Ancient DNA reveals origin of first Bronze Age civilizations in Europe

Finding shed light on role of migration in Neolithic to Bronze Age transition and emergence of Indo-European languages

CENTER FOR GENOMIC REGULATION

Research News

 

IMAGE: SKELETON OF ONE OF THE TWO INDIVIDUALS WHO LIVED IN THE MIDDLE OF THE BRONZE AGE AND WHOSE COMPLETE GENOME WAS RECONSTRUCTED AND SEQUENCED BY THE LAUSANNE TEAM. IT COMES... view more 

CREDIT: EPHORATE OF ANTIQUITIES OF KOZANI, HELLENIC MINISTRY OF CULTURE, GREECE. COURTESY OF DR GEORGIA KARAMITROU-MENTESSIDI.

The first civilisations to build monumental palaces and urban centres in Europe are more genetically homogenous than expected, according to the first study to sequence whole genomes gathered from ancient archaeological sites around the Aegean Sea. The study has been published in the journal Cell.

Despite marked differences in burial customs, architecture, and art, the Minoan civilization in Crete, the Helladic civilization in mainland Greece and the Cycladic civilization in the Cycladic islands in the middle of the Aegean Sea, were genetically similar during the Early Bronze age (5000 years ago).

The findings are important because it suggests that critical innovations such as the development of urban centres, metal use and intensive trade made during the transition from the Neolithic to the Bronze Age were not just due to mass immigration from east of the Aegean as previously thought, but also from the cultural continuity of local Neolithic groups.

The study also finds that by the Middle Bronze Age (4000-4,600 years ago), individuals from the northern Aegean were considerably different compared to those in the Early Bronze Age. These individuals shared half their ancestry with people from the Pontic-Caspian steppe, a large geographic region stretching between the Danube and the Ural rivers and north of the Black Sea, and were highly similar to present-day Greeks.

The findings suggest that migration waves from herders from the Pontic-Caspian steppe, or populations north of the Aegean that bear Pontic-Caspian Steppe like ancestry, shaped present-day Greece. These potential migration waves all predate the appearance of the earliest documented form of Greek, supporting theories explaining the emergence of Proto-Greek and the evolution of Indo-European languages in either Anatolia or the Pontic-Caspian Steppe region.

The team took samples from well-preserved skeletal remains at archaeological sites. They sequenced six whole genomes, four from all three cultures during the Early Bronze Age and two from a Helladic culture during the Middle Bronze Age.

The researchers also sequenced the mitochondrial genomes from eleven other individuals from the Early Bronze Age. Sequencing whole genomes provided the researchers with enough data to perform demographic and statistical analyses on population histories.

Sequencing ancient genomes is a huge challenge, particularly due to the degradation of the biological material and human contamination. A research team at the CNAG-CRG, played an important role in overcoming this challenge through using machine learning.

According to Oscar Lao, Head of the Population Genomics Group at the CNAG-CRG, "Taking an advantage that the number of samples and DNA quality we found is huge for this type of study, we have developed sophisticated machine learning tools to overcome challenges such as low depth of coverage, damage, and modern human contamination, opening the door for the application of artificial intelligence to palaeogenomics data."

"Implementation of deep learning in demographic inference based on ancient samples allowed us to reconstruct ancestral relationships between ancient populations and reliably infer the amount and timing of massive migration events that marked the cultural transition from Neolithic to Bronze Age in Aegean," says Olga Dolgova, postdoctoral researcher in the Population Genomics Group at the CNAG-CRG.

The Bronze Age in Eurasia was marked by pivotal changes on the social, political, and economic levels, visible in the appearance of the first large urban centres and monumental palaces. The increasing economic and cultural exchange that developed during this time laid the groundwork for modern economic systems--including capitalism, long-distance political treaties, and a world trade economy.

Despite their importance for understanding the rise of European civilisations and the spread of Indo-European languages, the genetic origins of the peoples behind the Neolithic to Bronze Age transition and their contribution to the present-day Greek population remain controversial.

