Modern evolutionary examples of protective colouration

Modern evolutionary examples of protective colouration Protective colouration is colouration that disguises or camouflages an animal against its background. Examples include camouflage – wherein an organism’s colouration evolves to allow it to blend in with its background, disruptive colouration – where an organism’s pattern breaks up its outline against the background and makes it harder for predators to identify, and mimicry – where a non-dangerous organism mimics a more dangerous one to scare off predators. The first subject I would like to discuss is the peppered moth. This is a relatively famous example of the evolution of protective colouration, and I feel it encapsulates my subject well. The peppered moth has two potential colourations, decided by its alleles. The dominant darker colouration and the recessive lighter colouration. In the pre-industrial period, the lighter colour variant was favoured as it allowed the peppered moths to more easily blend in with the silver birch trees that made up their habitat – with the darker coloured moths being more easily discovered and eaten by predators leading to the allele becoming less common in the population over time due to the predation selection pressure. During the industrial revolution however, factories produced large amounts of soot – leading to the birch trees near cities becoming coated and turning black. This caused the lighter peppered moths to no longer blend in with their surroundings – leading them to be more commonly caught by predators – whilst the less common darker coloured moths now blended in allowing them to survive and causing the darker allele to become more prevalent in the population. The most interesting part of the peppered moth’s history however is their response after the industrial revolution ended. In recent years, trees around cities have started to become cleaner causing the peppered moths to slowly begin to return to their original colouration. This is a very interesting example of humanity’s effect on the evolution of the species around them as it shows not only the impacts of pollution on the world around us, but also the impact when we begin to undo its effects. The next example I would like to focus on is a topic I have gained an understanding of through my own observations rather than through pre-established journals – that being the spread of a new colour variant through a population of wild pigeons in response to urbanisation and human activity. I will be specifically focusing on my local area for this section as it is the area I have been most clearly able to observe. The most common colouration for pigeons is mostly grey, with white, black or iridescent patches and up until recently the pigeons I have been able to observe locally were entirely this colouration – however recently I have begun to notice a change in the population, that being the increasing frequency of pigeons with either a fully white colouration or patches of white colouration far larger than previously seen. This was originally catalysed by the closing down of a local dovecot two years ago – releasing several white coloured pigeons into the local environment, however over time their numbers have increased. My personal theory is that this is an example of protective colouration evolving in response to human development as while suburban pigeons have few natural predators, many are killed in car accidents. The bright white colour allows the birds to stand out against the roads – meaning drivers are more likely to stop and increasing the birds’ chances of survival as opposed to the grey variant which blends in with roads and is harder to see – an advantage against traditional predators such as foxes but not against cars. This is also an interesting example of modern evolution as it shows an animal’s adaptation in response to an artificial predator. In conclusion, humans have been a driving force in many cases of protective colouration in recent years and analysing these examples can give us an interesting perspective on the effects of our developments on the world around us.