Scipionyx baby dinosaur discovery


This 24 March 2020 video says about itself:

The Baby Dinosaur With Fossilised OrgansScipionyx

The discovery that this baby dinosaur fossil had preserved large parts of the internal organs for over 110 million years was one of the greatest revelations in recent palaeontology. So what can this amazing fossil tell us about extinct dinosaur biology?

Bumblebees can make flowers bloom early


This July 2016 video says about itself:

Most flowering plants are more than willing to spread their pollen around. But some flowers hold out for just the right partner. Bumblebees and other buzz pollinators know just how to handle these stubborn flowers. They vibrate the blooms, shaking them until they give up the nutritious pollen.

By Susan Milius, May 21, 2020 at 3:02 pm:

Pollen-deprived bumblebees may speed up plant blooming by biting leaves

In a pollen shortage, bees can make tomatoes bloom early by nipping foliage

Here’s a bumblebee tip that might get a slowpoke plant to bloom early. Just bite its leaves.

At least three species of bumblebees use their mouthparts to snip little confetti bits out of plant foliage, researchers report in the May 22 Science. This foliage biting gets more common when there’s a pollen shortage, says Consuelo De Moraes, a chemical ecologist and entomologist at ETH Zurich.

Experiments show that mustard and tomato plants nibbled by Bombus terrestris bees bloomed earlier than unbitten plants by days, or even weeks, say De Moraes and her colleagues. So for the bumblebees, accelerating bloom times could be a lifesaver. When trying to found colonies in early spring, the bees rely on flower pollen as a protein source for raising their young.

Foteini Paschalidou, an ecologist now at France’s National Institute for Agricultural Research in Versailles-Grignon, was the first team member to call attention to the behavior. She was working on a different project with caged B. terrestris bees indoors. At first, De Moraes worried. “Is it something wrong with them?”

The bees’ supplier and some farmers who used them to pollinate crops assured the researchers that nipping happens elsewhere, although the team hasn’t found any accounts in the scientific literature.

To test a link between leaf biting and pollen shortages, the researchers did a caged-bee test. After three days without pollen, bumblebees trapped with nonblooming plants were more likely to poke holes in foliage than a bee group buzzing among plentiful flowers. When researchers swapped the bees’ situations, the insects now trapped without blooms started nibbling leaves.

Tests done on the roof of the lab building with bees free to seek flowers in rooftop planters and elsewhere also found a link between pollen shortage and increased leaf biting, the researchers report.

The notion that bee damage to a leaf could jump-start flowering originally struck coauthor Mark Mescher of ETH Zurich as a long shot. Yet in lab tests, tomato plants punctured five to 10 times by pollen-deprived bees bloomed 30 days earlier on average than undamaged plants. But the speed-up time varied by plant species. For instance, bee-nipped black mustard (Brassica nigra) bloomed only about 16 days early.

The bee-pestered plants’ acceleration is not entirely unprecedented. Some other forms of stress, including drought, skimpy nutrients and assault by leaf-eating insect pests, also have triggered early blooming, Mescher points out. But just what’s going on with the bee bites and how they might tap into the internal clock that triggers a plant to switch from leafing to flowering remain big questions.

So far, the best efforts of human scientists waiting with forceps and a razor on a lab rooftop to mimic bee activity in real time, bite by bite, on comparison plants have produced only modest acceleration in the black mustard, and no meaningful change in the tomatoes. So there might be something special in a bee bite.

In a happy accident, the outdoor trials attracted visits from two other Bombus species that checked out the plants on offer and also nicked holes in leaves. That confirms that leaf nibbling is not just some quirk of a commercial lineage of bees, although two long-time bumblebee watchers — Dave Goulson at the University of Sussex in England and Lynn Adler at the University of Massachusetts Amherst — say they’ve never noticed it.

