1)Explain why the plants artificially selected for increased reproductive capaci
ID: 102411 • Letter: 1
Question
1)Explain why the plants artificially selected for increased reproductive capacity will not necessarily show increased survival ability. (This question is related to natural selection)
2)The lobster is a well-known ocean dwelling crustacean which is especially popular in fine seafood restaurants. The carapace length of a lobster at reproduction (a measure of body size) is determined solely by environmental conditions, and ranges from 4 to 12 cm. The minimum carapace length a lobster must have to be captured by a lobster fisher (and end up on your dinner plate) is 9 cm.
a. Would you expect natural selection to act on carapace length in lobsters? Why or why not?
b. Assume that you took a sample of lobster larvae from the population before humans ever thought of eating them, grew them to maturity and measured their carapace length. After four decades of intensive fishing, you repeated the exercise. Would you expect the second sample to show an increase, a decrease or no change in mean carapace length? Explain your answer.
Explanation / Answer
Please find the answers below:
Answer 1: When a plant species is specifically selected for traits such as increased reproductive success, a trait which is independent of the fact whether the selected plant will be able to survive or not. This can be understood by considering natural selection. Here, the plant has been naturally selected for enhanced reproductive success which means that either the earlier qualities of plants were not able to survive or they were too less in number to signficantly contribute to the eco-system. Thus, the qualities of plants which showed increased reproductive capacities were gradually naturally selected since they could produce more number of offsprings which enhanced their population size in the environment. However, it is not at all necessary that this increase in population size would lead to increase in survival chances of the plants as well since survivability of a plant depends upon environmental factors such as availability of nutrients, predators and presence of herbivores etc.
Answer 2:
Part a) According to the information, the size of the lobster carpace is solely dependent upon environmental factors. However, excessive human encroachment and predation will lead to decrease in lobster population having shorter carapace sizes. This is because predation of the lobster with longer carapaces will gradually lead to decrease in population size of the lobsters. Thus, natural selection under the force of human encroachment will definitely play a critical role in the size-selection of lobster population.
Part b) The duration of four decades was incorporated with intensive fishing and thus the negative impact of human predation and excessive encroachment on lobsters with carapace sizes nearly 9cm will decrease. This is a classical example of natural selection where artificial forces lead to selection of a particular phenotypic feature in the organisms and thus select them for maintaining survivability of the population.
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