PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

High-ranking male hyenas have better chances with females because they are less "stressed"

Interacting with other males is more "stressful" for low-ranking than for high-ranking male spotted hyenas

High-ranking male hyenas have better chances with females because they are less
2021-01-19
(Press-News.org) Scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) have found that interacting with other males is more "stressful" for low-ranking than for high-ranking male spotted hyenas. This restricts the time and energy low-ranking males can invest in courting the most desirable females and is therefore a key factor for their lower reproductive success than their high-ranking rivals. This mechanism seems to be more important in determining the number and quality of offspring than physical traits such as attractiveness and fighting ability. These insights were possible owing to a combination of extensive field and lab work - over 20 years of searching and identifying thousands of hyenas in the Ngorongoro Crater in Northern Tanzania, monitoring their behaviour and life histories, and measuring the concentration of glucocorticoid metabolites in more than 400 faeces. The findings are published in the scientific journal Functional Ecology.

In most animal societies, resources are not shared equally among members of a group. Those at the top of the social hierarchy usually have preferential access to food, to resting locations and to the most desirable mating partners. Since evolutionary processes favour those who reproduce most, many animals invest considerable effort in reaching and maintaining a high rank, and intrasexual competition for access to mates is often intense. "We wanted to assess how males of different rank respond to competition, behaviourally and hormonally, and how exactly social rank influences reproductive success in group-living mammals", says Dr Oliver Höner, head of the Leibniz-IZW Ngorongoro Hyena Project. "One prominent hypothesis states that high-ranking males are more successful because they are stronger and/or more attractive thanks to their preferred access to resources. But empirical evidence in support of this hypothesis is limited." Another hypothesis emphasises the social dimension of dominance relationships and posits that the rank-related differences in the physiological costs ("stress") of male-male competition shape the behaviour and, ultimately, the reproductive success of males. "This has not been tested in systems in which the two hypotheses can be disentangled", Höner explains the aim of his team's investigation.

The scientists studied the interplay between male social rank, physiological costs and male investment in social and sexual activities. They used measurements of faecal glucocorticoid metabolite concentrations (fGMC) as biomarkers of "stress" and long-term behavioural data of 319 male hyenas. "When males courted females and interacted with male competitors, low-ranking males had higher fGMC than high-ranking males", lead author Eve Davidian says. "In contrast, fGMC did not vary with social rank when males were alone or when they courted females and rivals were absent." Low-ranking males tended to shy away from stressful competition; they spent more time alone and less time engaging in social and sexual activities than did high-ranking males. They also invested less than high-ranking males in courting the most desirable females. And males who invested little in courting females were rarely picked as sires. But why are low-ranking males more "stressed" by interactions with rivals? Eve Davidian assumes that the reason is related to the fact that these males are newcomers in the group. "These males lack friends they can rely on and hang out with and they also have no scapegoats they can redirect aggression onto, a behaviour that spotted hyenas often show and that is likely to help them release frustration and cope with stress."

This scientific investigation demonstrates that intrasexual competition can elicit rank-related differences in "stress", behaviour and reproductive success even in a species such as the spotted hyena in which dominance relationships are established based on nonviolent social conventions. In species in which males fight for dominance, the costs of competition may be even more prohibitive for low-ranking males. This may explain why in many of these species, low-ranking males do not court females or adopt "sneaky" tactics that minimise competition with rivals, such as approaching females when the high ranking males are busy elsewhere.

INFORMATION:


[Attachments] See images for this press release:
High-ranking male hyenas have better chances with females because they are less

ELSE PRESS RELEASES FROM THIS DATE:

Strong M-M' Pauli repulsion leads to repulsive metallophilicity

Strong M-M Pauli repulsion leads to repulsive metallophilicity
2021-01-19
A research team led by Professor Chi-Ming CHE and Dr Jun YANG, from the Research Division for Chemistry and Department of Chemistry at the Faculty of Science of the University of Hong Kong, has resolved a long-standing fundamental problem in the field of metal-metal closed-shell interaction. This work has been published in the journal Proceedings of the National Academy of Sciences (PNAS). Metal-Metal closed-shell interaction, also known as metallophilicity, has a huge impact in diverse fields of chemistry, such as supramolecular chemistry and organometallic chemistry. Early reports on metallophilicity could be traced back to the 1970s. Many leading theoretical chemists ...

