Dung beetle discovery revises biologists' understanding of how nature innovates

NOVEMBER 21, 2019 

by Indiana University

When studying how organisms evolve, biologists consider most traits, or features, as derived from some earlier version already present in their ancestors. Few traits are regarded as truly "novel." 

Insects were wingless, then winged. Animals were blind, then had eyes. 

And in biology textbooks, novelty has a strict definition: it must have no relationship to any structure found in an ancestor and no relationship to any other body part elsewhere in the organism. By this definition, a dolphin's pectoral fins are not a novelty because they are modified forelimbs that already existed. 

However, some experts argue this creates a problem since it means novelty must seemingly arise from nothing. It must "pop up out of the blue" in evolutionary time. 

Now evidence has emerged—in a study published Nov. 21 in the journal Science—that illuminates how new things can evolve. Moreover, this evidence has come from an unexpected source: the small, yet charismatic dung beetle. 

"Dung beetles are fascinating creatures," said Armin Moczek, the study's senior author and a professor in the IU Bloomington College of Arts and Sciences' Department of Biology. Among their many qualities, one structure has placed them at the forefront of discussions about novelty among researchers. That structure is their thoracic horn, which is regarded as a textbook example of an evolutionary novelty. This is because the thoracic horn is unique to horned beetles, and it appears to have no relationship to any other structure in the animal. 

Read on

Dung beetles navigate better under a full moon

February 5, 2019, Lund University

Of all nocturnal animals, only dung beetles can hold their course using polarized moonlight. Researchers at Lund University in Sweden have now shown that beetles can use polarized light when its signal strength is weak, which may allow them to find their bearings when artificial light from cities swamps natural moonlight.

"Our investigation reveals that these beetles would be sufficiently sensitive to orient themselves underneath a light-polluted city sky during a full moon. But they would be lost during a quarter or crescent moon," explains James Foster, researcher at the Department of Biology at Lund University.

Moonlight becomes polarized when it strikes particles in the upper atmosphere on its journey to Earth. In the study, the researchers show that the strength of this polarized light signal changes depending on the moon's phase. Polarized light from a quarter moon is only one-third as strong as at full moon, and just one-fifth as strong for a crescent moon.

"This is the very first evidence that the polarization of skylight changes over the lunar cycle," says James Foster.

Together with colleagues in Lund, Germany, South Africa and the U.S., he tested how dung beetles cope with this weak signal at night when using polarization as their compass to roll a dung ball in a straight line across the African savannah. On clear nights, they perceive this polarized light in a blue sky like humans observe on a sunny day—but thousands of times darker.

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Meet the unsung heroes of dung: Beetles found to reduce survival of livestock parasites

Date: November 17, 2016

Source: University of Bristol

Scientists from the University of Bristol have found that dung beetles can help farmers by reducing the development and survival of parasites in cowpats that cause serious illness in cattle during the summer months.

The study was led by Bryony Sands from the School of Biological Sciences, a NERC-funded PhD student and is published in the Journal of Applied Ecology.

Artificial cow pats were made using faeces collected elsewhere and were manipulated by adding dung beetles and varying simulated rainfall. After two weeks, parasitic larvae were taken from vegetation surrounding the cow pats.

The numbers of parasitic larvae found on vegetation around pats increased over the first six weeks, and remained high for at least ten weeks.

At first, there were more parasites found around pats that were colonised by dung beetles as opposed to un-colonised pats.

However, after eight weeks, fewer parasitic larvae were found around pats that were colonised by dung beetles. This pattern persisted for the rest of the ten week experiment.

Increased rainfall was achieved by periodically watering the pats. This led to more parasitic larvae being found on the pasture, suggesting that reduced development and survival of livestock parasites as a result of dung beetle activity can be overridden by heavy rainfall.

It was suggested that dung beetle activity ventilates cow pats, providing the right initial conditions for parasite egg hatching.

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New evidence connects dung beetle evolution to dinosaurs

Date: May 4, 2016

Source: Cleveland Museum of Natural History

Researchers have found an evolutionary connection between dinosaurs and dung beetles. An international team of scientists uncovered the first molecular evidence indicating that dung beetles evolved in association with dinosaurs. The findings place the origin of dung beetles (Scarabaeidae: Scarabaeinae) in the Lower Cretaceous period, with the first major diversification occurring in the middle of the Cretaceous. This timeline places their origins approximately 30 million years earlier than previously thought. The research explores the potential of a co-extinction with dinosaurs 66 million years ago. The study was published today in the open-access journal PLOS ONE.

Lead author Dr. Nicole Gunter of The Cleveland Museum of Natural History generated molecular (DNA) sequence data from 125 scarab beetles at the Australian National Insect Collection, CSIRO, which were aligned with previously published data to create a total dataset representing 450 beetle species. The data were used to create a dated molecular phylogeny of scarab beetles. Analyses compared timing and evolutionary relationships of herbivorous scarab subfamilies that feed directly on living plant tissue to saprophagous scarab subfamilies that feed on dead and decaying matter--including dung.

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Tracing the ancestry of dung beetles

Date: April 25, 2016

Source: Pensoft Publishers

One of the largest and most important groups of dung beetles in the world evolved from a single common ancestor and relationships among the various lineages are now known, according to new research by an entomologist from Western Kentucky University.

The study by Dr T. Keith Philips, recently published in the open access journal Zookeys, provides important insights into the evolution and diversity of these dung beetles, which make up about half of the world's dung beetle fauna.

The two tribes studied, the onthophagines and oniticellines, evolved from a single common ancestor and are found worldwide, except for Antarctica. These dung beetles make up the vast majority of species and dung beetle biomass in many ecosystems, feeding on mammal dung.

