It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, February 20, 2021
MONDO KUKRI
Unique feeding behavior of Asian kukri snakes gutting frogs and toads
After describing a unique behaviour in the Small-banded Kukri Snake (Oligodon fasciolatus) last September, two new studies, also led by Henrik Bringsøe, are now reporting the same gruesome feeding strategy in another two species: the Taiwanese Kukri Snake (Oligodon formosanus) and the Ocellated Kukri Snake (Oligodon ocellatus). In their research across Asia, the scientists also observed and contemplated other rare behaviours in kukri snakes.
CAPTION
An Ocellated Kukri Snake (Vietnam) first pierced this poisonous Asian common toad and buried its head deeply into the abdomen of the amphibian, as it was probably eating the organs. However, as seen in the photo, the kukri snake proceeded to swallow the toad whole.
CREDIT
James Holden
The closely related three species of snakes within the genus Oligodon have evolved an unusual behaviour where they pierce the abdomens of the amphibians, tear off their organs and swallow them one by one, keeping the prey alive for up to a few hours. Given that these species have also been recorded to feed in a more typical way: by swallowing their prey whole, the scientists find it likely that the alternative strategy has evolved specifically in their species group, in order to be able to eat larger animals. The latest findings are also published in the peer-reviewed, open-access scholarly journal Herpetozoa.
One of the new studies reports about two instances from Hong Kong, where Taiwanese Kukri Snakes were observed to disembowel Painted Burrowing Frogs (Kaloula pulchra). In one of the cases, the snake had cut open the belly of the frog and inserted its head into the frog's abdomen. Further, the reptile was seen to repeatedly rotate its body longitudinally in a "performance" also known as "death rolls". In the other case, reported in the study, the organs of the frog had been forced out of its abdomen. The researchers also provide video recordings of these unique behaviours.
"We believe that the purpose of these death rolls was to tear out organs to be subsequently swallowed," comments Bringsøe.
Meanwhile, the study mentions a new observation of one of the studied snake species (the Small-banded Kukri Snake, Oligodon fasciolatus), however preferring to swallow its Painted Burrowing Frog whole, after doing the same "death rolls", which led the scientists to think that it is the size of the prey that determines how exactly the snake would go about its dinner. The researchers also add that in both cases, the snake would eventually swallow its prey's remains.
The second newly published research paper studies a third species: the Ocellated Kukri Snake, which was observed to eat the toxic Asian Black-spotted Toad (Duttaphrynus melanostictus) in Vietnam. Initially, the snake was seen to have buried its large head eyes-deep into the amphibian's abdomen. Eventually, though, the snake swallowed the toad whole despite its toxicity, providing further evidence that kukri snakes are in fact resistant to the cardiac glycoside toxins of the toads.
"We hope that future observations may uncover additional aspects of the fascinating feeding habits of kukri snakes though we may indeed call them gruesome!" says Bringsøe.
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Research papers:
Bringsøe H, Suthanthangjai M, Suthanthangjai W, Lodder J, Komanasin N (2021) Gruesome twosome kukri rippers: Oligodon formosanus (Günther, 1872) and O. fasciolatus (Günther, 1864) eat Kaloula pulchra Gray, 1831 either by eviscerating or swallowing whole. Herpetozoa 34: 49-55. https://doi.org/10.3897/herpetozoa.34.e62688
Bringsøe H, Holden J (2021) Yet another kukri snake piercing an anuran abdomen: Oligodon ocellatus (Morice, 1875) eats Duttaphrynus melanostictus (Schneider, 1799) in Vietnam. Herpetozoa 34: 57-59. https://doi.org/10.3897/herpetozoa.34.e62689
VIDEO
CAPTION
A Taiwanese Kukri Snake with its head buried deep into the abdomen of a Painted Burrowing Frog. During the initial immobility of both individuals, the frog moves its long fourth toe of the left hind foot up and down 21 times. During the subsequent active struggle, the snake makes three rotations ("death rolls"), first two counterclockwise, then one clockwise.
CREDIT
Jonathan Rotbart
CAPTION
A Taiwanese Kukri Snake has cut open the abdomen of a Painted Burrowing Frog and has extracted several organs which it is biting and chewing. The video shows the snake in the process of swallowing. The observation took place in Hong Kong.
