Macro Evolution: Allopatric Speciation
Looks Can Be Deceiving!
• These meadowlarks look very similar yet they are not the same species.
Definition of Species
• A species is a group of interbreeding organisms that produce viable, fertile offspring in nature. • Members of a species will interbreed with one another but not other organisms outside of the species. (At least most of the time!)
Macroevolution vs. Microevolution
• Macroevolution is evolution on a scale of separated gene pools. • Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population.
Macroevolution Part II: Allopatric Speciation
• By contrast, these brittle stars look very different from one another, but they are the same species.
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Asexual Species
Asexual Species Even though asexual groups do not exchange genes, they do form recognizable groups. Most have evolved from a sexual species. Only those whose phenotype is best adapted to the environment, will continue to survive. However, it makes them less adapted to environmental change. Dandelions are asexual. The pollen is sterile and the egg is diploid.
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Ring Species
• A ring species is a connected series of neighboring populations, each of which can interbreed with closely sited related populations, but for which there exist at least two "end" populations in the series. • These end populations are too distantly related to interbreed, though there is a potential gene flow between each "linked" species. • Such non-breeding, though genetically connected, "end" populations may coexist in the same region thus closing a "ring".
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Ring Species
• Ensatina escholtzi is a salamander ring species that has a range along the coast and inside range of California. • All along this range, the salamanders interbreed, but the salamanders on the ends of the ring do not
• These meadowlarks look very similar yet they are not the same species.
Definition of Species
• A species is a group of interbreeding organisms that produce viable, fertile offspring in nature. • Members of a species will interbreed with one another but not other organisms outside of the species. (At least most of the time!)
Macroevolution vs. Microevolution
• Macroevolution is evolution on a scale of separated gene pools. • Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population.
Macroevolution Part II: Allopatric Speciation
• By contrast, these brittle stars look very different from one another, but they are the same species.
2
3
4
Asexual Species
Asexual Species Even though asexual groups do not exchange genes, they do form recognizable groups. Most have evolved from a sexual species. Only those whose phenotype is best adapted to the environment, will continue to survive. However, it makes them less adapted to environmental change. Dandelions are asexual. The pollen is sterile and the egg is diploid.
5
Ring Species
• A ring species is a connected series of neighboring populations, each of which can interbreed with closely sited related populations, but for which there exist at least two "end" populations in the series. • These end populations are too distantly related to interbreed, though there is a potential gene flow between each "linked" species. • Such non-breeding, though genetically connected, "end" populations may coexist in the same region thus closing a "ring".
6
Ring Species
• Ensatina escholtzi is a salamander ring species that has a range along the coast and inside range of California. • All along this range, the salamanders interbreed, but the salamanders on the ends of the ring do not