Question

page 2 and 3: (after reading pg 474-475)

• darwin’s three patterns of biodiversity (green headings)
• for each pattern include:
• an observation/example
• how did darwin discover this idea?
• darwin’s conclusion after returning home, thus far (pg 476)

Explanation:

This covers Darwin's three core biodiversity patterns, with details on observations, his discovery process, and post-voyage conclusions:

1. Pattern 1: Species vary globally

• Observation: Flightless rhea in South America vs. ostrich in Africa; both occupy grassland niches but are distinct species on separate continents.
• Discovery: Noted these similar, non-overlapping species across distant, ecologically matching regions during his voyage on the HMS Beagle.
• Conclusion: Species are uniquely adapted to their specific geographic regions, and these differences arose from long-term isolation and adaptation.

1. Pattern 2: Species vary locally

• Observation: Galápagos finches had different beak shapes on nearby islands; some suited for hard seeds, others for insects or nectar.
• Discovery: Studied finches and tortoises across Galápagos islands, noting subtle trait differences tied to each island's food sources and habitat.
• Conclusion: Local environmental pressures shape species traits, leading to distinct populations of closely related organisms in nearby areas.

1. Pattern 3: Species vary over time

• Observation: Fossils of giant extinct glyptodons in South America closely resembled living armadillos in the same region.
• Discovery: Compared fossil specimens collected during the voyage to living species in the same geographic areas.
• Conclusion: Living species share common ancestors with extinct species in their region, suggesting species change and evolve over long periods.

Answer:

1. Species Vary Globally

• Observation: Flightless rhea (South America) and ostrich (Africa) fill identical grassland roles but are distinct species.
• Discovery: Noted matching niches, distinct species across distant continents on the HMS Beagle.
• Conclusion: Species adapt uniquely to their geographic regions over time.

1. Species Vary Locally

• Observation: Galápagos finches have island-specific beak shapes for local food sources.
• Discovery: Studied trait differences in finches/tortoises across Galápagos islands.
• Conclusion: Local environments drive trait changes in closely related species.

1. Species Vary Over Time

• Observation: Extinct glyptodon fossils match living South American armadillos.
• Discovery: Compared voyage fossils to local living species.
• Conclusion: Living species descend from regional extinct ancestors, proving evolution over time.