This November 2017 video says about itself:
Climatic cooling during the Ordovician caused explosion of marine diversity
Read more here.
From Ohio University in the USA:
Early species developed much faster than previously thought
Landmark review of Great Ordovician Biodiversification Event
When Earth’s species were rapidly diversifying nearly 500 million years ago, that evolution was driven by complex factors including global cooling, more oxygen in the atmosphere, and more nutrients in the oceans. But it took a combination of many global environmental and tectonic changes occurring simultaneously and combining like building blocks to produce rapid diversification into new species, according to a new study by Dr. Alycia Stigall, Professor of Geological Sciences at Ohio University.
She and fellow researchers have narrowed in a specific time during an era known as the Ordovician Radiation, showing that new species actually developed rapidly during a much shorter time frame than previously thought. The Great Biodiversification Event where many new species developed, they argue, happened during the Darriwilian Stage about 465 million years ago. Their research, “Coordinated biotic and abiotic change during the Great Ordovician Biodiversification Event: Darriwilian assembly of early Paleozoic building blocks”, was published in Palaeogeography, Palaeoclimatology, Palaeoecology as part of a special issue they are editing on the Great Ordovician Biodiversification Event.
New datasets have allowed them to show that what previously looked like species development widespread over time and geography was actually a diversification pulse. Picture a world before the continents as we know them, when most of the land mass was south of the equator, with only small continents and islands in the vast oceans above the tropics. Then picture ice caps forming over the southern pole. As the ice caps form, the ocean recedes and local, isolated environments form around islands and in seas perched atop continents. In those shallow marine environments, new species develop.
Then picture the ice caps melting and the oceans rising again, with those new species riding the waves of global diversification to populate new regions. The cycle then repeats producing waves of new species and new dispersals.
Lighting the Spark of Diversification
The early evolution of animal life on Earth is a complex and fascinating subject. The Cambrian Explosion (between about 540 to 510 million years ago) produced a stunning array of body plans, but very few separate species of each, notes Stigall. But nearly 40 million years later, during the Ordovician Period, this situation changed, with a rapid radiation of species and genera during the Great Ordovician Biodiversification Event.
The triggers of the GOBE and processes that promoted diversification have been subject to much debate, but most geoscientists haven’t fully considered how changes like global cooling or increased oxygenation would foster increased diversification.
A recent review paper by Stigall and an international team of collaborators attempts to provide clarity on these issues. For this study, Stigall teamed up with Cole Edwards (Appalachian State University), a sedimentary geochemist, and fellow paleontologists Christian Mac Ørum Rasmussen (University of Copenhagen) and Rebecca Freeman (University of Kentucky) to analyze how changes to the physical earth system during the Ordovician could have promoted this rapid increase in diversity.
In their paper, Stigall and colleagues demonstrate that the main pulse of diversification during the GOBE is temporally restricted and occurred in the Middle Ordovician Darriwilian Stage (about 465 million years ago). Many changes to the physical earth system, including oceanic cooling, increased nutrient availability, and increased atmospheric oxygen accumulate in the interval leading up to the Darriwilian.
These physical changes were necessary building blocks, but on their own were not enough to light the spark of diversification.
The missing ingredient was a method to alternately connect and isolate populations of species through cycles of vicariance and dispersal. That spark finally occurs in the Darriwilian Stage when ice caps form over the south pole of the Ordovician Earth. The waxing and waning of these ice sheets caused sea level to rise and fall (similar to the Pleistocene), which provided the alternate connection and disconnection needed to facilitate rapid diversity accumulation.
Stigall and her collaborators compared this to the assembly of building blocks required to pass a threshold.
This 15 August 2019 video says about itself:
Exceptionally Detailed Fossil [Crane-]Fly Eyes Discovered In Denmark
The ancient eyes, each just 1.25mm across, belonged to a tiny crane-fly that lived 54 million years ago. Discovered by Lund University researchers, evidence of pigment within them is shedding new light on the evolution of compound eyes.
From Lund University in Sweden:
Composition of fossil insect eyes surprises researchers
August 15, 2019
Eumelanin — a natural pigment found for instance in human eyes — has, for the first time, been identified in the fossilized compound eyes of 54-million-year-old crane-flies. It was previously assumed that melanic screening pigments did not exist in arthropods.
“We were surprised by what we found because we were not looking for, or expecting it,” says Johan Lindgren, an Associate Professor at the Department of Geology, Lund University, and lead author of the study published this week in the journal Nature.
The researchers went on to examine the eyes of living crane-flies, and found additional evidence for eumelanin in the modern species as well.
