Question:hard

When comparing life-history traits across animal species, which one of the following relationships is LEAST expected under r-selection and K-selection theory?

Show Hint

r and K selected traits cluster together on a fast-slow spectrum; look for the one pair placed on opposite sides that the theory actually groups on the same side.
Updated On: Jul 20, 2026
  • Development time is positively correlated with age at first reproduction
  • Development time is negatively correlated with lifespan
  • Lifespan is positively correlated with body size
  • Lifespan is negatively correlated with number of offspring per breeding attempt
Show Solution

The Correct Option is B

Solution and Explanation

Step 1: Sort species into a fast-slow spectrum.
Think of every species sitting somewhere on a line from fast (r-selected) to slow (K-selected). A fast species develops quickly, breeds young, dies young, stays small and throws out many young each time. A slow species does the reverse on every one of these traits.

Step 2: Ask whether each pair of traits sits on the same side or opposite sides of that line.
Development time and age at first reproduction: both are small numbers for fast species and both are large numbers for slow species. Same side, so positive correlation, matching option (A).
Lifespan and body size: both small for fast species, both large for slow species. Same side, so positive correlation, matching option (C).
Lifespan and offspring per breeding attempt: fast species have short lives but many offspring, slow species have long lives but few offspring. These sit on opposite sides, so negative correlation, matching option (D).

Step 3: Now test option (B).
Development time and lifespan: a fast species has short development and a short life, both small. A slow species has long development and a long life, both large. These sit on the same side of the spectrum, so they should be positively correlated, not negatively.

Step 4: Spot the mismatch.
Only option (B) claims a negative correlation for two traits that the theory actually places on the same side of the fast-slow spectrum. Every other option correctly matches how the theory groups its traits.

Step 5: Conclude.
\[ \boxed{\text{Development time is negatively correlated with lifespan}} \]
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