Showing posts sorted by relevance for query BATS. Sort by date Show all posts
Showing posts sorted by relevance for query BATS. Sort by date Show all posts

Friday, October 27, 2023

 

Fruit, nectar, bugs and blood: How bat teeth and jaws evolved for a diverse dinnertime


Peer-Reviewed Publication

UNIVERSITY OF WASHINGTON

Jamaican fruit bat 

IMAGE: 

THIS JAMAICAN FRUIT BAT, ARTIBEUS JAMAICENSIS, HAS A SHORT JAW, LIKE MANY NOCTILIONOID FRUIT-EATING BATS.

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CREDIT: ALEXA SADIER



Link to full release with images:

https://www.washington.edu/news/2023/10/26/bat-teeth/


They don’t know it, but Darwin’s finches changed the world. These closely related species — native to the Galapagos Islands — each sport a uniquely shaped beak that matches their preferred diet. Studying these birds helped Charles Darwin develop the theory of evolution by natural selection.

A group of bats has a similar — and more expansive — evolutionary story to tell. There are more than 200 species of noctilionoid bats, mostly in the American tropics. And despite being close relatives, their jaws evolved in wildly divergent shapes and sizes to exploit different food sources. A paper published Aug. 22 in Nature Communications shows those adaptations include dramatic, but also consistent, modifications to tooth number, size, shape and position. For example, bats with short snouts lack certain teeth, presumably due to a lack of space. Species with longer jaws have room for more teeth — and, like humans, their total tooth complement is closer to what the ancestor of placental mammals had.

According to the research team behind this study, comparing noctilionoid species can reveal a lot about how mammalian faces evolved and developed, particularly jaws and teeth. And as a bonus, they can also answer some outstanding questions about how our own pearly whites form and grow.

“Bats have all four types of teeth — incisors, canines, premolars and molars — just like we do,” said co-author Sharlene Santana, a University of Washington professor of biology and curator of mammals at the Burke Museum of Natural History & Culture. “And noctilionoid bats evolved a huge diversity of diets in as little as 25 million years, which is a very short amount of time for these adaptations to occur.”

“There are noctilionoid species that have short faces like bulldogs with powerful jaws that can bite the tough exterior of the fruits that they eat. Other species have long snouts to help them drink nectar from flowers. How did this diversity evolve so quickly? What had to change in their jaws and teeth to make this possible?” said lead author Alexa Sadier, an incoming faculty member at the Institute of Evolutionary Science of Montpellier in France, who began this project as a postdoctoral researcher at the University California, Los Angeles.

Scientists don’t know what triggered this frenzy of dietary adaptation in noctilionoid bats. But today different noctilionoid species feast on insects, fruit, nectar, fish and even blood — since this group also includes the infamous vampire bats.

The team used CT scans and other methods to analyze the shapes and sizes of jaws, premolars and molars in more than 100 noctilionoid species. The bats included both museum specimens and a limited number of wild bats captured for study purposes. The researchers compared the relative sizes of teeth and other cranial features among species with different types of diets, and used mathematical modeling to determine how those differences are generated during development.

The team found that, in noctilionoid bats, certain “developmental rules” caused them to generate the right assortment of teeth to fit in their diet-formed grins. For example, bats with long jaws — like nectar-feeders — or intermediate jaws, like many insect-eaters, tended to have the usual complement of three premolars and three molars on each side of the jaw. But bats with short jaws, including most fruit-eating bats, tended to ditch the middle premolar or the back molar, if not both.

“When you have more space, you can have more teeth,” said Sadier. “But for bats with a shorter space, even though they have a more powerful bite, you simply run out of room for all these teeth.”

Having a shorter jaw may also explain why many short-faced bats also tended to have wider front molars.

“The first teeth to appear tend to grow bigger since there is not enough space for the next ones to emerge,” said Sadier.

“This project is giving us the opportunity to actually test some of the assumptions that have been made about how tooth growth, shape and size are regulated in mammals,” said Santana. “We know surprisingly little about how these very important structures develop!”

Many studies about mammalian tooth development were done in mice, which have only molars and heavily modified incisors. Scientists are not entirely sure if the genes and developmental patterns that control tooth development in mice also operate in mammals with more “ancestral” sets of chompers — like bats and humans.

