Prehistoric insect evolution in the Eocene

This 17 July 2018 video says about itself:

The Mystery of the Eocene’s Lethal Lake

In 1800s, miners began working in exposed deposits of mud near the town of Messel, Germany. They were extracting oil from the rock and along with the oil, they found beautifully preserved fossils of animals from the Eocene. What happened to these Eocene animals? And why were their remains so exquisitely preserved?

Two additional notes!

-At 00:56, we incorrectly labelled a Darwinius fossil as Thaumaturus. Thaumaturus was a fish and the fossil we show is definitely not a fish.

-Also, an additional image credit is required: Dmitry Bogdanov illustrated the fish we used to show scavengers.

From the Ludwig-Maximilians-Universität München in Germany:

Insect evolution during the Eocene epoch

October 25, 2019

Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich have shown that the incidence of midge and fly larvae in amber is far higher than previously thought. The new finds shed light on insect evolution and the ecology in the Baltic amber forest during the Eocene epoch.

In the Eocene epoch — between 56 and 33.9 million years ago — much of Northern Europe was covered by a huge forest, now referred to as the Baltic amber forest. The forest was probably dominated by pines and oaks, but also comprised representatives of many other deciduous species and conifers, including tropical taxa. The resins produced by the forest account for all of Europe’s amber, including the samples in which the LMU zoologists Viktor Baranov, Mario Schädel and Joachim T. Haug have now discovered many examples of entrapped midge and fly larvae. In a paper published in the online journal PeerJ, they point out that these finds refute the widespread notion that amber is devoid of such fossils. Their analysis also provides new evidence in relation to the ecology of the amber forests of Eocene age, which supports a new interpretation of this habitat as a warm to temperate seasonal humid forest ecosystem.

Flies and midges (Diptera) make up one of the most diverse groups of insects found in Germany. Their larval forms are an important element of many ecosystems and play a significant role in, for example, the decomposition and recycling of biomass. In spite of their ecological prominence, little is known about the evolution of dipteran larvae, and the fossilized specimens that have so far come to light — in particular those characteristic of terrestrial ecosystems — have so far been little studied. The authors of the new study have now identified more than 100 larvae in amber inclusions assembled by collectors in Northern Germany. The samples described come from either the Baltic or the Bitterfeld section of the amber forest. Most of the dipterans identified, belong to the group known as Bibionomorpha, whose evolutionary history extends over a period of more than 200 million years. With a total of 35 specimens, the group most frequently represented is the genus Mycetobia, which belongs to the Family Anisopodidae (whose members are commonly known as window gnats). Thanks to the abundance of this material, the researchers were able to reconstruct the relative growth rate of these larvae based on the length and width of the head capsule. The results confirmed that these gnats went through four larval stages, just like the present-day representatives of the same group. In addition, their overall morphology is very similar to that of extant window gnats. “Since the morphologies of the other fossil bibionomorphan larvae are also very reminiscent of their recent relatives, we can safely assume that they occupied habitats similar to those of our contemporary forms,” says Baranov, first author of the new paper. The presence of large numbers of Mycetobia larvae among the specimens examined therefore implies that Europe’s amber forests were characterized by moist conditions and an abundance of decaying organic matter. Moreover, the researchers also discovered the first fossilized larva that could be assigned to the [genus] Pachyneura (Diptera, Pachyneuridae) … Recent [species] are associated with dead wood in undisturbed woodland.

“Within the scientific community, a new interpretation of Europe’s amber forests is currently emerging. This is based on paleobotanical and isotope evidence which suggests that these woods constituted a warm-to-temperate seasonal ecosystem. Our findings provide further support for this picture,” Baranov explains. He and his colleagues argue that it is quite conceivable that, under the climatic conditions prevailing in Europe during the Eocene, a subtropical, seasonal forest would have supplied abundant amounts of decaying organic matter in the form of leaf litter and dead plants and animals, as well as bacterial biofilms and fungi. In any case, the dipteran larvae provide an independent source of information that can be used to reconstruct the nature of the paleohabitats. “Perhaps our most surprising find is a larva which we identified as a representative of a previously unknown group,” says Baranov. While this larva belongs among the march flies (Diptera, Bibionidae), it exhibits a very unusual combination of morphological characters which finds no parallel among modern representatives of this group.” In Baranov’s opinion, the specimen may document an experimental phase of their evolution, during which different lineages independently “discovered” similar sets of morphological traits.