CREDIT
Vince Natteri
New revelations of tiger genomes
Tiger genomes reveal signatures of population bottlenecks, recent divergence between subspecies, local adaptation, and ongoing impacts of fragmentation
Genetic variation is like money in the bank: the more you have, the better your chances of survival in the future. Population bottlenecks decrease genetic variation, especially in endangered species. An individual's genome comprises the events that have impacted genetic variation over time, and relatively recent sequencing technologies allow us to read and interpret genetic variation across the genome. Although tigers have received significant conservation attention, little is known about their evolutionary history and genomic variation. This is especially true for Indian tigers, and with 70% of the world's tigers living in India, such understanding is critical to tiger conservation.
A team of researchers from the National Centre for Biological Sciences (NCBS), Stanford University, and zoological parks and NGOs across the world recently completed a three-year project to gain insights into genomic variation in tigers and the processes that have sculpted it. The work, just published in Molecular Biology and Evolution, reiterates that tiger subspecies are genetically distinct and reveals that although Indian tigers have the highest total genetic variation, some individuals are inbred. Simulations based on the genomic data suggest relatively recent divergences between subspecies, and intense population bottlenecks. Analyses also indicate adaptation to cold environments in Russian far east tigers, and potential selection on body size in Sumatran tigers.
The team sequenced whole genomes from 65 individual tigers from four subspecies, with a specific aim to enhance genomes from wild tigers in different habitats in India. They used these data to conduct a variety of population genomic analyses that quantify genetic variability, and investigate the partitioning of genetic variation, possible impacts of inbreeding and founder events, demographic history (including population divergence) and possible signatures of local adaptation.
They found that total genomic variation in Indian tigers was higher than in other subspecies. However, several individual tigers in India had low variation, suggesting possible inbreeding and founding bottlenecks. Tigers from northeast India were the most divergent/different from other populations in India. "Given our results, it is important to understand why some Bengal tigers appear inbred and what the consequences of this are," says Anubhab Khan, co-first author, NCBS.
The history of tiger populations from across their current range shows recent divergences between tiger subspecies, within the last 20,000 years, which is concordant with a transition from glacial to interglacial climate change and increasing human impacts across Asia. These findings are in sharp contrast to an earlier study by ShuJin Luo and others in 2018 that suggested much older divergence times. The recent divergence between populations will need to be investigated further with expanded datasets and analyses of more tiger genomes.
The data and analyses also suggest strong bottlenecks in all tiger populations, highlighting the importance of population size decline on the erosion of genetic variation. "Most studies focusing on species of conservation concern use limited numbers of specimens to try to gain understanding into how genomic variation is partitioned. It is clear from our work here, and a growing number of other studies, that it is crucial to increase our sampling efforts and use caution when interpreting results from limited sample sizes," comments Ellie Armstrong, co-first and co-corresponding author, Stanford University.
Genomes of tigers in the Russian far east suggest adaptation to the cold, while those of Sumatran tigers suggest selection based on body size. Co-senior author Elizabeth Hadly of Stanford University says, "The tiger is an excellent example of the myriad historic events that sculpt species' genomic diversity and points to the importance of understanding this diversity as we attempt to stave off extinction of our most precious species on Earth. While some populations demonstrate the importance of adaptation to local conditions, other evidence suggests that particular populations may suffer the effects of climatic change in the Anthropocene." Such information will be critical to the success of genetic rescue efforts, which should take local adaptation into consideration.
'I have worked on Indian tiger genetic variation for over a decade and always wondered how they compared to other wild tigers. Our study reveals that while the total variation in Indian tiger genomes is high, they have also been dramatically shaped by population bottlenecks. The genomic variation of Indian tigers continues to be shaped by the ongoing loss of connectivity. Population management and conservation action must incorporate information on genetic variation. I hope doing so will help India maintain the gains in tiger conservation achieved so far,' says Uma Ramakrishnan, co-senior and co-corresponding author, NCBS.
Despite being one of the world's most charismatic species, tigers face uncertain futures primarily due to habitat fragmentation, human-wildlife conflict and poaching. As global tiger populations decline, so does their genetic diversity. But until now it's been unclear how the animals' dwindling numbers are affecting them at the genetic level.
To find out, researchers at Stanford University, the National Centre for Biological Sciences, India, and various zoological parks and NGOs sequenced 65 genomes from four of the surviving tiger subspecies. Their findings confirmed that strong genetic differences exist between different tiger subspecies but showed, surprisingly, that these differences emerged relatively recently, as Earth underwent a major climatic shift and our own species grew increasingly dominant.
The research, detailed in a new paper published this week in the journal Molecular Biology and Evolution, shows how genomics can help guide conservation efforts toward wild tigers and other species, said study co-leader Elizabeth Hadly, the Paul S. and Billie Achilles Professor in Environmental Biology in the School of Humanities and Sciences.