COVID-19 has multiple faces

2021-01-19
According to current studies, the COVID-19 disease which is caused by the SARS-CoV-2 coronavirus comprises at least five different variants. These differ in how the immune system responds to the infection. Researchers from the German Center for Neurodegenerative Diseases (DZNE) and the University of Bonn, together with other experts from Germany, Greece and the Netherlands, present these findings in the scientific journal "Genome Medicine". Their results may help to improve the treatment of the disease. Infection with SARS-CoV-2 can manifest in different ways: Many of those affected do not even seem to notice the presence of the virus in their bodies. In other ...

Carbon pricing's disappointing effect on the pace of technological change

2021-01-19
In order to achieve the goals of the Paris Agreement, the world must reach net-zero carbon emissions by 2050. Carbon pricing is viewed by many governments and experts as the most important climate policy instrument. However, a new study shows that carbon pricing has been less effective as a driver of technological change than was previously anticipated. While the introduction of carbon pricing systems has led to emissions reductions in some countries, they have not significantly stimulated technological change. Bringing about the necessary transformation will require sector-specific promotion of climate-friendly technologies, for example ...

Scientists produce the first in-vitro embryos from vitrified African lion oocytes

Scientists produce the first in-vitro embryos from vitrified African lion oocytes
2021-01-19
For this specific method of cryopreservation, oocytes are collected directly after an animal is castrated or deceased and immediately frozen at -196°C in liquid nitrogen. This technique allows the storage of oocytes of valuable animals for an unlimited time, so that they can be used to produce offspring with the help of assisted reproduction techniques. The aim is to further improve and apply these methods to save highly endangered species such as the Asiatic lion from extinction. The current research on African lions as a model species is an important step in this direction. The results are reported in the scientific journal Cryobiology. Lion oocytes are presumed to be very sensitive to chilling due to their high lipid content, resulting ...

Researchers develop sustainable catalysis process

Researchers develop sustainable catalysis process
2021-01-19
Acetals are important chemical compounds that are used, for example, in the production of certain medical agents. A new method now makes their synthesis easier and more environmentally friendly. Chemists at the University of Bonn have developed and optimized the sustainable catalytic process. State-of-the-art computer simulations were also used. The reaction is based on a mechanism that frequently occurs in nature, but has rarely been used in chemical synthesis up to now. The results are published in the journal Angewandte Chemie. The key step in the production of acetals is the bonding of two oxygen ...

Why remdesivir does not fully stop the coronavirus

Why remdesivir does not fully stop the coronavirus
2021-01-19
Remdesivir is the first drug against Covid-19 to be conditionally approved in Europe and the United States. The drug is designed to suppress the rapid replication of the SARS-CoV-2 virus in human cells by blocking the viral copying machine, called RNA polymerase. Researchers at the Max Planck Institute (MPI) for Biophysical Chemistry in Göttingen and the University of Würzburg have now elucidated how remdesivir interferes with the viral polymerase during copying and why it does not inhibit it completely. "After complicated studies, we come to a simple conclusion," Max Planck Director Patrick ...

Scientists streamline process for controlling spin dynamics

Scientists streamline process for controlling spin dynamics
2021-01-19
UPTON, NY--Marking a major achievement in the field of spintronics, researchers at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and Yale University have demonstrated the ability to control spin dynamics in magnetic materials by altering their thickness. The study, published today in Nature Materials, could lead to smaller, more energy-efficient electronic devices. "Instead of searching for different materials that share the right frequencies, we can now alter the thickness of a single material--iron, in this case--to find a magnetic medium that will enable the transfer of information across a device," said Brookhaven physicist and principal investigator Valentina ...

