Question

A new food requesting behaviour has been observed in bonnet macaques in Bandipur National Park. The macaques extend their hand and make a cooing sound only towards humans, which effectively results in food given to them. If this behaviour is to increase in frequency in the population over time by the process of natural selection, which one or more of the options below is/are necessary condition(s)?

• A. Food requesting behaviour must be transmitted from one generation to the next.
• B. All bonnet macaques in the area must show this behaviour
• C. Macaques who receive food using this behaviour are able to have more offspring.
• D. Food requesting behaviour must only be taught by parents to offspring

Hint:

With fixed lifespan and short time steps, track cohorts: each age class shifts right by one class; the oldest class ages out. If births are not mentioned, do not add a new 1–30 d cohort.

Answer 1

The Correct Option is A, C

Step 1: Conditions for natural selection.
For any trait (behavioural or morphological) to spread in a population by natural selection, three conditions must be satisfied: 1. \emph{Variation}: Individuals differ in the trait.
2. \emph{Heritability}: The trait must be passed on to the next generation.
3. \emph{Differential fitness}: Individuals with the trait must have greater reproductive success.


Step 2: Evaluate each option.
(A) \emph{Food requesting must be transmitted between generations.}
Yes — heritability is essential; otherwise the trait will not persist or spread.
(B) \emph{All macaques must show the behaviour.}
No — selection acts on variation. If all already show it, there is no differential advantage.
(C) \emph{Those with the behaviour must have more offspring.}
Yes — if food-requesting macaques secure more food and therefore raise more offspring, they have a fitness advantage.
(D) \emph{Must only be taught by parents.}
No — the mechanism of transmission does not matter. It can be genetic, learned from peers, or socially transmitted. The key is that it is inherited in some way.


Step 3: Conclusion.
Only (A) heritability and (C) fitness advantage are necessary conditions. Final Answer:
\[ \boxed{\text{(A) and (C)}} \]