Future studies could investigate whole genomes between the Mesolithic and Bronze Age in the Armenian and Caucasus to help further pinpoint the origins of migration into the Aegean, and to better integrate the genomic data with the existing archaeological and linguistic evidence.

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Revealing the impact of 70 years of pesticide use on European soils

UNIVERSITY OF CÓRDOBA

Research News

 

Pesticides have been used in European agriculture for more than 70 years, so monitoring their presence, levels and their effects in European soils quality and services is needed to establish protocols for the use and the approval of new plant protection products.

In an attempt to deal with this issue, a team led by the prof. Dr. Violette Geissen from Wageningen University (Netherlands) have analysed 340 soil samples originating from three European countries to compare the contentdistribution of pesticide cocktails in soils under organic farming practices and soils under conventional practices. This study was a combined effort of 3 EC funded projects addressing soil quality: RECARE (http://www.recare-project.eu/), iSQAPER (http://www.isqaper-project.eu) and DIVERFARMING.

The soil samples were obtained from two case study sites in Spain, 1 case study site in Portugal, and 1 case study site in the Netherlands; which covered four of the main European crops: horticultural products and oranges (in Spain), grapes (in Portugal), and potato production (in the Netherlands). Chemical analyses revealed that the total content of pesticides in conventional soils was between 70% and 90% higher than in organic soils, although the latter soils did also contain pesticide residues.

Although in 70% of conventional soils mixtures of up to 16 residues were detected per sample, only a maximum of five different residues were found in the organic soils. the residues most frequently found and in the greatest quantities were the herbicides Glyphosate and Pendimethalin. The samples were collected between 2015-2018, as no major changes occurred in terms of management, there are indicative of current situation, and likely of other Eu agricultural areas."

Once the presence of these pesticide cocktails in European agricultural soils is unfolded, it becomes necessary to have a greater understanding of the effects that these complex and cumulative mixtures have on soil health, an area in which there is currently a major lack of information.

The research team emphasis the need to define and introduce regulations and reference points on pesticide cocktails in soils in order to protect the soil's biodiversity, and the quality of crop production. Additionally, taking into account the persistence of residues in organic soils it is necessary to reconsider the time required for the transition from conventional agriculture to organic agriculture, making it dependent on the mix of residues in the soil at starting point and the time they take to degrade.

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Diverfarming is a project financed by the Horizon 2020 Programme of the European Commission, within the challenge of "Food Security, Sustainable Agriculture and Forestry, Marine, Maritime and Inland Water Research and the Bioeconomy" under agreement 728003, and which counts on the participation of the Universities of Cartagena and Córdoba (Spain), Tuscia (Italy), Exeter and Portsmouth (United Kingdom), Wageningen (Netherlands), Trier (Germany), Pecs (Hungary) and ETH Zurich (Switzerland), the research centres Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria (Italy), the Consejo Superior de Investigaciones Científicas (Spain) and the Natural Resources Institute LUKE (Finland), the agrarian organisation ASAJA, and the companies Casalasco and Barilla (Italy), Arento, LogísticaDFM and Industrias David (Spain), Nieuw Bromo Van Tilburg and Ekoboerdeij de Lingehof (Netherlands), Weingut Dr. Frey (Germany), Nedel-Market KFT and Gere (Hungary) and Paavolan Kotijuustola and Polven Juustola (Finland).

Geissen, Violette & Silva, Vera & Huerta, E. & Beriot, Nicolas & Oostindie, Klaas & Bin, Zhaoqi & Pyne, Erin & Busink, Sjors & Zomer, Paul & Mol, H. & Ritsema, Coen. (2021). Cocktails of pesticide residues in conventional and organic farming systems in Europe - Legacy of the past and turning point for the future. Environmental Pollution. 278. 116827. 10.1016/j.envpol.2021.116827

New Monarch butterfly breeding pattern inspires hope

WASHINGTON STATE UNIVERSITY

Research News

 

IMAGE: A MONARCH CATERPILLAR FOUND IN SAN FRANCISCO IN FEBRUARY. view more 

CREDIT: WSU

PULLMAN, Wash. -- A count of the Western Monarch butterfly population last winter saw a staggering drop in numbers, but there are hopeful signs the beautiful pollinators are adapting to a changing climate and ecology.

