Which observation about beetle populations supported Charles Darwin's theory of evolution?

The observation that individuals exhibit wide variation is crucial in supporting Charles Darwin's theory of evolution because it highlights the existence of different traits within a population. Variation is essential for natural selection, as it provides the raw material on which selective pressures can act. If all individuals within a population were identical, there would be no differences for natural selection to favor, and thus no evolution would occur over time.

In a population of beetles, some might be larger or possess different coloration, which could affect their survival and reproduction based on environmental factors such as predation or climate. This variation allows for better adaptability to changing environments and increases the likelihood of some individuals successfully passing their traits to the next generation, leading to the gradual evolution of the population. Darwin emphasized the importance of variation among individuals in his theory, as it is a key component in understanding how species adapt and change over time.