1. Compare and contrast micro- and macroevolution. 2. For the following situatio
ID: 70118 • Letter: 1
Question
1. Compare and contrast micro- and macroevolution.
2. For the following situations, state the likely outcome of the hybrid zone described.
a. Two species of butterfly live on Haleakal; the silversword butterfly lives at higher elevations and the rainbow eucalyptus butterfly lives at lower elevations. A thin hybrid zone between the two butterflies exists. The hybrids produced are more successful then their parent species during el niño years when weather conditions are warmer but during normal years, the hybrids are not as successful as their parent species.
b. Two different species of rockmover cichlid fishes live in Lake Victoria but they also reside in different lakes where the other species are not found. In allopatric populations, the males resemble each other but in sympatric populations the males look very different. Every so often, allopatric populations are able to come into contact with one another through flooding and hybrids are formed but in sympatric populations, the two species never form hybrids.
c. In the Artic National Wildlife refuge (ANWAR) two populations of reindeer: Northern Territory and Southern Territory Reindeer. A large glacier isolated the two populations but in the last 50 years, the glacier has retreated to a point where the populations can access mutual feeding grounds. As a result they have started to interbreed more frequently.
Explanation / Answer
1. Compare and contrast micro- and macroevolution. Mutation, genetic drift, selection and gene flow changes the allelic frequencies within a population. This change in allelic frequencies over a period of time in a population relates to microevolution known as variation or adoption. The changes occur over a short period of time with relatively less changes compared to macro evolution. The changes occur below the level of a species and results in varieties within a type and within a group. But the descendent is true type of its ancestors. Microevolution follows natural or artificial selection. Ex. Most of the insect populations showing resistance to DDT and many germs becoming resistant to antibiotics. The process of speciation, origin of new organisms from previously existing organisms but different from their ancestors relates to macro evolution and the changes occurs above the level of species. The macroevolution refers to major evolutionary changes over a period of time. Ex. descendence of fishes from invertebrates and whales from land mammals. Horizontal micro evolutionary changes might lead to vertical macro evolutionary changes.
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