The population, counted by citizen scientists at Monarch overwintering locations in southern California, dropped from around 300,000 three years ago to just 1,914 in 2020, leading to an increasing fear of extinction. However, last winter large populations of monarchs were found breeding in the San Francisco and Los Angeles areas. Prior to last winter, it was unusual to find winter breeding by monarchs in those locations.

"There's more to it than just counting overwintering butterflies," said David James, an associate professor in Washington State University's Department of Entomology. "It seems that Monarchs are evolving or adapting, likely to the changing climate, by changing their breeding patterns."

The larger numbers of reported sightings of winter breeding monarchs around the San Francisco Bay area prompted James to write a new commentary article in the journal Animal Migration.

The only way to count breeding populations last winter was to look at online citizen scientist observations, supported by limited field work, James said.

"There has been a huge increase in caterpillars in the Bay area, indicating that those populations are breeding," he said. "The data are limited and preliminary, but we think the population is at least double what has been reported. However, it's hard to tell since they're dispersed over much of California."

Past becomes present

James said this pattern of Monarch butterflies adapting looks familiar to him because he saw something similar while working on his Ph.D. dissertation over 40 years ago in Sydney, Australia.

In the late 1970s, the Monarch population in Australia saw huge declines. Scientists thought it was due to habitat loss, a common guess at one factor causing population declines in the western U.S. now.

"In Australia, Monarchs haven't gone extinct," James said. "They've just adapted and moved along with a smaller population. And there's no effort to preserve them there because they aren't a native species. They're just very resilient."

Sunnier outlook

Though the declining population is a concern, James believes Monarchs in the western U.S. will experience a similar plateau and not go extinct.

"San Francisco is very similar, climate-wise, to the area around Sydney," James said. "And seeing this winter breeding, which is something new we saw in Australia in the late 1970s, leads me to think that Monarchs will adapt well to the changing climate in the western US."

He is now working with citizen scientists to collect more data on winter breeding in California that can show this evolution and adaptability.

"The Monarch is like the cockroach of butterflies," James said. "It's very persistent and adaptable all around the world. The population decline is very worrying, but I remain optimistic that it will persist in the western US, although maybe at lower levels than before."

Why Monarchs matter

Monarchs are iconic and very popular, basically the poster insect when anyone thinks about butterflies. Their large orange wings with black accents are immediately recognizable. They're also important pollinators all along their migration routes, which in the western U.S. is basically from the Pacific Northwest to southern California. The loss of habitat for their favored milkweed is one reason for their dramatic population decline.

"Beyond their beauty is their role in ecology," James said. "They pollinate and they are also an important part of the food chain. There's a whole range of reasons why people care about them and don't want them to go extinct."

James is continuing his long-running Monarch tagging program, in which the butterflies are raised and tagged by people in the Northwest, including inmates at a prison, then released so they can migrate south for winter. He thinks he'll find more tagged monarchs around the Bay area in breeding, instead of in non-breeding overwintering colonies, as happened last winter.

He plans to work with citizen scientists to collect and crunch the data to come to solid scientific conclusions. Until then, he maintains his optimism about how well these butterflies adapt.

"We don't know if this adaptation will continue and how successful it will be," James said. "The western Monarch population is quite precarious right now. It's at a tipping point, and something is happening. We need to do more work to find out exactly what is happening."

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Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

Cryptic sense of orientation of bats localised: the sixth sense of mammals lies in the eye

LEIBNIZ INSTITUTE FOR ZOO AND WILDLIFE RESEARCH (IZW)

Research News

 

IMAGE: A CAPTURED NATHUSIUS BAT (PIPISTRELLUS NATHUSII) DURING THE EXPERIMENTS. view more 

CREDIT: PHOTO BY OLIVER LINDECKE

Mammals see with their eyes, hear with their ears and smell with their nose. But which sense or organ allows them to orient themselves on their migrations, which sometimes go far beyond their local foraging areas and therefore require an extended ability to navigate? Scientific experiments led by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), published together with Prof. Richard A. Holland (Bangor University, UK) and Dr. Gunārs P?tersons (Latvia University of Life Sciences and Technologies) now show that the cornea of the eyes is the location of such an important sense in migrating bats. If the cornea is anaesthetised, the otherwise reliable sense of orientation is disturbed while light detection remains unimpaired. The experiment suggests the localisation of a magnetic sense in mammals. The paper is published in the scientific journal Communications Biology.

