How male dragonflies adapt wing color to temperature

January 23, 2019, Case Western Reserve University

New research from Case Western Reserve University in how dragonflies may adapt their wing color to temperature differences might explain color variation in other animals, from lions to birds.

Further, the findings could also provide evolutionary biologists clues about whether rising global temperatures might adversely affect some species.

Michael Moore, a graduate biology student, and Ryan Martin, an assistant professor of biology, recently published their findings in the journal Ecology Letters.

"People have long been aware of variation in dragonfly wing color, but what we are showing in this new work is an overlooked environmental factor—how temperature affects coloration," Martin said. "This could turn out to also determine some of the really cool extravagant traits we like to look at, such as coloration in birds."

Their findings follow a two-year study that began with a hunch about how the wing color on male Blue Dasher dragonflies in the western United States was different from their counterparts in Northeast Ohio.

They reviewed vast amounts of dragonfly photographs compiled by citizen scientists on the website iNaturalist.org and then, with the help of graduate student Iulian Gherghel, cross-referenced that information with weather data.

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What is on the menu for dragonflies

Date:  October 3, 2017

Source:            University of Turku

Summary:

Researchers have discovered which species adult dragonflies and damselflies prey upon, as modern laboratory techniques have enabled the study of the insects' diet. In the study, prey DNA was extracted from the tiny dragonfly droppings and the researchers managed to identify dozens of prey species from the samples. The results shed light on dragonflies' position in natural food webs with an unprecedented specificity.

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Tiny dragonfly destroys records for insect migration

MARCH 3, 2016

by Brett Smith

Even though it’s only an inch and a half long, the dragonfly Pantala flavescens is capable of migrating from continent to continent and over oceans, according to a new study published in the journal PLOS ONE.

Using genetic analyses, the study team found populations in eastern Canada, Japan, and South America. They research said the only explanation for the common worldwide gene pool is an ability to migrate over long distances and breed in new locales.

“This is the first time anyone has looked at genes to see how far these insects have traveled,”  an assistant professor of biology at Rutgers University-Newark, said in a press release.

“If North American Pantala only bred with North American Pantala, and Japanese Pantala only bred with Japanese Pantala,” Ware said, “we would expect to see that in genetic results that differed from each other. Because we don't see that, it suggests the mixing of genes across vast geographic expanses.”

Explained by evolution

Ware said this theory make sense when you consider the way these dragonflies appear to have evolved.

“These dragonflies have adaptations such as increased surface areas on their wings that enable them to use the wind to carry them,” she said. “They stroke, stroke, stroke and then glide for long periods, expending minimal amounts of energy as they do so.”

The study team noted that dragonflies have, in fact, been observed crossing from Asia to Africa over the Indian Ocean.

“They are following the weather,” said study author Daniel Troast, who analyzed the DNA samples in Ware's lab. “They're going from India where it's dry season to Africa where it's moist season, and apparently they do it once a year.”

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The secret of dragonflies' flight

Date:

November 24, 2014

Source:

American Physical Society's Division of Fluid Dynamics

Summary:

Dragonflies can easily right themselves and maneuver tight turns while flying. Each of their four wings is controlled by separate muscles, giving them exquisite control over their flight. Researchers are investigating the physics behind this ability by recording high-speed video footage of dragonflies in flight and integrating the data into computer models.

Continued ...

Insects were first to fly

Ancient ancestors of today's dragonflies were the first to develop wings

Insects were the first type of living creature to develop wings and learn to fly new research shows.

"Our research shows that insects originated at the same time as the earliest land-based plants, about 480 million years ago," Director of CSIRO's Australian National Insect Collection and one of the authors on the paper David Yeates said.

"Then, about 400 million years ago, ancient ancestors of today's dragonflies and mayflies were the first to develop wings - giving them the ability to fly long before any other animal could do so.

"This was at about the same time that land-based plants developed height, showing they were able to rapidly adapt to their changing environment.

The findings also confirm that while biodiversity crises led to mass extinction events in many other groups, such as dinosaurs, insects continued to survive and diversify by quickly adapting to new situations and opportunities that arose.

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Light-colored butterflies and dragonflies thriving as European climate warms

Butterflies and dragonflies with lighter colours are out-competing darker-coloured insects in the face of climate change.

In a new study published in Nature Communications, scientists from Imperial College London, Philipps-University Marburg and University of Copenhagen have shown that as the climate warms across Europe, communities of butterflies and dragonflies consist of more lighter coloured species. Darker coloured species are retreating northwards to cooler areas, but lighter coloured species are also moving their geographical range north as Europe gets warmer.

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UK dragonfly numbers may be down after wet winter, conservationists warn

Overflowing rivers may have washed away nymphs but impact will not be seen until flying season

Damian Carrington

theguardian.com, Friday 4 April 2014 06.00 BST

The iridescent dragonflies that flit alongside the UK's waterways could become a rarer sight in coming years after this winter's deluge, the Canal and Rivers Trust (CRT) have warned.

The mosquitoes and midges that dragonflies prey upon may increase as a result, boosted by the pools and puddles left by southern Britain'swettest winter for at least 250 years.

There are 45 dragonfly and closely related damselfly species that breed in the UK. But while they are best known for their colourful, darting summer flights, they actually spend most of their lives as nymphs inrivers, canals and ponds. After three years underwater, they emerge as flying adults to mate and then die as soon as a week later.

Dr Mark Robinson, national ecologist at the CRT, said overflowing rivers are known to wash the nymphs away. "If you think about life in rivers that burst their banks, most of it has been spread over the fields over the last few months," he said. "The nymphs are then just pickings for birds and small mammals. As they spend three years in the water, if you lose a year it can take a long time to recover."

Continued

Rare dragonflies reintroduced into Cheshire

White-faced darter dragonfly back in Cheshire's Delamere Forest

June 2013. One of the first stages of an ambitious five-year plan to reintroduce one of the UK's rarest dragonflies back into the region - after a decade of absence - has been successfully completed.

The white-faced darter dragonfly was last seen in the wild in Cheshire over the pools of Delamere Forest in 2003. The Cheshire Wildlife Trust project team has now announced that in recent days they have seen adult white-faced darters flying, and recorded evidence of a number of other individuals emerging from the water in a specially selected pool where they were translocated earlier in the summer.

Improved habitat

The return of the dragonflies comes after several years of dedicated work to reinstate and improve lost habitats in partnership with the Forestry Commission, Cheshire West & Chester Council and a meticulous translocation process and carefully planned reintroduction. Such a scheme has only been attempted twice before in the UK, again with white-faced darters in Cumbria and with the southern damselfly in Devon.

It's hoped the combined approach of creating suitable areas for the dragonflies to survive in pools within the forest, coupled with annual translocations and careful monitoring will see a self-sustaining population of white-faced darters back in the region within ten years.

Continued

One million UK dragonfly records!

The British Dragonfly Society (BDS) started work on the new Atlas in 2008 when the database held 530,000 records.

Dragonfly atlas reaches 1,000,000 records

March 2013. The British Dragonfly Society (BDS) now has more than one million records of dragonflies in the UK! This stunning and remarkable achievement has been reached after a co-ordinated recording effort fuelled by the society's atlas project. The project started in 2008 with the aim of mapping the complete distribution of dragonflies in Britain.

1 millionth record

During the five year survey period the total number of observations of dragonflies has almost doubled and the target of one million records has been achieved. This milestone was marked this week by a special award to Ingrid Twissell. Her record of a Ruddy Darter from Tewkesbury in Gloucestershire on 9th August 2012 was the one millionth entry to the BDS database. She was presented with a signed Richard Lewington print of a Ruddy Darter at the British Dragonfly Society's annual Recorders' Conference. This milestone in recording also coincides with the 30th anniversary of the BDS.

