Keeping to a beat is linked to reproductive success in male Rock Hyraxes

Peer-Reviewed Publication

BRITISH ECOLOGICAL SOCIETY

 

IMAGE: A MALE ROCK HYRAX IN THE EIN GEDI NATURAL RESERVE SINGING. view more 

CREDIT: AMIYAAL ILANY

A behavioural study published in the British Ecological Society’s Journal of Animal Ecology has linked reproductive success in male rock hyraxes to their ability to maintain rhythm during courtship songs.

You only need to take a look at the adoring fans of famous musicians to realize being rhythmically skilled is a desirable trait. In male rock hyraxes, singing frequency and rhythm could be seen as indicators of individual quality by potential mates – signalling information about their health and suitability as a partner.

“We have been studying hyraxes for the past 20 years and have previously found several patterns in their songs that are common features of human language and music,” said Dr Vlad Demartsev, now a postdoctoral researcher in the Department of Biology at the University of Konstanz and the Max Planck Institute of Animal Behaviour, who collected the data for this study during their time at Tel Aviv University.

“Their songs have regional dialects so individuals living in proximity sing more similarly to each other. They tend to sing in crescendo (getting louder as the song progresses) and reach peak complexity towards the end of their songs, maybe to keep the audience engaged and listening to the signals.”

Rhythm plays a crucial role in the communication of some animals. “One assumption is that rhythm has evolved so that animals that call in groups can better synchronize their songs – like musicians in a band or singers in a choir," explains Dr Vlad Demartsev.

However, unlike many other animals known to communicate through song, hyraxes usually sing alone.

To investigate the role of rhythm in mammalian courtship songs scientists observed the daily morning activity of hyrax communities between 2002 and 2013 in Ein Gedi Natural Reserve, eastern Israel. The researchers captured information about the hyrax's location, behaviours, and vocalizations while recording the identities of their nearest neighbours. Genetic information for each hyrax was then analysed alongside audio recordings back at the lab.

Publishing their findings in the British Ecological Society Journal of Animal Ecology, the researchers showed that, while singing, hyrax males keep a stable isochronous rhythm, with sounds occurring at regular intervals.

Dr Lee Koren, who co-founded the hyrax study with Dr Eli Geffen, and is now a researcher at the Faculty of Life Sciences at Bar-Ilan University said: “Male hyraxes that sing more frequently tend to have more surviving offspring. Song rhythms and stability are related to reproductive success and thus potentially hold information about individual quality.”

Since certain physiological ailments may have a negative effect on the ability of hyraxes to produce precise, rhythmic calls, the researchers suggest male hyrax courtship song rhythm could be an indicator of health and suitability as mates to prospective female partners.

Speaking of the future for this field of research, Dr Vlad Demartsev added: “It would be fascinating to compare animal species who sing individually and species that sing in groups.”

Rhythm has now been shown to act as an advertisement for individual quality in some species, while in others it helps in coordinating signals from different individuals within a group. However, it's not yet known if different rhythmic patterns are used for these two different functions.

CAPTION

A male rock hyrax in the Ein Gedi Natural Reserve singing.

CREDIT

Eran Gissis

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The vocalisations of a male rock hyrax in the Ein Gedi Natural Reserve.

CREDIT

Lee Koren

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The vocalisations of a male rock hyrax in the Ein Gedi Natural Reserve.

CREDIT

Lee Koren

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JOURNAL

Journal of Animal Ecology

DOI

10.1111/1365-2656.1380 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Male rock hyraxes that maintain an isochronous song rhythm achieve higher reproductive success

ARTICLE PUBLICATION DATE

13-Sep-2022

Keep the beat!

Peer-Reviewed Publication

UNIVERSITY OF KONSTANZ

Rhythmic accuracy pays off, as researchers from Konstanz (Germany) and Israel show in their behavioural study on the courtship song of the rock hyrax. Males that sang more often and kept the beat with greater precision had higher reproductive success than their less rhythmically accurate peers.

