Alternative transcript:

fossil record provides a series of changes that occurred over time; comparison of anatomical characteristics reveals shared ancestry/common ancestry - Molecular Biology- comparing DNA/gene or protein sequences from organisms (closely-related organisms will have similar DNA, RNA, and protein (amino acid) sequences). This also gives evidence of a common ancestor Embryology- embryos of different vertebrates look alike in their early stages, giving the superficial appearance of a relationship Comparative anatomy-Homologous structures - structures (body parts/anatomy) which are similar in different species because the species have common descent. They may or may not perform the same function. An example is the forelimb structure shared by cats and whales. Vestigial structures are anatomical features that are still present in an organism (although often reduced in size) even though they no longer serve a function. Whales, which evolved from land mammals, have vestigial hind leg bones in their bodies. -Biogeography- patterns of past evolution are found in the natural geographic distribution of related species, similarity of endemic island species to nearby mainland species. Eocene Oligocene Miocene Pliocene Pleistocene Recent The traits that help an organism survive in a particular environment are "selected" in natural selection. Overtime, natural selection results in changes in the inherited characteristics of a population. These changes increase species fitness (survival rate). Conditions required for natural selection: There is variation in traits. For example, some beetles are green and some are brown. There is differential reproduction. Since the environment can't support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown (camouflage with the bark of trees) beetles do. There is heredity. The surviving brown beetles have brown baby beetles because this trait has a genetic basis. End result The advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. Eventually, all individuals in the population will be brown. Foreleg Tooth Miohippus Equus Pliohippus Merychippus 22 Eohippus 1 3 million yr. ago CO 7 million yr. ago 25 Million yr ago 40 million yr ago 60 million yr ago Fossil Evidence - Horse