Researchers discover potential new therapy for chemotherapy-resistant breast cancer

2021-01-19
Scientists have discovered a molecule that can selectively kill cells of a hard-to-treat subtype of breast cancer, which could lead to a new therapy. The study, led by researchers at RCSI University of Medicine and Health Sciences, is published in the current edition of Science Advances. Triple negative breast cancer is a subtype of breast cancer which is mainly treated with chemotherapy. Unfortunately, up to 70% of patients with this form of breast cancer develop resistance to treatment. The researchers tested different molecules to see if they could selectively kill the cells of this type of breast cancer while sparing normal ...

As the American hemp industry grows, so does our understanding of hemp diseases

As the American hemp industry grows, so does our understanding of hemp diseases
2021-01-19
As hemp begins to reemerge as an important crop in the United States, scientists are beginning research into the diseases that might prevent the crop from flourishing. A study published in the December issue of Plant Health Progress is one of the first to study the potential disease and disorder limitations for hemp production in the southeastern United States. Lindsey Thiessen, a plant pathologist at North Carolina State University, worked with colleagues to evaluate hemp samples from North Carolina and observed 16 different diseases. They found Fusarium flower blight most consistently followed by Helminthosporium ...

UN disaster aid is driven by humanitarian need rather than by strategic donor interests

UN disaster aid is driven by humanitarian need rather than by strategic donor interests
2021-01-19
A new study published in PNAS finds that aid provided by the United Nations (UN) in the aftermath of climate-related disasters is driven by humanitarian need rather than by strategic donor interests. The results underline the importance of climate-related hazards for understanding aid disbursements. The study 'Humanitarian need drives multilateral disaster aid' provides the first estimation of UN climate-related disaster aid worldwide. Although it cannot be entirely ruled out that powerful donor states' interests shape UN aid flows, the UN seems able to fend off donor states' strategic ...

LAST 30 PRESS RELEASES:

Corpse flowers are threatened by spotty recordkeeping

Riding the AI wave toward rapid, precise ocean simulations

Are lifetimes of big appliances really shrinking?

Pink skies

Monkeys are world’s best yodellers - new research

Key differences between visual- and memory-led Alzheimer’s discovered

% weight loss targets in obesity management – is this the wrong objective?

An app can change how you see yourself at work

NYC speed cameras take six months to change driver behavior, effects vary by neighborhood, new study reveals

New research shows that propaganda is on the rise in China

Even the richest Americans face shorter lifespans than their European counterparts, study finds

Novel genes linked to rare childhood diarrhea

New computer model reveals how Bronze Age Scandinavians could have crossed the sea

Novel point-of-care technology delivers accurate HIV results in minutes

Researchers reveal key brain differences to explain why Ritalin helps improve focus in some more than others

Study finds nearly five-fold increase in hospitalizations for common cause of stroke

Study reveals how alcohol abuse damages cognition

Medicinal cannabis is linked to long-term benefits in health-related quality of life

Microplastics detected in cat placentas and fetuses during early pregnancy

Ancient amphibians as big as alligators died in mass mortality event in Triassic Wyoming

Scientists uncover the first clear evidence of air sacs in the fossilized bones of alvarezsaurian dinosaurs: the "hollow bones" which help modern day birds to fly

Alcohol makes male flies sexy

TB patients globally often incur "catastrophic costs" of up to $11,329 USD, despite many countries offering free treatment, with predominant drivers of cost being hospitalization and loss of income

Study links teen girls’ screen time to sleep disruptions and depression

Scientists unveil starfish-inspired wearable tech for heart monitoring

Footprints reveal prehistoric Scottish lagoons were stomping grounds for giant Jurassic dinosaurs

AI effectively predicts dementia risk in American Indian/Alaska Native elders

First guideline on newborn screening for cystic fibrosis calls for changes in practice to improve outcomes

Existing international law can help secure peace and security in outer space, study shows

Pinning down the process of West Nile virus transmission

[Press-News.org] High-ranking male hyenas have better chances with females because they are less "stressed"
Interacting with other males is more "stressful" for low-ranking than for high-ranking male spotted hyenas