Name: Problem 4 (10 pts). You are studying an island with an unusually high numb

Question

Name: Problem 4 (10 pts). You are studying an island with an unusually high number of Pisonia trees. You notice that a species of local seabird has unusually oily feathers, and seems like it gets tangled in the trees less often. You therefore plan an experiment to test whether natural selection for avoiding Pisonia entanglement is driving increased oiliness of this bird's feathers in the local seabird population. You have access to banded seabirds, seabird feathers, an extensive collection of more than 100 seabirds that died in the last year due to Pisonia entanglement, a seabird breeding facility, an established biochemical procedure for quantifying feather oilyness and Pisonia seeds collected from the island. i. List the conditions that are necessary and sufficient for evolution by natural selection. Underline each condition, briefly explain why it is necessary for evolution by natural selection, then give an example of why it is necessary for evolution by natural selection in the specific context of Pisonia seed stickiness. ii. Describe an experiment or analysis you could use to test whether each condition you listed is present.

Explanation / Answer

I)

There are basic tenets of natural selections also called conditions which go as follows

1. more individuals are born than the nature can support.

2. individuals within a given population are variable

3.  variations are heritable changes.

4. individuals with heritable traits fitting the environment will survive.

Variation is a major characteristic of every population and this variations help in competition between the individuals of the population. In every generation the population multiplies at a level that becomes diificult for the nature to handle so nature has evolved this method of selection. in this process individuals with fitting traits to the environment will only be able to survive and reproduce in that situation.thus the future population will have better off-spring that are evolved to survive in that environment.

Pistonia grandis is a mysterious tree which grows in the island with high concentration of guano chemical compounds. germination of seeds and hence multiplication of the tree population is a task for the tree. For the purpose of dispersal of its seeds to neighbouring islands and far places the tree has developed a mechanism of generation of highly sticky resin loaded seeds that stick on to the seabird feathers and get dispersed when the birds carryout their preening of feathers. so the pistonia trees have evolved with the variation in the seed property that has allowed them to compete with other tree species of the island and helped it to get dispersed and survive in the guano soil and emerge out as a succeful fittest surviving tree population in that island. However its natural selection has a negative accidental side-effect of killing the seabird by entanglement due to trapping of feathers in excesively sticky seeds. Excessive stickiness of seeds has proved to be helpful for the seeds in staying bound to the bird feathers for a longer time before reaching its ambient soil.

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