Final answer:
A neon blue stripe on red sided garter snakes could be a result of natural selection if the trait affects the snakes' survival or reproduction. Similar to the color variation examples in side-blotched lizards and Trinidad guppies, if the blue stripe provides a reproductive or survival advantage under certain conditions, it is indeed natural selection.
Step-by-step explanation:
The genetic change resulting in a neon blue stripe in a population of red sided garter snakes could potentially be an instance of natural selection if the trait provides an adaptive advantage or disadvantage that affects the snakes' survival or reproduction. However, to confirm whether it is natural selection, there must be evidence that the blue-striped snakes have a higher or lower fitness in their environment relative to snakes without this trait. For example, if blue-striped males are preferred by females when the population is mostly non-blue striped or vice versa, or if the stripe affects their camouflage and therefore predation risk, that could indicate natural selection in action.
Looking at the provided examples, such as the side-blotched lizards and Trinidad guppies, we see that color variations can be favored under different population dynamics or environmental conditions.
This shows how shifts in phenotypic traits, like coloration, can be part of a cycle of natural selection where different traits are advantageous at different times, leading to a fluctuation in the frequency of these traits in the population. So, if the neon blue stripe results in increased reproductive success or survival, it would indeed be a result of natural selection.