Older male crickets attract more females—but have less sex

MAY 24, 2019

by University of Exeter

Older male crickets are better at getting females to live with them—but they mate less than younger rivals once they find a partner.

Meanwhile younger males have a harder time enticing females back to their burrows—but more mating happens if they succeed.

University of Exeter scientists studied field crickets to see if a male's age affected how attractive females found them.

"Females choose mates to get the best genes for their offspring," said Dr. Rolando Rodríguez-Muñoz of the Centre for Ecology and Conservation on the University of Exeter's Penryn Campus in Cornwall.

"It's possible that the oldest males have the best genes because they've shown they can live for a long time.¬

"On the other hand, females might favour younger males whose sperm have not accumulated possibly harmful mutations that will be passed on to offspring.

Continued

Venom becomes more potent as brown snakes age

Date: May 16, 2017

Source: University of Queensland

The "blood nuking" capabilities of adult brown snake venom only come about after an amazing transformation.

New research led by University of Queensland scientist Associate Professor Bryan Fry has shown the venom of young brown snakes attacks the nervous system, while the venom of older snakes has dangerous effects on the circulatory system.

"This is because young brown snakes specialise in lizards, then specialise in mammals as adults," Dr Fry said.

"Young brown snakes may produce clinical symptoms like that of a death adder, as they seek out and paralyse sleeping lizards.

"Once older, their venom contains toxins that cause devastating interference with blood clotting, causing rodent prey to become immobilised by stroke.

"Although the venom is diluted in the much larger blood volume of a human and do not cause stroke, bite victims can still die from internal bleeding."

Dr Fry, of the UQ School of Biological Sciences' Venom Evolution Laboratory said brown snakes were highly venomous and were found in mainland Australia, with the eastern brown snakes also found in New Guinea.

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Spread of ages is key to impact of disease, animal study finds - via Herp Digest

Date: March 24, 2017

Source: University of Edinburgh

How a disease outbreak affects a group of animals depends on the breakdown of ages in the population, research has shown.

The findings could help scientists better understand how events such as disease outbreaks may affect certain groups in a population.

Scientists sought to examine how a spread of ages can influence a population's health, by simulating an outbreak of disease in small marine animals.

With lab experiments and computer modelling, they found that disease spread can vary depending on the age at which individuals are exposed to infection, and the age at which females in the group become mothers.

Experiments in the latest study found that offspring of younger mothers were more at risk from infection. The finding builds upon previous knowledge that younger individuals are more at risk.

Taking these factors into account, computer models showed that when death rates are high, disease can spread faster -- even as populations fall. This contradicts the expectation that disease should spread most easily in dense populations, in which individuals interact more.

Researchers from the University of Edinburgh carried out lab experiments with water fleas, examining how four generations of the small crustaceans responded to a common bacterial infection. Their results were used to build a mathematical model of how the organisms might respond in the long term to threats such as incidence of disease.

Their study, published in Ecology Letters, was funded by the Natural Environment Research Council and the Wellcome Trust.

Jess Clark, of the University of Edinburgh's School of Biological Sciences, who led the study, said: "Many societies around the world are experiencing aging populations, and investigating the impact of this might lend valuable insight into how such populations might respond to an outbreak of disease."

Story Source:

Materials provided by University of Edinburgh. Note: Content may be edited for style and length.

/story_source

Journal Reference:

1 Jessica Clark, Jennie S. Garbutt, Luke McNally, Tom J. Little. Disease spread in age structured populations with maternal age effects. Ecology Letters, 2017; 20 (4): 445 DOI: 10.1111/ele.12745

Elephant age estimated from voice: A powerful conservation tool?

Date:

March 6, 2014

Source:

Taylor & Francis

Summary:

Researchers have been able to estimate the age of an elephant based on its vocal sounds. Results showed that they could distinguish infants, calves, juveniles, and adults with 70 percent accuracy and youngsters (infants/calves) from adults with 95 percent accuracy. The call feature that was most useful for doing this was overall frequency -- not surprisingly, since vocal frequency usually decreases as an animal grows larger.

Continued

Favorite Tastes Change with Age, Rat Study Shows

Tastes change with age, at least in rats, new research suggests.

Younger rats prefer more sugar and umami flavor in foods and showed a stronger aversion to bitter foods compared with elderly rats, according to a study presented today (July 30) at the annual meeting of the Society for the Study of Ingestive Behavior.

"To our knowledge, this is the first report demonstrating a reduced aversion to bitter taste in aged rats," study co-author Chizuko Inui-Yamamoto, a researcher at Osaka University in Japan, said in a statement.

Continued

Aging Male Giraffes Go Black, Not Gray

Male giraffes become more illustrious with age, but rather than the silvery locks that distinguish the likes of Sean Connery and George Clooney, the hairy blotches on these long-necked mammals darken with age.

And new research suggests the appearance change takes about 1.8 years to complete, with male giraffes being completely covered in coal-black blotches by an average age of 9.4 years.

"What is fascinating about the color change is that it goes from light to dark," study researcher Fred Bercovitch, of the Primate Research Institute & Wildlife Research Center, Kyoto University, told LiveScience. "In gorillas who turn silverback, and in men, the color gets lighter, not darker with age." 

Continued:  http://www.livescience.com/19686-aging-male-giraffes-black-spots.html