The first serious freezing of the year will kill the adult dragonflies.
This video from Australia says about itself:
25 February 2017
From the Yale-NUS College in Singapore:
Beetles’ bright colors used for camouflage instead of warning off predators
First study to examine beetle colouration in their natural habitat prompts discovery
December 4, 2017
NUS College Postdoctoral Fellow Eunice Tan has discovered that the bright colour patterns of beetles are not a warning signal to predators as previously believed, but actually a form of camouflage, turning an old assumption on its head. Dr Tan, along with four collaborators from Australia and Spain, examined 51 species of Australian leaf beetles in their natural habitats, and discovered that each beetle’s colour pattern is similar to the host plants that the beetle lives on, suggesting that those conspicuous colours help the beetle blend in with the plants it inhabits. The study was recently published as an open-access article in the peer-reviewed journal Frontiers in Ecology and Evolution.
As the first ecologist to examine the colour patterns of live leaf beetles in relation to their host plants, Dr Tan contextualised the colour patterns of beetles to their natural habitats, which allowed her to challenge the prevailing theory among coleopterists — scientists who study beetles — that the bright colours of leaf beetles developed as a deterrent signal to predators. These colourful markings were assumed to be a warning to predators against eating the beetles, which are able to secrete poisonous chemicals in self-defence. However, this idea was based on earlier studies, which focused on using museum collections of beetle specimens for their analyses. While this method affords researchers a large number of samples, the discolouration of deceased specimens made accurate colour analysis of the beetles impossible. Furthermore, such methodology also fails to take into account the colouration of each beetle’s natural environment.
Dr Tan and her team spent 17 months photographing live beetles in 32 locations across four Australian states, in order to compare each beetle’s colouration to the colour of the leaf it was found on. Taking into account the evolutionary relationship between the different beetle species, Dr Tan discovered that different species of beetles had colour patterns similar to those of their host plants. This suggests that the colourations have a camouflaging effect, rather than serving an aposematic (predator-deterring) function. This camouflage effect was particularly pronounced in beetles which fed on multiple types of plants, as they had to blend into many different environments.
“It was long thought that conspicuous colour patterns served to advertise the distastefulness of an organism to its predators. However, we have found that this cannot be the sole reason that conspicuous colour patterns developed in leaf beetles. In general, the beetles had colouration similar to that of their host plants, suggesting that there is natural selection at play and therefore some evolutionary advantage for these beetles to use camouflage as a defensive strategy against predators,” shared Dr Tan.
Through her field studies, Dr Tan also observed the impact of ecological factors on the evolution of different beetle species’ colouration patterns. Dr Tan’s study found that both larger and smaller beetle species in her sample had similar levels of colour contrast against their backgrounds. However, the larger beetle species were more likely to be found in darker environments than their smaller cousins, suggesting that they were employing a hiding strategy against predators, despite having similar conspicuous colouration to their smaller cousins. An ecological property, the brightness of the environment, was therefore a potential factor influencing the evolution of beetle colouration.
Taken together, the findings of this study “point to a complex suite of factors driving natural selection, such as types of predators and host plant choice, which affect the evolution of colouration in leaf beetles,” said Dr Tan. Challenging the assumption that the sole explanation for bright coloration in leaf beetles is meant to ward off predators, Dr Tan postulated that the variety of anti-predator strategies in leaf beetles that she has found may explain their successful spread into a variety of habitats.
Translated from Dutch Vroege Vogels radio:
Dragonflies on watercolors
Friday, December 1, 2017
At the end of the nineteenth century, the Belgian Baron Edmond de Sélys Longchamps drew and painted many hundreds of dragonflies. Not for fun, but for science.
An important and valuable collection. Still, the folders with dragonfly aquarelles fell into oblivion. But in 2002 they were found again, almost literally under a layer of dust in a cabinet at the Royal Belgian Institute of Natural Sciences in Brussels.
Since then the Dutch dragonfly researchers Karin Verspui and Marcel Wasscher have studied the drawings. ‘We are talking about a time when there was obviously no good photography yet. This kind of drawings and watercolors were the gold standard for describing species”, says Verspui. ‘There are very special examples, including many so-called holotype specimens. These are the original individuals used to describe a new species. Where most of the type specimens themselves have completely lost their color, these watercolors are still of exceptional quality. These drawings deserve a larger audience”, says Verspui.
The digitized watercolors can be found on the RBINS site.
Ms Verspui said today on radio that Baron Edmond de Sélys Longchamps was an amateur entomologist. Nevertheless, he wrote scientific descriptions of about 700 dragonfly and damselfly species; about a third of the 2000 species known to science then.
New butterfly species discovered in Russia with an unusual set of 46 chromosomes
November 27, 2017
Summary: Finding a new species is a rare event in easy-to-see and well-studied organisms like butterflies, especially if they inhabit well-explored areas such as Europe. Researchers have now discovered the previously unknown South-Russian blue using an array of modern research techniques. Furthermore, the new species was found to possess 46 chromosomes, just like a human, whereas its closest relative has 68 chromosomes.
What looked like a population of a common butterfly species turned out to be a whole new organism, and, moreover — one with a very peculiar genome organisation.
Discovered by Vladimir Lukhhtanov, entomologist and evolutionary biologist at the Zoological Institute in St. Petersburg, Russia, and Alexander Dantchenko, entomologist and chemist at the Moscow State University, the startling discovery was named South-Russian blue (Polyommatus australorossicus). It was found flying over the northern slopes of the Caucasus mountains in southern Russia. The study is published in the open access journal Comparative Cytogenetics.
“This publication is the long-awaited completion of a twenty-year history,” says Vladimir Lukhtanov.
In the mid-nineties, Vladimir Lukhtanov, together with his students and collaborators, started an exhaustive study of Russian butterflies using an array of modern and traditional research techniques. In 1997, Alexander Dantchenko who was mostly focused on butterfly ecology, sampled a few blue butterfly specimens from northern slopes of the Caucasus mountains. These blues looked typical at first glance and were identified as Azerbaijani blue (Polyommatus aserbeidschanus).
However, when the scientists looked at them under a microscope, it became clear that they had 46 chromosomes — a very unusual number for this group of the blue butterflies and exactly the same count as in humans.
Having spent twenty years studying the chromosomes of more than a hundred blue butterfly species and sequencing DNA from all closely related species, the researchers were ready to ascertain the uniqueness of the discovered butterfly and its chromosome set.
Throughout the years of investigation, it has become clear that caterpillars of genetically related species in the studied butterfly group feed on different, but similar plants. This discovery enables entomologists to not only discover new butterfly species with the help of botanic information, but also protect them.
“We are proud of our research,” says Vladimir Lukhtanov. “It contributes greatly to both the study of biodiversity and understanding the mechanisms of biological evolution.”