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Difficulty: MediumEvolution and Adaptation

In a coastal population of marine iguanas, individuals with broader, flattened tails can swim more efficiently against strong ocean currents to forage on underwater algae. According to the principles of natural selection, how will this population most likely change over many generations if strong ocean currents persist?

  1. A
    Individual iguanas will flatten and broaden their tails through continuous swimming exercise and pass those acquired physical changes to their offspring.
  2. B
    The allele responsible for broad tails will automatically become dominant over other alleles regardless of reproductive rates.
  3. Iguanas with broader tails will survive and reproduce more successfully, increasing the frequency of broad tails in the population over time.Answer
  4. D
    Each iguana will intentionally modify its genetic makeup to produce broader tails in response to the environmental need.

Answer

Iguanas with broader tails will survive and reproduce more successfully, increasing the frequency of broad tails in the population over time.
Natural selection operates because individuals with traits that confer a survival or foraging advantage are more likely to survive, reproduce, and pass those inherited traits to their offspring. Over multiple generations, the frequency of the beneficial trait increases in the population.

Step-by-Step Solution

1
Identify the existing inherited variation and environmental selective pressure.
The population possesses natural variation in tail shape, and strong ocean currents create a selective pressure where swimming efficiency directly affects foraging success.
Natural selection requires preexisting genetic variation upon which selective pressures can act.
2
Determine the effect of the advantageous trait on individual fitness.
Iguanas with broader tails forage more effectively, achieve better nutrition, and have higher survival and reproductive success.
Differential reproductive success is the fundamental driver of evolutionary change in populations.
3
Deduce the population-level outcome across subsequent generations.
Because broad-tailed individuals leave more offspring that inherit the trait, the proportion of broad-tailed iguanas in the population increases over generations.
Evolution is a change in allele and trait frequencies in a population over time, not within single individuals.

Key Concept

Natural selection acts on preexisting inherited variations, leading to differential reproductive success and gradual adaptation of populations over generations.
Estimated Time:1m 0s
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Topics

Evolution and Adaptation

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