Sadier, Santana and their colleagues believe their project, which is ongoing, can start to answer these questions in bats — along with many other outstanding questions about how evolution shapes mammalian features. They’re expanding this study to include noctilionoid incisors and canines, and hope to uncover more of the genetic and developmental mechanisms that control tooth development in this diverse group of bats.

“We see such strong selective pressures in these bats: Shapes have to closely match their function,” said Santana. “I think there are many more evolutionary secrets hidden in these species.”

Co-authors are Neal Anthwal, a research associate at King’s College London; Andrew Krause, an assistant professor at the Durham University in the U.K.; Renaud Dessalles, a mathematician with Green Shield Technology; Robert Haase, a researcher at the Dresden University of Technology in Germany; UCLA research scientists Michael Lake, Laurent Bentolila and Natalie Nieves; and Karen Sears, a professor at UCLA. The research is funded by the National Science Foundation.

The pale-faced bat, Phylloderma stenops, is a noctilionoid bat with an omnivorous diet.

CREDIT

Sharlene Santana/University of Washington

For more information, contact Santana at ssantana@uw.edu and Sadier at alexa.sadier@gmail.com.

NSF grant numbers: 2017738, 201780

Wednesday, June 02, 2021

 

Sick bats also employ 'social distancing' which prevents the outbreak of epidemics

New study from Tel Aviv University reveals that bats also resort to isolation which can assist in preventing mass contagion

TEL-AVIV UNIVERSITY

Research News

IMAGE

IMAGE: IMAGES OF BATS. view more 

CREDIT: YUVAL BARKAI.

The Covid-19 pandemic has introduced us to expressions like 'lockdown', 'isolation' and 'social distancing', which became part of social conduct all over the world. Now it appears that bats also maintain social distancing which might help prevent the spread of contagious diseases in their colonies. In a new study published in Annals of the New York Academy of Science, researchers from Tel Aviv University demonstrate that sick bats, just like ill humans, prefer to stay away from their communities, probably as a means for recovery, and possibly also as a measure for protecting others. The study was conducted by postdoctoral researcher Dr. Kelsey Moreno and PhD candidate Maya Weinberg at the laboratory of Prof. Yossi Yovel, Head of the Sagol School of Neuroscience and a researcher at School of Zoology at the George S. wise Faculty of Life Sciences.

The study monitored two colonies of Egyptian fruit bats - one living in an enclosure and the other in its natural environment. To examine the behavior of bats when they get sick, the researchers injected several bats in each group with a bacteria-like protein, thereby stimulating their immune response without generating any real danger to the bats. Tests revealed symptoms such as a high fever, fatigue and weight loss, and the 'ill' bats' behavior was tracked with GPS.

The researchers discovered that the 'sick' bats chose to keep away from the colony. In the first group, they left the bat cluster of their own accord and kept their distance. In the second group the 'ill' bats likewise moved away from the other bats in the colony, and also stayed in the colony and did not go out in search of food for two successive nights.



CAPTION

Images of bats.

CREDIT

Yuval Barkai.

Research student Maya Weinberg explains that this social distancing behavior is probably caused by the need to conserve energy - by avoiding the energy-consuming social interactions in the group. Weinberg emphasizes, however, that this behavior can also protect the group and prevent the pathogen from spreading within the colony. Moreover, the fact that sick bats don't leave the cave, prevents the disease from spreading to other colonies. "The bats' choice to stay away from the group is highly unusual for these animals. Normally these bats are extremely social creatures, living in caves in very crowded conditions," says Weinberg. "In fact, the 'sick' bats' behavior is very reminiscent of our own during recovery from an illness. Just as we prefer to stay home quietly under the blanket when we are ill, sick bats, living in very crowded caves, also seek solitude and peace as they recuperate."

Prof. Yovel adds that the study's findings suggest that the likelihood of bats passing pathogens to humans under regular conditions is very low, because sick bats tend to isolate themselves and stay in the cave. "We observed that during illness bats choose to stay away from the colony and don't leave the cave, and thus avoid mixing with other bats. This suggests that in order to encounter a sick bat, people must actually invade the bats' natural environment or eliminate their habitats. In other words, if we protect them, they will also protect us."


