Question

The large number of honeycreeper species on the Hawailan Islands is an example of a adaptive radiation. b genetic drift. c stabilizing selection. d horizontal gene transfer. e microevolution.

Short answer

The best answer is (a) adaptive radiation.

Step-by-step solution

Understand the Various Terms

Firstly, understand what each term means. Adaptive radiation refers to the process where organisms diversify rapidly into a multitude of new forms, particularly when a change in the environment makes new resources available. Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generations due to chance. Stabilizing selection is a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value. Horizontal gene transfer is the movement of genetic material between unicellular and/or multicellular organisms other than by the transmission of DNA from parent to offspring. And finally, microevolution is the change in allele frequencies that occurs over time within a population.

Apply the Definitions to the Example

Now, look at the definition of each term and consider which best describes the given scenario. The scenario is talking about a large number of honeycreeper species on the Hawaiian Islands. There is no indication that there was change due to chance (which might indicate genetic drift), nor that there was transfer of genetic information from another species (which might indicate horizontal gene transfer). In addition, the mere presence of a large number of species does not necessarily imply microevolution or stabilizing selection. However, the existence of a large number of species in a specific area can often be due to adaptive radiation, when a single ancestral species radiates into a variety of species to fill available ecological niches

Determine the Answer

Based on the definitions and understanding of the terms provided, the process that best describes the given scenario - a large number of honeycreeper species in the Hawaiian Islands - is adaptive radiation.

Key concepts

Evolutionary Biology

Evolutionary biology is a key field of science that examines the changes in organisms over time. These changes can be driven by various factors such as mutations, genetic drift, migration, and natural selection. Understanding evolutionary biology helps us to comprehend how species adapt to their environments and evolve into a multitude of forms. It explores the origin of species, their genetic makeup, and how they interact within ecosystems.

• Evolution explains the diversity of life on Earth.
• It accounts for why organisms are well-suited to their environments.
• It helps in conservation efforts by understanding how species might respond to environmental changes.

The study of evolutionary biology provides insights into complex processes, like adaptive radiation, which have shaped the variety of species we see today.

Speciation

Speciation is the evolutionary process by which populations evolve to become distinct species. This occurs when groups within a species become isolated and evolve differently over time due to various factors such as geographic barriers, ecological changes, or mating preferences.

• Allopatric speciation happens when a physical barrier divides a population.
• Sympatric speciation occurs without geographic separation, often through genetic divergence.

Different forms of speciation show the many ways life diversifies and adapts to new challenges. It is a foundational concept in understanding biodiversity.

Hawaiian Islands Biodiversity

The Hawaiian Islands are a hotspot for biodiversity, particularly due to their unique ecological and geographical characteristics. Sitting isolated in the Pacific Ocean, these islands offer a variety of habitats ranging from rainforests to volcanic landscapes, each providing opportunities for unique species to evolve. This isolation has made Hawaii a prime location for studying evolutionary processes like adaptive radiation.

• The islands host a significant number of endemic species found nowhere else on Earth.
• Isolation has allowed species to evolve independently into new forms.

Understanding Hawaiian biodiversity gives insight into the larger processes of island biogeography and species evolution.

Honeycreeper Species

Honeycreeper species are a prime example of adaptive radiation, as they have diversified into numerous forms found exclusively in Hawaii. Descended from a single ancestor, these birds diversified to exploit various ecological niches throughout the islands. Some species have developed specialized beaks for nectar feeding, while others evolved to feed on insects or seeds.

• Each species has adapted to specific types of food sources.
• They exhibit a wide range of colors and song varieties.

The diversification of honeycreepers is a fascinating demonstration of how isolation and environmental variety can lead to a wide range of adaptations in an animal lineage.

Natural Selection

Natural selection is a driving force of evolution, where organisms with traits better suited to their environment tend to survive and reproduce more than others. Over time, this process leads to the evolution of species as advantageous traits become more common in the population.

• It explains how and why new species have come into being.
• Adaptive traits provide survival advantages in specific environments.

Natural selection is fundamental to understanding adaptive radiation, as it explains how diverse species develop from a common ancestor by exploiting different niches in their environment.