pollination

Scientists unravel the evolution and relationships for all European butterflies in a first

For the first time, a complete time-calibrated phylogeny for a large group of invertebrates is published for an entire continent. A German-Swedish team of scientists provide a diagrammatic hypothesis of the relationships and evolutionary history for all 496 European species of butterflies currently in existence. Their study provides an important tool for evolutionary and ecological research, meant for the use of insect and ecosystem conservation.

For the first time, a complete time-calibrated phylogeny for a large group of invertebrates is published for an entire continent.

The figure shows the relationships of the 496 extant European butterfly species in the course of their evolution during the last 100 million years.
*Image by Dr Martin Wiemers*

In a recent research paper in the open-access, peer-reviewed academic journal ZooKeys, a German-Swedish team of scientists provide a diagrammatic hypothesis of the relationships and evolutionary history for all 496 European species of butterflies currently in existence. Their study provides an important tool for evolutionary and ecological research, meant for the use of insect and ecosystem conservation.

In order to analyse the ancestral relationships and history of evolutionary divergence of all European butterflies currently inhabiting the Old continent, the team led by Martin Wiemers – affiliated with both the Senckenberg German Entomological Institute and the Helmholtz Centre for Environmental Research – UFZ, mainly used molecular data from already published sources available from NCBI GenBank, but also contributed many new sequences, some from very local endemics for which no molecular data had previously been available.

The phylogenetic tree also includes butterfly species that have only recently been discovered using molecular methods. An example is this Blue (*Polyommatus celina*), which looks similar to the Common Blue. It used to be mistaken for the Common Blue in the Canary Islands and the southwestern part of the Mediterranean Region.
*Photo by Dr Martin Wiemers*

Butterflies, the spectacular members of the superfamily Papilionoidea, are seen as an important proponent for nature conservation, as they present an excellent indicator group of species, meaning they are capable of inferring the environmental conditions of a particular habitat. All in all, if the local populations of butterflies are thriving, so is their habitat.

Furthermore, butterflies are pollinating insects, which are of particular importance for the survival of humans. There is no doubt they have every right to be recognised as a flagship invertebrate group for conservation.

While many European butterflies are seriously threatened, this one: Madeiran Large White (Pieris wollastoni) is already extinct. The study includes the first sequence of this Madeiran endemic which was recorded in 1986 for the last time. The tree demonstrates that it was closely related to the Canary Island Large White (Pieris cheiranthi), another threatened endemic butterfly, which survives only on Tenerife and La Palma, but is already extinct on La Gomera.
Photo by Dr Martin Wiemers

In recent times, there has been a steady increase in the molecular data available for research, however, those would have been only used for studies restricted either to a selected subset of species, or to small geographic areas. Even though a complete phylogeny of European butterflies was published in 2019, also co-authored by Wiemers, it was not based on a global backbone phylogeny and, therefore, was also not time-calibrated.

In their paper, Wiemers and his team point out that phylogenies are increasingly used across diverse areas of macroecological research, such as studies on large-scale diversity patterns, disentangling historical and contemporary processes, latitudinal diversity gradients or improving species-area relationships. Therefore, this new phylogeny is supposed to help advance further similar ecological research.

The study includes molecular data from 18 localised endemics with no public DNA sequences previously available, such as the Canary Grayling (Hipparchia wyssii), which is only found on the island of Tenerife (Spain).
Photo by Dr Martin Wiemers

Original source:

Wiemers M, Chazot N, Wheat CW, Schweiger O, Wahlberg N (2020) A complete time-calibrated multi-gene phylogeny of the European butterflies. ZooKeys 938: 97-124. https://doi.org/10.3897/zookeys.938.50878

A new hope: One of North America’s rarest bees has its known range greatly expanded

The Macropis Cuckoo Bee is one of the rarest bees in North America, partly because of its specialized ecological associations. It is a nest parasite of oil-collecting bees of the genus Macropis which, in turn, are dependent on oil-producing flowers of the genus Lysimachia.

In fact, the cuckoo bee – which much like its feather-bearing counterpart does not build a nest of its own, but lays its eggs in those of other species instead – is so rare that it was thought to have gone extinct until it was collected in Nova Scotia, Canada, in the early 2000s. As a result, the Macropis Cuckoo Bee was brought to the attention of the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).

Recently, an individual reported from Alberta, Canada, brought new hope for the survival of the species. In addition to previously collected specimens from Ontario, this record greatly expands the known range of the cuckoo.

Scientists Dr Cory S Sheffield, Royal Saskatchewan Museum, Canada, who was the one to rediscover the “extinct” species in Nova Scotia, and Jennifer Heron, British Columbia Ministry of Environment & Climate Change Strategy, present their new data, and discuss the conservation status of this species in their paper, published in the open access journal Biodiversity Data Journal.

“This species has a very interesting biology,” they say, “being a nest parasite – or cuckoo – of another group of bees that in turn have very specialized dietary needs.”