Goulson says he’s fascinated by the idea. B. terrestris commonly cuts holes in plant parts, but in a slightly different context. Instead of groping for nectar through the natural openings of flowers, these and other bumblebees often just bite little holes through the outer wall of a flower for a sip. “I can imagine that hungry bees unable to find flowers might try biting leaves in desperation,” Goulson says. Flower biting might thus have evolved into leaf biting, though, as Mescher points out, it could have happened the opposite way, too.

With those intriguing ideas buzzing around, clearly now is a great time to go watch bees.

Diplocaulus, prehistoric Permian ‘hammerhead salamanders’


This 22 May 2020 video about Diplocaulus says about itself:

The Hammerheaded Salamander

This boomerang head has been a part of every prehistoric background scene. Why is this, and what did it do with those horns?

Why darter fish have stripes


This August 2016 video from the USA says about itself:

Darters are a small, wonderfully colored bottom-dwelling fish that looks more suited to live in a coral reef or tropical aquarium than the cold fast-flowing streams of the Smokies.

A diversity of darter species in the Park is indicative of the excellent water quality the Smokies has due to its protection from anthropogenic expansion.

The Great Smoky Mountains National Park has over a dozen species of these charismatic fish, and has one of the best-protected habitats for darters in the country.

From the University of Maryland Baltimore County in the USA:

How the darter got stripes: Expanding a sexual selection theory explains animal patterns

May 22, 2020

Summary: Scientists have shown for the first time that there is a strong correlation between the complex patterns on male darters and their highly-variable environments. The findings support and expand upon sensory drive theory, which states that the environment influences which sexual signals, like visual patterns, are selected for. Previous sensory drive research looked at simple signals (e.g. colors), but Hulse used Fourier analysis to greatly expand that work.

Samuel Hulse, a Ph.D. candidate at UMBC, spent a lot of time in waders over the last two years. He traipsed from stream to stream across the eastern U.S., carefully collecting live specimens of small, colorful freshwater fish known as darters and taking photos of their habitats. Then he brought them back to the lab to capture high-quality images of their coloration patterns.

Hulse developed a precise, quantitative analysis of those visual patterns, such as stripes, spots, and various mottled looks. His work shows, for the first time, a strong correlation between the complicated patterns on male fish and the fishes’ highly variable environments. The results were published today in Nature Communications.

These findings represent a major expansion of a theory in sexual selection known as “sensory drive”, which emphasizes how an animal’s environment can influence what sexual signals — like visual patterns — are selected for over time.

Driving progress

So far, sensory drive has successfully explained examples such as coloration in cichlids, a group of freshwater fish in Africa. Hulse was working to expand on this research.

Different species of cichlids live at different depths, and which colors the fish can easily see changes as you go deeper and there is less light. Why does this matter? The idea of sensory drive is that animals perceive visual signals, like colors, as more attractive when they are easier for their brains to process. And which signals are easier to process is dependent on the environment. When male fish are perceived as more attractive, they are more likely to reproduce, and their colors are more likely to be passed to the next generation of fish. So, if the theory of sensory drive is true, eventually, most male fish will have colors that are easy for mates to perceive in their particular environment.

In cichlid fish, “you see this depth-dependent change in the male colors as you go deeper,” Hulse says. With the new work, “we were able to expand on this theory to explain more complicated traits, such as visual patterns,” like stripes and spots.

Using math to understand biology

Hulse, who is also taking courses toward an M.S. in mathematics at UMBC, brought his quantitative skills to bear on this research. He used a measure called Fourier analysis to examine his fish images, looking at variations in color contrast.

For example, if you were to look at a photo of a grassy hill under a bright blue sky, the greatest contrast in brightness would be between the large areas above and below the horizon line. That contrast is on a larger scale than the differences in brightness between, say, tiny blades of grass. The differences between each blade are small, but occur frequently across the image.

Fourier analysis can translate the contrast patterns in an image into a representative set of mathematical sine and cosine waves. The low-frequency waves, which only swoop up and down once or twice across the entire image, represent large-scale differences, like above and below the horizon. High-frequency waves swoop up and down many times across an image and represent small-scale differences, like between blades of grass.