A research team led by Dr Oliver Lindecke and PD Dr Christian Voigt from Leibniz-IZW demonstrated for the first time that environmental signals that are important for navigating over long distances are picked up via the cornea of the eyes. They conducted experiments with Nathusius' bats (Pipistrellus nathusii) during the late summer migration period. In bats of one test group, the scientists locally anaesthetised the cornea with a drop of oxybuprocaine. This surface anaesthetic is widely used in ophthalmology, where it is used to temporarily desensitise the patients' cornea when eyes of humans or animals get overly irritated. Effects on orientation, however, had not been previously recorded. In another test group of bats, the research team anaesthetised the cornea of only one eye. The individuals in the control group were not anaesthetised, but instead received an isotonic saline solution as eye drops. All animals in this scientific experiment were captured within a migration corridor at the coastline of the Baltic Sea and released singly in the open field 11 kilometres inland from the capture site immediately after treatment. The scientists first used bat detectors to make sure that there were no other bats above the field at the time of release that the test animals could have followed. The person observing the direction of movement of released bats was unaware about how bats were treated experimentally. "The control group and the group with unilateral corneal anaesthesia oriented themselves clearly in the expected southerly directions, whereas the bats with bilateral anaesthetised corneas flew off in random directions," explains Dr Oliver Lindecke, first author of the paper. "This evident difference in behaviour suggests that corneal anaesthesia disrupted a sense of direction, yet orientation apparently still works well with one eye." As corneal treatment wears off after a short time, the bats were able to resume their journeys south after the experiment. "We observed here for the first time in an experiment how a migrating mammal was literally blown off course - a milestone in behavioural and sensory biology that allows us to study the biological navigation system in a more targeted way."

In order to rule out the possibility that the anaesthetisation of the cornea also affects the sense of sight and that the scientists would thus come to the wrong conclusions, they carried out a complementary test. Once again divided into experimental and control groups, they tested whether the response of bats to light changed after anaesthesia of the corneas on one or both sides. "We know from previous research that bats prefer an illuminated exit when leaving a simple Y-shaped labyrinth," explains PD Dr Christian Voigt, head of the Leibniz-IZW Department of Evolutionary Ecology. "In our experiment, the animals with one-sided or two-sided anaesthesia also showed this preference; we therefore can rule out that the ability to see light was altered after corneal treatment. The ability to see light would of course also influence long-distance navigation."

Many vertebrates such as bats, dolphins, whales, fish and turtles, for example, are able to safely navigate in darkness, whether it is under the open night sky, when it is cloudy at night or in caves and tunnels as well as in the depths of the oceans. For many decades, scientists have been searching for the sense or a sensory organ that enables animals to perform orientation and navigation tasks that seemed difficult to imagine for people. A magnetic sense, so far only demonstrated in a few mammals but poorly understood, is an obvious candidate. Experiments suggest that iron oxide particles within cells may act as "microscopic compass needles", as is the case in some species of bacteria.

Recent laboratory experiments on Ansell's mole-rat, relatives of the well-known naked mole rats that spend their lives in elaborate underground tunnel systems, suggest that the magnetic sense is located in the eye. Such a (magnetic) sense of orientation has not been checked in migratory mammals nor has it been possible to identify the specific organ or tissue which could provide the morphological basis for the required sensory receptors. The experiments of the team around Lindecke and Voigt now provide, for the first time, reliable data for the localisation of a sense of orientation in free-ranging, migratory mammals. Exactly what the sense in the cornea of the bats looks like, how it works and whether it is the long sought-after magnetic sense must be shown in future scientific investigations.