"The increasing dominance of humans across the world means that our understanding of which attributes of species and populations are best suited to the Anthropocene becomes ever more important," said Hadly, referring to the proposed geological epoch marked by significant human impact on the environment.
"Some populations are well adapted to a future dominated by humans and our new climates and others are not, so any type of management of species should be informed by what we can glean from their genomes," added Hadly, who is also a senior fellow at the Stanford Woods Institute for the Environment. "Conservation genomics is far from a perfect science, but this tiger study hints at the power of adequate sampling across both the species range and its genome."
The study reveals that the world's existing tiger subspecies began exhibiting signs of dramatic and recent contractions starting only around 20,000 years ago - a period that coincided with both the global transition out of the Pleistocene Ice Age and the rise of human dominance in Asia. Each subspecies of tiger the team studied showed unique genomic signatures as a consequence of their increasing isolation from one another.
For example, local environmental genomic adaptation to cold temperatures was found in the Siberian (or Amur) tigers, the northernmost tigers found in the Russian Far East. These adaptations were absent in the other tiger subpopulations studied. Tigers from Sumatra, meanwhile, showed evidence of adaptations for body size regulation, which could help explain their overall smaller size. Despite these adaptations, tigers from these populations have low genetic diversity, suggesting that if populations continue to decline, genetic rescue may need to be considered.
One form that rescue might take is through the mating of different tiger subspecies together as a way of increasing their genetic diversity and protecting against the ill effects of inbreeding. Inbreeding occurs when populations are so small and isolated from other populations that related individuals breed with each other. Over time, this leads to lower genomic diversity and to the emergence of recessive diseases, physical deformities and fertility problems that often result in behavioral, health and population declines. Although increasing genetic diversity is one goal, another might be to select for inherited traits that confer higher survival in a changing world.
Even Bengal tigers from India, which comprise about 70 percent of the world's wild tigers and exhibit relatively high genomic diversity compared to other subspecies, showed signs of inbreeding in some populations, the study concluded.
"Some Bengal tiger populations are essentially small islands surrounded by an inhospitable sea of humanity. These tigers cannot disperse and so have only their close relatives to choose as mates," Hadly said.
While many studies investigating endangered species using genomics sequences from a single or just a few individuals, this work reiterates that individuals are not likely to be representative of a population or species status. Further work investigating the consequences of potential inbreeding and diversity declines across the subspecies are needed.
"As genomics has become available to conservation, it is apparent that collaborative studies to investigate the diversity within species are critical," said study first author Ellie Armstrong, a Stanford PhD student in Hadly's lab. "Inferences made from single genomes, while excellent additions to our knowledge of diversity in general, cannot be extrapolated to entire species, especially when using captive animals to infer adaptation to complex habitat change."
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Other Stanford co-authors on the study, titled "Recent Evolutionary History of Tigers Highlights Contrasting Roles of Genetic Drift and Selection," include former postdoctoral scholars Ryan Taylor and Stefan Prost; PhD students Jonathan Kang and Sergio Redondo; Gregory Barsh, professor of genetics and pediatrics, emeritus; Dmitri Petrov, professor of biology; and Christopher Kaelin, staff geneticist.
Magnetic attraction: Breakthrough test for malaria
After nearly a decade of research, a new test that detects the magnetic properties of malaria-infected blood could soon be used to help eliminate the mosquito-borne disease.
Dr Stephan Karl, a Senior Research Fellow in Malaria and Vector Biology at James Cook University's Australian Institute of Tropical Health and Medicine, has led an international study to field-test a new tool in the fight to eliminate the disease, which had 229 million reported cases in 2019.
"Malaria is easily treated but it is actually hard to diagnose, and because of that there can be over-treatment, which we have seen can lead to the spread of drug-resistant malaria," Dr Karl said.
"Improving malaria diagnosis, especially through the development of practical methods for resource-limited places, is important and timely."
The international team including the University of Augsburg's Professor Istvan Kezsmarki, with the PNG Institute of Medical Research and the Burnet Institute, developed and tested the method called rotating-crystal magneto-optical detection (RMOD).
Dr Karl said malaria parasites break down blood in such a way that heme molecules in the blood assemble themselves into organic crystallites containing magnetic iron, which is detected by the RMOD method.
"I've studied the magnetic properties of malaria infected blood since 2006, and we engaged with Professor Kezsmarki's team in 2013 to demonstrate the sensitivity of this test using human malaria parasites," Dr Karl said.
