Why are there so many different species of honeycreeper living on the Hawaiian Islands?

• A. They are the result of hybridization between unrelated bird species.
• B. They migrated seasonally from the mainland and returned each year.
• C. They evolved through adaptive radiation after colonizing the islands, filling different ecological niches.
• D. They were all introduced by humans from different parts of the world.

Answer: (C)

Verified step by step guidance

1. Understand the concept of adaptive radiation: Adaptive radiation occurs when a single ancestral species diversifies into multiple species, each adapted to a unique ecological niche. This process is often driven by geographic isolation and the availability of diverse habitats.
2. Recognize the unique environment of the Hawaiian Islands: The islands are isolated and have a variety of ecological niches, such as different elevations, vegetation types, and food sources. This isolation prevents gene flow from mainland species and promotes speciation.
3. Identify the role of colonization: When the ancestral honeycreeper species arrived on the Hawaiian Islands, it encountered an environment with little competition and abundant resources, allowing it to diversify into multiple species.
4. Examine ecological niches: Each honeycreeper species evolved specialized traits, such as beak shapes, to exploit specific food sources (e.g., nectar, seeds, insects) and habitats, reducing competition among species.
5. Rule out incorrect options: Hybridization between unrelated bird species, seasonal migration, and human introduction do not explain the diversity of honeycreepers. The correct explanation is adaptive radiation, driven by ecological opportunities and isolation on the Hawaiian Islands.