91Ó°ÊÓ

Research on elk in Yellowstone National Park was conducted to determine how body condition affects survival of the elk over the winter months. It was found that the probability of survival of female elk is greater when they have accumulated 15% or more body fat by the end of fall. Female elk with body fat less than 10% in late fall were found to be at high risk of not surviving the winter. Explain why this pattern is likely to be observed. (credit: USGS Northern Prairie Wildlife Research Center) a. In winter, the availability of food decreases. So, there needs to be a certain threshold level of energy their bodies store in the form of fat to ensure their survival. b. In winter, the availability of food increases. So, there should be a certain threshold level of energy in their bodies stored in the form of fat to ensure their survival. c. In winter, elk’s requirement for food increases due to increase in metabolic activities. So, there should be a certain threshold level of energy in their bodies stored in the form of fat to ensure their survival. d. Elk release more energy in winter. So, there should be a certain threshold level of energy in their bodies stored in the form of fat to ensure their survival.

Step by step solution

01

Understand the Impact of Food Availability in Winter

In winter, food availability typically decreases. This lack of food means that the elk need to rely more on their body fat as an energy source to survive through the winter months where they cannot forage as effectively.

02

Relate Body Fat to Survival Probability

The probability of survival increases with higher body fat because the fat acts as a stored energy reserve. Female elk with 15% or more body fat have enough stored energy to maintain their vital functions throughout the winter.

03

Assess the Risks for Elk with Low Body Fat

Female elk with less than 10% body fat lack sufficient energy reserves to survive the winter. This deficiency puts them at a high risk of not surviving as they are unable to maintain proper metabolic functions without an adequate energy supply.

04

Analyze the Choices

Option (a): Correct - It aligns with the observed pattern, as decreased food availability necessitates stored body fat for energy. Option (b): Incorrect - Increased food availability is contrary to the scenario described. Option (c): Incorrect - While elk's metabolic activities may increase, the primary reason is decreased food availability. Option (d): Incorrect - Energy release is not the main consideration; the key factor is maintaining energy supply through stored body fat.

Unlock Step-by-Step Solutions & Ace Your Exams!

• Full Textbook Solutions

  Get detailed explanations and key concepts

• Unlimited Al creation

  Al flashcards, explanations, exams and more...

• Ads-free access

  To over 500 millions flashcards

• Money-back guarantee

  We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

body fat

Body fat plays a critical role in the winter survival of elk. During winter, food becomes scarce in Yellowstone National Park. As a result, elk rely heavily on their body fat, which acts as a major energy reservoir. Adequate body fat ensures that elk have enough stored energy to sustain their metabolic activities, which are crucial for survival in extreme conditions. Elk with at least 15% body fat have a significantly higher probability of surviving the winter because they can draw upon these reserves when food is not available.
On the other hand, female elk with less than 10% body fat are at a high risk of not surviving the winter. Their insufficient fat stores mean they cannot maintain their metabolic processes efficiently, leading to increased vulnerability. Thus, maintaining a certain level of body fat becomes a life-or-death factor for elk during harsh winters.

food availability

Food availability is a major determinant of elk survival during wintertime. In winter, the natural availability of food sources like grass and leaves diminishes. The reduction in food sources means that elk cannot rely on daily foraging to meet their energy needs. This scarcity necessitates that elk must have sufficient energy reserves stored as body fat accumulated during the earlier months.
The decreased food availability makes it imperative for elk to have already stored enough body fat before winter sets in. When food is not available, elk utilize these fat reserves as their primary energy source. Hence, the survival of elk in winter is directly linked to how much food they had access to before winter and how effectively they converted it into body fat.

energy reserves

Energy reserves, primarily stored as body fat, are essential for elk to survive the winter months. This stored energy supports various metabolic functions when external food sources are scarce. Elk need a certain level of energy reserves to keep their bodily functions running smoothly, including maintaining body temperature and fuelling physical activities.
Female elk with 15% or more body fat have adequate energy reserves to last through the winter, increasing their chances of survival. Conversely, elk with lower body fat percentages face higher mortality risks because they lack the necessary energy stores. Therefore, building up energy reserves before winter is vital for the elk’s long-term survival and overall health.

metabolic functions

Metabolic functions are processes that are essential for maintaining the life of the elk. These include everything from cellular respiration to body temperature regulation. During winter, when food is scarce, maintaining these metabolic functions becomes challenging. This is where body fat and stored energy reserves come into play.
Since elk cannot forage effectively in winter due to reduced food availability, they depend on their body fat to fuel these vital functions. Without sufficient body fat, their metabolic functions may slow down or deteriorate, leading to weakened physical condition and decreased chances of survival. Hence, adequate body fat helps elk sustain their metabolic processes throughout the harsh winter months.