Answer:
In this case, the population of moths you're referring to has a number of variations. Here they are:
1. Wing Color Variation: The moths have two phenotypic variations for wing color, brown and white. This is a clear physical trait that can change based on the genetic makeup of the moth.
2. Survival Variation: Out of every 100 eggs laid, only about 10 moths survive to adulthood. This could imply a variation in the fitness or adaptability of the offspring, where only the most fit or adaptable (in terms of avoiding predators, finding food, or handling environmental conditions, for example) survive.
3. Seasonal Environment Variation: The environment where the moths live changes with the seasons. In winter, the trees lose their leaves, which may affect the camouflage ability of the moths depending on their wing color. This is a temporal variation in the environment, which can potentially influence the survival rates of the different moth variations.
4. Predation Variation: The predators of the moths are birds, which hunt for the moths as they rest on the dark tree bark. The level of predation can vary based on factors like the bird population size, hunting efficiency, and the visibility of the moths.
Each of these variations plays a role in the survival and reproduction of the moths and could lead to evolutionary changes in the population over time, especially if certain traits (like wing color) increase the moths' survival and reproductive success.