Science

Eleanor Drinkwater’s Colourful History of Discovery

Source: Karls Alfrink (via Flickr)

By Holly Giles

 

The annual Wallace lecture run by the Royal Society of Biology is eagerly anticipated by many in the field. This year’s lecture took a different approach through a webinar meaning members of the society and students were able to tune in from home to hear Eleanor Drinkwater explain the evolution of colour in nature and how far ecologists have gone from Wallace’s initial findings.

 

Wallace may not be a name you have heard of, but he is famous in biology for coming up with the theory of natural selection at the same time as Darwin and was a leading thinker in the idea of species being region specific; he is the “father of biogeography”. Some of Wallace’s most revolutionary findings were in the colour of animals and their use of colour to warn away predators. This warning of toxicity is commonly red, orange and yellow and teaches predators to avoid them.

 

Eleanor Drinkwater added to this theory with the knowledge that other animals use colour to mimic that of toxic animals in the environment. A non-toxic animal may choose to become red to confuse predators into thinking it is also toxic. This then prompts toxic animals to evolve and triggers a constant arms race between the toxic and non-toxic groups, both with the objective of avoiding predators.

 

Drinkwater also explained Wallace’s theory of startle displacement. This is when organisms use colour to scare away a predator. An ingenious example of this is seen in the vampire squid; this animal lives in the dark so it’s regular ink would have no effect. To overcome this, it has adapted to produce a bioluminescent substance when threatened which sticks to the predator, making them glow and causing other larger predators to come and eat it. This process is referred to as the burglar alarm hypothesis and shows the evolutionary intelligence of the vampire squid.

 

A particular species of interest for Drinkwater is the orchid mantis. This species has adapted to appear like an orchid flower, in order to attract insects which it can then eat. Interestingly it has now been seen that the orchid mantis has evolved to look like a mix of the flowers in the area and can be seen as an average of the surrounding plants. This means it attracts as many insects as possible and has even been shown to be more successful at attracting insects than the flowers it is mimicking.

 

Drinkwater was keen to express that while entomology (the study of insects) has been around for hundreds of years, there is still much more to learn. Topics of current research include looking if the startle response (technically referred to as deimatic displays) are produced in order to trick the predator or are made by the prey due to fear.

 

Another focus of research is whether the genes for colour are able to mutate more quickly than other genes, giving colour an advantage in the arms race, this is a particular focus of those at Cambridge University. We also are yet to understand the evolutionary history of the animals like the orchid mantis and how they evolved to look like these plants.

 

Finally, research is now able to advance rapidly due to increasing technology. Drinkwater explained that while an animal may not appear camouflaged to us, it is designed to be camouflaged only to its predator. To understand this, we need to be able to manipulate the visual systems of other animals and new technology lets us see organisms through the eyes of the prey, helping us to understand why they look the way they do.

 

There is still much to learn and discover about entomology and, due to the advancements made possible through technology, we are now, as Wallace once said, “in one of the most curious chapters in natural history”. Drinkwater provided an interesting and engaging talk, enjoyed by over 70 of the society’s members.

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