By comparing the fossilized eyes with optic tissues from living crane-flies, the researchers were able to look closer at how the fossilization process has affected the conservation of compound eyes across geological time.
The fossilized eyes further possessed calcified ommatidial lenses, and Johan Lindgren believes that this mineral has replaced the original chitinous material.
This, in turn, led the researchers to conclude that another widely held hypothesis may need to be reconsidered. Previous research has suggested that trilobites — an exceedingly well-known group of extinct seagoing arthropods — had mineralized lenses in life.
“The general view has been that trilobites had lenses made from single calcium carbonate crystals. However, they were probably much more similar to modern arthropods in that their eyes were primarily organic,” says Johan Lindgren.
Compound eyes are found in arthropods, such as insects and crustaceans, and are the most common visual organ seen in the animal kingdom. They are made up of multiple tiny and light-sensitive ommatidia, and the perceived image is a combination of inputs from these individual units.
Unique dietary strategy of a tropical marine sponge
August 14, 2019
Research conducted at the University of Hawaiʻi (UH) at Mānoa School of Ocean and Earth Science and Technology (SOEST) on a marine sponge in Kāneʻohe Bay, Oahu revealed a unique feeding strategy, wherein the sponge animal acquires important components of its diet from symbiotic bacteria living within the sponge.
Coral reefs are one of Hawaiʻi’s most important natural resources and support fisheries and the state’s economy. Marine sponges are important components of coral reef ecosystems, but in Hawaiʻi, the Indo-Australian sponge Mycale grandis is an invasive alien species that was only first documented in the islands in the late 1990s. M. grandis is now found in and near major harbors of the Main Hawaiian Islands as well as within Kāneʻohe Bay.
Alien and invasive species are one of the threats to endemic and native species, which are vulnerable due to their evolution in the remote archipelago. M. grandis competes with coral for space on the reef, but unlike coral, which build hard rocky substrate with their skeletons, M. grandis is a soft, non-reef building animal and does not provide the same habitat for other reef organisms.
In a study led by Dr. Joy Leilei Shih for her doctoral research at UH Mānoa, the diet of M. grandis sponges collected from Kāneʻohe Bay was elucidated by using a new application of a technique that relies on naturally occurring stable isotopes to understand the origin of specific compounds in the tissues of plants and animals. In this case, the team tested where amino acids, the building blocks of proteins in tissues, in the sponge came from. Did they originate from food caught and filtered from seawater or were they supplied to the sponge from the microbes living within the sponge itself?
When one organism consumes another, elemental properties in the prey are conserved and leave behind a unique chemical pattern with the predator. By assessing the chemical difference between predator and prey tissues, Shih and colleagues found the diet of sponges did not originate from photosynthesizing microbes (such as seen in corals) and M. grandis feeding did not follow general patterns of other multicellular animals. Instead, the isotopic patterns of the sponge and its symbiotic microbes were not different from one another, indicating the sponge obtains nutrition through the uptake of amino acids originating from their symbiotic microbes.
“While we knew that the symbionts of sponges play an important role in their diet, the mechanism by which it occurred was unknown,” said Shih. “The only way to produce the observed amino acid isotopic pattern, or fingerprint, if you will, is through the direct transfer of amino acids from their symbiotic bacteria.”
“The patterns we detected in M. grandis and its symbionts are very interesting, as they suggest sponges may be actively capturing materials in seawater to support the needs of their microbial community, which in turn supply the sponge with essential tissue building blocks,” said Dr. Chris Wall, a postdoctoral researcher at UH Mānoa and a co-author on the study.
“The symbiosis we see between the sponge and its microbial community is remarkable,” said Shih. “We know that sponges rely on their symbionts for a variety of purposes including chemical defense, metabolite removal, and now we have insight into this well-tuned and efficient feeding strategy and the major role these microbial symbionts play in sponge nutrition. The intimate relationship between sponges and their symbionts developed over their long evolutionary history. Sponges are the oldest multi-cellular animal on earth. That’s why they are so well-adapted and resilient.”
Marine sponges in Hawaiʻi are not well studied. A study by the Smithsonian Institution-organized MarineGEO Hawaiʻi program in 2017 identified 150 previously unseen sponge species in Hawaiʻi, roughly one third of which are new species. Previously, only about 10 sponge species were known to exist in Kāneʻohe Bay. The researchers’ new approach to investigating sponge feeding strategies can be applied to future research on other marine sponges in Hawai’i and elsewhere. Sponges play an important role in the nutrient dynamics of coral reefs, and in the future, sponges may rise to dominate coral reefs as corals decline from direct pressure from human activity and climate change. This work provides new insights into the biology of sponges and shows the importance of marine microbes to the diet of an invasive sponge.
