#Virginia, #microfossils; #oldestGreenSeaweeds
Virginia (United States), Feb 24 (Canadian-Media): Virginia Tech paleontologists have made a remarkable discovery in China: 1 billion-year-old micro-fossils of green seaweeds that could be related to the ancestor of the earliest land plants and trees that first developed 450 million years ago, phys./news reports said.
A photo of a green seaweed fossil dating back 1 billion years. The image was captured using a microscope as the fossil itself is 2 millimeters long, roughly the size of a flea. The dark color of this fossil was created by adding a drop of mineral oil to the rock in which it's embedded, to create contrast.
Image Credit: Virginia Tech
The micro-fossil seaweeds—a form of algae known as Proterocladus antiquus—are barely visible to the naked eyed at 2 millimeters in length, or roughly the size of a typical flea. Professor Shuhai Xiao said the fossils are the oldest green seaweeds ever found. They were imprinted in rock taken from an area of dry land—formerly ocean—near the city of Dalian in the Liaoning Province of northern China. Previously, the earliest convincing fossil record of green seaweeds were found in rock dated at roughly 800 million years old.
The findings—led by Xiao and Qing Tang, a post-doctoral researcher, both in the Department of Geosciences, part of the Virginia Tech College of Science—are featured in the latest issue of Nature Ecology & Evolution (link not active until embargo lifts). "These new fossils suggest that green seaweeds were important players in the ocean long before their land-plant descendants moved and took control of dry land," Xiao said.
"The entire biosphere is largely dependent on plants and algae for food and oxygen, yet land plants did not evolve until about 450 million years ago," Xiao said. "Our study shows that green seaweeds evolved no later than 1 billion years ago, pushing back the record of green seaweeds by about 200 million years. What kind of seaweeds supplied food to the marine ecosystem?"
Shuhai said the current hypothesis is that land plants—the trees, grasses, food crops, bushes, even kudzu—evolved from green seaweeds, which were aquatic plants. Through geological time—millions upon millions of years—they moved out of the water and became adapted to and prospered on dry land, their new natural environment. "These fossils are related to the ancestors of all the modern land plants we see today."
However, Xiao added the caveat that not all geobiologists are on the same page—that debate on the origins of green plants remains debated. "Not everyone agrees with us; some scientists think that green plants started in rivers and lakes, and then conquered the ocean and land later," added Xiao, a member of the Virginia Tech Global Change Center.
There are three main types of seaweed: brown (Phaeophyceae), green (Chlorophyta), and red (Rhodophyta), and thousands of species of each kind. Fossils of red seaweed, which are now common on ocean floors, have been dated as far back as 1.047 billion years old.
"There are some modern green seaweeds that look very similar to the fossils that we found," Xiao said. "A group of modern green seaweeds, known as siphonocladaleans, are particularly similar in shape and size to the fossils we found."
Photosynthetic plants are, of course, vital to the ecological balance of the planet because they produce organic carbon and oxygen through photosynthesis, and they provide food and the basis of shelter for untold numbers of mammals, fish, and more. Yet, going back 2 billion years, Earth had no green plants at all in oceans, Xiao said.
It was Tang who discovered the micro-fossils of the seaweeds using an electronic microscope at Virginia Tech's campus and brought it to Xiao's attention. To more easily see the fossils, mineral oil was dripped onto the fossil to create a strong contrast.
"These seaweeds display multiple branches, upright growths, and specialized cells known as akinetes that are very common in this type of fossil," he said. "Taken together, these features strongly suggest that the fossil is a green seaweed with complex multicellularity that is circa 1 billion years old. These likely represent the earliest fossil of green seaweeds. In short, our study tells us that the ubiquitous green plants we see today can be traced back to at least 1 billion years."
According to Xiao and Tang, the tiny seaweeds once lived in a shallow ocean, died, and then became "cooked" beneath a thick pile of sediment, preserving the organic shapes of the seaweeds as fossils. Many millions of years later, the sediment was then lifted up out of the ocean and became the dry land where the fossils were retrieved by Xiao and his team, which included scientists from Nanjing Institute of Geology and Paleontology in China.