Professor Kezsmarki said the success of the field study, which involved nearly 1000 suspected malaria patients in a high-transmission area of Papua New Guinea, was an exciting breakthrough.
"After years of in-lab optimisation of the device, in collaboration with Dr Karl we demonstrated the great potential of RMOD in fast and reliable malaria field tests performed in Papua New-Guinea," Prof Kezsmarki said.
"We showed that RMOD performs well in comparison to the most reliable existing method," he said.
"It's very promising, as RMOD testing can be conducted after a short training session and provides test results within 10 minutes. From a funding perspective the cost is very low since no expensive reagents are used," said Dr Karl.
He said the team aimed to refine the prototype device so that, eventually, performing a test would be as simple as pushing a button.
"There are other hurdles to overcome too, at the moment the RMOD has difficulty discriminating between current and previous malaria infections and we are working on a solution for this," said Dr Karl.
Cone snail venom shows potential for treating severe malaria
Study finds anti-adhesion drugs may hold the key to treating malaria, COVID-19, aids and other emerging diseases
Severe forms of malaria such as Plasmodium falciparum may be deadly even after treatment with current parasite-killing drugs. This is due to persistent cyto-adhesion of infected erythrocytes even though existing parasites within the red blood cells are dead. As vaccines for malaria have proved less than moderately effective, and to treat these severe cases of P. falciparum malaria, new avenues are urgently needed. Latest estimates indicate that more than 500 million cases of malaria and more than 400,000 deaths are reported worldwide each year. Anti-adhesion drugs may hold the key to significantly improving survival rates.
suggests that these conotoxins could potentially treat malaria. The study provides important leads toward the development of novel and cost-effective anti-adhesion or blockade-therapy pharmaceuticals aimed at counteracting the pathology of severe malaria.
Results, published in the Journal of Proteomics, expand the pharmacological reach of conotoxins/ conopeptides by revealing their ability to disrupt protein-protein and protein-polysaccharide interactions that directly contribute to the disease. Similarly, mitigation of emerging diseases like AIDS and COVID-19 also could benefit from conotoxins as potential inhibitors of protein-protein interactions as treatment. Venom peptides from cone snails has the potential to treat countless diseases using blockage therapies.
"Molecular stability, small size, solubility, intravenous delivery, and no immunogenic response make conotoxins excellent blockade-therapy candidates," said Andrew V. Oleinikov, Ph.D., corresponding author and a professor of biomedical science, FAU's Schmidt College of Medicine. "Conotoxins have been vigorously studied for decades as molecular probes and drug leads targeting the central nervous systems. They also should be explored for novel applications aimed to thwart amiss cellular responses or foil host parasite interactions through their binding with endogenous and exogenous proteins. Further investigation is likely to yield breakthroughs in fields continuously toiling for more efficient therapeutic approaches such as cancer, autoimmune diseases, novel emerging viral diseases as well as malaria where venom-based peptidic natural products can be put into practice."
The disruption of protein-protein interactions by conotoxins is an extension of their well known inhibitory action in many ion channels and receptors. Disabling prey by specifically modulating their central nervous system is a ruling principle in the mode of action of venoms.
CAPTION
Conus nux, a species of sea snail
CREDIT
Fred Pflueger, Ph.D.
"Among the more than 850 species of cone snails there are hundreds of thousands of diverse venom exopeptides that have been selected throughout several million years of evolution to capture their prey and deter predators," said Frank Marí, Ph.D., corresponding author and senior advisor for biochemical sciences at the National Institute of Standards and Technology. "They do so by targeting several surface proteins present in target excitable cells. This immense biomolecular library of conopeptides can be explored for potential use as therapeutic leads against persistent and emerging diseases affecting non-excitable systems."
For the study, researchers used high-throughput assays to study Conus nux collected off the Pacific coast of Costa Rica. They revealed the in vitro capacity of cone snail venom to disrupt protein-protein and protein-polysaccharide interactions that directly contribute to pathology of P. falciparum malaria. They determined that six fractions from the venom inhibit the adhesion of recombinant P. falciparum erythrocyte membrane protein 1 (PfEMP-1) domains to their corresponding receptors, which express on the endothelial microvasculature and the placenta.
The results are noteworthy as each of these six venom fractions, which contain a mostly single or a very limited set of peptides, affected binding of domains with different receptor specificity to their corresponding receptors, which are proteins (CD36 and ICAM-1), and polysaccharide. This activity profile suggests that the peptides in these conotoxin fractions either bind to common structural elements in the different PfEMP1 domains, or that a few different peptides in the fraction may interact efficiently (concentration of each is lower proportionally to the complexity) with different domains.
