Evidence of Evolution Part 3
Darwin’s third line of evidence came from bio-geography., the study of the geographic distribution of plants and animals.
- Darwin's “Law of Succession” contents that living organisms in an area most closely resemble fossils found in the same location. Oceanic islands are missing many types of animals. Hawaii has no native mammals, reptiles, or amphibians. These animals as well as freshwater fish, are also missing on St. Helena, a remote oceanic island in the middle of the South Atlantic Ocean. The native groups that are present on these islands - mainly plants, insects, and birds consist of numerous similar species. The Galapagos archipelago as 23 species of birds, of which 14 are finches. No where in the world will you find an area in which 2/3 of the birds are finches. The animals and the plants inhabiting oceanic islands bear the greatest similarity to species found on the nearest mainland.
- The kinds of organisms found on oceanic islands are those that can get there easily. Insects and birds can fly to islands, and the seeds of plants can be transported by winds, ocean currents, or in the stomachs of birds.
