Suppose that a culture of humans believes narwhal horn is go

Suppose that a culture of humans believes narwhal horn is good for them, and they set out to gather all the narwhal horn they can. Heritable variation for horn size exists in the narwhal population, from very small to very large. Whalers only capture and kill narwhals with very large horns to maximize profit. Identify what evolutionary force or event is affecting the narwhal population’s gene pool. Then predict the future of horn phenotypes in the narwhal population. Be sure to identify by name the relevant characteristic pattern studied in class.

Solution

Narwhals are marine animals which bear similarity with whales but has a unique feature of possessing a long tusk or horn. The tusks of narwhal are modified canine tooth which acts as a sensory tool to communicate among members of the population, and might be also used as a predatory tool.

The tusked narwhals are considered as the \'unicorn of the sea\' and are valued among many cultures of humans for the horns. This has caused hunting and poaching of the narwhals and made them a nearly threatened species as documented by the IUCN.

Current scenario

Whalers or the whaling ships capture the narwhal and kill them to obtain the large horns. Since among the narwhal population, the horn sizes vary from very small to very large, killing of the narwhals only with large horns will cause selection pressure in the members of the species.

Future predictions

The elimination of large-horned narwhals from the population will lead to a natural selection of the narwhals with smaller horns. A directional selection will lead to better survival of the small horn narwhals and consequently, more breeding will occur leading to an increase in the population of narwhals with smaller horns.

Genetic drift might occur leading to the accumulation of genes responsible for smaller horn pehnotypes in the narwhal species.