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Define the difference(s) between Microevolution and Macroevolution. Give an example of each to support your discussion.
Microevolution is defined as evolutionary change within a species or small group of organisms, especially over a short period. Microevolution as an example is the resistance of bacteria to certain antibiotics, such as the evolution of gonorrhea into super-gonorrhea. The mutation of this bacteria resulted it into a super bacterium that build a strong resistance against antibiotics as a survival technique.
Macroevolution is an evolutionary change within a species over a long-time period. Macroevolution refers to major evolutionary changes over time and the origin of new species from a previously existence species, giving birth to a whole new species. An example that illustrates macroevolution is the different taxonomic groups within the primates.
As you can see microevolution happens on a small scale resulting in small changes within a species whereas, macroevolution is on a large scale of evolutionary changes resulting into formation of a new species.
In this chapter, you were introduced to the 4 evolutionary processes. What are each of these processes and provide an example of each.
Natural selection is responsible for evolutionary changes in organisms. In every generation within a species genetic mutation can occur. This is when heritable variation lead to differential success in survival and reproduction, which can increase the frequency of alleles that contribute to success in survival and reproduction. For example, a bright white rabbit in a wooded habitat will stick out visually to predators whereas a grey or brown rabbit has the phenotypic advantage and less likely will be caught by a predator due to their ability to blend into their environmental habitat. This is known as Directional Selection due to selective pressure that gives certain phenotypes an advantage or disadvantage.
Unlike Natural selection, mutation is the ultimate source of new variations within a species, by creating new alleles which increases genetic diversity. This occurs randomly in respect to fitness of the affected alleles. When alterations occur in the DNA of an organism, new alleles are created for a gene. For example, people with who are lactose intolerant can’t digest lactose which is the sugar base found in milk, this is normal as a grown adult. Fully grown adults who are lactose tolerant is a result of a DNA mutation that caused a gene variation to continue to produce the enzyme lactase which breaks down the sugar lactose in the digestive system after infancy.
Genetic drift occurs when a sudden reduction in a population size takes place and random changes in gene frequencies from one generation to the next occurs. This can be due to disaster or disease and out migration. Genetic drift has a greater impact on small populations than large ones. For example, such an environmental catastrophic disaster occurs that causes a species to reduce significantly otherwise known as the bottleneck effect.
Genetic flow is a result of gene exchange when individuals of one populations leave and join another population and breed. This will result in a sudden expansion and may be responsible for a marked change in allele frequencies. An example would be such as the domesticated reindeer in western Alaska who escaped and mates with migrating caribou, this adds the alleles for short legs and tame behavior.