New praying mantis species discovered in Peru

This 17 October 2019 video from the USA says about itself:

Dr. Gavin Svenson, the Cleveland Museum of Natural History’s Director of Research & Collections and Curator of Invertebrate Zoology, discovered a new species of praying mantis on an insect survey expedition in the Amazon Rainforest. The mantis, named Vespamantoida wherleyi, is brightly colored and mimics wasps in an effort to ward off predators—a combination that has never been seen before. The discovery and analysis have had widespread implications for the Mantoididae family.

From the Cleveland Museum of Natural History in the USA:

Scientists discover new species of wasp-mimicking praying mantis

Peruvian mantis represents the first known example of a praying mantis species conspicuously mimicking a wasp

October 17, 2019

Cleveland Museum of Natural History Director of Research & Collections and Curator of Invertebrate Zoology Dr. Gavin Svenson and former Case Western Reserve University graduate student, Henrique Rodrigues, have discovered a new species of praying mantis, described as the first known mantis species to conspicuously mimic a wasp. In addition, the new species joins one previously described species within a newly erected genus Vespamantoida. The results of the team’s findings were published today in the online journal PeerJ.

The new species, named Vespamantoida wherleyi, was discovered near the Amazon River in Peru in 2013 during a general entomological survey of the field site. The male specimen was attracted to a light trap, and its bright coloration and wasp-like shape and behavior immediately caught the team’s eye.

“Typically, the majority of species differentiation is discovered and confirmed within a lab or collection setting,” explains Dr. Svenson. “To have that rare eureka moment where you know you have found something new in the field is incredibly exciting.”

The mantis exhibited a bright red-orange coloration, as well as the body structure, erratic locomotion patterns, and even antennae behavior typically associated with most wasp species. This apparent style of mimicry, known as Batesian mimicry, is a strategy in which a mostly harmless organism adopts the appearance, and occasionally the behaviors, of an organism known to pose a greater threat to would-be predators.

“In nature, when you are intentionally conspicuous, you are advertising something,” says Dr. Svenson. “When you are a species that can be easily taken as prey, you advertise because you want predators to think that you are poisonous, or could injure them, or any combination of unpleasant factors that tell the predator to think twice before pursuing you.”

In the mantis world, mimicry of vegetation is a fundamental strategy, but wasp mimicry in adults is unique, and limited to just one family, of which Vespamantoida is now a part. Until the discovery of V. wherleyi, however, mantis mimicry strategies were theorized to aid the mantis primarily in hiding from predators, and occasionally in luring prey. The conspicuous appearance and behavior of V. wherleyi represent a novel form of defensive mimicry whereby the mantis imitates a harmful organism’s natural defense signals to warn predators away. It is a strategy that is unique among known mantises.

“There are about 2,500 species of mantises described,” says Dr. Svenson. “I’d put a bet on there being about 5,000. So, I think we’re just halfway there. I think the most interesting thing about this family of mantises is the fact that most of the adults do mimic wasps, and that is quite unique for praying mantises. I think the next natural thing is to study the evolutionary biology of the lineage. If wasp mimicry is successful in this lineage, why has it not evolved in the other lineages as well? Why have no other species within the family evolved brightly colored wasp mimicry? We’re just not sure.”

Big new wasp species discovery in Africa

This August 2018 video is about hornets and wasps.

From the University of Turku:

New large-sized insect species discovered in tropical forest

October 9, 2019

Scientists at the Biodiversity Unit of the University of Turku in Finland have studied the diversity of tropical parasitoid wasps for years. Parasitoid wasps are among the most species rich animal taxa on Earth, but their tropical diversity is still poorly known. Recently, the research group sampled Afrotropical rhyssine wasps, which are among the largest wasps. Scientists from three countries and research institutes participated in the research led by the University of Turku research group.

