Study reveals rare example of convergent evolution, plant-insect coevolution and evidence of an increasingly complex web of life from 165 to 125 million years ago
Large butterfly-like insects known as Kalligrammatid lacewings, which fluttered through Eurasian fern- and cycad-filled woodland during the Mesozoic Era, have been extinct for more than 120 million years. But with new fossil analyses, scientists at the Smithsonian's National Museum of Natural History have discovered that these ancient lacewings were surprisingly similar to modern butterflies, which did not appear on Earth for another 50 million years.
Through taxonomic, anatomical and geochemical studies, scientists led by Smithsonian paleoecologist Conrad Labandeira revealed that Kalligrammatid lacewings likely served as important pollinators during mid-Mesozoic times, using mouthparts that were strikingly similar to the elongated, tubular structures that modern butterflies have to sip nectar-like fluids from flowering plants. What's more, their wings bore eyespot patterns that closely resemble those found on some butterflies today, which may have helped to distract or deter potential predators.
Labandeira and his colleagues--an international team of geochemists, botanists, entomologists and paleobiologists--reported their findings Feb. 3, in the journal Proceedings of the Royal Society B. Their findings represent a striking example of convergent evolution between these two unrelated lineages, in which the two distinct groups of organisms evolve similar traits as they interact to similar features in their environments.
Paleobiologists have known for more than 100 years that Kalligrammatid lacewings lived in Eurasia during the Mesozoic. But the insects have remained largely enigmatic until recent discoveries of well-preserved fossils from two sites in northeastern China. Thanks to extensive lakes that limited oxygen exposure in these areas during mid-Jurassic through early Cretaceous time, paleontologists have been able to recover exquisitely preserved fossils that retain much of their original structure.
Labandeira, who is the museum's curator of fossil arthropods, began the analysis of Kalligrammatid fossils from these sites by producing precise drawings of specimens using a camera lucida. This projection device lets artists trace fine features, such as the head and mouthparts of insects, while viewing them under a microscope. Labandeira's drawings depicted insects with surprisingly long, tubular proboscises.
"Various features of the mouthparts all indicate that these things were sucking fluids from the reproductive structures of gymnosperm plants," Labandeira said. That idea was supported by an analysis of a bit of material lingering within the food tube of one fossil, which was found to contain only carbon. Had the insect been feeding on blood, its final meal would have left traces of iron in the food tube as well.
Although the lacewings' mouthparts were strikingly similar to those of modern butterflies, there were no nectar-producing flowers in these Mesozoic forests. Paleobotanist David Dilcher of Indiana University, a member of the research team, said that like many Mesozoic insects, Kalligrammatids would have fed on sugary pollen drops produced by seed plants, transferring pollen between male and female plant parts as they did so.
A now-extinct group of plants called bennettitaleans, whose deep, tubular reproductive structures may have been accessed by kalligrammatid proboscises, likely was the primary food source for the co-occurring lacewings. But variations in proboscis shapes among the fossils suggest the insects were associated with a wide variety of host plants.
Careful observation of the fossils also revealed the presence of scales on wings and mouthparts, which, like the scales on modern butterflies, likely contained pigments that gave the insects vibrant colors. Based on similarities between Kalligrammatid wing patterns and those found on modern nymphalid butterflies (a group that includes red admirals and painted ladies), Labandeira said Kalligrammatids might have been decorated with red or orange hues.
That discovery prompted the team to examine the chemical composition of various regions of the Kalligrammatid's patterned wings, particularly the wing eyespots, an eye-like marking that might have deterred potential predators in Mesozoic woodlands. In modern butterflies with eyespots, the dark center of the mark is formed by a concentration of the pigment melanin. A sensitive chemical analysis indicated that the Kalligrammatids, too, had melanin at the center of their eyespots.
"That, in turn, suggests that the two groups of insects share a genetic program for eyespot production," Labandeira said. "The last common ancestor of these insects lived about 320 million years ago, deep in the Paleozoic. So we think this must be a developmental mechanism that goes all the way back to the origins of winged insects."
Taken together, the team's findings highlight two ways in which relationships between plant-hosts and their pollinator species drove evolution, Dilcher said. "Here, we've got coevolution of plants with these animals due to their feeding behavior, and we've got coevolution of the lacewings and their predators. It's building a web of life that is more and more complex."
Ryan Lavery | EurekAlert!
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy