{ Evolution Evidence revisited Fossils Fossils: Document patterns of evolution Provide physical evidence of changes in various groups of organisms Show that present day organisms are different than those of long ago Show that extinctions have occurred Biogeography Biogeography= The scientific study of the geographic distribution of species Continental drift= The slow movement of Earths continents over time Example: Island species Island species are more like the species of the nearest mainland, even if the environment is quite different, rather than like other distant islands with similar environments. Homology Homology= similarity resulting from common ancestry Homologous structures derive from a common ancestor, but may have evolved to perform different functions They are so similar that it would be very unlikely that they could have developed independently in each species. Example: Skeletal homologies-forelimbs 2014 Pearson Education, Inc. Figure Humerus Carpals Radius Human Ulna Metacarpals Phalanges WhaleCatBat Vestigial structures- a type of homologous structure. Structures or remnants of structures that no longer serve a function in an organism, but did in its ancestors Can give clues, especially in the fossil record, of the progression of evolutionary changes Examples: Tail bones Hip bones in whales Many human structures Analogous structures= similar features that occur because of convergent evolution. They have the same function, but organisms do not share a common ancestor Convergent evolution= the independent evolution of similar features in different lineages Examples- Jointed legs in mammals and insects- locomotion Direct observation = evolution in action Examples: Lactose intolerance MRSA- methicillin resistant Staph. aureus Nylon eating bacteria Others you might want to explore MDR TB- multi drug resistant tuberculosis Soapberry bugs 1.Directional selection 2.Disruptive selection 3.Stabilizing selection 4.Sexual selection Homework: Due THURSDAY 12/10 Define each Give an example of each Four modes of natural selection.