Researchers can look at the relationships between those waves — how much high-frequency versus low-frequency contrast there is in the image. Hulse’s work looked at that measure to examine the visual relationship between a habitat and the fish that lived in it. And sure enough, his calculations revealed a strong correlation, providing evidence of sensory drive in male darters.

Moving past “wishy-washy terminology”

One argument against the idea that these patterns are attractive to females is the idea of camouflage. Wouldn’t it make sense for animals to match the visual patterns of their environment to avoid getting eaten rather than to attract females? Darters are under strong predation pressure, so, Hulse says, it’s a valid point.

However, the fact that he found that only male fish match their environment is a strong argument in favor of sensory drive. Predators don’t discriminate between males and females, so you would expect females to also match their environment if camouflage was the reason.

“Quantitatively describing visual patterns is a big challenge, and there’s not one easy way to do that, so being able to use tools like Fourier analysis is wonderful,” Hulse says. “That actually lets us quantify some of these things that have historically been very hard to describe other than with wishy-washy terminology.”

Perfect timing

Tamra Mendelson, professor of biological sciences, is Hulse’s advisor and a co-author on the new paper. She had just begun formulating the ideas for this research with visual ecologist Julien Renoult, a colleague at Centre National de la Recherche Scientifique (CNRS) in Montpellier, France, and another co-author, when Hulse joined her laboratory in 2016.

“Julien had inspired me to take concepts from a field called human empirical aesthetics, which is the mathematical and biological basis of human appreciation of art, and apply them to animals’ appreciation of other animals,” Mendelson says. “I was super excited about it, but I didn’t have the mathematical chops to really take it as far as it could go.”

So, when Hulse arrived, “It was a perfect match. Sam is the ideal student to be doing this project.”

Hulse also spent several months in France working with Renoult to iron out some of the statistical challenges of the work — which were many. “The data analysis became a lot more complicated than we thought, and there were a lot of technical snags,” Hulse says. “So it was really great to be able to be there working directly with Julien, who has a lot of background with these sorts of methods.”

Bringing it all together

Hulse was drawn to this work by the unique blend of skills it requires. “I love the interdisciplinary nature of it. We’re bringing together field biology, sensory biology, a little bit of neurobiology, and image analysis,” he says. “That’s one of the most attractive things about this project for me — how much I get to learn and how much I get to take little pieces from so many different areas.”

Now, Hulse, Mendelson, and Renoult are excited to see where their new work leads. “There’s not a lot of theory in sexual selection that can be used to explain why you see one pattern evolve in one animal where you see a different one evolve in a closely related species,” Hulse says.

The new findings open the door to much more exploration with different species, including animals that live on land. In any group of animals that relies on vision, has visually distinct environments, and where the animals have distinct habitat preferences, Hulse argues, “this theory should hold.”

Pleistocene South African animals and early humans


This 27 April 2019 video says about itself:

Pelorovis (“monstrous sheep”) is an extinct genus of African wild cattle.

It first appeared in the Pliocene, 2.5 million years ago, and became extinct at the end of the Late Pleistocene about 12,000 years ago or even during the Holocene, some 4,000 years ago.

Studies show that the early forms of the genus (P. turkanensis and P. oldowayensis) are close relatives, and possibly the first members, of the genus Bos.

In contrast, the late Pleistocene form (Pelorovis antiquus) seems to be a close relative of the modern African buffalo (Syncerus caffer).

Pelorovis resembled an African buffalo, although it was larger and possessed longer, curved horns.

Pelorovis probably weighed about 1,200 kilograms (2,600 lb), with the largest males attaining 2,000 kilograms (4,400 lb).

This ranks it as one of the largest bovines, and indeed ruminants ever to have lived, rivaling the extinct American long-horned bison (Bison latifrons) and the extant African giraffe (Giraffa camelopardis).

The bony cores of the horns were each about 1 meter (3.3 ft) long; when covered with keratin (which does not survive fossilization) they could have been up to twice this length.