#Ecology; #BirdMigration; #MPYC; #EnergyEfficiency
New York, Feb 19 (Canadian-Media): Neither wind, nor rain—nor massive sheets of ice—have kept Earth's birds from their appointed rounds of migrating to better climes, according to a new study, phys.org/news reports said.
Bird migration. Image credit: CCO Public Domain
That's the conclusion of a new study from the Max Planck-Yale Center for Biodiversity Movement and Global Change (MPYC), which simulated global bird migrations during scenarios of past climate conditions. The researchers said that, in the Americas in particular, migrating birds successfully maneuvered vastly changing landscapes in the past 50,000 years.
"Our simulations predict that bird migration worldwide has remained relatively constant over this period, suggesting an origin for this phenomenon that is older than the glacial cycles of recent Earth history," said first author Marius Somveille, a former MPYC researcher who is starting a postdoctoral position at Colorado State University.
Yet there has been regional variation in migrating birds' response to climate change, the researchers said. In the Americas, for example, there has been a larger increase in the distances that birds have migrated over the past 50,000 years, compared with other parts of the world.
"In the last ice age, up to about 18,000 years ago, North America had an ice sheet that covered a large part of the continent and prevented bird species from living there," said Yale's Walter Jetz, senior author of the study, professor of ecology and evolutionary biology, and co-director of MPYC.
"This ice sheet retreated and birds colonized the land—and those birds were likely highly migratory, as seasonality in this area was pronounced. Our simulations suggest that toward the present this part of the world has seen both migratory distances and migration activity significantly increase," he said.
The study appears in the journal Nature Communications.
Using existing data about the global distribution of migratory birds, the researchers created a model that predicted migrations based on energy efficiency: They positioned each species' breeding and non-breeding ranges in a way that accounted for the availability of food and how much energy birds would reasonably expend during migration.
To estimate migration activity far in the past, the researchers applied their model to reconstructions of past climate conditions.
Co-author and MPYC co-director Martin Wikelski of the Max Planck Institute of Animal Behavior said the findings may be of use to conservationists and policymakers because the simulations "have the potential to inform predictions of how future climate change will impact bird migrations."
#AnimalRemains; #SaharanEnvironment; #catfish; #Tilapia; #TakarkorirockShelter; #HistoryMuseumOfBelgium; #SaharanTadrartAcacusMountains
Belgium, Feb 19 (Canadian-Media): Catfish and tilapia make up many of the animal remains uncovered in the Saharan environment of the Takarkori rock shelter in southwestern Libya, according to a study published February 19, 2020 in the open-access journal PLOS ONE by Wim Van Neer from the the Natural History Museum in Belgium, Belgium and Savino di Lernia, Sapienza University of Rome, Italy, and colleagues, phys.org/news reports said.
View of Takarkori shelter from the west. Credit: Savino di Lernia, 2020
Today, the Saharan Tadrart Acacus mountains are windy, hot, and hyperarid; however, the fossil record shows that for much of the early and middle Holocene (10,200 to 4650 years BP), this region was humid and rich in water as well as life, with evidence of multiple human settlements and diverse fauna.
Rock shelters within the Tadrart Acacus preserve not only significant floral and faunal remains, but also significant cultural artifacts and rock art due to early Holocene occupation of these shelters. In this study, the authors worked with the Libyan Department of Antiquities in excavating parts of the Takarkori rock shelter to identify and date animal remains found at this site and investigate shifts in the abundance and type of these animal remains over time.
Fish remains made up almost 80 percent of the entire find overall, which numbered 17,551 faunal remains total (19 percent of these were mammal remains, with bird, reptile, mollusc, and amphibian remains the last 1.3 percent). All of the fish and most of the other remains were determined to be human food refuse, due to cut marks and traces of burning—the two fish genera at Takarkori were identified as catfish and tilapia.