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Study co-authors are Alberto Padilla, Ph.D., first author and a former graduate student, FAU's Schmidt College of Medicine; Sanaz Dovell, Ph.D., a former student in FAU's Charles E. Schmidt College of Science; Olga Chesnokov, Ph.D., research associate, FAU's Schmidt College of Medicine; aand Mickelene Hoggard, Ph.D., Chemical Sciences Division, National Institute of Standards and Technology.
This research is supported in part by the National Institute of Allergy and Infectious Diseases (grants R21A137721 and R01AI092120) awarded to Oleinikov.
About the Charles E. Schmidt College of Medicine:
FAU's Charles E. Schmidt College of Medicine is one of approximately 155 accredited medical schools in the U.S. The college was launched in 2010, when the Florida Board of Governors made a landmark decision authorizing FAU to award the M.D. degree. After receiving approval from the Florida legislature and the governor, it became the 134th allopathic medical school in North America. With more than 70 full and part-time faculty and more than 1,300 affiliate faculty, the college matriculates 64 medical students each year and has been nationally recognized for its innovative curriculum. To further FAU's commitment to increase much needed medical residency positions in Palm Beach County and to ensure that the region will continue to have an adequate and well-trained physician workforce, the FAU Charles E. Schmidt College of Medicine Consortium for Graduate Medical Education (GME) was formed in fall 2011 with five leading hospitals in Palm Beach County. The Consortium currently has five Accreditation Council for Graduate Medical Education (ACGME) accredited residencies including internal medicine, surgery, emergency medicine, psychiatry, and neurology.
About Florida Atlantic University:
Florida Atlantic University, established in 1961, officially opened its doors in 1964 as the fifth public university in Florida. Today, the University serves more than 30,000 undergraduate and graduate students across six campuses located along the southeast Florida coast. In recent years, the University has doubled its research expenditures and outpaced its peers in student achievement rates. Through the coexistence of access and excellence, FAU embodies an innovative model where traditional achievement gaps vanish. FAU is designated a Hispanic-serving institution, ranked as a top public university by U.S. News & World Report and a High Research Activity institution by the Carnegie Foundation for the Advancement of Teaching. For more information, visit http://www.fau.edu.
New UCF study examines leeches for role in major disease of sea turtles in Florida
The disease fibropapillomatosis causes sea turtles to develop tumors on their bodies, which can limit their health and mobility
ORLANDO, Feb. 18, 2021 - University of Central Florida researchers are homing in on the cause of a major disease of sea turtles, with some of their latest findings implicating saltwater leeches as a possible factor.
The disease, known as fibropapillomatosis, or FP, causes sea turtles to develop tumors on their bodies, which can limit their mobility and also their health by interfering with their ability to catch and eat prey.
While the cause of FP isn't known, saltwater leeches have been suspected to play a role due to their frequent presence on areas of sea turtles where FP tumors often develop, such as on their eyes, mouths and flippers.
The results, which were published recently in the journal Diseases of Aquatic Organisms, are the first evidence of a significant association between leeches and the disease in sea turtles, according to the researchers.
"Florida is one of the areas most heavily impacted by FP," says Anna Savage, an associate professor in UCF's Department of Biology and study co-author. "Over the past three decades, approximately half of the green turtle juveniles encountered in the Indian River Lagoon have FP tumors, which is one of the highest rates documented," she says.
Sea turtle health is important because the ancient marine reptiles contribute to healthy oceans and coastlines by grazing and maintaining sea grass beds.
All sea turtles are categorized as threatened or endangered because of threats from pollution, coastal development and fishing, in addition to infectious diseases.
Central Florida's Atlantic coastline hosts about one-third of all green turtle nests in the state and is one of the most important nesting areas in the world for loggerheads.
Knowing if leeches play a role in the disease transmission can help researchers better understand and predict its spread, as well as inform conservation actions, such as leech removal in sea turtle rehabilitation centers.
The Process
The study's lead author and a recent undergraduate alumna of UCF's Biology Department, Leah Rittenburg, spearheaded the research and was responsible for the genetic analyses.
To find out a possible connection between leeches and FP, the researchers documented the presence of leeches on green and loggerhead turtles captured from the Indian River Lagoon and also used genetic analyses to determine if leeches collected from the turtles contained chelonid alphaherpesvirus 5, or ChHV5, the virus most likely responsible for disease development in an individual turtle.
