Research news

The world with moth and bird eyes

Professor Johanna Mappes and postdoctoral researcher Bibiana Rojas Zuluaga from Department of Biological and Environmental Science at the University of Jyväskylä, Finland participated in international collaboration and researched how the wood tiger moths see the world with moth and bird eyes.

Animals use colour in many ways. Colour can mediate protection from predators, mate choice, comunication between conspecifics, and thermoregulation, and is thus involved in individual reproduction and survival. Colours can make animals easily recognizable, and can send signals to other species as well. For example, birds that prey on colourful moths can detect them easily but, as the moths taste bad, birds learn their warning colouration, and soon learn not to attack them.

- We already know that animals are able to see and produce colors that us humans cannot, specifically in the ultraviolet and infrared zones, but in order to understand how animals use these colours and what these may communicate, we need to “view” the world through the animals’ eyes, says Professor Johanna Mappes from Department of Biological and Environmental Science at University of Jyväskylä, Finland.

Animals live in a colourful world
The wood tiger moths may not have a human’s sharp vision, but their eyes beat us in many ways. The human eye can see that wood tiger moths have black-and-white forewings, and males have yellow or white hindwings, while female hindwings are red or orange. But how are wood tiger moths seen by other moths and by birds? Researchers looked at the moths through their own eyes, and with the eyes of a bird that preys on them. They found that these moths have three types of light detector cells (photoreceptors), most sensitive to the ultraviolet, blue and green part of the light spectrum, and combined this knowledge with measurements of their wing colours in established colour vision models.

Wood tiger moths see the world differently
The researchers noticed that moths themselves see the yellow and white males as having clearly different colours, mostly because the white males also reflect a lot of ultraviolet light. However, they are unable to see red and orange females as differently coloured. This means that female colouration is most likely not playing a role in mate choice by males. Birds, as expected, can detect all these moths’ colours without difficulty. Additionally, as these birds have been shown to learn more the red colour more quickly, they are probably selecting for the red colouration in females.

- We concluded that females may use the white and yellow colour of males for mate choice, but more work is needed to better understand the complex relationship between the moths’ colouration and their predators, says Mappes.

The research was published in the Functional Ecology on 15th of March, 2018.

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