Question

You are studying finches on the Galápagos Islands. What evidence do you need to show common descent and adaptation to the environment? (pages \(518-23\) )

Short answer

To show common descent and adaptation among finches on the Galápagos Islands, gather evidence by following these steps: (1) Observe and document morphological traits of different finch species, such as beak size and shape, and identify patterns between these traits and respective food sources. (2) Collect and analyze DNA samples from each species, comparing their genetic makeup to identify common descent and divergence. (3) Investigate different habitats on the islands and assess their correlation with specific morphological traits in finches. (4) Study fossil evidence of ancestral finch species to understand their evolution and adaptation over time. (5) Combine the morphological, genetic, and fossil data to create a phylogenetic tree showing the relationships and common ancestry among the finch species.

Step-by-step solution

Morphological Variation

Morphological variation is the differences in the shapes, sizes, and structures of organisms. Observe and document the various morphological traits of finches found on the Galápagos Islands, such as beak size and shape, body size, and feather coloration. Take photographs and measurements of each finch species. Analyze the morphological variations and try to identify patterns and correlations between beak shapes and sizes and their respective food sources.

Genetic Evidence

Collect samples of DNA from each finch species found on the islands. You can do this by capturing a specimen from each species and extracting the DNA from the blood or feathers. Analyze the DNA sequences and compare them between the different species of finches. Look for similarities and differences in their genetic makeup, which could indicate common descent and divergence.

Habitat Analysis

Investigate and document the different habitats and ecological niches found on the Galápagos Islands. This includes the types of trees, plants, and other food sources available. Assess the specific diets of each finch species, discovering and noting their preferred food sources and their foraging behavior. Examine the correlation between the finches' habitats and their respective morphological traits, such as beak size and shape.

Fossil Record

Search for fossil evidence of ancestral finch species. Study these fossils to gain insight into how the finches have evolved over time and adapted to the unique environment of the Galápagos Islands. Compare the fossils to both modern-day finches and mainland species to understand the process of divergence and adaptation.

Phylogenetic Analysis

Compile the morphological, genetic, and fossil data and create a phylogenetic tree or cladogram that shows the relationships and common ancestry among the different finch species found on the Galápagos Islands.