Based on the relative dates for these remains, the amount of fish decreased over time (from 90 percent of all remains 10,200-8000 years BP versus only 40 percent of all remains 5900-4650 years BP) as the number of mammal remains increased, suggesting the inhabitants of Takarkori gradually focused more on hunting/livestock. The authors also found the proportion of tilapia specifically decreased more significantly over time, which may have been because catfish have accessory breathing organs allowing them to breathe air and survive in shallow, high-temperature waters—further evidence that this now-desert environment became less favorable to fish as the aridity increased.
The authors add: "This study reveals the ancient hydrographic network of the Sahara and its interconnection with the Nile, providing crucial information on the dramatic climate changes that led to the formation of the largest hot desert in the world. Takarkori rock shelter has once again proved to be a real treasure for African archaeology and beyond: a fundamental place to reconstruct the complex dynamics between ancient human groups and their environment in a changing climate."
#UnitedKingdom; #FreshwaterInsects; #Ecology; #Hydrology; #NERC
United Kingdom, Feb 17 (Canadian-Media): Many insects, mosses and lichens in the UK are bucking the trend of biodiversity loss, according to a comprehensive analysis of over 5,000 species led by UCL and the UK Centre for Ecology & Hydrology (UKCEH).
Spider. Image credit: CCO Public Domain
The researchers say their findings on UK biodiversity between 1970 and 2015, published in Nature Ecology & Evolution, may provide evidence that efforts to improve air and water quality could be paying off.
"By looking at long-term trends in the distribution of understudied species, we found evidence of concerning declines, but we also found that it's not all bad news. Some groups of species, particularly freshwater insects, appear to be undergoing a strong recovery," said the study's lead author, Dr. Charlie Outhwaite (UCL Centre for Biodiversity & Environment Research, UK Centre for Ecology & Hydrology, and the RSPB).
Funded by the Natural Environment Research Council (NERC), the researchers analysed trends in the distribution of invertebrates (such as insects and spiders), bryophytes (such as mosses) and lichens over a 45-year period, to see whether they were following the same declining trends reported in better-studied groups such as mammals, birds and butterflies.
Across all 5,214 species surveyed, overall occupancy (distribution) was 11% higher in 2015 than in 1970. The researchers were not able to estimate the total numbers of each species, but gauged how well each species was doing by whether its geographic range was expanding or shrinking.
They found substantial variation between the different groups, and between individual species within each group. Among the four major groups studied, only one of them—terrestrial non-insect invertebrates (mainly spiders, centipedes and millipedes) - exhibited an overall trend of declining distribution (by 7% since 1970).
More positively, freshwater insects, such as mayflies, dragonflies and caddisflies, have undergone a strong recovery since the mid-1990s, recently surpassing 1970 levels following a 47% decline from 1970 to 1994. Mosses and lichens have also increased in average occupancy (distribution) by 36%, while terrestrial insects, such as ants and moths, exhibited a slight increase.
The data included over 24 million records, each identifying a sighting of a particular species in a particular location, sourced from numerous biological recording schemes. People from across the UK have been contributing to the recording schemes on a volunteer basis for decades.
While the volunteers used inconsistent methods to collect their records, having such a vast quantity of data enabled the researchers to analyse it effectively using occupancy modelling techniques.
"Our study demonstrates the power of citizen science, as anyone can contribute to impactful academic research. We couldn't have done this research without the hard work of thousands of volunteers who have contributed to recording schemes over the years," said Dr. Outhwaite.
While the study period only went back to 1970, other research suggests that many of the species studied would have been experiencing long-term declines dating back to the industrial revolution or further, due to pollution or habitat losses from agricultural expansion and urbanisation.
While they did not investigate the particular reasons for the declines and recoveries found in this study, the researchers say that it's likely that environmental protection initiatives are helping some species recover. Mosses and lichens are known to be susceptible to air pollution, while freshwater insects likely benefited from improvements in waste water treatment since the early 1990s.
#HumanDrivenCarbonEmissions, #WarmClimate; #ClimateChange; #Ecosystem
Dublin (Ireland), Feb 10 (Canadian-Media): The world is waking up to the fact that human-driven carbon emissions are responsible for warming our climate, driving unprecedented changes to ecosystems, and placing us on course for the sixth mass extinction event in Earth's history, phys.org/news reports said.
