Scientists shocked to discover new species of green anaconda, the world’s biggest snake

Shutterstock Bryan G. Fry, The University of Queensland

The green anaconda has long been considered one of the Amazon’s most formidable and mysterious animals. Our new research upends scientific understanding of this magnificent creature, revealing it is actually two genetically different species. The surprising finding opens a new chapter in conservation of this top jungle predator.

Green anacondas are the world’s heaviest snakes, and among the longest. Predominantly found in rivers and wetlands in South America, they are renowned for their lightning speed and ability to asphyxiate huge prey then swallow them whole.

My colleagues and I were shocked to discover significant genetic differences between the two anaconda species. Given the reptile is such a large vertebrate, it’s remarkable this difference has slipped under the radar until now.

Conservation strategies for green anacondas must now be reassessed, to help each unique species cope with threats such as climate change, habitat degradation and pollution. The findings also show the urgent need to better understand the diversity of Earth’s animal and plant species before it’s too late.

Scientists discovered a new snake species known as the northern green anaconda. Bryan Fry

An impressive apex predator

Historically, four anaconda species have been recognised, including green anacondas (also known as giant anacondas).

Green anacondas are true behemoths of the reptile world. The largest females can grow to more than seven metres long and weigh more than 250 kilograms.

The snakes are well-adapted to a life lived mostly in water. Their nostrils and eyes are on top of their head, so they can see and breathe while the rest of their body is submerged. Anacondas are olive-coloured with large black spots, enabling them to blend in with their surroundings.

The snakes inhabit the lush, intricate waterways of South America’s Amazon and Orinoco basins. They are known for their stealth, patience and surprising agility. The buoyancy of the water supports the animal’s substantial bulk and enables it to move easily and leap out to ambush prey as large as capybaras (giant rodents), caimans (reptiles from the alligator family) and deer.

Green anacondas are not venomous. Instead they take down prey using their large, flexible jaws then crush it with their strong bodies, before swallowing it.

As apex predators, green anacondas are vital to maintaining balance in their ecosystems. This role extends beyond their hunting. Their very presence alters the behaviour of a wide range of other species, influencing where and how they forage, breed and migrate.

Anacondas are highly sensitive to environmental change. Healthy anaconda populations indicate healthy, vibrant ecosystems, with ample food resources and clean water. Declining anaconda numbers may be harbingers of environmental distress. So knowing which anaconda species exist, and monitoring their numbers, is crucial.

To date, there has been little research into genetic differences between anaconda species. Our research aimed to close that knowledge gap.

Green anaconda have large, flexible jaws. Pictured: a green anaconda eating a deer. JESUS RIVAS

Untangling anaconda genes

We studied representative samples from all anaconda species throughout their distribution, across nine countries.

Our project spanned almost 20 years. Crucial pieces of the puzzle came from samples we collected on a 2022 expedition to the Bameno region of Baihuaeri Waorani Territory in the Ecuadorian Amazon. We took this trip at the invitation of, and in collaboration with, Waorani leader Penti Baihua. Actor Will Smith also joined the expedition, as part of a series he is filming for National Geographic.

We surveyed anacondas from various locations throughout their ranges in South America. Conditions were difficult. We paddled up muddy rivers and slogged through swamps. The heat was relentless and swarms of insects were omnipresent.

We collected data such as habitat type and location, and rainfall patterns. We also collected tissue and/or blood from each specimen and analysed them back in the lab. This revealed the green anaconda, formerly believed to be a single species, is actually two genetically distinct species.

The first is the known species, Eunectes murinus, which lives in Perú, Bolivia, French Guiana and Brazil. We have given it the common name “southern green anaconda”. The second, newly identified species is Eunectes akayima or “northern green anaconda”, which is found in Ecuador, Colombia, Venezuela, Trinidad, Guyana, Suriname and French Guiana.

We also identified the period in time where the green anaconda diverged into two species: almost 10 million years ago.

The two species of green anaconda look almost identical, and no obvious geographical barrier exists to separate them. But their level of genetic divergence – 5.5% – is staggering. By comparison, the genetic difference between humans and apes is about 2%.

The two green anaconda species live much of their lives in water. Shutterstock

Preserving the web of life

Our research has peeled back a layer of the mystery surrounding green anacondas. This discovery has significant implications for the conservation of these species – particularly for the newly identified northern green anaconda.

Until now, the two species have been managed as a single entity. But each may have different ecological niches and ranges, and face different threats.

Tailored conservation strategies must be devised to safeguard the future of both species. This may include new legal protections and initiatives to protect habitat. It may also involve measures to mitigate the harm caused by climate change, deforestation and pollution — such as devastating effects of oil spills on aquatic habitats.

