GED Science TestLife ScienceHard
A group of scientists is studying a population of deer in a forest. They observe that over several generations, the average antler size of male deer has significantly decreased. Which of the following is the most likely explanation for this observation, assuming natural selection is at play?
- AA new predator that targets deer with larger antlers.
- BA genetic mutation causing smaller antlers to spontaneously appear.
- CClimate change leading to reduced nutrient availability for antler growth.
- DIncreased availability of food sources favoring smaller deer.
Show answer & explanationAnswer & explanation
Correct answer: A. A new predator that targets deer with larger antlers.
Natural selection favors traits that increase survival and reproduction. If a new predator targets deer with larger antlers, those deer are less likely to survive and reproduce, leading to a decrease in the average antler size in the population over generations as smaller-antlered deer are more likely to pass on their genes.
Why the other options are wrong
- B. While mutations introduce variation, a single mutation wouldn't explain a significant population-wide trend over generations without a selective pressure making it advantageous.
- C. Reduced nutrient availability might cause smaller antlers in individual deer, but for it to be a mechanism of natural selection, it would need to differentially affect survival/reproduction based on antler size, which isn't directly stated or implied as strongly as predation.
- D. Increased food availability would generally support larger antler growth, not smaller.
Natural Selection
The process by which organisms better adapted to their environment tend to survive and produce more offspring. It drives evolutionary change by favoring advantageous traits.
- Variation exists within populations
- Heritable traits are passed to offspring
- Differential survival and reproduction
- Adaptation to the environment
- Leads to changes in allele frequencies over time
Memory trick: Varied traits struggle to survive and reproduce, leading to change.