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Evolution Occurs in Patterns Macroevolution is a large-scale evolutionary change, that usually occurs over long periods of time, and leads to formation of a new species. There are four major evolutionary patterns: 1. Divergent evolution a. Adaptive radiation b. Allopatric speciation c. Sympatric speciation 2. Convergent evolution 3. Coevolution 4. Extinction 1. Divergent Evolution Divergent evolution describes evolution toward ______________________________________. a. Adaptive radiation – when an ________________ species undergoes _______________ changes in response to ________________ changes, resulting in many _____________ species. Like Galapagos finches, the descendent species are still finches but adapted to a wide range of environments. b. Allopatric speciation – a starting population is ______________________________ and over time the separated groups can evolve into _______________________________. c. Sympatric speciation – a new species forms ____________________ the ancestor species. This usually occurs with ______________________ changes in plants. 2. Convergent Evolution Convergent evolution occurs when _____________ ________________________________ Each species has _______________ adapted to similar environmental conditions. Evolving wings lets an animal catch prey and escape predation. This often results in _________ structures like the wings. 3. Coevolution Coevolution occurs when adaptations in one species cause ______________________________________________ _____________________________. The evolutionary paths of predators and prey are connected. When the predator runs faster so do does the prey or both species become extinct. Many hosts and parasites coevolve. Many plants can only reproduce if their __________________ _________________________________ 4. Extinction When the Burgess Shale fossils were first examined by Charles Walcott he mistakenly thought that all the ancient fossils would have descendent species alive today. Some ________________________ _______________________. We now know that many of the Burgess Shale fossils represent extinct species. What known species could Walcott possibly have connected to this fossil? The Rate of Evolutionary Change Darwin and many other evolutionary biologists assumed evolution would always occur at a _______ ___________________________. In 1972 Stephen Jay Gould and Niles Eldredge suggested an alternative model, _________________________________. They stated that evolutionary history has many _______________________________________________________ in species. This equilibrium can be followed by a _______________________ with _________ evolutionary changes as species adapt to a __________ _____________________ climate, geology or environment. Evidence now shows that both models of evolutionary change are ____________________________ . Evolution occurs in patterns What are the important patterns of evolution? Macroevolution is a large-scale evolutionary change, that usually occurs over long periods of time, and leads to formation of a new species. There are four major evolutionary patterns: 1. Divergent evolution a. Adaptive radiation b. Allopatric speciation c. Sympatric speciation 2. Convergent evolution 3. Coevolution 4. Extinction 1. Divergent Evolution Divergent evolution describes evolution toward different traits in closely related species. a. Adaptive radiation – when an ancestral species undergoes rapid genetic changes in response to environmental changes, resulting in many descendent species. Like Galapagos finches, the descendent species are still finches but adapted to a wide range of environments. b. Allopatric speciation – a starting population is geographically divided and over time the separated groups can evolve into different species. c. Sympatric speciation – a new species forms beside the ancestor species. This usually occurs with polyploidy changes in plants. 2. Convergent Evolution Convergent evolution occurs when similar traits arise in unrelated species. Each species has independently adapted to similar environmental conditions. Evolving wings lets an animal catch prey and escape predation. This often results in analogous structures like the wings. 3. Coevolution Coevolution occurs when adaptations in one species cause further adaptations in a mutualistically related species. The evolutionary paths of predators and prey are connected. When the predator runs faster so do does the prey or both species become extinct. Many hosts and parasites coevolve. Many plants can only reproduce if their flowers match a specific pollinator. 4. Extinction When the Burgess Shale fossils were first examined by Charles Walcott he mistakenly thought that all the ancient fossils would have descendent species alive today. Some fossils are for extinct species. We now know that many of the Burgess Shale fossils represent extinct species. What known species could Walcott possibly have connected to this fossil? The Rate of Evolutionary Change Darwin and many other evolutionary biologists assumed evolution would always occur at a steady rate called gradualism. In 1972 Stephen Jay Gould and Niles Eldredge suggested an alternative model, punctuated equilibrium. They stated that evolutionary history has many long periods with little evolutionary change in species. This equilibrium can be followed by a shorter time with many evolutionary changes as species adapt to a rapidly changing climate, geology or environment. Evidence now shows that both models of evolutionary change are occurring together.