Our research is also a reminder of the complexities involved in biodiversity conservation. When species go unrecognised, they can slip through the cracks of conservation programs. By incorporating genetic taxonomy into conservation planning, we can better preserve Earth’s intricate web of life – both the species we know today, and those yet to be discovered.

Bryan G. Fry, Professor of Toxicology, School of the Environment, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→February 19, 2024

Tea Drinkers Live Longer

Four Green Teas in White Bowls Credit: A Girl With Tea / Wikimedia Commons

Drinking tea at least three times a week is linked with a longer and healthier life, according to a study published today in the European Journal of Preventive Cardiology, a journal of the European Society of Cardiology (ESC). "Habitual tea consumption is associated with lower risks of cardiovascular disease and all-cause death," said first author Dr. Xinyan Wang, Chinese Academy of Medical Sciences, Beijing, China. "The favorable health effects are the most robust for green tea and for long-term habitual tea drinkers." The analysis included 100,902 participants of the China-PAR project with no history of heart attack, stroke, or cancer. Participants were classified into two groups: habitual tea drinkers (three or more times a week) and never or non-habitual tea drinkers (less than three times a week) and followed-up for a median of 7.3 years. Habitual tea consumption was associated with more healthy years of life and longer life expectancy. For example, the analyses estimated that 50-year-old habitual tea drinkers would develop coronary heart disease and stroke 1.41 years later and live 1.26 years longer than those who never or seldom drank tea. Compared with never or non-habitual tea drinkers, habitual tea consumers had a 20% lower risk of incident heart disease and stroke, 22% lower risk of fatal heart disease and stroke, and 15% decreased risk of all-cause death. 

Green tea, Credit: MASA / Wikimedia Commons

The potential influence of changes in tea drinking behavior were analysed in a subset of 14,081 participants with assessments at two time points. The average duration between the two surveys was 8.2 years, and the median follow-up after the second survey was 5.3 years. Habitual tea drinkers who maintained their habit in both surveys had a 39% lower risk of incident heart disease and stroke, 56% lower risk of fatal heart disease and stroke, and 29% decreased risk of all-cause death compared to consistent never or non-habitual tea drinkers. Senior author Dr. Dongfeng Gu, Chinese Academy of Medical Sciences, said: "The protective effects of tea were most pronounced among the consistent habitual tea drinking group. Mechanism studies have suggested that the main bioactive compounds in tea, namely polyphenols, are not stored in the body long-term. Thus, frequent tea intake over an extended period may be necessary for the cardioprotective effect." In a subanalysis by type of tea, drinking green tea was linked with approximately 25% lower risks for incident heart disease and stroke, fatal heart disease and stroke, and all-cause death. However, no significant associations were observed for black tea. Dr. Gu noted that a preference for green tea is unique to East Asia. "In our study population, 49% of habitual tea drinkers consumed green tea most frequently, while only 8% preferred black tea. The small proportion of habitual black tea drinkers might make it more difficult to observe robust associations, but our findings hint at a differential effect between tea types." Two factors may be at play. First, green tea is a rich source of polyphenols which protect against cardiovascular disease and its risk factors including high blood pressure and dyslipidaemia. Black tea is fully fermented and during this process polyphenols are oxidised into pigments and may lose their antioxidant effects. Second, black tea is often served with milk, which previous research has shown may counteract the favourable health effects of tea on vascular function. Gender-specific analyses showed that the protective effects of habitual tea consumption were pronounced and robust across different outcomes for men, but only modest for women. Dr. Wang said: "One reason might be that 48% of men were habitual tea consumers compared to just 20% of women. Secondly, women had much lower incidence of, and mortality from, heart disease and stroke. These differences made it more likely to find statistically significant results among men." She added: "The China-PAR project is ongoing, and with more person-years of follow-up among women the associations may become more pronounced." The authors concluded that randomized trials are warranted to confirm the findings and provide evidence for dietary guidelines and lifestyle recommendations. Funding: Chinese Academy of Medical Sciences (CAMS) Innovation Fund for Medical Sciences (2017-I2M-1-004); National Key R&D Program of China (2017YFC0211700 and 2018YFC1311703).

• Contacts and sources: The European Society of Cardiology
• Publication: Tea consumption and the risk of atherosclerotic cardiovascular disease and all-cause mortality: The China-PAR project. Wang X, Liu F, Li J, et al. . Eur J Prev Cardiol. 2019. doi:10.1177/2047487319894685.
• 2China-PAR: Prediction for ASCVD Risk in China project Source: https://www.ineffableisland.com:

Read More........→January 22, 2020

Evolutionary biologists urged to adapt their research methods

Synthesizing ancestral molecules can give a clearer view of genetic evolution, says Shozo Yokoyama. Photo of olive baboon by Nivet Dilmen, via Wikipedia Commons.