The horns pointed away from the head, each forming a half-circle in the species Pelorovis oldowayensis and Pelorovis turkanensis.

The horns of Pelorovis antiquus were also magnificent but resembled in shape more those of the water buffalo (Bubalus).

P. antiquus was even placed in the genus Bubalus by early specialists.

Pelorovis oldowayensis was broadly the same size as modern African buffalo, but its legs were longer, and the elongated head of this species was reminiscent to those of the modern Alcelaphinae.

Pelorovis antiquus was about the same size, but it was more robust.

Pelorovis antiquus disappeared around 12,000 years ago from southern and eastern Africa. Fossil and archaeological evidence indicates that this species lived in North Africa until 4,000 years ago.

Pelorovis oldowayensis occurred in sub-Saharan Africa and disappeared 800,000 years ago.

The best fossils of Pelorovis oldowayensis are known from the Olduvai Gorge in Tanzania; a complete skeleton of Pelorovis antiquus was found near Djelfa in Algeria.

From the University of Colorado Denver in the USA:

Migration patterns reveal an Eden for ancient humans and animals

May 22, 2020

Summary: Researchers have discovered a new migration pattern (or lack of) at Pinnacle Point, a now-submerged region in South Africa. While it was first believed large omnivores would travel to follow the growth of vegetation to survive, our researcher came to a completely new conclusion through studying antelope teeth! They discovered that this region was an Eden to all living species that called it home, including the earliest humans.

Pinnacle Point, a series of archaeological sites that overlook a now-submerged section of South Africa’s coastline and one of the world’s most important localities for the study of modern human origins, was as much of an Eden for animals as it was for early humans. Jamie Hodgkins, PhD, assistant professor of anthropology at University of Colorado Denver, and her team drilled ancient herbivore teeth to find that many local animals stayed put in the ecologically rich ecosystem, which may explain why humans flourished there, too.

Home to the Earliest Modern Humans

Home to some of the richest evidence for the behavior and culture of the earliest clearly modern humans, the submerged shelf called the Palaeo-Agulhas Plain (PAP) once formed its own ecosystem. Co-author Curtis Marean, PhD, Arizona State University, has worked with teams of scientists for decades to reconstruct the locale back into the Pleistocene, the time period that spanned from 2.6 million to 11,700 years ago.

In this study, the researchers looked specifically at antelope migratory patterns at Pinnacle Point. This series of cave sites that sit on the modern South African coast offers archaeological materials from humans who were living and hunting there back to 170,000 years ago.

“During glacial cycles, the coastal shelf was exposed,” said Hodgkins. “There would have been a huge amount of land in front of the cave sites. We thought it was likely that humans and carnivores were hunting animals as they migrated east and west over the exposed shelf.”

A Lack of Migratory Pattern

Hodgkins and her team wanted to understand those migratory patterns. They studied the carbon and oxygen isotopes within the tooth enamel of many large herbivores, including Redunca, or reedbuck, a nonmigratory antelope. Tooth enamel can reveal a pattern of migration by tracking changing levels of carbon from the plants an animal eats as its teeth grow.

In general, wetter, cooler environments are home to C3 plants; hotter, drier environments are home to C4 plants. Animals like lush vegetation, which means they tend to follow the rain patterns: in this case east for summer rain (C4 grasses), and west for winter rain (C3 grasses). If animals were migrating between summer and winter rainfall zones, their tooth enamel would register that annual C3 and C4 plant rotation as a sinusoidal curve as their teeth grew.

A) Map of South Africa (SA) showing the distribution of C4 grasses associated with the percentage of summer rain from east to west along the coast, and with the winter rainfall zone in the west (modified from Vogel, 1978); B) A map of SA showing the area of the Greater Cape Floristic Region with the expanded PAP and hypothesized animals migration (i.e. It is hypothesized that animals would have been undertaking long-distance migrations between the east coast in summer rainfall zone and west coast in the winter rainfall zone)

But when Hodgkins and her team used the nonmigratory reedbuck as their control animal, they found that the enamel from its typically migratory pals — like the wildebeest, hartebeest, and springbok — showed no discernible migratory pattern. Most animals seemed happy right where they were.