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Publication

Lindecke O, Holland RA, P?tersons G, Voigt CC (2021): Corneal sensitivity is required for orientation in free-flying migratory bats. Communications Biology. DOI: 10.1038/s42003-021-02053-w

A surprising discovery: Bats know the speed of sound from birth

Bats' "supersense" of time

TEL-AVIV UNIVERSITY

Research News

IMAGE: PROF. YOSSI YOVEL view more 

CREDIT: TEL AVIV UNIVERSITY

A new Tel Aviv University study has revealed, for the first time, that bats know the speed of sound from birth. In order to prove this, the researchers raised bats from the time of their birth in a helium-enriched environment in which the speed of sound is higher than normal. They found that unlike humans, who map the world in units of distance, bats map the world in units of time. What this means is that the bat perceives an insect as being at a distance of nine milliseconds, and not one and a half meters, as was thought until now.

The Study was published in PNAS.

In order to determine where things are in a space, bats use sonar - they produce sound waves that hit objects and are reflected back to the bat. Bats can estimate the position of the object based on the time that elapses between the moment the sound wave is produced and the moment it is returned to the bat. This calculation depends on the speed of sound, which can vary in different environmental conditions, such as air composition or temperature. For example, there could be a difference of almost 10% between the speed of sound at the height of the summer, when the air is hot and the sound waves spread faster, and the winter season. Since the discovery of sonar in bats 80 years ago, researchers have been trying to figure out whether bats acquire the ability to measure the speed of sound over the course of their lifetime or are born with this innate, constant sense.

Now, researchers led by Prof. Yossi Yovel, head of the Sagol School of Neuroscience and a faculty member of the School of Zoology in the Faculty of Life Sciences and his former doctoral student Dr. Eran Amichai (currently studying at Dartmouth College) have succeeded in answering this question. The researchers conducted an experiment in which they were able to manipulate the speed of sound. They enriched the air composition with helium to increase the speed of sound, and under these conditions raised bat pups from the time of their birth, as well as adult bats. Neither the adult bats nor the bat pups were able to adjust to the new speed of sound and consistently landed in front of the target, indicating that they perceived the target as being closer - that is, they did not adjust their behavior to the higher speed of sound.

Because this occurred both in the adult bats that had learned to fly in normal environmental conditions and in the pups that learned to fly in an environment with a higher-than-normal speed of sound, the researchers concluded that the rate of the speed of sound in bats is innate - they have a constant sense of it. "Because bats need to learn to fly within a short time of their birth," explains Prof. Yovel, "we hypothesize that an evolutionary 'choice' was made to be born with this knowledge in order to save time during the sensitive development period."

Another interesting conclusion of the study is that bats do not actually calculate the distance to the target according to the speed of sound. Because they do not adjust the speed of sound encoded in their brains, it seems that they also do not translate the time it takes for the sound waves to return into units of distance. Therefore, their spatial perception is actually based on measurements of time and not distance.

Prof. Yossi Yovel: "What most excited me about this study is that we were able to answer a very basic question - we found that in fact bats do not measure distance, but rather time, to orient themselves in space. This may sound like a semantic difference, but I think that it means that their spatial perception is fundamentally different than that of humans and other visual creatures, at least when they rely on sonar. It's fascinating to see how diverse evolution is in the brain-computing strategies it produces."

Large bumblebees start work earlier

UNIVERSITY OF EXETER

 VIDEO: BUMBLEBEES IN THE STUDY view more 

CREDIT: KATIE HALL

Larger bumblebees are more likely to go out foraging in the low light of dawn, new research shows. University of Exeter scientists used RFID - similar technology to contactless card payments - to monitor when bumblebees of different sizes left and returned to their nest.

The biggest bees, and some of the most experienced foragers (measured by number of trips out), were the most likely to leave in low light.

Bumblebee vision is poor in low light, so flying at dawn or dusk raises the risk of getting lost or being eaten by a predator.

However, the bees benefit from extra foraging time and fewer competitors for pollen in the early morning.

