All my thoughts about
the wonderful bright colours of the tropics has been blown to bits by current
colour research.
The colour of plants,
birds, and animals seem so much brighter in tropical regions – like parrots,
exotic fruit, hibiscus, frogs and so on. Ecologist Rhiannon Dalrymple from the
University of New South Wales in Australia is the first person to test whether
the colours of the tropics are really so bright, so vivid (Global Ecology and
Biogeography, Canberra Times, September 25, 2015).
Dalrymple maintains
that tropical species are not more colourful than plants and animals living
further from the equator. On average, she said, tropical species were less
colourful than temperate species. Now that is surprising!
For the experiments,
Dalrymple used a spectometre machine to measure the intensity of colour of more
than 500 species of birds, more than 400 species of butterflies, and more than
300 plant varieties. She also measured the UV colour levels that humans cannot
see, but which are visible to animals.
Supervisor of the
research, Angela Moles, said early explorers often collected the most
interesting and colourful plants and animals from tropical regions mainly because they could be sold
to museums and collectors for more money. This is probably why we first
believed that tropical species were more colourful. There was a collection
bias.
Over the years, as more people visited tropical locations, it did
seem that the light and heat produced extraordinary plants and
animals with brighter plumage or skin. However, it’s only now that the colour intensity has been tested that
we find that there is no link between the heat and light in the tropics and the
coloured feathers, fur, hide, scales, iridescence, or skin of tropical species.
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