CSIR NET 2022 | Life Science: Evolution and Behaviour | 14 November

Pink salmon (Onchorhynchus gorbuscha) in the Pacific Northwest have been decreasing in size in recent years. In 1945, fishermen started being paid by the pound, rather than per individual, for the salmon they caught, and they increased the use of gill netting, which selectively takes larger fish. The selectivity of gill netting can be shown by comparing the average size of salmon taken by gill netting with those taken by an unselective fishing technique: the difference ranged from 0.14-0.22 kg. Therefore, after gill netting was introduced, smaller salmon had a higher chance of survival. The selection favoring small size in the salmon population was intense, because fishing effort is highly efficient a about 75-80% of the adult salmon swimming up the rivers under investigation were caught in these years. The average weight of salmon duly decreased, by about one-third, in the next 25 years. This is an example in favour of:

Based on the above phylogeny and the distribution of red and blue character states among the extant species, and using the principle of parsimony, which of the following is the correct inference about plumage colour of the ancestor at the root P?