"Larger bumblebees have bigger eyes than their smaller-sized nest mates and many other bees, and can therefore see better in dim light," said lead author Katie Hall, of the University of Exeter.

"We might expect all bumblebee foragers to leave the colony to forage as soon as there is enough light to allow them to fly.

"In fact, colonies seem to regulate the start of foraging.

"There is a balance of risks and rewards in low light - and most bees wait for higher light levels when they can see better and fly faster, with less risk from predators or getting lost and running out of energy.

"Our finding that more experienced bees are more likely to fly in lower light suggests that knowledge of food locations helps them navigate safely."

The study tracked the bees' behaviour over five days during warm periods of the flowering season.

Only a small proportion of foragers left the colony at dawn when light levels were below 10 lux.

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Katie Hall's work was funded by the Biotechnology and Biological Sciences Research Council - South West Biosciences Doctoral Training Partnership.

The study was carried out as part of a wider collaboration with the South Devon Area of Outstanding Natural Beauty.

The paper, published in the journal Ecology and Evolution, is entitled: "Onset of morning activity in bumblebee foragers under natural low light conditions."

The ants, bees and wasps of Canada, Alaska and Greenland - a checklist of 9250 species

PENSOFT PUBLISHERS

Research News

 

IMAGE: AMERICAN PELECINID WASP (PELECINUS POLYTURATOR) FROM DRIFTWOOD PROVINCIAL PARK, ONTARIO, CANADA view more 

CREDIT: HENRI GOULET

Knowing what species live in which parts of the world is critical to many fields of study, such as conservation biology and environmental monitoring. This is also how we can identify present or potential invasive and non-native pest species. Furthermore, summarizing what species are known to inhabit a given area is essential for the discovery of new species that have not yet been known to science.

For less well-studied groups and regions, distributional species checklists are often not available. Therefore, a series of such checklists is being published in the open-access, peer-reviewed Journal of Hymenoptera Research, in order to address the issue for a group of organisms that, despite its size and diversity, is still poorly known: the insect order Hymenoptera, which includes ants, bees and wasps. The surveyed area spreads across northern North America, which comprises Canada, Alaska (U.S.) and Greenland (Denmark), and occupies about 9.3% of the world's total land mass.

The last distributional survey of Hymenoptera in North America was published in 1979, where about 6000 described species were recorded from Canada and 600 from Alaska. The current survey lists 8933 species in Canada and 1513 in Alaska, marking an increase of 49% and 152%, respectively. A total of 9250 described species are recorded from northern North America. Considering that there are approximately 154,000 described species of Hymenoptera, northern North America has about 6% of the current world total.

Highlights of the series will include updated distributions of over 900 species of bees, which will provide valuable insight into native pollinators at a time when honey bees are in decline. Nearly 230 species of ants and over 100 species of vespid wasps (hornets and yellow jackets) are recorded, including pest species such as the widespread pharaoh ant and the newly invasive Asian giant hornet in British Columbia.

By far, the majority of species of Hymenoptera found in northern North America and the world are parasitoids, which develop on or in other invertebrate hosts and are therefore of great interest to the biological control of pests. Of the 9250 species recorded, more than three-quarters (over 7150 species) are parasitoids. These distributional lists provide essential baseline information required prior to undertaking studies to introduce biological control agents of invasive pests that may have escaped their native, natural enemies when they arrived in North America.

The topical collection "Checklists of the Hymenoptera of Canada, Alaska and Greenland" is to contain a total of eleven papers, where the introduction and the first two checklists: of sawflies (758 species) and one of the groups of "microhymenoptera" (the chalcidoid parasitic wasps) (1246 species) have just been published.The other checklists are to follow over the next several years. The associated data are also being uploaded to the Global Biodiversity Information Facility (GBIF), allowing for periodic updates over time.

When complete, this will be the largest species checklist for any group of organisms in northern North America. Considering that it is estimated that we currently have documented less than half of the species of Hymenoptera present in northern North America, there is still a great amount of work to do on this fascinating group of insects.

