In the beetles, what leads directly to reproductive success?

• A. The beetles with traits best suited to the environment survive.
• B. The beetles with the brightest colors mate more.
• C. The beetles with random mutations reproduce more.
• D. The beetles that feed on the most abundant prey reproduce less.

Answer: (A)

The main idea is that reproductive success is tied to fitness in natural selection: individuals that have traits well suited to their environment survive longer and leave more offspring, passing those traits to the next generation. In beetles, if a trait helps them avoid predators, find food, or cope with the surroundings, those beetles are more likely to live long enough to reproduce and to have more offspring. Over time, the advantageous trait becomes more common in the population because it directly increases reproductive success.

While bright colors might influence mate choice in some cases, they aren’t a universal guarantee of more offspring and can even increase predation in some environments. Random mutations occur continually, but not all mutations boost reproduction, only those that improve fitness. Reproducing more due to abundant prey isn’t guaranteed if other factors limit reproduction or survival. So the direct driver of reproductive success here is having traits that are best suited to the environment, leading to more surviving offspring.