"Our historical data, collected by the UCF Marine Turtle Research Group between 2006 and 2018, revealed that leech parasitism was significantly associated with FP in green turtles but not in loggerhead turtles," Rittenburg says.
"For the genetic analysis, about one-fifth of the leeches we collected were positive for ChHV5, and one leech species trended towards coming from FP-positive turtles, further supporting the hypothesis that leeches may act as ChHV5 transmitters," she says.
Now that the researchers have demonstrated a relationship between FP and leeches, they want to evaluate more specifically if leeches transmit the turtle herpesvirus, which would provide stronger evidence that the virus in an underlying cause of FP.
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Study co-authors were Jake R. Kelley, a master's student in UCF's Department of Biology, and Kate L. Mansfield, an associate professor in UCF's Department of Biology and director of the UCF Marine Turtle Research Group.
The research was funded by grants from UCF's Office of Undergraduate Research and by a Florida Sea Turtle License Plate grant.
Savage received her doctorate in ecology and evolutionary biology from Cornell University. She is a member of UCF's Genomics and Bioinformatics Cluster and joined UCF's Department of Biology, part of UCF's College of Sciences, in 2015.
IMAGE: THIS DIAGRAM ILLUSTRATES THE LONGFIN DAMSELFISH-MYSID RELATIONSHIP, WHERE THE NICHE CREATED BY THE TERRITORIAL ALGAE FARMING LONGFIN DAMSELFISH PROVIDES A PROTECTIVE REFUGE TO MYSIDS, LEADING TO INCREASED SURVIVAL. IN TURN,... view more
CREDIT: ILLUSTRATION BY ROHAN BROOKER
Throughout nature, there are instances of animals aiding one another and living together in mutually beneficial relationships that have helped shape the world's landscapes and biodiversity.
These domesticator-domesticate relationships form when one species provides multigenerational support to another species in exchange for a resource or service that benefits both species. An example of this type of relationship is how early humans domesticated gray wolves. The wolves were attracted to the human encampments, which provided them with protection and resources, and the wolves, in turn, helped the humans increase their hunting proficiency.
One area of the world where these mutually beneficial relationships could be examined further, however, is underwater.
A new study involving researchers from the University of Delaware looked at how a mutually beneficial relationship formed in the waters of Belize. Researchers discovered that longfin damselfish aggressively defend algal farms on which they feed, which provides a protective refuge for planktonic mysid shrimps, which in turn excrete nutrients onto the farms, enriching the algae on which the damselfish feed.
The paper was recently published in Nature Communications. Rohan Brooker, a former post-doctoral researcher at UD, served as the lead author and Danielle Dixson, associate professor in University of Delaware's School of Marine Science and Policy in the College of Earth, Ocean and Environment, served as one of the co-authors on the study.
The research was conducted in the field on the shallow reef habitat surrounding the Smithsonian's Carrie Bow Cay Research Station in Belize from January through April of 2018, however the idea and initial data was conducted when Brooker was a post-doctoral researcher in Dixson's lab and continued through his post-doctoral position at the University of Saskatchewan, Canada.
Aggressive fish
Dixson said that longfin damselfish are known to aggressively defend the algal farms that they consider to be their turf, and while they aren't a very big fish, they are tenaciously territorial.
"They will come after you if you go into their territory," said Dixson. "They'll try and bite you, and they'll try to scare everything away. They're really aggressive even though they're not very big. So they create this bubble that they protect, and one of the things that they don't bother chasing off are these mysids."
Mysids are tiny, clear planktonic crustaceans that live together by the hundreds in cloud-like structures. Using the damselfish as a kind of fence or a security system for their area, the mysids that lived within the damselfish farms were attacked less often than mysids that lived outside of the farms.
In return for this protection, the mysids provide a benefit to the damselfish by excreting nutrients onto the algae that the damselfish eat.
The damselfish that hosted the mysids in their communities exhibited a better body condition than those fish who did not host mysids in their communities.
To determine the effect of mysids on longfin damselfish body condition, the researchers looked at the hepatosomatic index (HSI), which can reflect the health or stored energy of a fish's liver and can indicate the relationship between the diet and physical condition of the damselfish. They compared the HSI of the fish who lived with the mysids to those who lived without the mysids and found that those fish living with the mysids had a higher HSI than those who had no mysids on their alga farms.
This could be for several reasons. For instance, within the mysid-associated farms, the algal composition was significantly different than those farms without mysids. Mysid-associated farms contained a significantly higher proportion of brown algae, which increases the structural complexity of damselfish farms and can serve as a catalyst for the growth of palatable turf-algae, the preferred food source for the damselfish.