CAPTION

Prof. Yossi Yovel

CREDIT

Tel Aviv University


Friday, April 17, 2020

Happy International Bat Appreciation Day! Why on Earth Would We Celebrate Bats?

April 17 is International Bat Appreciation Day, a day reminding us to show love to our flying friends who play a key role in ecosystems all over the world.


Happy International Bat Appreciation Day!

(TMU) — Today, April 17th, is celebrated as International Bat Appreciation Day—a day meant to remind us to show love to our flying pollinator friends who play a critical role in environments and ecosystems all over the world.

Bats are the common name for roughly 1,400 species that have been discovered, and these fabulous creatures make up about 20 percent of mammal species after rodents. An estimated 48 bat species live in the United States, and three states—Texas, Oklahoma, and Virginia—have their own official state bats. What makes bats unique among mammals is their ability to fly naturally and in a sustained manner.

In general, bats are a very misunderstood creature. No doubt, we can understand if a bat flying in the middle of the night gives some people the creeps—their depiction in pop culture associates them with spooky things like Dracula, the blood-sucking vampire.


April 17th is National #BatAppreciationDay. Bats play an important role in many ecosystems around the world. They are crucial pollinators for cactus species and many other tropical plants, they help control insect populations & also disperse seeds!
Why are bats important to you? pic.twitter.com/YLB69M22Ms
— EveryBat (@EveryBat) April 17, 2020

But as various scientific studies show, most bats eat a wide variety of insects, balancing the population of such creepy-crawlers and nuisance bugs like locusts, flies, scorpions, moths, centipedes, and mosquitos.

Other bat species are frugivores and enjoy such fruits as figs, mangoes, bananas, and dates, as well as seeds and the pollen of flowers. And yes, three types of vampire bats do exist in Central and South America, but humans have no reason to fear them.

Most bats are nocturnal creatures that come out at night, with many using their extreme sense of hearing and ability to see in the dark to get around. A large variety of bats use a trick called echolocation that relies on sonar to navigate, avoid obstacles, and find food—not unlike dolphins. However, some bats in Southeast Asia fly and hunt their meals during the daytime.



Today is International Bat appreciation day 🦇 pic.twitter.com/EdC4iaQemS
— Wildlife World Zoo, Aquarium & Safari Park (@ZooWildlife) April 17, 2020

And while bees and butterflies often get the lion’s share of credit for their role as pollinators, bats are no less important to providing us with a crucial link in our food supply. As the Bat Conservation Trust explains, some 500 plant species rely on bats to pollinate their flowers. This includes various species of banana, mango, guava, durian, and agave—the succulent, pollen-rich plant that provides us with tequila. Many of these plants actually co-evolved with bats over the course of millennia.

Before reading the above information, some of you may have asked: why would we be celebrating these god-forsaken creatures when they were the source of the coronavirus that causes CoViD-19? Aren’t they the reason that we’re being quarantined indoors, jobless and bored, and now we’re supposed to celebrate them?

Well, as Deutsche Welle aptly put it: a bat didn’t “cause” the coronavirus pandemic. We did. More specifically, it was likely the fault of the rampant, illegal trafficking of wild animals.

Today is International Bat Appreciation Day! Despite all the bad press, bats are actually pretty cool and very important in nature. We have a lot to learn about bats, viruses and disease – read our blog to learn more:https://t.co/wCfEfAnNY9#virology #bats #batappreciationday pic.twitter.com/Gt7A67I5B
— The Science Social (@TheSciSocial) April 17, 2020

While some bats have been shown to carry a number of infections deadly to humans—including Ebola, rabies, and SARS (severe acute respiratory syndrome), among others—the vast majority of bats aren’t infected. There also isn’t any solid scientific proof that CoViD-19 took flight from bats yet, although there is plenty of conjecture and speculation. Some believe that pangolins may have acted as an intermediary for the novel coronavirus. Either way, bats that do carry coronaviruses pose zero threat to humans provided they are left undisturbed in the wild.

Sadly, a combination of misinformation, long-standing ignorance, and mass hysteria over the coronavirus led to villagers in Peru attacking our winged friends last month and killing hundreds of the creatures.

