Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Evidence of Evolution Evidence of Common Ancestry (Element 1) 1. Biogeography: Geographical distribution of species. • Studying distribution of species in terms of their geography and history (where they live now or lived historically) • E.g. Ratites, tree ferns – Gondwanaland • Studies make use of present distribution, rock layers, pollen record, fossils as evidence. 2. Fossil Record: Fossils and the order in which they appear in layers of sedimentary rock (strongest evidence). • Fossil record is now remarkably complete with many species well studied. It has been discovered on average that a species lasts for 5-10 million years. Most change in the gene pool occurs early on in a species’ population, then they tend to stay stable until extinction occurs. 3. Comparative Anatomy • Parts of animals or plants are compared to show similarities and differences. Homologous structures Structures that may have very different form and function may have an underlying similarity, resulting from a common ancestry. E.g. Mammal limbs Check out http://evolution.berkeley.edu/evolibrary/ article/0_0_0/homology_01 Analogous structures Have the same function but a different ancestry. • Vestigial organs – Organs that have become reduced or lost their function. 4. Embryology: Study of structures that appear during embryonic development. The early embryo stages of vertebrates (fish, reptiles, amphibians, birds, mammals) are all similar even though the adults are very different. • The more similarities there are chemically the closer the organisms are thought to be. • Geneticists study percentage similarity between DNA sequences of species. • Cytochrome-C is a protein involved in cell respiration. Scientists have compared the sequence of amino acids in many different species for this protein. 5. Molecular Biology: DNA and proteins • Species that have more similar patterns of amino acids are more closely related. Number amino acids in Cytochrome-C sequence different to humans Chimps 0 Dog 13 Duck 17 Horse 17 Kangaroo 12 Moth 36 Penguin 18 Rabbit 12 Rhesus monkey 1 Tuna 31 turtle 19