By Carol Clark: To truly understand the mechanisms of natural selection, evolutionary biologists need to shift their focus from present-day molecules to synthesized, ancestral ones, says Shozo Yokoyama, a biologist at Emory University. Yokoyama presented evidence for why evolutionary biology needs to make this shift on Friday, February 15, during the American Academy of Arts and Sciences (AAAS) annual meeting in Boston. “This is not just an evolutionary biology problem, it’s a science problem,” says Yokoyama, a leading expert in the natural selection of color vision. “If you want to understand the mechanisms of an adaptive phenotype, the function of a gene and how that function changes, you have to look back in time. That is the secret. Studying ancestral molecules will give us a better understanding of genes that could be applied to medicine and other areas of science.” For years, positive Darwinian selection has been studied almost exclusively using comparative sequence analysis of present-day molecules, Yokoyama notes. This approach has been fueled by increasingly fast and cheap genome sequencing techniques. But the faster, easier route, he says, is not necessarily the best one if you want to arrive at a true, quantitative result. “If you only study present-day molecules, you’re only getting part ofFish provide clues for how environmental factors can lead to vision changes. Photo of scorpionfish by Andrew David, NOAA's Fisheries Collection.

the picture, and that picture is often wrong,” he says. Yokoyama has spent two decades teasing out secrets of the adaptive evolution of vision in fish and other vertebrates. Five classes of opsin genes encode visual pigments and are responsible for dim-light and color vision. Fish provide clues for how environmental factors can lead to vision changes, since the available light at various ocean depths is well quantified. The common vertebrate ancestor, for example, possessed ultraviolet vision, which is suited to both shallow water and land. “As the environment of a species sinks deeper in the ocean, or rises closer to the surface and moves to land, bits and pieces of the opsin genes change and vision adapts,” Yokoyama says. “I’m interested in exactly how that happens at the molecular level.” Molecular biologists can take DNA from an animal, isolate and clone its opsin genes, then use in vitro assays to construct a specific visual pigment. The pigment can be manipulated by changing the positions of the amino acids, in order to study the regulation of the gene’s function. In 1990, for example, Yokoyama identified the three specific amino acid changes that switch the human red pigment into a green pigment. A few years later, another group of researchers confirmed Yokoyama’s findings, but found that the three changes only worked in one direction. In order to reverse the process, and turn the green pigment back to red, it took seven changes. “They discovered this weird quirk that didn’t make sense,” Yokoyama says. “Why wouldn’t it take the same number of changes to go in either direction? That question was interesting toUnlike many other animals, most primates, including humans, have both a red and a green pigment, enabling them to distinguish red from green and vice-versa. Photo by Richard Ruggiero, U.S. Fish and Wildlife Service.

me.” He spent 10 years researching and pondering the question before he realized the key problem: The experiments were conducted on present-day molecules. When the earliest mammalian ancestors appeared 100 million years ago, they had only the red pigment. Around 30 million years ago, the gene for the red pigment duplicated itself in some primates. One of these duplicated red pigments then acquired sensitivity to the color green, turning into a green pigment. “At the point that the three changes in amino acids occurred in this pigment, other mutations were happening as well,” Yokoyama says. “You have to understand the original interactions of all of the amino acids in the pigment, which means you have to look at the ancestral molecules. That’s the trick.” In other words, just as changes in an animal’s external environment drive natural selection, so do changes in the animal’s molecular environment. Statistical analysis allows Yokoyama and his collaborators to travel back in time and estimate the sequences for ancestral molecules. “It’s a lot of work,” he says. “We don’t have a clear picture of every intermediate species. We have to do a step-by-step retracing, screening for noise in the results at each step, before we can construct a reliable evolutionary tree.” In 2008, Yokoyama led an effort to construct the most extensive evolutionary tree for dim-light vision, including animals from eels to humans. At key branches of the tree, Yokoyama’s lab engineered ancestral gene functions, in order to connect changes in the living environment to the molecular changes. The lengthy process of synthesizing ancestral proteins and pigments and conducting experiments on them combines microbiology with painstaking techniques of theoretical computation, biophysics, quantum chemistry and genetic engineering. This multi-dimensional approach allowed Yokoyama’s lab in 2009 to identify the scabbardfish as the first fish known to have switched from ultraviolet vision to violet vision. And Yokoyama pinpointed exactly how the scabbardfish made the switch, by deleting an amino acid molecule at site 86 in the chain of amino acids in the opsin gene. “Experimenting on ancestral molecules is the key to getting a correct answer to problems of natural selection, but there are very few examples of that being done in evolutionary biology,” Yokoyama says. Source: eScienceCommons

Read More........→May 27, 2013