All of the following are niches. Which one is a fundamental niche? A population of ants can create a huge ant mound, but does not attempt to do so because birds keep destroying it. A population of fish can live in any depths of water, but some only go deep when it is time to eat. A population of squirrels enjoy a variety of nuts; however, they only eat nuts from the trees that grow in its ecosystem. A population of birds can build nests at any altitude; however, they build low to the ground due to strong winds up high.

## Step 1<br />The concept of a "niche" in ecology refers to the specific role or function of an organism within an ecosystem. A "fundamental niche" is the full potential range of physical and biological conditions under which an organism can exist. This is in contrast to a "realized niche," which is the actual conditions under which the organism lives, often limited by competition or predation.<br /><br />## Step 2<br />Let's analyze each option:<br /><br />1. A population of ants can create a huge ant mound, but does not attempt to do so because birds keep destroying it. This describes a realized niche, as the ants' potential behavior (building a mound) is limited by the presence of birds.<br /><br />2. A population of fish can live in any depths of water, but some only go deep when it is time to eat. This also represents a realized niche, as the fish's potential depth range is limited by their feeding habits.<br /><br />3. A population of squirrels enjoy a variety of nuts; however, they only eat nuts from the trees that grow in its ecosystem. This is a realized niche, as the squirrels' diet is limited by the types of trees available in their ecosystem.<br /><br />4. A population of birds can build nests at any altitude; however, they build low to the ground due to strong winds up high. This is a realized niche, as the birds' nesting behavior is limited by environmental factors (strong winds).<br /><br />## Step 3<br />The question asks for the fundamental niche among the given options. A fundamental niche would be the one where the organism's behavior or characteristics are not limited by external factors such as competition or predation. In this case, the second option, where the fish can live in any depths of water, represents a fundamental niche. This is because it describes the full potential range of conditions under which the fish can live, without any limitations imposed by external factors.