Rhyssines are sizeable wasps that parasitise the beetle or wasp larvae of decaying wood. The largest species can grow over ten centimetres in length. Females carry an extremely long ovipositor, which is used to drill through wood, stab and paralyse the host, and lay eggs.

Large-sized insect species are usually known better than small species, but tropical rhyssines are an exception.

“A good example of how poorly tropical rhyssines are known is the species Epirhyssa overlaeti, which is the largest African rhyssine. Only two females were known before, one collected in the 1930s in the Congo and the other one in Cameroon in the 1980s. Now, at one single Ugandan site, we found large numbers of both females and males. This completely changed what is known of the distribution of the species,” says Doctoral Candidate Tapani Hopkins from the Biodiversity Unit of the University of Turku, who led the project.

Scientists at the Biodiversity Unit of the University of Turku have previously studied the diversity of rhyssine wasps especially in the Amazonian lowland rainforest.

“In our Amazonian research, we have described ten large-sized South-American species new to science and our understanding of the diversity of South American tropical rainforest parasitoid wasps has changed. Extending the research to the African continent is important, because our goal is to understand the global diversity of the parasitoid insects which are extremely species rich,” says Professor in Biodiversity Research Ilari Sääksjärvi from the Biodiversity Unit of the University of Turku.

In the newest study, two new African tropical parasitoid wasp species were described.

“We named one of the new species Epirhyssa quagga, because its colouration resembles that of a zebra. The other species became Epirhyssa johanna. The name Johanna refers to my wife,” Hopkins says delightedly.

Stick insect evolution, birds and mammals

This 8 October 2019 video says about itself:

These Giant Leaf Insects Will Sway Your Heart | Deep Look

Giant Malaysian leaf insects stay still – very still – on their host plants to avoid hungry predators. But as they grow up, they can’t get lazy with their camouflage. They change – and even dance – to blend in with the ever-shifting foliage.

From the University of Göttingen in Germany:

Was early stick insect evolution triggered by birds and mammals?

October 7, 2019

Stick and leaf insects are a diverse and strikingly bizarre group of insects with a worldwide distribution, which are more common in tropical and subtropical areas. They are famous for their impressively large body size, compared to other insects, and their remarkable ability to camouflage themselves as twigs, leaves or bark in order to hide from potential predators. A team of international researchers led by the University of Göttingen has now generated the first phylogenomic tree of these insects. The results have been published in the journal Frontiers in Ecology and Evolution.

“Previously the relationships between stick insects were inferred based on just a handful of genes. This is the first study in which more than 2,000 genes were analysed for each species,” explains Dr Sven Bradler from the University of Göttingen and senior author of the study. 38 species of stick and leaf insects from all over the world were investigated by the researchers of the 1KITE project (1,000 Insect Transcriptome Evolution). “Previous studies were unable to explain the early evolution of these insects. This has now changed with the new and much more extensive dataset that can even reconstruct the origin of the oldest lineages,” adds Dr Sabrina Simon, first author of this study from the University Wageningen.

The most surprising finding is that the relationships between the early emerging groups of stick and leaf insects largely disprove the earlier assumptions. In fact, the genealogy reflects more the geographic distribution than the anatomical similarity of the animals. The authors revealed a New World lineage of purely North and South American species and a group of Old World origin that comprises species from Africa to New Zealand.

The biogeographic history was reconstructed by Sarah Bank, PhD student at the University of Göttingen and coauthor of the study, which resulted in further unexpected results: “The flamboyant stick insects of Madagascar, for instance, descended from a single ancestral species who colonised the island approximately 45 million years ago.”

The age estimation of the phylogenetic tree suggests that most of the old lineages emerged after the dinosaurs became extinct 66 million years ago. Thus, the remarkable camouflage of stick and leaf insects most probably evolved afterwards as adaptation against predatory mammals and birds.

“Stick insects become more and more important as model organisms for evolutionary research. The new comprehensive molecular dataset won’t be exhaustively analysed for quite some time and will provide exciting insights into the function of the numerous detected genes,” explains Bradler with regard to future studies.