionary / applied context	20%	10	Integrates evolutionary theory: for (a) Connell & Slatyer models' predictive power; for (b) evolutionary stable strategies in aggression, optimal territory size theory; for (c) applied aquaculture—FFDA schemes, Blue Revolution, sustainable yield enhancement through species diversification, climate adaptation	Mentions applied aspects superficially (food security, fish production figures) without evolutionary framework; or evolutionary context without application	No evolutionary or applied context; purely academic treatment missing real-world significance of succession theory or aquaculture economics

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