The hosts, bees of the genus Macropis (which themselves are quite rare) are entirely dependent on plants of the primrose genus Lysimachia. Moreover, they only go after those Lysimachia species whose flowers produce oil droplets, which the insects collect and feed to their larvae. Thus, Macropis bees require these oil-producing flowers to exist just like Macropis cuckoo bees need their hosts and their nests. Curiously, this reliance, as suggested by previous studies on related European species, has made the female cuckoos develop the ability to find their host’s nests by the smell of the floral oils.

“This level of co-dependence between flower, bee, and cuckoo bee, makes for a very tenuous existence, especially for the cuckoo,” the authors comment. “The recent specimen from Alberta lets us know that the species is still out there, and is more widespread than we thought.”

In conclusion, the authors suggest that continuing to monitor for populations of rare bees, and documenting historic records, are crucial for conservation status assessments of at-risk species.

“Biodiversity Data Journal provides a great venue to share this type of information with our colleagues for regional, national, and international efforts for species conservation,” they note.

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Original source:

Sheffield C, Heron J (2018) A new western Canadian record of Epeoloides pilosulus (Cresson), with discussion of ecological associations, distribution and conservation status in Canada. Biodiversity Data Journal 6: e22837. https://doi.org/10.3897/BDJ.6.e22837

Claims that declines of pollinator species richness are slowing down in Europe revisited

Having conducted a thorough interpretation of the results of a recent study that inferred decrease in the biodiversity loss among pollinators across Europe, Dr Tom J. M. Van Dooren reveals that this conclusion cannot in fact be drawn. It is only supported for the bee fauna in the Netherlands. His study is published in the open access journal Nature Conservation.

Changes in pollinator abundances and diversity are of major concern. Pollinator diversity is quantified by their species richness: the number of species from a specific taxonomic group of pollinating animals present at a given time in a given area. A recent study, adopted in the recent UN IPBES Pollination Report draft summary, inferred that pollinator species richnesses are decreasing more slowly in recent decades in several taxonomic groups and European countries.

However, Dr Tom J. M. Van Dooren, affiliated with both Naturalis Biodiversity Center, the Netherlands, and the Institute of Ecology and Environmental Sciences of Paris, France, has now published his own study to show in detail the inaccuracies that the earlier conclusion has been based on.

Among other points, the scientist notes that the earlier study contained no explicit statistical comparisons between species richness changes in different periods. The earlier study also treated richness changes at country level and small spatial resolution as equivalent, while they probably represent different processes.

“Plants in Great Britain at the smallest spatial scales suggest a reduced rate of changes, but the results for larger spatial scales are not significant,” he illustrates. “The same holds for butterflies in the Netherlands.”

Dr Tom J. M. Van Dooren only finds support in the results of the earlier publication for a decelerating decline in bumblebees and other wild bees in the Netherlands. “This is in fact one taxon, the bees Anthophila, in a single country, the Netherlands”, he notes.

“The lack of robustness points again to the possibility that results found in the data can be due to changes in the shapes of species accumulation curves,” Dr Tom J. M. Van Dooren summarises. “Therefore the status of the statement on decelerating declines in the Pollination Report should be adjusted accordingly.”

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Original source:

Van Dooren TJM (2016) Pollinator species richness: Are the declines slowing down? Nature Conservation 15: 11-22. doi: 10.3897/natureconservation.15.9616

Photo credit:

Aiwok, Wikimedia Commons, CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)

Bee populations expanded during global warming after the last Ice Age

The Australian small carpenter bee populations appear to have dramatically flourished in the period of global warming following the last Ice Age some 18,000 years ago.

The bee species is found in sub-tropical, coastal and desert areas from the north-east to the south of Australia. Researchers Rebecca Dew and Michael Schwarz from the Flinders University of South Australia teamed up with Sandra Rehan, the University of New Hampshire, USA, to model its past responses to climate change with the help of DNA sequences. Their findings are published in the open access Journal of Hymenoptera Research.

“You see a rapid increase in population size from about 18,000 years ago, just as the climate began warming up after the last Ice Age,” says lead author Rebecca Dew. “This matches the findings from two previous studies on bees from North America and Fiji.”

“It is really interesting that you see very similar patterns in bees around the world,” adds Rebecca. “Different climate, different environment, but the bees have responded in the same way at around the same time.”

In the face of future global warming these finding could be a good sign for some of our bees.

However, the news may not all be positive. There are other studies showing that some rare and ancient tropical bees require cool climate and, as a result, are already restricted to the highest mountain peaks of Fiji. For these species, climate warming could spell their eventual extinction.

“We now know that climate change impacts bees in major ways,” says Rebecca, “but the challenge will be to predict how those impacts play out. They are likely to be both positive and negative, and we need to know how this mix will unfold.”

Bees are major pollinators and are critical for many plants, ecosystems, and agricultural crops.

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Original source:

Dew RM, Rehan SM, Schwarz MP (2016) Biogeography and demography of an Australian native bee Ceratina australensis (Hymenoptera, Apidae) since the last glacial maximum. Journal of Hymenoptera Research 49: 25-41. doi: 10.3897/JHR.49.8066