Final answer:
Accumulating sufficient body fat prior to winter increases the chances of bison survival by acting as an energy reserve and aiding in maintaining body heat, an advantage conferred through natural selection. Cold tolerance and, to a lesser extent, behavioral adaptations such as migration may also affect winter survival.
Step-by-step explanation:
The question examines the characteristics that would enhance the chances of bison surviving a harsh winter. Based on research conducted on elk in Yellowstone National Park, which found a higher probability of survival in female elk with greater than 15% body fat before winter, we can infer that body fat is similarly crucial for bison. The accumulated body fat acts as an energy reserve during the winter when food is scarce, supporting metabolic activities and maintaining body heat. This adaptation is a result of natural selection, as individuals with higher body fat reserves are more likely to survive and reproduce, passing this advantageous trait onto their offspring.
Furthermore, physiological adaptations such as cold tolerance also play a significant role in an animal's survival during colder months. Species with greater cold tolerance are better equipped to withstand harsh winter climates without expending exorbitant amounts of energy. Lastly, behavioral adaptations like migration to warmer areas can also contribute to survival; however, this is less applicable to bison, who are typically non-migratory and need to withstand the winter in place.