Evidence of Evolution • Evolution is a continuous process of gradual modifications or changes in organisms. • Patterns of evolution can be detected by viewing species in relation to one another. • Evidence of evolution can be found through different fields of science.
Fossil Evidence Bones, Molds, Casts, Amber
Fossil Record • Fossils in the lower layers were present on earth before fossils in the upper layers. • Law of superposition. • Descent with modification (Darwin’s first law of evolution). • Fossils show similarities and differences.
Biogeography • Involves the mapping and study of the patterns of distribution of fossils and living organisms within and between the world's regions.
Embryological Development • Compares the similarities of developing vertebrate embryos indicating common ancestry.
Homologous and Analogous Structures • Modified structure that is seen among different groups of descendents • Provide strong evolutionary relationships • Shows that several different species have one common ancestor • Also known as comparative anatomy
Comparative Anatomy • Wings are analogous, though bones are homologous
Homologous Structures • Differences – appearance and function • Similarities – skeletal structure, derived from same embryological development • Forelimbs of the following organisms are homologous because they have the same internal skeletal structure even though they look different externally and have different functions.
Analogous Structures • Similarities – function and appearance • Differences – embryological development and internal structure • Butterfly wings and bird wings are analogous because they have the same function and appearance even though they have a different internal structure and develop differently.
Vestigial Structures (useless feature) • Body structure that is greatly reduced in function that may have been useful to an ancestor. • Ex: human appendix, whale femur, coccyx ear muscles, wisdom teeth
Scientists can compare DNA sequences, amino acids sequences or proteins to view similarities and differences among organisms. Biochemistry (Similarities in Macromolecules) • The amino acid sequence in human hemoglobin and gorilla hemoglobin differ by one amino acid, while human and frog hemoglobin differs by 67 amino acids.
Mechanisms/Patterns of Evolution • Divergent Evolution -occurs when isolated populations of a species evolve independently • Ex: Different food available in different habitats (Galapagos Finches) -Eventually, separated populations will become so different they can no longer interbreed (results in new species)
Mechanisms/Patterns of Evolution • Convergent Evolution -When different species with different ancestors develop similar characteristics -Environment selects similar phenotypes -Ex: Sharks and porpoises (fish vs. mammal) develop streamlined bodies and fins (analogous structures)
Mechanisms/Patterns of Evolution • Coevolution - two or more species evolve in response to each other • Flowers & pollinators