In a natural population of tortoises living on an island, individuals with longer necks can reach higher leaves on tall bushes during dry seasons, whereas short-necked tortoises struggle to find food. Over several generations, the proportion of long-necked tortoises in the population increases significantly. According to Charles Darwin's theory of natural selection, which of the following best explains this change?
- Tortoises with naturally longer necks had higher survival rates and produced more offspring, passing on their advantageous trait.Answer
- BIndividual tortoises repeatedly stretched their necks to reach food, and this stretched neck was inherited by their offspring.
- CThe environmental dry season caused targeted genetic mutations in short-necked tortoises to help them survive.
- DShort-necked tortoises intentionally altered their physical structure to prevent the entire population from dying out.
Answer
Tortoises with naturally longer necks had higher survival rates and produced more offspring, passing on their advantageous trait.
Darwin's theory of natural selection states that variations exist naturally within a population. When environmental conditions create competition for resources (such as food scarcity during dry seasons), individuals possessing favorable inherited traits (such as longer necks) are better adapted, survive longer, and reproduce more successfully. Over generations, these advantageous traits become more prevalent in the population.
Step-by-Step Solution
Key Concept
Differential Survival and Reproduction based on Inherited Variation