Hexbyte Glen Cove Grey camouflage 'better than zebra stripes' thumbnail

Hexbyte Glen Cove Grey camouflage ‘better than zebra stripes’

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Credit: Pixabay/CC0 Public Domain

Dull, featureless camouflage provides better protection from predators than zebra stripes, according to a new study.

Biologists explaining the existence of such stripes have proposed the “motion dazzle hypothesis”, which suggests that high-contrast patterns can make it difficult for predators to track a .

University of Exeter scientists tested this using a touch-screen game called Dazzle Bug in which visitors to Cornwall’s Eden Project had to catch a moving rectangular “bug”.

Bug patterns were programmed to “evolve” to find the best camouflage strategy.

“Surprisingly, targets evolved to lose patterns and instead match their backgrounds,” said senior author Dr. Laura Kelley, of the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall.

“Our results indicate that low-contrast, featureless targets were hardest to catch when in motion.”

Lead author Dr. Anna Hughes, now at the University of Essex, added: “The presence of highly visible and striking patterns on many animals such as zebras has puzzled biologists for over a century, as these markings are conspicuous to predators.

“Early naturalists suggested that these patterns might create ‘motion dazzle’, making it hard for predators to estimate the speed or direction of their prey.

“Dazzle patterning was used on ships in World War One and has been tested in numerous studies, but its protective effects remain unclear—largely due to experiments being small-scale tests of a limited range of patterns.”

The scientists tackled this problem using citizen science—more than 77,000 people played Dazzle Bug at the Eden Project, tracking more than 1.5 million “bugs” in total.

“Our findings provide the clearest evidence to date against the motion dazzle hypothesis and suggest that protection in motion may rely on completely different mechanisms to those previously assumed,” Dr. Hughes said.

The paper, published in the journal Proceedings of the Royal Society B, is entitled: “The evolution of patterning during movement in a large-scale citizen science game.”

More information:
An online version of the game is available to play at www.dazzle-bug.co.uk

The evolution of patterning during movement in a large-scale citizen science game, Proceedings of the Royal Society B, rspb.royalsocietypublishing.or … .1098/rspb.2020.2823

Grey camouflage ‘better than zebra stripes’ (2021, January 12)
retrieved 13 January 2021
from https://phys.org/news/2021-01-grey-camouflage-zebra-stripes.html

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Hexbyte Glen Cove First Australian night bees recorded foraging in darkness thumbnail

Hexbyte Glen Cove First Australian night bees recorded foraging in darkness

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(Reepenia bituberculatav) Nomiine bee with night foraging activity. Credit: James Dorey, Flinders University

Australian bees are known for pollinating plants on beautiful sunny days, but a new study has identified two species that have adapted their vision for night-time conditions for the first time.

The study by a team of ecology researchers has observed foraging behaviour by a nomiine (Reepenia bituberculata) and masked (Meroglossa gemmata) , with both developing enlarged compound and simple eyes which allow more light to be gathered when compared to their daytime kin.

Published in the Journal of Hymenoptera Research, the researchers explain that this improved low-light ability could potentially also exist in other Australian species secretly active at night, with their image processing ability best observed through high-resolution close-up images.

Lead author Ph.D. Candidate James Dorey, in the College of Science & Engineering at Flinders University, says the two Australian bee species active at night and during twilight hours are mostly found in Australia’s tropical north, but there could potentially more in arid, subtropical and maybe even temperate conditions across the continent.

“We have confirmed the existence of at least two crepuscular bee species in Australia and there are likely to be many more that can forage both during the day and into the early morning or evening under low light conditions. It’s true that bees aren’t generally known to be very capable when it comes to using their eyes at night, but it turns out that low-light foraging is more common than currently thought,” says Mr Dorey.

Masked bee species (Meroglossa gemmata) with night foraging activity in Australia. Credit: James Dorey, Flinders University

“Before this study, the only way to show that a bee had adapted to low-light was by using difficult-to-obtain behavioural observations, but we have found that you should be able to figure this out by using high-quality images of a specific bee.”

Mr Dorey says bees that forage during dim-light conditions aren’t studied enough with no previously reliable published records for any Australian species.

“Our study provides a framework to help identify low-light-adapted bees and the data that is needed to determine the behavioural traits of other species. This is important as we need to increase efforts to collect bee species outside of normal hours and publish new observations to better understand the role that they play in maintaining ecosystems.”

The researchers outline why more needs to be understood about the behaviour of bee species to help protect them from the potential impacts of climate change.

“Global weather patterns are changing and temperatures in many parts of Australia are rising along with the risk of prolonged droughts and fires. So, we have to improve our understanding about insects pollinating at night or in milder parts of the day to avoid potential extinction risks or to mitigate loss of pollination services.”

“This also means we have to highlight the species that operate in a narrow window of time and could be sensitive to , so conservation becomes an important concern. Because quite frankly, we have ignored these up until now.”

The new paper, Morphometric comparisons and novel observations of diurnal and low-light foraging bees (2020) by James B Dorey (Flinders University), Erinn P.Fagan Jeffries (University of Adelaide), Mark I. Stevens (South Australian Musuem, UniSA), Michael P. Schwarz (Flinders University) has been published in The Journal of Hymenoptera Research.

More information:
James B. Dorey et al, Morphometric comparisons and novel observations of diurnal and low-light-foraging bees, Journal of Hymenoptera Research (2020). DOI: 10.3897/jhr.79.57308

First Australian night bees recorded foraging in darkness (2020, October 30)
retrieved 2 November 2020
from https://phys.org/news/2020-10-australian-night-bees-foraging-darkness.html

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part may be reproduced without the written permission. The content is provided for information purposes only.