A young entomologist is trying to increase body hairs in Drosophila. His original population has a mean of 7.5 hairs, and he selects flies with a mean of 10 hairs to inter-mate and produce his next generation. The mean number of hairs in the resulting population was 9.

1. What is the narrow-sense heritability (h2) for number of body hairs in this Drosophila population (show your work)?

2. What would have been the mean number of body hairs in the next population if she had selected individuals with a mean of 8.5 hairs?

3. If she wanted a mean of 10 hairs in the progeny, what should have been the mean number of hairs in the individuals selected as parents?

Explanation:

1) homologous features:

these are the features or structures that have a similar structure in several different organisms but function in a unique way in all of them. these structures indicate anatomical similarities as well as the same ancestry of different organisms. for example, the forelimb of birds, humans, dogs, and whales, perform different functions in all these organisms. but when we analyze the layout of bones or layout of the arrangement, we find that it is very similar across all of them. this indicates that, the ancestor of all these organisms was, but with the passage of time when organism dispersed, and environmental conditions changed, it was evolved into different organisms as per favorable conditions.

2) molecular biology:

as we know that all living organisms are a compilation of billions and trillions of unique biological molecules, that group in a unique fashion to constitute the whole organism. interestingly, some biological molecules and the process of their formation can provide sound evidences of evolution. for example, DNA, a sequence of nucleotides in DNA, amino acids, the process of transcription, translation, etc.

the study of evolution through molecular uniformity has led to the foundation of a novel branch of evolution called phylogenetics. the sequence of nucleotides in DNA is used to find the best possible ancestor of any organism. for example, phylogenetic analysis has found that the origin of eukaryotes is from prokaryotes over the period of time.

3) fossil records:

fossils are the preserved remains of previously living organisms or their traces, dating from the distant past. this doesn't mean that fossils represent the complete skeleton of an organism because many organisms don't even fossilize and those who fossilize don't have complete remains. nonetheless, the fossils that humans have collected offer unique insights into evolution over long timescales. for example, the study of horse fossils has enabled the scientists to reconstruct a large, branching "family tree" for horses and their now-extinct relatives.

answer: a. a gene that causes a specific trait.

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