The problem led to Peru’s National Service of Wild Forests and Fauna (SERFOR) reminding locals that “bats are not our enemies,” and explaining that “70 percent of the [bat] species in the world feed off insects, many of which are harmful to agriculture and our health, like mosquitoes that spread dengue and other diseases.”

So with that in mind, let’s remember that bats are nothing to be scared of. Indeed, we hope that we’ve provided our readers with plenty of good reasons to not only appreciate bats, but to cherish and protect these good friends to our species. When it comes to bats, the facts make clear that to know them is to love them.

By Elias Marat | Creative Commons | TheMindUnleashed.com

Monday, November 01, 2021

 

Sending up the bat signal on forest use by endangered species

bats
Credit: CC0 Public Domain

Deep in an Indiana forest, a team of scientists skulked atop hillsides after dark. Carrying radios and antennas, they fanned out, positioning themselves on opposite ridges to wait and listen. Their quarry? Endangered Indiana bats and threatened northern long-eared bats.

The goal was to track individual bats from the moment they left the roost at dusk to the time they returned near dawn. Having fitted each bat with a tiny radio transmitter, the scientists traversed the dark forest to triangulate the bats' positions through the night. The work was painstaking, and it took four years to track just 58 individuals.

The results are published in Forest Ecology and Management.

Tracking the bats' movements through Indiana's state forests didn't just provide some of the first descriptions of the foraging behavior and home ranges of these species. It also revealed the animals' preference for certain timber harvesting strategies, such as thinning and patch cuts.

"There's a perceived conflict between  and endangered bats. Folks would like to harvest without any restrictions, but because these bats are there, they have to pay attention to when they're present and what kind of habitat they're using, and then potentially change the timing or the nature of harvests or prescribed fires to accommodate for the bats," says Joy O'Keefe, assistant professor in the Department of Natural Resources and Environmental Sciences at the University of Illinois and co-author on the study.

Tim Divoll, a data scientist at SWCA Environmental Consultants and lead author on the paper, adds, "We know a lot about where these bats like to roost, but no one has studied the foraging behaviors in detail when both species share the same forest. That's going to tell us a lot more about how they use these forests and how we might accommodate the variety of behaviors."

The research team was interested in whether timber harvest strategies and other forest management decisions had a positive, neutral, or negative impact on the bats.

"We found, with the exception of larger clear cuts, most of these harvest types are probably neutral for these bats. In some cases, they might even be positive, but we didn't really find any evidence that small patch cuts and thinning are negative. So, I'd say the way they're already managing these forests is compatible with bat conservation," O'Keefe says.

Indiana bats and northern long-eared bats need all the conservation help they can get. Like an increasing number of bat species, both suffer from extreme habitat loss and the detrimental effects of the fungal disease white-nose syndrome.

"White-nose syndrome has really devastated northern long-eared bats in this forest. It turns out we did this study just in the nick of time, because right after we finished the study in 2017, we could no longer catch them out there. Their populations just tanked. Thankfully, my students caught four individuals this year," O'Keefe says. "The results of this study will help forest managers to make decisions that boost bat populations recovering from this disease."

Because the Indiana bat has been on the  since the law's inception in 1967, it has received a great deal of research attention. The northern long-eared bat isn't as well studied, having only been federally listed as threatened in 2015 due to white-nose syndrome. So, much of what the research team observed for the species was previously unknown.

According to the study, the home range for northern long-eared bats is about half the size of Indiana bats, and they spend most of their time foraging near ponds, in forest sections that were previously thinned, or in patch cuts smaller than 10 acres.

Indiana bats had similar preferences for previously thinned sections and small cuts, but more of them ventured across larger clear cuts.

O'Keefe says the difference in home range size may come down to foraging strategy. Northern long-eared bats are gleaners, meaning they scoop up their insect prey from surfaces, at least some of the time. If they can find enough to eat on the trees near their roost, they don't need to go far to fill up. Indiana bats eat flying insects, so they might have to fly farther to locate swarms of bugs.

Without spending years tracking individual bats, these subtleties might have been lost.

"When you put in the effort to track many individual bats over multiple nights, then you have a much more robust and precise way of assessing how they use habitat," O'Keefe says. "It was a lot of work to get these data points. Every time we tracked one bat, there were four people on the landscape, each with an antenna and receiver, listening for several hours. So, what we did is pretty remarkable."