When it comes to courtship songs in the animal kingdom, most people probably think of songbirds greeting the dawn – to the delight of some and the annoyance of others. But there are also species of mammals in which the males try to charm females by singing. One of them is the rock hyrax (Procavia capensis), a land-living mammal common to the western part of the Near East and to Africa.

In a recent study published in the Journal of Animal Ecology, researchers from the University of Konstanz (Germany), Tel Aviv University (Israel), and Bar Ilan University (Israel), have now taken a closer look at the song of the rock hyrax. They observed the animals in the Ein Gedi Natural Reserve in eastern Israel and recorded their songs, which they later analyzed in the laboratory together with genetic samples from individual males. The researchers focused on the question of whether there is a link between the rhythmic characteristics of the song and the reproductive success of the animals.

Rhythm as a sign of good health
It has been known for quite some time that rhythm plays a role not only in our music but also in the communication of some animals. "One assumption is that rhythm has evolved so that animals that call in groups can better synchronize their songs – like musicians in a band or singers in a choir", says Dr Vlad Demartsev, first author of the study and currently a postdoctoral researcher in the Department of Biology at the University of Konstanz.

From an evolutionary perspective, however, rhythm could also serve the function of signalling the health condition and thus the suitability of the male as a sexual partner to the females. "The reasoning here is that certain physical or physiological limitations inevitably have a negative effect on the ability to produce precise, rhythmic calls", Demartsev explains a second common hypothesis about the evolution of rhythm in animal songs.

In the current study, the researchers were able to show, by combining acoustic analyses and long-term genetic assessment of relatedness, that males with a high proportion of rhythmically precise elements in their courtship song produced more offspring than those with a lower proportion. In addition, males that sang more frequently than their peers had a slightly higher reproductive success.

Since rock hyraxes usually sing alone and not in a choir, it is likely that the aspect of song synchronization did not play a decisive role in the evolution of their rhythmic courtship songs. "The fact that rhythmically stable males produce more offspring rather supports the assumption that high rhythmic stability serves as an indicator of male quality for females and, thus, is particularly attractive to them", Demartsev says.

 

Key facts: Original publication: Vlad Demartsev, Michal Haddas-Sasson, Amiyaal Ilany, Lee Koren, Eli Geffen (2022) Male rock hyraxes that maintain an isochronous song rhythm achieve higher reproductive success. Journal of Animal Ecology. DOI: 10.1111/1365-2656.1380 Dr Vlad Demartsev is a postdoctoral researcher in the Department of Biology at the University of Konstanz and a Humboldt Research Fellow. The published data were collected during his time at Tel Aviv University (Israel). Funding: Israel Science Foundation, U.S.-Israel Binational Science Foundation, Alexander von Humboldt Foundation.

 

Note to editors:

You can download photos here:

Link: https://www.uni-konstanz.de/fileadmin/pi/fileserver/2022/immer_schoen_c_eran_gissis_2.png
Caption: Male rock hyrax singing
Copyright: Eran Gissis

Link: https://www.uni-konstanz.de/fileadmin/pi/fileserver/2022/immer_schoen_c_eran_gissis.png
Caption: Male rock hyrax singing
Copyright: Amiyaal Ilany

 

A sound file and a video can be found at:

Link: https://soundcloud.com/amiyaal-ilany/rock-hyrax-song
Copyright: Amiyaal Ilany

Link: https://youtu.be/_6uJ53guwMo
Copyright: Eyal Bartov

 

Contact:
University of Konstanz
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Phone: + 49 7531 88-3603
Email: kum@uni-konstanz.de

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JOURNAL

Journal of Animal Ecology

DOI

10.1111/1365-2656.1380 

ARTICLE TITLE

Male rock hyraxes that maintain an isochronous song rhythm achieve higher reproductive success.

ARTICLE PUBLICATION DATE

13-Sep-2022

Current vaccine approach not enough to eradicate measles

New study models the feasibility of eliminating measles and rubella

Peer-Reviewed Publication

UNIVERSITY OF GEORGIA

Current vaccination strategies are unlikely to eliminate measles, according to a new study led by faculty at the University of Georgia. 