Scotland and Wales

Even more impressive than reaching the target of one million records has been the extent of coverage for the new atlas, particularly in Scotland and Wales. Here potential dragonfly habitat in virtually all under-recorded areas has been surveyed for records. This has only been possible through the dedicated efforts of a small team of volunteers coordinated by the British Dragonfly Society's Dragonfly Recorder Network. Coverage has also been aided by recorders arranging dragonfly recording holidays to more remote parts of the British Isles. As a result, the atlas to be published later this year will provide a comprehensive picture of the current status of these fascinating insects and allow future changes to be monitored.

Continued

Using dragonflies as climate change indicators

Climate change indicators effects on biodiversity

March 2013. Monitoring communities of climate sensitive species, such as insects, could enable scientists to develop indicators for climate change effects on biodiversity and help devise policies to protect it.

With climate change, flora and fauna shift their seasonal inner clock. For example, fruit tree blossom earlier than previous years. But many species may not be able to adapt as quickly as the climate changes, according to a recent report by the European Environmental Agency. As a result, there is currently a need to develop simple metrics of climate impacts on biodiversity. This could help policy makers to develop biodiversity protection measures to mitigate and adapt to the effect of climate change.

Insects - Good climate indicators
Insects, for example, are good climate indicators as their development depends on temperature. German scientists have now found that the regional composition of butterfly and dragonfly communities has already changed in the last decades. This is according to a study called "Climate Change and Biodiversity" about to be published within two months. "We know a great deal from modelling studies [about climate impact on biodiversity], but we know to a lesser extent what really happens," Maik Denner, one of the study's co-authors, tells youris.com. He works as a nature conservation scientist at the State Office for the Environment, Agriculture and Geology in Dresden, Germany.

The study is based on using biodiversity monitoring to assess the effect of climate change, as established biodiversity monitoring programmes such as existing ones in Switzerland, the UK and Germany's North Rhine-Westphalia. In their study, the scientists used species distribution and monitoring data to calculate the so-called community temperature index (CTI) of butterflies and, for the first time, dragonflies.

Continued:  http://www.wildlifeextra.com/go/news/climate-dragonflies.html

Dragonfly Shows Human-Like Power of Concentration

Dragonflies lack humans' big brains, but they still get the job done, according to new research that suggests that these insects have brain cells capable of feats previously seen only in primates.

Specifically, the dragonflies can screen out useless visual information to focus on a target, a process called selective attention. The new study, published Dec. 20 in the journal Current Biology, is the first to find brain cells devoted to selective attention in an invertebrate animal.

Selective attention is crucial for responding to one stimulus among the dozens of distractions that clamor for notice at any given time, said Steven Wiederman of the University of Adelaide in Australia.

Continued:  http://www.livescience.com/25849-dragonfly-human-like-brain-cells.html

Engineer Looks to Dragonflies, Bats for Flight Lessons

Dec. 13, 2012 — Ever since the Wright brothers, engineers have been working to develop bigger and better flying machines that maximize lift while minimizing drag.

There has always been a need to efficiently carry more people and more cargo. And so the science and engineering of getting large aircraft off the ground is very well understood.

But what about flight at a small scale? Say the scale of a dragonfly, a bird or a bat?

Hui Hu, an Iowa State University associate professor of aerospace engineering, said there hasn't been a need to understand the airflow, the eddies and the spinning vortices created by flapping wings and so there haven't been many engineering studies of small-scale flight. But that's changing.

The U.S. Air Force, for example, is interested in insect-sized nano-air vehicles or bird-sized micro-air vehicles. The vehicles could fly microphones, cameras, sensors, transmitters and even tiny weapons right through a terrorist's doorway.

So how do you design a little flier that's fast and agile as a house fly?

Hu says a good place to start is nature itself.

And so for a few years he's been using wind tunnel tests and imaging technologies to learn why dragonflies and bats are such effective fliers. How, for example, do flapping frequency, flight speed and wing angle affect the lift and thrust of a flapping wing?