This 2009 video says about itself:
Adults and larvae of Hydrophilidae
From the University of Kansas in the USA:
New water beetle species show biodiversity still undiscovered in at-risk South American habitats
August 13, 2019
Researchers from the University of Kansas have described three genera and 17 new species of water scavenger beetles from the Guiana and Brazilian Shield regions of South America, areas seen as treasure houses of biodiversity. The beetles from the countries of French GuianaFrench Macron wants destructive gold mining in French Guiana, Suriname, Brazil, Guyana and Venezuela were discovered through fieldwork and by combing through entomological collections at the Smithsonian Institution and KU.
The beetles are described in a new paper in ZooKeys, a peer-reviewed journal.
Lead author Jennifer Girón, a KU doctoral student in ecology & evolutionary biology and the Division of Entomology at KU’s Biodiversity Institute, said the new species hint at vast biodiversity left to be described in regions where resource-extraction operations today are destroying huge swaths of natural habitat.
“The regions we’ve been working on, like Venezuela and Brazil, are being degraded by logging and mining,” she said. “Eventually, they’re going to be destroyed, and whatever lives there is not going to be able to survive. At this point, we don’t even know what’s there — there are so many different kinds of habitats and so many different resources. The more we go there, and the more we keep finding new species, the more we realize that we know next to nothing about what’s there.”
According to Girón and co-author Andrew Short, associate professor of ecology & evolutionary biology at KU, fieldwork and taxonomic work on Acidocerinae (a subfamily of the family Hydrophilidae of aquatic beetles) during the past 20 years have exposed “an eye-opening diversity of lineages and forms resulting in the description of seven of the 11 presently recorded genera since 1999.”
The KU researchers said the three new genera they’ve now added to Acidocerinae possibly have remained obscure until now because many of the species inhabit seepages — areas where groundwater rises to the surface through mud or flow over rocks near rivers or streams.
Girón and Short discovered some of the new species during a field trip to Suriname.
“I have only been to one of the expeditions there,” Girón said. “Before that, I had no experience collecting aquatics. But Andrew (Short) has been to those places many times. It’s very remote, in the heart of the jungle. We went four hours in a bus and then four more hours in a boat up the river. There is a field station for researchers to go and stay for a few days there. We looked for the beetles along the river, forest streams and also in seepages.”
During their fieldwork, Girón and Short, along with a group of KU students, sought the seepages that were rich hunting grounds for acidocerine aquatic beetles.
“If you’re along a big river, you’re not as likely to find them,” Girón said. “You have to find places where there’s a thin layer of running water or small pools on rocks. They’re more common around places with exposed rock, like a rock outcrop or a cascade. These habitats have been traditionally overlooked because when you think of collecting aquatic beetles or aquatic insects in general, you think of rivers or streams or ponds or things like that — you usually don’t think about seepages as places where you would find beetles. So usually you don’t go there. It’s not that these aquatic beetles are especially rare or hard to find. It’s more like people usually don’t collect in these habitats.”
Girón said the descriptions of the new aquatic beetles also underscore the usefulness of museum collections to ongoing scientific research in biodiversity.
“It’s important to highlight the value of collections,” she said. “Without specimens housed in collections, it would be impossible to do this kind of work. Nowadays, there has been some controversy about whether it is necessary to collect specimens and deposit them in collections in order to describe new species. Every person that has ever worked with collections will say, ‘Yes, we definitely need to maintain specimens accessible in collections.’ But there are recent publications where authors essentially just add a picture of one individual to their description without actual specimens deposited in collections, and that can be enough for them to publish a description. The problem with that is there would be no reference specimens for detailed comparisons in the future. For people who do taxonomic work and need to compare many specimens to define the limits of different species, one photo is not going to be enough.”
To differentiate and classify the new species, Girón and Short focused on molecular data as well as a close examination of morphology, or the bodies of the aquatic beetles.
“This particular paper is part of a bigger research effort that aims to explain how these beetles have shifted habitats across the history of the group,” Girón said. “It seems like habitat has caused some morphological differences. Many aquatic beetles that live in the same habitats appear very similar to each other — but they’re not necessarily closely related. We’ve been using molecular techniques to figure out relationships among species and genera in the group.”
Girón, who grew up in Colombia and earned her master’s degree in Puerto Rico, said she hoped to graduate with her KU doctorate in the coming academic year. After that, she will continue her appointments as research associate and acting collections manager at the Natural Science Research Laboratory of the Museum of Texas Tech University.