Final answer:
Female Wapiti Elks with body fat percentages above 10% have a much smaller likelihood of becoming pregnant due to natural selection favoring those with higher fat reserves for survival and reproductive success in harsh winter conditions.
Step-by-step explanation:
The biggest characteristic to take away from a Wapiti Elk, considering natural selection, is their body fat percentage in relation to survival and reproductive success. Research indicates that female elk with higher body fat percentages, specifically above 10%, have greatly reduced chances of becoming pregnant compared to those with more body fat. This trait is likely a result of natural selection because those with adequate body fat reserves can survive harsh winter conditions, whereas those with less than 10% body fat are at a high risk of not surviving. Elk with adequate fat reserves can not only survive but also carry out successful pregnancies, thus passing on this genetic trait to their offspring.
During winter, the metabolic activities of elk increase, elevating their food requirements. Therefore, having a threshold level of energy stored in the form of fat is crucial for their survival. This physiological adaptation is especially seen during the migration period, where they move from summer feeding grounds in mountain meadows to lower valleys in winters. This pattern can be observed as behavioral changes, physiological changes, seasonal changes, and migration in elk.