Dung beetles are well known to many people because many species are colorful and active in the daytime. Additionally, many taxa have unusual behaviors, such as making and rolling balls of dung away from a dung pile. Often thought of as nature's garbage collectors, the important ecosystem service offered by dung beetle helps recycle nutrients, reduces parasites, and can even help seeds germinate.

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Two brand new dung beetle species from montane grazing sites and forests in Mexico

Date: March 15, 2016

Source: Pensoft Publishers

While carrying out a biodiversity study, a Mexican-Italian research team discovered three new dung beetle species in montane forests disturbed by livestock grazing. Mexico has been a mecca for naturalists, and its dung beetle species are among the best known in the world. This is why the discovery of new species there is noteworthy. The present study, published in the open-access journal ZooKeys, describes two of them and highlights the need to further explore the biodiversity of disturbed ecosystems.

Mexico is a country that holds a vast number of creatures and ecosystems. There is in fact a fascinating phenomenon: tropical forests that have close affinities with South America co-occurring with temperate and arid areas shared with North America. Thus, Mexico has been particularly attractive to explorers ever since the 19th century.

A group of animals that has woken up a special interest for studies in Mexico is the so-called 'dung beetles'. As their name suggests, dung beetles are insects that feed mainly on mammal faeces.

For decades, an international research team, led by Dr Gonzalo Halffter, has studied dung beetles across the world, especially in Mexico. As a consequence, the Mexican species are some of the best-known. However, Dr Halffter and his team are not interested exclusively in dung beetles, but also in evolutive phenomena, the effects of land-use change, ecosystems modification by human activities, and conservation biology. Such concerns seem to be of particular importance now that the terrestrial ecosystems in Mexico have been severely destroyed and disturbed by people.

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Dung Beetles Follow the Milky Way: Insects Found to Use Stars for Orientation

Jan. 24, 2013 — An insect with a tiny brain and minimal computing power has become the first animal proven to use the Milky Way for orientation. Scientists from South Africa and Sweden have published findings showing the link between dung beetles and the spray of stars which comprises our galaxy.

Although their eyes are too weak to distinguish individual constellations, dung beetles use the gradient of light to dark provided by the Milky Way to ensure they keep rolling their balls in a straight line and don't circle back to competitors at the dung pile.

"The dung beetles don't care which direction they're going in; they just need to get away from the bun fight at the poo pile," said Professor Marcus Byrne from Wits University.

Byrne and his team previously proved that dung beetles use the sun, the moon and polarised light for orientation. In their experiments, they gave the beetles "caps" which blocked light from reaching their eyes. The team also discovered that the beetles climb on top of their dung balls to perform an orientation "dance" during which they locate light sources to use for orientation.

Now, further experiments, conducted under the simulated night sky of the Wits Planetarium, have shown that the beetles also use the Mohawk of the Milky Way -- giving new meaning to dancing with the stars!

Continued:  http://www.sciencedaily.com/releases/2013/01/130124123203.htm

That's Hot! Beetles Dance on Poop Balls to Keep Cool

Dung beetles can use balls of poo much like air-conditioning units to cool themselves, researchers say.

Dung beetles roll up nutritious balls of excrement up to 50 times heavier than their own bodies to feed their young. They roll the balls walking backward, with their heads near the ground. The ancient Egyptians envisioned that the sun was rolled around the sky in much the same way, making the dung (or scarab) beetle an important symbol in ancient Egyptian religion.

Past research showed these insects routinely dance in circles on top of their feasts of dung to help navigate away from rival beetles as quickly as possible. As scientists looked for this dancing, they noticed the beetles climbed onto the excrement balls most often during the midday heat.



Continued: http://www.livescience.com/24176-dung-beetles-keep-cool-balls.html

Dung Beetle's Poop Preference: Smellier the Better

Dung beetles prefer the smelliest poop they can find, new research on the insects suggests. Odorous dung from omnivores, which eat a diet of both plants and animals, seems to be the most attractive to the beetles.

Some of the top choices? Human and chimpanzee dung.

"This novel research indicates that native dung beetle species will respond to dung from exotic animals," study researcher Wyatt Hoback, a professor at the University of Nebraska at Kearney, said in a statement

Dung beetles are usually pretty specific in their poop tastes, but researchers were wondering how they would react to exotic droppings, like those left by imported mammals on game farms. This was a problem in Australia, when humans imported cows and other large herbivores in 1778. The dung beetles didn't enjoy the bovine droppings, and instead flies and other parasites had a heyday.

Continued:  http://www.livescience.com/19668-dung-beetle-poop-preference.html

Dung beetles brought back to battle bushflies

Scientists are hoping bushflies may be all but eradicated from Perth and the South-West under a new program to re-introduce dung beetles into the region.

The dung beetle program was suspended over a decade ago but a former CSIRO scientist has lobbied successfully to have it restored.

Two European species of beetle, one from France and one from Spain, will be imported from next March.

They will then be gradually introduced to breeding sites in the Peel and Boyup Brook districts.
John Feehan, who once ran the program for CSIRO and now operates an independent consultancy, says it will take time but bushflies will eventually be eradicated:

"Both species will work in early Spring and that's the very time that the bushfly population builds up into their millions so the beetles are just filling a little gap in the year that was not previously filled," he said.

Mr Feehan says it may be a little while before the results become evident.

"Bringing these beetles into Australia they have to go through very strict quarantine system," he said.
"They then have to be mass reared so it may be quite a few years before there is any particular result."
He praised the efforts of Canning MP Don Randall who he said had actively lobbied for the program.

http://www.abc.net.au/news/2011-10-28/dung-beetles-to-be-reintroduced/3605798