CAPTION

A cuckoo wasp of the genus Hedychridium from Manitoulin Island, Ontario, Canada

CREDIT

Henri Goulet

Original sources:

Bennett AMR (2021a) Checklists of the Hymenoptera of Canada, Alaska and Greenland - Introduction. Journal of Hymenoptera Research 82: 1-19. https://doi.org/10.3897/jhr.82.60054

Bennett AMR (2021b) Checklist of the Hymenoptera of Canada, Alaska and Greenland. Agriculture and Agri-Food Canada. Checklist dataset https://doi.org/10.5886/4piso5 [accessed via GBIF.org: 12 March 2021].

Goulet H, Bennett AMR (2021) Checklist of the sawflies (Hymenoptera) of Canada, Alaska and Greenland. Journal of Hymenoptera Research 82: 21-67. https://doi.org/10.3897/jhr.82.60057

Huber JT, Bennett AMR, Gibson GAP, Zhang YM, Darling DC (2021) Checklist of Chalcidoidea and Mymarommatoidea (Hymenoptera) of Canada, Alaska and Greenland. Journal of Hymenoptera Research 82: 69-138. https://doi.org/10.3897/jhr.82.60058

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

CAPTION

Pigeon tremex (Tremex columba) from Manitou Lake, Manitoulin Island, Ontario, Canada

CREDIT

Henri Goulet

USAGE REST

Bees thrive where it's hot and dry: A unique biodiversity hotspot located in North America

PENSOFT PUBLISHERS

Research News

 

IMAGE: ONE OF THE SPRING-ACTIVE DESERT BEES, FEMALE CENTRIS CAESALPINIAE ON FLOWER OF KRAMERIA view more 

CREDIT: BRUCE D. TAUBERT

The United States-Mexico border traverses through large expanses of unspoiled land in North America, including a newly discovered worldwide hotspot of bee diversity. Concentrated in 16 km2 of protected Chihuahuan Desert are more than 470 bee species, a remarkable 14% of the known United States bee fauna.

This globally unmatched concentration of bee species is reported by Dr. Robert Minckley of the University of Rochester and William Radke of the United States Fish and Wildlife Service in the open-access, peer-reviewed Journal of Hymenoptera Research.

Scientists studying native U.S. bees have long recognized that the Sonoran and Chihuahuan deserts of North America, home to species with interesting life histories, have high bee biodiversity. Exactly how many species has largely remained speculation. Together with students from Mexico, Guatemala and the United States, the authors made repeated collections over multiple years, identifying more than 70,000 specimens.

Without such intensive collecting, a full picture of the bee diversity would not have been possible. Most of these bee species are solitary, without a queen or workers, which visit flowers over a 2-4 week lifespan and specialize on pollen and nectar from one to a few plants. Furthermore, these desert species experience periodic drought, which the immature stages survive by going into dormancy for years, much like the seeds of the desert plants they pollinate.

CAPTION

One of the late-summer desert bees, a long-horned female bee of the Svastra genus, on a flower of Verbesina enceliodes

CREDIT

Bruce D. Taubert

Additionally, bee diversity is notoriously difficult to estimate and compare among studies, because of differences in the collecting techniques and the size of the studied area. An unexpected benefit of the regular and intensive sampling for this study was the opportunity to test if the observed bee diversity approached the true bee diversity in this region, or if many more species were yet to be found. In this case, the larger San Bernardino Valley area is home to 500 bee species, only slightly above the number of species recovered along the border - an unusually robust confirmation of the researchers' estimate.

What we know about the decline of bees due to human activity, along with that of other pollinators, is based primarily on diversity data from human-modified habitats. Needed is baseline information on native bees from pristine areas to help us assess the magnitude and understand the ways in which humans impact bee faunas. This study from the Chihuahuan Desert is therefore an important contribution towards filling that knowledge gap from one of the bee biodiversity hotspots in the world.