Dixson said that it was interesting to see this relationship form in a natural environment and could lead to more studies looking at domesticator-domesticate relationships in the wild.
"We know that domesticator-domesticate relationships happen in nature," said Dixson. "But this is the first example we have found of this type of relationship underwater. Maybe this paper could spark other people to examine different commensal pathways or mutualistic behaviors that we see as potentially being something similar to this."
IMAGE: TWO RECENT DISCOVERIES SHOWED ODOROUS STRUCTURES IN ADULT MALE CURAC?AOAN LONG-NOSED BATS (LEPTONYCTERIS CURASOAE) AND FRINGE-LIPPED BATS (TRACHOPS CIRRHOSUS), CREATED BY SMEARING BODILY FLUIDS. view more
CREDIT: MARIANA MUÑOZ-ROMO AND PAUL B. JONES.
When falling in love, humans often pay attention to looks. Many non-human animals also choose a sexual partner based on appearance. Male birds may sport flashy feathers to attract females, lionesses prefer lions with thicker manes and colorful male guppies with large spots attract the most females. But bats are active in the dark. How do they attract mates? Mariana Muñoz-Romo, a senior Latin American postdoctoral fellow at the Smithsonian Tropical Research Institute (STRI) and National Geographic explorer, pioneers research to understand the role of odors in bat mating behavior.
"Aside from their genitalia, most male and female bat species look identical at first glance. However, a detailed examination during mating season reveals odor-producing glands or structures that are only present in male bats. Long interested in this understudied sexual difference, and working with long-nosed bats, Leptonycteris curasoae, in Venezuela, Muñoz-Romo discovered that males exhibit an odorous dorsal patch in the mating season consisting of a mixture of saliva, feces, urine and/or semen that seems to attract reproductive females.
Later in Panama, Muñoz-Romo investigated the "perfumes" from smelly crusts that male fringe-lipped bats, Trachops cirrhosus, meticulously apply to their forearms during mating season. These studies deepened her interest in odor and its role in bat mating systems, and her conviction that odor may be bats' secret weapon to choosing a mate in the dark."
Studies across a range of mammalian species show that just by smelling a potential mate, an individual can assess its sex, age, sexual receptiveness, health, social status, group membership and identity. This is a whole lot of personal information in one sniff, suggesting that odor may be a more important factor for mate choice and reproduction.
Alongside STRI staff scientist Rachel Page and renowned Boston University bat ecologist, Thomas H. Kunz, Muñoz-Romo combed through all published articles on the topic. Together, they found reports of odor-producing structures in 121 bat species from 15 different bat families. This represents nearly 10% of all known bat species and over 70% of bat families. Odors come from very different parts of bats' bodies, from their heads and mouths to their wings or genitalia. Not only are chemical signals potent and effective for communication in dark conditions, they also do not impede the bats' ability to fly.
"We believe that these key factors--nocturnality and powered flight--combined with scent-producing glands common across mammals, promoted the evolution of a great diversity of the odorous displaying structures we find in bats," Muñoz-Romo said.
Although researchers know very little about these structures so far, the new review of the subject opens up promising new avenues for bat research. There are potentially many more odor-related structures waiting to be discovered.
"Future investigations should consider the importance of the timing of odor production and sexual behavior, because most of these traits are displayed during a specific and usually short time of the year--the mating season," Muñoz-Romo said. "Answering new questions about the nature and development of the odorous traits, as well as understanding which traits female bats prefer, are key to understanding why differences between males and females evolved. We also want to understand the chemistry of bat perfumes--what compounds make them attractive."
In another recent publication, Muñoz-Romo, Page and colleagues suggest that the size of the odorous crusts found on the forearms of male T. cirrhosus allow females to evaluate potential mates during the time of year when they were fertile.
"While differences between males and females (sexual dimorphism) in bats have long been overlooked, new tools are giving us an ever-expanding window into their previously cryptic social lives," Page said. "The patterns revealed here sharpen the focus of investigations going forward, in particular highlighting the importance of seasonally present odor-producing glands and soft tissues. With so many bat species still to be studied, it will be extremely exciting to see what lies on the horizon. We only wish that our dear friend and colleague, Tom Kunz, whose insight inspired this work, had lived to see the publication of this review."
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Members of the research team are affiliated with STRI, Universidad de Los Andes (Venezuela) and Boston University. The work supporting this review was funded by these three institutions at different points in time.