The researchers' findings were based on a few dozen bats in a specific forest in south-central Indiana, but the patterns likely hold for other forests in the bats' range.

"I think as long as you maintain a heterogeneous forest that has all these different components—mature forest, thinned forest, some openings—they're probably both going to be happy, at least from the foraging perspective," O'Keefe says.

The article, "Endangered Myotis bats forage in regeneration openings in a managed ," is published in Forest Ecology and Management. Additional co-authors include Stephen Aldrich, Indiana State University; and Scott Haulton, Indiana Department of Natural Resources. The study is part of the 100-year Hardwood Ecosystem Experiment, a partnership of the Indiana Department of Natural Resources, Purdue University, Ball State University, the University of Indianapolis, Indiana State University, and Drake University. Funding for the project was provided by the Indiana Division of Forestry and the U.S. Fish & Wildlife Service and Wildlife Management Institute.

How bats relocate in response to tree loss

More information: Timothy J. Divoll et al, Endangered Myotis bats forage in regeneration openings in a managed forest, Forest Ecology and Management (2021). DOI: 10.1016/j.foreco.2021.119757

Journal information: Forest Ecology and Management 

Provided by University of Illinois at Urbana-Champaign 

Wednesday, August 28, 2024


Metal baseball bats still help Little Leaguers hit a little better

WHO DO YA WANT ME TO HIT BOSS?

Washington State University



PULLMAN, Wash. – While meant to simulate wood bats, regulation USA Baseball metal bats are more forgiving than wood for young players who might not connect with the ball on a bat’s optimal “sweet spot.”

After testing wood bats and two types of metal bats with youth players, Washington State University researchers found that the exit speed of a hit ball was as much as 5% faster with metal bats over wood. Analyzing the data, they found that the performance of the USA Baseball metal bats at the sweet spot was similar to wood. It was when the hits were on less optimal areas that there was a bigger difference.

“There’s more of a penalty when you’re not on the sweet spot with wood bats than with the other metal bats,” said Lloyd Smith, director of WSU’s Sport Science Laboratory and lead author on the study published in The Journal of Sports Engineering and Technology.

Smith’s team has been working with USA Baseball to develop a new wood-like metal bat standard. This study further investigated the performance of the bats designed to meet that standard with lab and field studies—in comparison to wood bats as well as the metal bats previously used in youth baseball, known as BPF 1.15.  

The researchers had 52 players, with an average age of 12, take several swings with each type of bat in a batting cage for a total of more than 1,500 swings. The players, bats and balls all had motion sensors attached to measure speed of the swing as well as the balls’ exit speed.

As expected, baseballs hit with the BPF 1.15 metal bats had higher exit speeds than the wood bats, since these metal bats were discontinued in youth leagues because of their performance advantage. For the USA Baseball standard bats, the exit speeds were closer to that of wood but were still on average higher. The data analysis revealed that the difference was in hits that were outside the highest performance spot on the bat.

Metal bats were adopted in amateur baseball leagues back in the 1970s in part because wood bats break and can be costly over time. Soon players noticed the hollow metal bats conferred an advantage from their “trampoline effect” –an advantage that grew as companies competed to make a better bat. Seeing potential hazards and changes to the game from these metal bats, league officials tried to reign this in starting in the 1990s, ultimately restricting the use of metal bats to those that performed in a similar way to wood.

As this study shows, a small performance advantage remains even with the USA Baseball bat, but it is one that is acceptable to officials. There are also good reasons for leagues and coaches to use them over wood bats, Smith said. Namely, that performance advantage and their lighter weight can mean better batting averages for young players which can help leagues keep kids more excited about the game.

“Wood is still heavy. Part of baseball is hitting the ball far, but the other part is just hitting the ball,” he said. “If you have a heavy bat, you're going to have a harder time making contact because it’s harder to control.”

Notably, despite the bat performance differences in this study, the skill of the hitters was still the biggest factor in how fast the ball came off the bat. Smith emphasized that if players really want to improve their batting average, the best thing to do is not to improve their bat, but themselves.

“If you’re really trying to hit the ball far, you’re going to get a much bigger payoff by working out and getting stronger, especially if you’re a young kid and growing fast. That’s going to have a much larger effect on how hard you hit the ball, then on what bat you buy,” he said.