Original source:

Minckley RL, Radke WR (2021) Extreme species density of bees (Apiformes, Hymenoptera) in the warm deserts of North America. Journal of Hymenoptera Research 82: 317-345. https://doi.org/10.3897/jhr.82.60895

CAPTION

One of the spring-active desert bees, male Centris caesalpiniae on a flower of Acacia

CREDIT

Bruce D. Taubert

USAGE RESTRICTIONS

The secret life of bee signals can

communicate colony health

Recording the electrostatic energy of honeybee hives offers a 'canary in the coalmine' look into ecosystem threats and environmental conditions

FRONTIERS

Research News

 

IMAGE: HIVE CONSTRUCTION AND MEASURING DEVICES. (A) FRONT AND SIDE VIEW OF THE HIVE. A PLASTIC TUBE CONTAINING A GPS RECEIVER WAS FIXED TO A SIDEWALL (NOT SHOWN). THE WEIGHT OF... view more 

CREDIT: BENJAMIN H. PAFFHAUSEN, JULIAN PETRASCH, UWE GREGGERS ET AL.

Honeybees have a complex communication system. Between buzzes and body movements, they can direct hive mates to food sources, signal danger, and prepare for swarming - all indicators of colony health. And now, researchers are listening in.

Scientists based in Germany - with collaborators in China and Norway - have developed a way to monitor the electrostatic signals that bees give off. Basically, their wax-covered bodies charge up with electrostatic energy due to friction when flying, similar to how rubbing your hair can make it stand on end. That energy then gets emitted during communications.

"We were thrilled by the potential of directly accessing the social communication of bees with our method," says Dr. Randolf Menzel, of the Free University of Berlin. "For the first time we can ask the bees themselves whether their colony is in a healthy condition or whether they suffer from unfavorable environmental conditions including those caused by humans."

The paper, recently published in the open access journal Frontiers in Behavioral Neuroscience, likens honeybee colonies to a canary in a coal mine. Bees are usually among the first species to be affected by pollutants such as insecticides, and weakened communications can signal their damaging effects. Such evidence may point to potential harm to other wildlife and ecosystems in a way that is quicker and cheaper than other methods.

Menzel and his colleagues worked with 30 beekeepers across Germany over a period of five years. They placed sensors and a central recording device inside and outside a specially designed hive, and monitored the honeybees' electrostatic field (ESF) data.

They were particularly interested in what is known as the "waggle dance," a sophisticated messaging system in which honeybees walk in a figure-eight pattern, then "waggle" back and forth through the stretched part of the intersection. This bee ballet communicates flight directions and distance. "Other bees follow the dancing bee, read the message of the dancer, and apply the information about distance and direction to an attractive food source in their outbound flights," says Menzel.

The primary purpose of their research study was to measure the feasibility of their recording system, which did indeed work, although Menzel notes that scaling up their system would be challenging, and "to get meaningful knowledge about the impact of pesticides and health conditions of bees in a larger area, we will have to use many devices across that area."

Still, the researchers learned more about hive communication, and found what Menzel described as "unexpected phenomena." For example, they found that bees perform waggle dances at night as well as during the day, and that insecticides used for treatment against pest mites had a negative impact on honeybees' communication. They also found that ESF signals were emitted in preparation of swarming, and that their strength didn't depend on environmental conditions such as humidity and UV radiation.

Menzel says that their system collected a large amount of data, and that they need further studies to improve and finetune interpretation. "So far we have only begun to apply machine learning algorithms to separate and quantify the electrostatic field signals." In the future though, it's possible that eavesdropping on bees may provide rich and important information beyond the local pollen hotspot. Their communications could be crucial in understanding - and protecting - whole ecosystem

CAPTION

Representative examples of three classes of ESF (electrostatic field) signals. (A) Waggle-dance-related signals (WRS). The electrograms show the time/frequency diagram in false colors (signal power) for two frequency bands, the low frequency of the abdomen waggling (WRS_L) and the high frequency of the wing vibrations (WRS_H). (B) Short pulse related signals (SRS) with the time courses and corresponding electrograms for two kinds of SRS. (C) Fanning related signals (FRS). Note the different time scales.

CREDIT

Benjamin H. Paffhausen, Julian Petrasch, Uwe Greggers et al.