Speciation and Species Concepts

Speciation and Species Concepts - Speciation and Species...

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Speciation and Species Concepts Vocabulary Microevolution changes in allele frequencies within a population over time Macroevolution the broad pattern of evolution over long periods of time Biological Species Concept a species is a population that is or has potential to produce viable offspring Prezygotic barriers block fertilization from occurring by blocking mating of individuals or by blocking fertilization of an egg after mating Postzygotic barriers blocking a hybrid of two species from developing or mating Morphological species concept a species is made up of a population that has the same body shape and structural features Allopatric speciation a speciation event that was triggered by a geographical separation of a population Sympatric speciation a speciation event that occurs in a population that lives in the same geographic region Hybrid zone an area which members of different species meet, mate, and produce offspring Adaptation and Natural Selection As you remember, “no selection” is one of the 5 conditions for the Hardy-Weinberg to be true, for evolution to not occur. So when the population faces selective pressures, it evolves in response to those pressures. In this exercise, we will look at the effect of different selective pressures and how they change the genetic frequencies of the population. You are a predator and your diet consists primarily of colored beads. The color of the beads is derived from one gene, of which a homozygous dominant (RR) gives the green
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phenotype, a heterozygote (Rr) gives the mint phenotype, and the homozygous recessive (rr) gives the blue phenotype. Calculate the initial allele and genotype frequencies for the population of beads Predict the frequencies for the next generation if the Hardy-Weinberg equilibrium holds true. Now you get to hunt and “eat” your favorite color of beads. Calculate the allele and genotype frequencies after you eat your prey. Are they different than your Hardy-Weinberg prediction? Why? What caused the change in allele and genotypic/phenotypic frequencies? If this selection continues for many generations, what will happen to the allele and genotypic/phenotypic frequencies? Now, a mutation in the beads’ genome has made the green phenotype (RR) poisonous,
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Speciation and Species Concepts - Speciation and Species...

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