Continued:  http://www.sciencedaily.com/releases/2012/12/121213121136.htm

Migrant dragonflies and damselflies colonising southern England

Damselflies colonise East Anglia & migrant dragonflies benefit from our late summer

September 2012. Recent warm, sunny weather appears to have benefitted several migrant dragonflies and damselflies in Southern England, according to the British Dragonfly Society (BDS).

During late-August and September (2012) the BDS received sightings' reports of Lesser Emperor, Southern Migrant Hawker, Migrant Hawker and Red-veined Darter dragonflies, as well as for two unusual Emerald damselflies - the Southern and Willow Emeralds.

Lesser Emperor - First seen in UK in 1996
The Lesser Emperor, a smaller relative of the more common Emperor Dragonfly, was first discovered in the UK only as recently as 1996. Although still very rare, it has now become an annual migrant to UK shores, one which has even managed to breed successfully on occasion at sites in Cornwall and Kent. Within the last few weeks the species has been recorded in Hampshire, Kent, East Sussex and Suffolk, with egg-laying being reported from some of these sites.

Continued:  http://www.wildlifeextra.com/go/news/migrant-dragonflies.html

Good year for dragonflies and damselflies

Spectacular display of downy emeralds

December 2011: This year has proved a bumper year for dragonflies and damselflies in the Cotswold Water Park (CWP) with record numbers of the park's rarest species and additional records of new arrivals.

In one of the most spectacular sights, more than 100 downy emerald dragonflies were seen emerging simultaneously at a lake near Somerford Keynes. This is all the more amazing considering this is a nationally scarce species and the focus of conservation action in the CWP.


Over half of the species of UK dragonfly and damselfly can be found at the park, often in extraordinarily high numbers. There are swarms of millions of tiny blue damselflies in May and June, often being buzzed by a larger hawker dragonfly, iridescent in the sunlight as it twists and turns upon its prey.

Some of the UK's most important dragonfly populations
The CWP supports a massive range of wildlife, ranging from waterbirds to bats and aquatic plants, and the dragonfly populations are amongst the most important in the UK.

As dragonflies are a clear indicator of habitat quality and climate, the monitoring of the dragonfly population provides important clues regarding minor changes to climate and habitat quality, and will provide an important record for future generations.

Gareth Harris, CWP Trust's biodiversity manager, says: ‘Four years of detailed survey by some expert surveyors have produced fantastic results and some surprising results. New breeding sites for nationally scarce species such as downy emerald have been located, including the exciting discovery of the mass emergence in spring 2011.'

Steve Prentice of the British Dragonfly Society, says: ‘Working with the Cotswold Water Park Trust will make a significant contribution to the new national atlas for dragonflies, ensuring that this major inland wetland is surveyed in detail to monitor the effects of increasing area of habitat creation and the impact of climate change.'

Claire Install, conservation officer at the British Dragonfly Society, said: ‘CWP is a great place to see dragonflies and damselflies. They are incredible to watch with their bright colours and aerobatic skills. By recording what they see people can contribute to something that will be useful for years to come.'

http://www.wildlifeextra.com/go/news/dragonflies-cotswolds.html

Longest insect migration revealed

Every year, millions of dragonflies fly thousands of kilometres across the sea from southern India to Africa.

So says a biologist in the Maldives, who claims to have discovered the longest migration of any insect.

If confirmed, the mass exodus would be the first known insect migration across open ocean water.

It would also dwarf the famous trip taken each year by Monarch butterflies, which fly just half the distance across the Americas.

Biologist Charles Anderson has published details of the mass migration in the Journal of Tropical Ecology.

Each year, millions of dragonflies arrive on the Maldive Islands, an event which is well known to people living there.

"But no-one I have spoken to knew where they came from," says Anderson, an independent biologist who usually works with organisations such as the Maldivian Marine Research Centre to survey marine life around the islands.

Their appearance is especially peculiar because the 1200 islands that make up the Maldives lie 500 to 1000km from the mainland of southern India, and all are coral cays with almost no surface freshwater, which dragonflies need to complete their lifecycle.