“They weren’t struggling at Pinnacle Point,” says Hodgkins. “We now know that powerful river systems supplied the expanded coast, thus animals didn’t have to be migratory. It was a great location, resource-wise. During interglacials when the coast moved closer to the caves humans had shellfish and other marine resources, and when the coast expanded in glacial times hunters had access to a rich, terrestrial environment. Hunters wouldn’t need to be as mobile with all of these herbivores wandering around.”

Thriving in an Ecogeological Haven

Hodgkins’ team’s findings of this prehistoric Eden echoed another recent discovery. Seventy-four-thousand years ago, one of Earth’s largest known eruptions at Mount Toba in Sumatra, Indonesia, created a global winter, causing population crashes. In 2018, researchers from Marean’s group found that humans at Pinnacle Point not only survived, but thrived in the haven.

Hodgkins says this is just a first attempt at using isotopic data to test the hypothesis of east and west migration patterns at these sites and further research will be done.

“It is quite possible that animal migration patterns changed as the coastline moved in and out during glacial and interglacial cycles,” said Hodgkins.

Funders for this project include the National Science Foundation, the Hyde Family Foundations, and the John Templeton Foundation at the Institute of Human Origins (IHO) at Arizona State University.

Japanese rice fish, male or female?


This 21 September 2019 video says about itself:

This is my new DIY Japanese Rice Fish mini pond. Japanese Rice Fish are called Medaka here in Japan and they are one of the most common pet fish here.

Rice fish look similar to guppies but they are actually pretty different in the way that these lay eggs whereas guppies are livebearers giving birth to live young. Adding to this, Japanese Rice Fish are super hardy. This doesn’t mean that you should neglect them but it means that they are very tolerant to fluctuating water conditions, they don’t require a filter, an air pump, or a heater.

From Nagoya University in Japan:

The ins and outs of sex change in medaka fish

May 21, 2020

Larval nutrition plays a role in determining the sexual characteristics of Japanese rice fish, also called medaka (Oryzias latipes), report a team of researchers led by Nagoya University. The findings, published in the journal Biology Open, could further understanding of a rare condition in humans and other vertebrates, where they genetically belong to one sex but also have characteristics of the other.

Decades ago, scientists found that medaka fish often undergo sex reversal in the wild. This involves genetically female larvae (meaning they have two X chromosomes) going on to develop male characteristics, or vice versa. This has made medaka fish a model organism for studying environmental sex development and other biological processes they have in common with vertebrates.

Now, Nagoya University reproductive biologist Minoru Tanaka and colleagues in Japan have gained further insight into the factors that affect medaka sex reversal, potentially providing direction for future research into similar conditions in other species.

Scientists had already discovered that environmental factors, such as temperature changes in the brackish and fresh waters where medaka fish live, are likely involved in their sex reversal. Tanaka and his team wanted to know if nutrition also played a role.

They starved medaka larvae for five days. This was enough time to affect their metabolism without killing them. Three to four months later, the team examined the fish and found that 20% of the genetically female medaka had developed testes and characteristically male fins. The same did not occur in larvae that were not starved.

Further tests showed that sex reversal in the fish was associated with reduced fatty acid synthesis and lipid levels. Specifically, starvation suppressed a metabolic pathway that synthesizes an enzyme called CoA, and disrupted a gene called fasn. These disruptions led to reductions in fatty acid synthesis. The scientists also found that a male gene, called dmrt1, was involved in the female-to-male reversal.

“Overall, our findings showed that the sex of medaka fish is affected by both the external environment and internal metabolism,” Tanaka says. “We believe lipids may represent a novel sex regulation system that responds to nutritional conditions.”

The team next plans on identifying other internal factors involved in medaka sex reversal. Future research should try to find the tissues or organs that sense changes in the internal environment and then produce key metabolites to regulate sex differentiation.