EGYPTOLOGY/ENTOMOLGY
Dung beetles show their love by sharing the load
Before mating, some male and female dung beetles work together to move their brood balls to a location unknown to either.
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BEFORE MATING, SOME MALE AND FEMALE DUNG BEETLES WORK TOGETHER TO MOVE THEIR BROOD BALLS TO A LOCATION UNKNOWN TO EITHER.
view moreCREDIT: WITS UNIVERSITY
Dung beetles share the load when it comes to showing their affection for each-other, when transporting a “brood ball”.
Dung Beetles are known for collecting piles of dung for various uses. One of these is called a “brood ball”, where they lay an egg in each ball, after they have buried it. When the egg hatches, the larva uses the ball as a nursery, eating the ball from the inside out, shaving off layers to keep the ball intact.
“The brood ball is a vehicle that the adult beetles use to get their genes into the next generation,” says Professor Marcus Byrne of the School of Animal, Plant and Environmental Studies at the University of the Witwatersrand (Wits University), in Johannesburg, South Africa.
Byrne and Professor Marie Dacke of the Vision Group at Lund University, Sweden, have studied the navigational behaviour of dung beetles for over two decades. They have found that dung beetles’ source of food is never at the same location, and consequently they have an extremely limited way of memorising environmental cues around the dung. Instead they make use of the stars, wind and the sun and moon, among others, to find their way away from dung sources to avoid competition.
Ball-rolling dung beetles transport balls of dung and bury them in the soil, for feeding or breeding. After carefully constructing a dung ball at the dropping site, these beetles immediately roll it away along a linear path avoiding intra- and interspecific competition for food and nesting sites.
In their latest study, published in The Proceedings of the Royal Society B, Byrne, Dacke and lead author Dr Claudia Tocco (formerly at Wits and now at Lund University, Sweden) found that when transporting a brood ball, male and female dung beetles work together transporting the ball to a location that neither of them know about beforehand.
“It is important to note that each individual ant or spider involved in the cooperative transport of food strives towards the same final known destination; either a nest or a tightly spun shelter, in which to store the food,” says Tocco. “In contrast, pairs of male and female dung beetles fluently collaborate to transport food to a location unknown to either party at the start of their common journey.”
For their study, Byrne and colleagues studied the transport behaviour of brood balls by pairs of the Southern African Sisyphus fasciculatus and European Sisyphus schaefferi. Both these species of dung beetles are small in size and associated with woodland habitats, where they commonly encounter obstacles on their rolling paths, usually plant material that falls from the trees.
The team found that pairs of Sisyphus beetles cooperate in the transportation of brood balls, resulting in greater transport efficiency in the face of obstacles. This cooperation is driven by coordinated movements where the male steers while the female primarily assists in lifting the ball whenever obstacles need to be climbed.
The characteristic straight-line escape not only guarantees that the ball-rolling beetles will not inadvertently return to the competition at the dropping site, but also effectively maximizes the beetles’ distance from it with every step taken.
When paired up for mating, the exact location at which the pair chooses to stop and bury their brood ball is also selected on the go, on the basis of the properties of the terrain being traversed.
“To ensure smooth and effective transport, efficient communication must be taking place between the male and female of the beetle pair. However, the mechanism that allows the beetle pair to communicate and coordinate their joint actions is currently not known,” says Byrne. This opens up opportunities to investigate collaboration in many other fields, such as robotics.
JOURNAL
Proceedings of the Royal Society B Biological Sciences
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Bottlenecks and beehives: how an invasive bee colony defied genetic expectations
Adaptability despite low genetic diversity could be a good sign for threatened species
Peer-Reviewed PublicationIMAGE:
ASIAN HONEYBEE SWARM IN CAIRNS, QUEENSLAND.
view moreCREDIT: DR ROS GLOAG
For more than a decade, invasive Asian honeybees have defied evolutionary expectations and established a thriving population in North Queensland, much to the annoyance of the honey industry and biosecurity officials.
Research published today in Current Biology has shown the species, Apis cerana, has overcome what is known as a genetic bottleneck to grow from a single swarm into a population of more than 10,000 colonies over a 10,000 square kilometre area – which is about the size of Greater Sydney.
Co-lead author Dr Rosalyn Gloag from the University of Sydney School of Life and Environmental Sciences said: “Our study of this bee population shows that some species can quickly adjust to new environments despite starting with very low genetic diversity relative to their native-range populations.”
Dr Gloag said that high genetic diversity is generally assumed to be important for a population to quickly adapt to changing environmental conditions, such as when a species is translocated or experiences rapid environmental change caused by natural or climate change disasters.
“However, we have shown that this invasive population of honeybees has rapidly adapted since its arrival, despite having suffered a steep loss in genetic diversity,” she said.
The research team highlight the importance of this case study for understanding population resilience in general.
“This is even more important as we observe many species dealing with anthropogenic climate change,” Dr Gloag said.
Studying the invasive population in Queensland gave the research team a rare complete genetic timeline of a natural invasion, beginning from soon after the bees arrived.
The arrival of the colony in 2007, likely from Papua New Guinea, was of concern to Australian biosecurity because of the parasites the bees can carry. Ultimately these bees were found not to be carrying the most feared of its parasites, the varroa mite, which has since arrived in Australia by an unknown route, threatening the domestic honey industry.
“We were lucky to have a complete sample timeline of this invasive population thanks to the incredible efforts of the Queensland Department of Agriculture and Fisheries, which sampled the population extensively during the early years of the incursion as part of an eradication attempt,” Dr Gloag said.
“Although that attempt was unsuccessful, the biological material collected has been incredibly valuable for understanding how these invasions proceed. And that in turn helps us prepare better for future invasions,” she said.
Access to this comprehensive sample set allowed the scientists to re-sequence entire genomes of 118 individual bees collected over 10 years.
“We could essentially observe natural selection acting over time in a population that started with low genetic diversity,” Dr Gloag said. “From this unique vantage point, we could see that selection was acting on the variation in genomes that had arrived with the handful of original bees. It wasn’t variation that arose later by mutations.
“In other words, some species with very low genetic diversity can adapt very quickly,” she said.
“While this might be bad news for environments coping with newly arrived invasive species, it’s potentially good news for populations that have temporary crashes in the face of climate change or other natural or human-induced disasters, such as bushfires.”
The study was done in collaboration with scientists at York University (Canada), IPB University (Indonesia), Bandung Institute of Technology (Indonesia) and the CSIRO (Australia).
Dr Ros Gloag from the School of Life and Environmental Sciences at the University. Dr Gloag is pitcured here with a tetragonula hive (not the Asian honeybees of the study).
A single Asian honeybee (photo taken in its natural range in China).
CREDIT
Ben Oldroyd/The University of Sydney
Swarm of invasive Asian honeyb [VIDEO] |
DOWNLOAD research, images and videos of the bees at this link.
RESEARCH
Dogantzis, K, Gloag, R, et al (2024) ‘Post-invasion selection acts on standing genetic variation despite a severe founding bottleneck’ Current Biology DOI: 10.1016/j.cub.2024.02.010
DECLARATION
The authors declare no competing interests. Research was conducted with assistance from the Australian Research Council, the Natural Sciences and Engineering Research Council (Canada) and the Ministry of Research, Technology and Higher Education (Indonesia).
JOURNAL
Current Biology
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Post-invasion selection acts on standing genetic variation despite a severe founding bottleneck
ARTICLE PUBLICATION DATE
29-Feb-2024
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