The paper, which published today in The Lancet Global Health, explores the feasibility of eliminating measles and rubella using predominant vaccination strategies in 93 countries with the highest disease burden.

Despite marked reductions in the number of new measles and rubella cases worldwide, gaps remain between current levels of transmission and disease elimination. 

“Measles is one of the most contagious respiratory infections out there, and it moves quickly, so it’s hard to control,” said lead author Amy Winter, an assistant professor of epidemiology and biostatistics at UGA’s College of Public Health. 

The basic reproduction number (R0) for measles, which represents the number of people that one infected person is likely to transmit that disease to in a fully susceptible population, is roughly 18. By comparison the R0 for the original SARS-CoV-2 virus is estimated to be around three.

In 2017, the World Health Organization director general requested a report on the feasibility of measles and rubella eradication. One component of this report was to use transmission models to evaluate the theoretical feasibility of eradication of the two viruses given different vaccination strategies.

The assessment was a collaboration with the WHO Strategic Advisory Group of Experts Measles and Rubella Working Group, the World Health Organization, the U.S. Centers for Disease Control and Prevention, and five modeling groups.

Using four national disease transmission models and one sub-national model, the modeling groups projected the annual case rates for measles and rubella for two vaccination scenarios.

Both vaccination scenarios use the two predominant vaccination approaches of routine vaccination as part of childhood immunization schedules and nationwide vaccination campaigns.

The first “business as usual” vaccination scenario continues vaccination coverage and campaigns into the future. The second “intensified investment” vaccination scenario optimally improved vaccination coverage over time. This scenario also included vaccination campaign cessation criteria – a stopping point for when campaigns are no longer deemed necessary because a large enough proportion of the population has been inoculated.

The models show that current vaccine strategies could eliminate rubella and congenital rubella syndrome in all 93 counties, but not measles. 

“The current strategy that we use, which is focused on improving routine vaccination coverage and supplementing it with nationwide vaccination campaigns until routine vaccination is high enough, that alone is not going to be sufficient to reach measles elimination. We need novel approaches,” said Winter. 

The authors evaluated two strategies that could help move a country to elimination faster and reduce the probability of measles outbreaks: One, improve how supplemental vaccine campaigns are delivered to ensure they are reaching children who are not receiving routine vaccinations.

Two, improve vaccine coverage equity by focusing routine and supplemental vaccination on sub-regions with the lowest vaccination coverage first to get them up to par.

“A world that is permanently free of measles and rubella would be an incredible achievement for humanity. Our work suggests that to reach this goal, we need to make vaccine coverage much more equal,” said co-author Mark Jit, professor of vaccine epidemiology at the London School of Hygiene & Tropical Medicine.

“In other words, we need to work even harder to bring measles and rubella vaccination to the most underserved people around the world.”

The final strategy the authors present is a reconsideration of cessation criteria. Currently, most countries stop supplementing routine vaccines with vaccination campaigns once they reach elimination status, said Winter, but the models suggest that outbreaks are still likely to occur if countries rely on routine vaccines alone.

It’s critical, Winter warns, to remain vigilant to surveil for rubella and measles cases and rapidly respond to potential outbreaks even after elimination is achieved.

“We have a globally connected world, so there’s this constant pressure of importations of the viruses in places where it’s already eliminated,” she said. “That’s why keeping vaccination coverage high and continuing to improve surveillance for these diseases is important.”

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JOURNAL

The Lancet Global Health

ARTICLE TITLE

Feasibility of measles and rubella vaccination programmes for disease elimination: a modelling study

ARTICLE PUBLICATION DATE

13-Sep-2022

This fungus shrinks in size to better infect the brain

Finding could spur new strategies to prevent the leading cause of fungal meningitis

Peer-Reviewed Publication

UNIVERSITY OF UTAH HEALTH

 

IMAGE: THE INFECTIOUS FUNGUS CRYPTOCOCCUS NEOFORMANS RAPIDLY ENLARGES AND SHRINKS IN SIZE TO WITHSTAND DIFFERENT MICROENVIRONMENTS IN THE BODY. view more 

CREDIT: STEVEN DENHAM

(Salt Lake City) - A fungus that is a common cause of fungal meningitis undergoes a remarkable transformation once it enters the body, allowing it to infect the brain, according to new research by scientists at University of Utah Health. Studies in mice show that as the fungal intruder travels through the body, it shrinks and acquires characteristics that help infection to spread, all in a matter of days.