IMAGE: YELLOW WARBLERS ARE FOUND THROUGHOUT NORTH AMERICA AND FLY TO CENTRAL AND SOUTH AMERICA FOR WINTER. RACHAEL BAY, ASSISTANT PROFESSOR OF EVOLUTION AND ECOLOGY AT UC DAVIS, AND COLLEAGUES HAVE... view more
CREDIT: JONATHAN EISEN
As climate change takes hold across the Americas, some areas will get wetter, and others will get hotter and drier. A new study of the yellow warbler, a widespread migratory songbird, shows that individuals have the same climatic preferences across their migratory range. The work is published Feb. 17 in Ecology Letters.
"What's amazing is that the birds track similar climates despite the fact that they have migrated thousands of miles," said Rachael Bay, assistant professor in the Department of Evolution and Ecology, College of Biological Sciences at the University of California, Davis. "It seems that individual birds may be adapted to particular climate regimes."
Yellow warblers (Setophagia petechia) breed throughout North America and fly south to Central and South America to spend the winter. A previous study by Bay and colleagues found links between genetic variation and precipitation across North America, suggesting that certain individuals might be adapted to dry conditions while others thrive in wet conditions. In the current study, the authors were able to use genetics to predict where birds captured on their wintering grounds in Central and South America would end up breeding and compare climate patterns in their winter and summer areas.
Individual birds showed preferences for drier or wetter areas, but not for warmer or cooler areas. In other words, birds that bred in relatively dry parts of North America -- such as California's Central Valley -- overwintered in dry parts of South or Central America.
"This is the first demonstration of using individual genetic tracking to link climates across the migratory cycle within a bird species," Bay said.
Impact of climate change
This range of climatic preferences could have consequences for how the birds respond to climate change. Bay speculates that the variation she and her colleagues found might provide the raw material for the species to adapt to changing climate conditions. For example, populations that are adapted to drier conditions might displace those adapted to wetter ones. In fact, Bay and colleagues have already found that population sizes of yellow warblers changed with precipitation across years.
Bay collected data for the study during her postdoctoral research, in collaboration with banding stations and collecting sites in North and South America. Bay and her colleagues are now eager to see whether individuals of other bird species also track climate during migration.
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Additional authors on the paper are Daniel Karp, Department of Wildlife, Fish and Conservation Biology, UC Davis; James Saracco, The Institute for Bird Populations, Petaluma, California; William Anderegg, University of Utah; Luke Frishkoff, University of Texas at Arlington; David Wiedenfeld, American Bird Conservancy, The Plains, Virginia; Thomas Smith, UCLA; and Kristen Ruegg, Colorado State University, Fort Collins.
The work was supported by grants from the National Science Foundation, National Geographic, California Energy Commission and First Solar Inc.
Fugitive Spanish rapper arrested after taking refuge at Catalan university
Spanish rapper Pablo Duro, known professionally as Pablo Hasel, raises a fist on Tuesday as he is arrested by police at Lleida University in Catalonia, where he took refuge in the building after refusing to report to prison. Photo by Paul de la Calle/EPA-EFE
Feb. 16 (UPI) -- Authorities on Tuesday arrested a Spanish rapper who spent a day holed up at a university in Catalonia, purportedly to avoid going to prison over a series of tweets.
Pablo Rivadulla Duro, known by his stage name Pablo Hasel, was told to report to prison by Friday for a conviction involving tweets that officials said glorified terrorism and insulted the Spanish Crown.
Officials say Duro missed the deadline and took refuge inside Catalonia's Lleida University on Monday, along with dozens of supporters who erected a barricade inside with chairs and desks.
"Long live the struggle," Duro said upon his exit, according to The Guardian. "We will never stop. They will never beat us."
At issue was the prison sentence given Duro for his conviction on expressing support for terrorist organizations, such as the now defunct Basque group ETA and the Marxist GRAPO.
The conviction also said he was guilty of accusing King Felipe VI, and predecessor King Juan Carlos, of several crimes in a series of tweets.
Spain's highest criminal court ruled in 2018 that Duro's lyrics and comments went beyond the limits of free speech and were expressions of "hatred and attacks on honor."
Duro, 32, was initially sentenced to two years, but an appellate court later cut the term to nine months. The Supreme Court upheld the decision last year.
The case sparked public debate about freedom of expression and the Spanish government has since announced plans to reform the criminal code to eliminate prison for such offenses.
The rapper has avoided prison in the past for writing and sharing songs that praised terrorist groups. He was also sentenced in 2016 for assaulting a journalist and attacking a witness at a trial, though those rulings have both been appealed.
