Hide and seek, lepidoptera style

Bugs are amazing, they out do so many other species in their ability to adapt and have a huge impact in human existence. They can be largely beneficial of tremendously harmful, but what happens when we have a large impact on them? When we as a society change their habitat? We accelerate extinction and alter their security and ecology.

But one species did take our negative impact and evolved to a more singular suitable colour, rapidly.

 

The peppered moth in Brittan has a famous story behind it and has even had an evolutionary theory designed around its particular adaptation. During the latter half of the nineteenth century, the industrial revolution boomed in England and caused mass amounts of pollution to be pumped into the skies. As the soot covered the trees of nearby forests, it also killed the lichens covering the trees over hundreds of acres of forests. The insects that were morphologically adapted to these habitats suddenly became very visible making them easy prey for predators.

The report I looked into is about explaining the peppered moth’s evolution and doubting some of the scrutiny against this evolutionary idea. They examined the areas on the trees the moths rested and how the different species of lichens on the trees reacted to the pollution and what effect this had on prey. And also the predators and their “bird’s eye view” of the different visibilities of the moths.

The peppered moth theory in evolution works as a way to describe the role of natural selection pressures of predators on prey. This works on how the prey species is able to adapt to become more camouflaged in an ever changing environment. The reason this drastic change in species aspect is so important is because it happed so rapidly when they had a large natural selection pressure against them.The light coloured moths were mostly caught and the shift was towards the dark morphs. This caused directional natural selection:

 

This worked well as an easy way to explain natural selection, but there was still the idea that the moths rarely rested on the trunks during the day, and instead up in the canopy and branches. This was later found true due to their behaviour, but when lichens were more present, they also hung out on the trunks.

The moth species Biston betularia is a species of moth that has a varying morphological structure. The species has a dominant allele for a dark coloured body, while the recessive produces speckled white bodied moths. These are called “morphs” and are varied in there type. The report looks at the two drastic types that were the bases of the study. The dark carbonaria (the dark moth) and typical (the light coloured moth).when the pollution changed the trees black and killed off all the lichens, the white coloured morph was readily picked off the trees and were decreased from there originally high abundance. As the darker moths are easily hidden, the flourished with the new camouflage and increased in numbers.

 

Dark moth morphs (carbonaria) and the white (typical)

So to assess the visibility theory of the species to predators, a measurement was made to look at the different visibilities of the moths with the different background habitats. They then compared the view of human eyes, compared to the inferred views of predator birds.

They found in there research that areas of habitat with no lichen camouflage, the light coloured moths were easily seen on this plain canvas. But as the lichens mottled colour itself reflected UV light, this assumes that when the lichens are present, they are able to hide the moths.

With temporal and spatial changes occurring in their environment, the soot and pollution has since been cleaned up and the lichens are starting recolonization of the forests. They are starting to repopulate on the newest trunks and branches that aren’t as polluted first, with the older trunks being last.

So, as it stands. Even if we change the habitat so drastically that total habitat morphology is altered, it’s reassuring that species are able to select their safest feature to survive this.

This report showed that there i s in fact a way for a trait to be rapidly selected for if they are able to out survive predation through camouflage to their surrounding environment.

I think there’s always been something about moths that have always interested me. I have always been scared of the dark (but luckily have sort of grown past that) but i have constantly had an aspiration for an insect that is only active at night then during the day plays a form of hide and seek against trees- hoping for the best. There not so up themselves I reckon with the wing and body colours. They use their scales to make natural patterns, creating such amazing camouflage, and are now shown to be able to adapt in to their environment rapidly.

 

Here is a link to the report:

http://onlinelibrary.wiley.com/doi/10.1046/j.1420-9101.2000.00170.x/pdf