Question

What is the correct general scheme of the fungal succession on herbivore dung:
A. Basidiomycetes
B. Discomycetes
C. Phycomycetes
D. Pyrenomycetes
Choose the correct answer from the options given below:

• A. A, B, C, D
• B. A, C, B, D
• C. B, A, D, C
• D. C, B, D, A

Hint:

Think of fungal succession on dung as a race for food. The fastest sprinters (\textbf{P}hycomycetes) eat the easy food (sugars) first. Then come the marathon runners (\textbf{A}scomycetes) that can digest tougher food (cellulose). Finally, the ultra-marathoners (\textbf{B}asidiomycetes) arrive to break down the hardest food (lignin).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The question asks for the typical sequence of fungal groups (succession) that colonize herbivore dung. This ecological succession is driven by the fungi's different enzymatic capabilities to break down organic compounds of varying complexity.
Step 2: Detailed Explanation:
The succession of coprophilous (dung-inhabiting) fungi generally follows this pattern:

First Stage - Phycomycetes (C): (Now often classified as Zygomycetes). These are the pioneers, like {Mucor} and {Pilobolus}. They grow very rapidly, utilizing the simple, soluble sugars and carbohydrates readily available in the dung. They usually appear within the first few days.
Second Stage - Ascomycetes (B and D): After the simple sugars are depleted, Ascomycetes appear. They have enzymes (cellulases) to break down more complex carbohydrates like cellulose. This group includes Discomycetes (cup fungi, like {Ascobolus}) and Pyrenomycetes (flask fungi, like {Sordaria}). They typically appear after the Phycomycetes. The order between Discomycetes (B) and Pyrenomycetes (D) can vary, but they represent the middle stage.
Third Stage - Basidiomycetes (A): These are the final colonizers, appearing after several weeks. Fungi like {Coprinus} (a mushroom) have powerful enzymes (ligninases) to decompose the most resistant components of the dung, such as lignin and complex cellulose.
The overall sequence is from simple sugar consumers to cellulose decomposers to lignin decomposers.
Step 3: Final Answer:
The correct chronological order is C (Phycomycetes) \(\rightarrow\) B (Discomycetes) \(\rightarrow\) D (Pyrenomycetes) \(\rightarrow\) A (Basidiomycetes). This corresponds to option (D).