Ex: Vestigial Structures These are some of the most interesting homologous structures which have marginal, if any, use or importance to the organism. They are historical remnants of structures which had important functions in ancestors. Ex: the whales of today lack hind limbs, but have vestiges of pelvic and leg bones of their four-footed terrestrial ancestors. Vestigial organs are evidence of evolution - shows linkage to a past ancestor.

4. Comparative Embryology - comparison of structures that appear during development of different organisms A sign that vertebrates evolved from a common ancestor: all of them have have an embryonic stage in which gill pouches appear on sides of throat At this stage, embryos of fish, frogs, snakes, birds & apes look more alike than different. As development progresses, the vertebrates take on more distinctive features.

5. Molecular Biology- there is a common genetic code shared by all species. This genetic language has been passed along through all branches of evolution since an early form of life. Ex: DNA bases same, RNA, amino acids, use ATP for energy. Ex: In above chart- chimps & humans are less than 2% different in DNA sequences

Darwin Review: 1. Overproduction of offspring; competition for limited resources and struggle for existence 2. Individual variation 3. Differential reproductive success (natural selection). Environment (nature) determines who is fit. Those most fit survive & reproduce. Favored traits accumulate in population over generations = adaptive evolution. 1.Overproduction of spores 2.Variation in beetles

Natural Selection in Action Ex: Evolution of finches on Galapagos Islands: the islands were colonized by finches that strayed from the South American mainland, then diversified on the different islands.Adaptive evolution/radiation. Ex: Pesticides - do not create resistant individuals, but selects for resistant insects that were already present in the population Large ground finch Woodpecker finchSmall tree finch