Which of the following observations helped Darwin shape his concept of descent with modification? a. Species diversity declines farther from the equator. b. Fewer species live on islands than on the nearest continents. c. Birds live on islands located farther from the mainland than the birds' maximum nonstop flight distance. d. South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.

Key Concepts

Descent with Modification

Descent with modification is a key principle of Darwin's theory of evolution, which posits that species evolve over time through gradual changes. This concept suggests that all living organisms share a common ancestor and that the diversity of life arises from adaptations to different environments. It emphasizes the role of natural selection in shaping these modifications, leading to the emergence of new species.

Biogeography

Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. It provides insights into how species are related to their environments and how geographical barriers can influence evolutionary processes. Observations from biogeography, such as species similarities on islands versus continents, support the idea of descent with modification by illustrating how isolation and environmental factors drive diversification.

Natural Selection

Natural selection is the mechanism by which individuals with advantageous traits are more likely to survive and reproduce, passing those traits to the next generation. This process leads to the adaptation of species to their environments over time. Darwin's observations of variations among species, such as those found in different habitats, helped him formulate the idea that natural selection drives the evolution of species through descent with modification.