Question

After reading the following prompt, propose a scientific study to determine whether or not evolution is occurring. In your answer, include the type of data you will need to collect, and the calculations you will use to figure out if the mechanism at work is natural selection or genetic drift. Is this population genetics research or quantitative genetics research?

Case #2: In elephants, trunks comes in a variety of lengths such that this trait exhibits a continuously variable phenotype: long, short, and everything in between. The size of an elephant’s trunk is determined by several genes, but it can also be influenced by environmental factors. The average trunk length in a population of elephants 20 years ago was 1.4 meters.

Answer 1

Since the trunk size is not of defined proportions ,most probably it's the action of quantitative inheritance. So there must be multiple genes affecting the size of the trunks. It can also be influenced by environmental factors. For determining whether it's the action of natural selection or genetic drift we must understand these terms.

Natural selection- It's the selection of a particular type of trunk due to reproductive success.

Genetic drift- It's the selection of a particular type of of trunk just by chance.

So in order to prove the selection of trunk is by natural selection we have to collect the data correlating trunk size and mating success along with mate choice. If according to the data there is a relationship between trunk size and mating success then it must be a natural selection.

However it is also given that the trunk size is also dependent on environmental factors . So we have to collect data from. Different environments and correlate with the trunk size. There may be a natural calamity that might have selected a particular trunk size randomly confined to that particular area which doesn't have any correlation with reproductive success. In that case it would result in genetic drift. So if there is no data correlated to mate success but there is selection of a particular trunk size confined to an area,that is the result of genetic drift.

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