1- Tasmanian devils once inhabited most of present day Australia, but only an is
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Question
1- Tasmanian devils once inhabited most of present day Australia, but only an isolated population on the island of Tasmania has survived to present day. What process has likely affected Tasmanian devils as a result of this history?
2- Considering the principles of mutation, natural selection, and genetic drift do you expect adaptive evolution to occur more rapidly in small or large populations? What about non adaptive evolution? For each answer, please explain your reasoning.
3- In a natural population of outbreeding plants, the variance of the total number of seeds per plant is 16. From the natural population, 20 plants are taken into the laboratory and developed into separate true-breeding lines by self-fertilization
Explanation / Answer
Tasmanian devils once inhabited most of present day Australia, but only an isolated population on the island of Tasmania has survived to present day. What process has likely affected Tasmanian devils as a result of this history?
a genetic bottleneck
2- Considering the principles of mutation, natural selection, and genetic drift do you expect adaptive evolution to occur more rapidly in small or large populations? What about non adaptive evolution? For each answer, please explain your reasoning.
Adaptive evolution will occur more rapidly in a large population. Adaptation occurs through the process of natural selection, which is more effective in large populations because there are more mutations (some may be beneficial) and the effects of random genetic drift are relatively weak compared to a small population. Non-adaptive evolution would be more likely in a small population because genetic drift is stronger. Genetic drift is the result of random sampling error, without regard to the fitness effects of alleles. Thus, in a small population, slightly deleterious alleles may be fixed by drift.
3- In a natural population of outbreeding plants, the variance of the total number of seeds per plant is 16. From the natural population, 20 plants are taken into the laboratory and developed into separate true-breeding lines by self-fertilizationwith selection for high, low, or medium number of seedsfor 10 generations. The average variance in the tenth generation in each of the 20 sets is about equal and averages 5.8 across all the sets.
Repeated selfing results in homozygosity so plants within each of the 20 sets were genetically identical. Therefore the variance must have been envirinmental variance and this can be subtracted from the population variance in order to obtain genetic variance.
H2 = (16 - 5.8)/16 = 10.8/16 = 68%
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