Anderson noticed the dragonflies after he first arrived in the Maldives in 1983. He started keeping detailed records each year from 1996 and now collates data collected by local observers at other localities in the Maldives, in India and on vessels at sea.

When Anderson compared these observations with those made of dragonflies appearing in southern India, he found a clear progression of arrival dates from north to south, with dragonflies arriving first in southern India, then in the Republic of Maldives' capital Male, and then on more southern atolls.

Each year, dragonflies first appear in Male between 4 and 23 October, with a mean arrival date of 21 October. Dragonfly numbers peak in November and December, before the insects then disappear once more. The insects arrive in waves, with each staying for no more than a few days.

Over 98% of the dragonflies recorded on the islands are Globe skimmers (Pantala flavescens), but Pale-spotted emperors (Anax guttatus), Vagrant emperors (A. ephippiger), Twisters (Tholymis tillarga) and Blue perchers (Diplacodes trivialis) also appear in some numbers.
The dragonflies then reappear between April and June.

Longest journey
The dragonflies are clearly migrating from India across the open sea to the Maldives, says Anderson.

"That by itself is fairly amazing, as it involves a journey of 600 to 800km across the ocean," he says.

Quite how they do it was a bit of a mystery, as in October at least they appear to be flying against the prevailing winds.

However, in October, and continuing into November and December, a weather system called the Inter-tropical Convergence Zone moves southwards over the Maldives.

Ahead of the ITCZ the wind blows towards India, but above and behind it the winds blow from India. So it seems that the dragonflies are able to reach Maldives by flying on these winds at altitude above 1000m.


But that is not the end of the animals' epic adventure.

"As there is no freshwater in Maldives for dragonflies, what are they doing here?" asks Anderson.

"I have also deduced that they are flying all the way across the western Indian Ocean to East Africa."

Anderson has gathered a wealth of circumstantial evidence to back his claim.

Large numbers of dragonflies also start appearing in the northern Seychelles, some 2700km from India, in November, and then in Aldabra in the Seychelles, 3800km from India, in December.

That matches the slow southerly movement of the Inter-tropical Convergence Zone weather system, behind which winds blow steadily from India to East Africa.

It is also known that Globe skimmers appear in large numbers through eastern and southern Africa.

In Uganda, they appear twice each year in March or April and again in September, while further south in Tanzania and Mozambique they appear in December and January.

Record breakers
That strongly suggest that the dragonflies take advantage of the moving weather systems and monsoon rains to complete an epic migration from southern India to east and southern Africa, and then likely back again, a round trip of 14,000 to 18,000km.

"The species involved breeds in temporary rainwater pools. So it is following the rains, taking sequential advantage of the monsoon rains of India, the short rains of East Africa, the summer rains of southern Africa, the long rains of East Africa, and then back to India for the next monsoon," says Anderson.

"It may seem remarkable that such a massive migration has gone unnoticed until now. But this just illustrates how little we still know about the natural world."

The monarch butterfly is often cited as having the longest migration of any insect, covering around 7000km in an annual round trip from Mexico to southern Canada.

On average, it takes four generations of butterflies to complete the journey.

Anderson believes that the dragonflies survive the ocean flights by gliding on the winds, feeding on other small insects.

They too, take four generations to make the full round trip each year.

He says the migratory paths of a number of insect-eating bird species, including cuckoos, nightjars, falcons and bee-eaters, follow that of the dragonfly migration, from southern India to their wintering grounds in Africa. That suggests the birds feed on the dragonflies as they travel.

"They [fly] at the same time and altitudes as the dragonflies. And what has not been realised before is that all are medium-sized birds that eat insects, insects the size of dragonflies," he says.
Extraordinary ability
"There are earlier records of swarms of Globe skimmers flying out to sea, and at sea," Anderson continues.

"But it was always assumed that those dragonflies were doomed. Which says rather more about our earth-bound lack of imagination than it does about the globe skimmers' extraordinary flying abilities."



Matt Walker Editor, Earth News


http://news.bbc.co.uk/earth/hi/earth_news/newsid_8149000/8149714.stm