Final answer:
The purple-legged wasp population showing resistance to the Bt toxin exemplifies natural selection, wherein advantageous traits like toxin resistance are passed down, potentially leading to an evolutionary shift in the population.
Step-by-step explanation:
The color of wasp legs can vary among species, but for the population of insects I've been asked about, which were originally distinguished by the colors on their thorax and legs, we are focusing on a sub-group with purple legs and another with orange legs. The observation that the purple-legged group may be increasingly resistant to the Bt (Bacillus thuringiensis) toxin supports the idea of natural selection and adaptation. Insects with particular traits that confer an advantage in their environment, such as toxin resistance, are more likely to survive and reproduce, passing those traits on to the next generation.
This phenomenon can lead to a shift in the population's characteristics over time, much like the case of beetles changing coloration to be better camouflaged from predators. Similarly, wasps and other insects often use coloration for protection, with mimicry being a common strategy to avoid predation. Thus, the purple-legged wasps may represent an evolutionary shift towards increased survival through toxin resistance in their particular habitat.