The discovery could lead to new strategies for blocking Cryptococcus neoformans infection and preventing detrimental effects on the host. C. neoformans is the leading cause of a rare but deadly swelling of the brain that occurs in people with weakened immune systems.

“Cryptococcus cells in the lungs are very diverse with different sizes and different appearances. So, when my graduate student showed me pictures of the uniformity of cells from the brain, I was shocked,” says Jessica Brown, Ph.D., associate professor of pathology at U of U Health and the study’s senior author. “It suggested that there was some very strong reason why only this population of cells were making it that far into the body.” Her former graduate student, Steven Denham, PhD, is leading author on the study. Their research recently published online in the peer-reviewed journal Cell Host & Microbe.

The fungus adapts rapidly to withstand microenvironments in the body

Brown’s fascination with the fungus came from the observation that it thrives in so many different habitats. In the wild, the organism lives in rotting wood and bird droppings. If it is inadvertently inhaled, the fungus can survive in the lungs and then travel in the bloodstream to the brain and other organs, each of which has its own challenging micro-environment.

Previously, other scientists found that the fungus copes with living in the lungs by growing to 10 times its normal size, presumably becoming too large for the host immune system to destroy. But in other parts of the body, fungal cells are much smaller. Brown wondered, could the cells’ extra-small size be another type of advantage? Perhaps that characteristic helps them colonize other organs, such as the brain.

To find out, her team infected mice with various sizes of C. neoformans. They found that in comparison to medium and large cells, the smallest cells preferentially infected the brain. These cells were not only diminutive but differed in other ways. Compared to larger fungal cells, they had unique features on their surface that were similarly important for accessing the brain. They also turned on a different set of genes.

This evidence suggested that the small fungal cells, that Brown dubbed “seed” cells, were not just miniature versions of larger cells. They had undergone a wholesale change.

After searching for triggers, Brown’s group found that a specific chemical—phosphate—could induce the shift. Knowing that phosphate is released when tissue is damaged during infection, Brown speculates that the chemical accumulates in the lungs, the first site where fungi settle after entering the body. This allows the fungal cells to reconfigure themselves as seed cells, which enables the infection to spread further.

From bird guano to the brain

Oddly enough, the fungi’s ability to effectively target the brain may have originated from a unique source: bird guano. C. neoformans thrive in pigeon droppings, which have high levels of the seed cell-triggering molecule, phosphate. Brown’s team found that the gooey stuff nudges C. neoformans into that alternate state like nothing else they had tried.  

Brown thinks this could demonstrate how the fungus’ pathogenicity arose in the first place. “We think that selective pressures from environmental niches like pigeon guano are somehow able to confer to C. neoformans the ability to infect mammals,” she says.

Regardless of how the fungus’ infectious property arose, Brown’s team is now trying to block that ability with FDA-approved drugs. They are determining whether there may be an existing compound that blocks C. neoformans from becoming seed cells that could provide a ready-to-go remedy for preventing or treating fungal meningitis.

# # #

In addition to Brown, co-authors are Steven T. Denham, Brianna Brammer, Krystal Y. Chung, Morgan A. Wambaugh, Joseph M. Bednarek, Li Guo, and Christian T. Moreau from U of U Health.

The research published as, “A dissemination-prone morphotype enhances extrapulmonary organ entry by the fungus Cryptococcus neoformans” with support from the National Institutes of Health.

About University of Utah Health

University of Utah Health  provides leading-edge and compassionate care for a referral area that encompasses Idaho, Wyoming, Montana, and much of Nevada. A hub for health sciences research and education in the region, U of U Health has a $428 million research enterprise and trains the majority of Utah’s physicians and health care providers at its Colleges of Health, Nursing, and Pharmacy and Schools of Dentistry and Medicine. With more than 20,000 employees, the system includes 12 community clinics and five hospitals. U of U Health is recognized nationally as a transformative health care system and provider of world-class care.

