The population size of mountain pine beetles in the American Northwest has long been held in check by freezing temperatures during the winters. As winters warm, populations of pine beetles are increasing, killing whitebark pine forest. Grizzly bears rely on the nuts of whitebark pine trees. Do you think climate change is affecting the fitness of the grizzly bear population?


a. No, because climate change is affecting the beetles, not the bears.
b. Yes, because climate change is decreasing the food supply of the bears, which means they will be less strong.
c. Yes, because climate change is decreasing the food supply of the bears, which is likely to reduce their ability to survive or reproduce.

Verified step by step guidance

1. Identify the key components of the problem: climate change, mountain pine beetles, whitebark pine trees, and grizzly bears.
2. Understand the relationship between these components: Warmer winters lead to increased pine beetle populations, which in turn kill more whitebark pine trees.
3. Analyze the impact on whitebark pine trees: As the number of these trees decreases, the availability of their nuts, a food source for grizzly bears, also decreases.
4. Consider the definition of biological fitness, which includes an organism's ability to survive and reproduce in its environment.
5. Evaluate how the reduced availability of a key food source (whitebark pine nuts) due to climate change could affect the grizzly bears' ability to survive and reproduce, thus impacting their fitness.

Key Concepts

Climate Change and Ecosystem Dynamics

Climate change refers to long-term alterations in temperature and weather patterns, which can significantly impact ecosystems. In this context, warming winters allow mountain pine beetle populations to thrive, leading to the decline of whitebark pine trees. This shift in the ecosystem can have cascading effects on species that depend on these trees, such as grizzly bears, highlighting the interconnectedness of climate factors and biological communities.

Food Supply and Animal Fitness

Animal fitness is defined as an organism's ability to survive and reproduce in its environment. A stable food supply is crucial for maintaining the health and reproductive success of a species. In the case of grizzly bears, the decline of whitebark pine due to beetle infestations reduces their food sources, which can lead to decreased strength, survival rates, and reproductive success, ultimately affecting the population's fitness.

Trophic Interactions

Trophic interactions describe the feeding relationships between organisms in an ecosystem, often illustrated through food webs. Grizzly bears are primary consumers that rely on the nuts of whitebark pine trees, which are affected by the population dynamics of mountain pine beetles. Changes in one trophic level, such as the decline of a food source, can disrupt the entire food web, impacting the health and viability of dependent species like the grizzly bear.