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10.2 Darwin’s Observations KEY CONCEPT Darwin’s voyage provided insight on evolution. 10.2 Darwin’s Observations Early scientists proposed ideas about evolution. • Evolution is the biological change process by which descendants come to differ from their ancestors. • A species is a group of organisms that can reproduce and have fertile offspring. These scientists included: • Linnaeus •Lamarck •Darwin (we’ll focus here) 10.2 Darwin’s Observations Darwin observed differences among island species. • Variation is the difference in a physical trait between individuals . – Galápagos saddle backed tortoises that live in areas with tall plants have long necks and legs. – Domed tortoises that live in wet areas with short plants have shorter necks and legs. 10.2 Darwin’s Observations Darwin observed differences among island species. • Finches are another example. – Finches with strong, thick beaks live in areas with a lot of large, hard shell nuts. – Finches with delicate beaks live in areas where small insects and fruits are readily available. 10.2 Darwin’s Observations • An adaptation is a feature that allows an organism to better survive in its environment. – Species are able to adapt to their environment. – Adaptations can lead to genetic change in a population. 10.2 Darwin’s Observations Darwin observed fossil and geologic evidence supporting an ancient Earth. • Fossil evidence included: • Darwin found fossils of extinct animals that resemble modern animals. (ex: Glyptodon- a giant extinct armadillo, resembled modern armadillos) • Darwin found fossil shells from marine organisms high up in the Andes mountains.