Biology Question of the Day

1. The percent of dark rabbits shows a clear increasing trend with a large change, consistent with selection favoring dark fur in the new environment. (correct answer)
2. The percent of dark rabbits shows a decreasing trend, consistent with selection favoring light fur after the wildfire.
3. The percent of dark rabbits is stable over time, indicating no evolutionary change in fur color.
4. The percent of dark rabbits fluctuates randomly with no overall direction, so the wildfire likely had no effect.

Explanation: This question tests your ability to interpret evolutionary trend data showing how populations change over time, including identifying trend direction, assessing magnitude of change, and recognizing correlations with environmental factors. Evolutionary trends reveal patterns of population change across time: INCREASING TREND (trait value or frequency rising over successive generations—8mm → 9mm → 10mm → 11mm) indicates selection FAVORING that trait (directional selection making it more common), DECREASING TREND (frequency falling—60% → 45% → 30% → 15%) indicates selection AGAINST that trait (making it less common), STABLE TREND (frequency staying similar—50% → 48% → 51% → 50%) indicates NO NET SELECTION or stabilizing selection (no evolution occurring for that trait), and FLUCTUATING TREND (up and down—30% → 50% → 35% → 55% → 40%) suggests either TRACKING environmental variation (environment changes, favored trait changes) or genetic drift (random fluctuation). The MAGNITUDE of change indicates selection strength: large change (10% to 90% = 80 percentage points) suggests strong selection, small change (50% to 55% = 5 points) suggests weak selection or drift. When trend CORRELATES with environmental change (antibiotic use increases → resistance increases in parallel, drought occurs → beak size increases), this strongly suggests the environmental factor is driving selection (causal relationship likely)! The percentage of dark rabbits rises steadily from 22% in 2011 to 70% in 2019 after the wildfire darkened the soil, displaying an increasing trend with large magnitude (48 percentage points over 8 years), likely correlating with the environmental change favoring camouflage via dark fur. Choice A correctly identifies this increasing direction, large change, and implied selection in the new environment. Choice B errs by claiming a decrease, which ignores the consistent upward progression in the data. Strategically, measure total change (70% - 22% = 48 points, large) and note post-event timing, similar to resistance rising with antibiotics. You're mastering this—apply to any shift after an event for insightful conclusions!