Understanding r- and K-Selection Theory

r- and K-selection theory describes two contrasting strategies species use to adapt to their environments, influencing their life-history traits.

• r-selection: Favors rapid reproduction and growth, common in unstable environments. Traits include short lifespan, early reproduction, high fecundity, and small body size.
• K-selection: Favors efficient resource use and survival near carrying capacity, common in stable environments. Traits include long lifespan, delayed reproduction, lower fecundity (but often larger offspring), and larger body size.

Analyzing Life-History Trait Correlations

We need to identify the relationship LEAST expected based on these contrasting strategies:

• Option 1: Development time & Age at first reproduction
  Longer development times generally lead to a later age at first reproduction. This positive correlation is consistent with K-selection (slow development, delayed reproduction) and is generally expected.
• Option 2: Development time & Lifespan
  r-selected species typically have short development times and short lifespans (negative correlation). K-selected species typically have long development times and long lifespans (positive correlation). A universal *negative* correlation across all species (meaning short development implies long life, and long development implies short life) contradicts the typical K-selection pattern and is therefore the LEAST expected relationship.
• Option 3: Lifespan & Body size
  Larger body size is often associated with longer lifespans, a common trait in K-selected species. This positive correlation is expected.
• Option 4: Lifespan & Number of offspring per attempt (Fecundity)
  Species often trade-off lifespan with high fecundity. Producing many offspring (high fecundity, typical of r-selection) often correlates with a shorter lifespan, while producing fewer offspring (lower fecundity, typical of K-selection) allows for a longer lifespan. This negative correlation is expected.

Conclusion

The relationship least expected under r- and K-selection theory is that development time is negatively correlated with lifespan, as K-selected species typically exhibit both long development times and long lifespans, indicating a positive correlation.