Which of the following best illustrates an example of an ecological niche?

An ecological niche encompasses the role and position a species has within its environment, including all the interactions it has with biotic and abiotic factors. The first choice— a bird species that only eats seeds—best illustrates this concept because it describes not just the diet of the bird, but the specific way it interacts with its ecosystem. This includes its method of foraging, the types of habitats it occupies, its relationships with other species (like plants that produce seeds), and how it impacts the ecosystem as a seed consumer and potentially seed disperser.

In contrast, the other options don’t fully capture the multifaceted nature of an ecological niche. A body of water's temperature refers to a physical characteristic, which, while important to organisms living in that environment, does not represent a specific organism's role or interactions. A large forest ecosystem describes a habitat or community but lacks the focus on a specific species' functional role. Finally, cells dividing through mitosis pertains to a biological process rather than an organism's role within an ecological context. Thus, the bird species illustrates a clear example of an ecological niche, detailing its specific place and function within its ecosystem.