Geologists studying the Lower Jurassic (Pliensbachian) Belemnite Marl Member mudstone succession in Dorset, UK, showing orbitally paced variations of the sediment composition similar to the studied core in Wales. Image Credit: Dr Micha Ruhl
However, new research publishing this week in leading international journal PNAS, sheds fresh light on the complicated interplay of factors affecting global climate and the carbon cycle—and on what transpired millions of years ago to spark two of the most devastating extinction events in Earth's history.
Using chemical data from ancient mudstone deposits in Wales, an international team involving scientists from Trinity College Dublin discovered that periodic changes in the shape of Earth's orbit around the Sun were partly responsible for changes in the carbon-cycle and global climate during and in between the Triassic-Jurassic Mass Extinction (around 201 million years ago, when around 80% of the species on Earth disappeared forever) and the Toarcian Oceanic Anoxic Event (around 183 million years ago).
In addition, volcanic activity released large amounts of greenhouse gases into the oceans and atmosphere at that point in time, which resulted in major global carbon cycle perturbations as well as global climate and environmental change.
Dr. Micha Ruhl, Assistant Professor in Sedimentology at Trinity, said:
"Our work shows that for the 18 million years or so in between the Triassic-Jurassic mass extinction and the Toarcian Oceanic Anoxic Event, Earth's global carbon-cycle was in a constant state of change."
Eccentricity of the Earth's orbit around the Sun. The fluctuation between a nearly circular and elliptical orbit drives cyclic changes in the Earth's environment, including the global carbon cycle. Credit: Marisa Storm
"Periodic changes in the shape of Earth's orbit around the sun impacted on the amount of energy received by Earth from the sun, which in turn impacted climatic and environmental processes, as well as the carbon-cycle, on local, regional and global scales."
"Although this phenomenon is well known for having caused the glacial cycles in more recent times, the present study shows that these external forcing mechanisms on Earth's systems were also operating, and controlling Earth's carbon cycle in the distant past, even during non-glacial times when Earth was marked by hot-house climate conditions."
Present-day orbital configurations and solar system processes should have resulted in a future return to glacial conditions. However, anthropogenic carbon release will likely have disrupted this natural process, causing rapid global warming, rather than a steady return to cooler climates.
#MinnesotaOffersIncentives; #BeefriendlyWildFlowers; #Bumblebee; #ExtinctionOfSpecies;
Minnesota (United States), Feb 4 (Canadian-Media): An incentive of nearly a million dollar has been made by the state of Minnesota, United States for people to transform their lawns into bee-friendly wildflowers, clover and native grasses, media reports said.
Bumblebee. Image credit: Facebook
With a goal to provide food sources for pollinators of all kinds, and specifically to bumblebee, which is on the brink of extinction, the citizens are being urged by the the state to stop spraying herbicide, stop mowing so often so that their lawns re-wild into a more natural state.
Importance of bumblebees to the region is evident by the research of James Wolfin, a bee habitat researcher at University of Minnesota, which says that bumblebees vibrate at frequency that unlocks pollen not reached by other insects.
Pollinators have become more dependent on urban and suburban lawn flowers due to the loss of native prairies and forests across the country.
Wolfin's research is focused on bee lawns, which are grassy yards with small flowers such as Dutch white clover, creeping thyme, self heal, ground plum and dandelions.
Besides being excellent food source for bees, the flowers are both cheap to plant and easy to maintain.
“A pound of Dutch white clover is about $7 and it grows low enough that people wouldn’t even have to change the way they mow their lawn,” Wolfin
Around 55 of Minnesota’s 350 bee species depend on white clover alone, he notes.
“So just by not treating white clover like a weed and letting it grow in a yard provides a really powerful resource for nearly 20% of the bee species in the state,” Wolfin said.
The program is expected to begin in spring of 2020.
Citizens inhabiting bumblebee zones are eligible for grants up to $500, while people living in zones of secondary and tertiary importance to bees are eligible for $350 and $150 respectively.