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JOURNAL

Cell Host & Microbe

DOI

10.1016/j.chom.2022.08.017 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

A dissemination-prone morphotype enhances extrapulmonary organ entry by the fungus Cryptococcus neoformans

ARTICLE PUBLICATION DATE

12-Sep-2022

Beyond sound: Bimodal acoustic calls used in mate-choice and aggression by red-eyed treefrogs

Peer-Reviewed Publication

GETTYSBURG COLLEGE

 

VIDEO: A MALE RED-EYED TREEFROG RESPONDS TO SOUND AND VIBRATIONS OF A RIVAL MALE'S CALL BY PRODUCING AGGRESSIVE VIBRATIONAL SIGNALS. view more 

CREDIT: DR. MICHAEL CALDWELL

One would be hard-pressed to take a walk outside without hearing the sounds of calling animals. During the day, birds chatter back and forth, and as night falls, frogs and insects call to defend territories and to attract potential mates. For several decades, biologists have studied these calls with great interest, taking away major lessons about the evolution of animal displays and the processes of speciation. But there may be a lot more to animal calls than we have realized.

A new study appearing in the Journal of Experimental Biology by Dr. Michael Caldwell and student researchers at Gettysburg College demonstrates that the calls of red-eyed treefrogs don’t just send sounds through the air, but also send vibrations through the plants. What’s more, these plant vibrations change the message that other frogs receive in major ways. The researchers played sound and vibrations produced by calling males to other red-eyed treefrogs surrounding a rainforest pond in Panama. They found that female frogs are over twice as likely to choose the calls of a potential mate if those calls include both sound and vibrations, and male frogs are far more aggressive and show a greater range of aggressive displays when they can feel the vibrations generated by the calls of their rivals.

“This really changes how we look at things,” says Caldwell. “If we want to know how a call functions, we can’t just look at the sound it makes anymore. We need to at least consider the roles that its associated vibrations play in getting the message across.”

Because vibrations are unavoidably excited in any surface a calling animal is touching, the authors of the new study suggest it is likely that many more species communicate using similar ‘bimodal acoustic calls’ that function simultaneously through both airborne sound and plant-, ground-, or water-borne vibrations. “There is zero reason to suspect that bimodal acoustic calls are limited to red-eyed treefrogs. In fact, we know they aren’t,” says Caldwell, who points out that researchers at UCLA and the University of Texas are reporting similar results with distantly related frog species, and that elephants and several species of insect have been shown to communicate this way. “For decades,” says Caldwell, “..we just didn’t know what to look for, but with a growing scientific interest in vibrational communication, all of that is rapidly changing.”

This new focus on animal calls as functioning through both sound and vibration could set the stage for major advances in the study of signal evolution. One potential implication highlighted by the team at Gettysburg College is that “we may even learn new things about sound signals we thought we understood.” This is because both the sound and the vibrational components of bimodal acoustic signals are generated together by the same organs. So, selection acting either call component will also necessarily shape the evolution of the other. 

The red-eyed treefrog is one of the most photographed species on the planet, which makes these findings all the more unexpected. “It just goes to show, we still have a lot to learn about animal behavior,” reports Dr. Caldwell. “We hear animal calls so often that we tune most of them out, but when we make a point to look at the world from the perspective of a frog, species that are far more sensitive to vibrations than humans, it quickly becomes clear that we have been overlooking a major part of what they are saying to one another.”

This research was performed at the Smithsonian Tropical Research Institute and Gettysburg College, with funding from the Smithsonian Institution and the Cross-disciplinary Science Institute at Gettysburg College.

Female choice trial (VIDEO)

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JOURNAL

Journal of Experimental Biology

DOI

10.1242/jeb.244460 

ARTICLE TITLE

Beyond sound: bimodal acoustic calls used in mate-choice and aggression by red-eyed treefrogs