Frogs breed young to beat virus

-

Frogs from groups exposed to a deadly virus are breeding at younger ages, new research suggests.

Scientists studying European common frogs in the UK compared groups ("populations") exposed to ranavirus and those free from the disease.

While the youngest breeding frogs in disease-free populations are four years old, frogs in virus-exposed groups breed as young as two.

The reasons for this are not yet clear, but the team - led by researchers from the University of Exeter and the Zoological Society of London - warn that this decrease in breeding age means disease-exposed populations are at greater risk of local extinction sparked by environmental changes.

Frogs gather at breeding spots such as ponds and then disperse, but most return to the same ponds year after year.

"Our research shows that the ages of the frogs that return to breed varies between populations which are known to have ranavirus and those which don't," said Dr Lewis Campbell, who conducted the research during his PhD at the University of Exeter's Penryn Campus in Cornwall.

"We found significantly fewer old frogs and significantly more young frogs at populations which have ranavirus.

"It's possible that the more times an older frog returns to the same infected breeding pond, the more likely they are to become diseased and die.

"The absence of older frogs may then create an opportunity for younger - and therefore smaller and less competitive - frogs to successfully breed.

"With high mortality among older frogs, it's also possible that natural selection pressure has favoured those that are genetically disposed to breed younger."

Ranavirus, first recorded in the UK in the 1980s, can cause severe skin sores and internal bleeding. It is usually fatal.

In the new study, which incorporated data collected by citizen scientists, breeding frogs in disease-free populations were most commonly six to eight years old, while in populations where ranavirus was present they were mostly three to six years old.

Commenting on the differences between the two kinds of frog population, Dr Campbell, now of the University of Wisconsin-Madison, said: "Our models suggest both infected and uninfected populations can continue to thrive in normal conditions.

"But disease-exposed populations appear to depend heavily on younger breeders that don't produce as many offspring as older, larger frogs.

"For these populations, an environmental change such as a late frost - that would kill frogspawn and further lower the number of offspring produced - could cause that population to collapse (known as a local extinction)."

He added: "We live in times of increasing environmental change, so understanding how wildlife diseases change the ability of their hosts to cope with such uncertainty is increasingly critical."

Dr Xavier Harrison, of the Zoological Society of London, said: "We often think of the negative consequences of wildlife disease as being the death of infected individuals in the short term.

"But this study shows that even when a population seems to have survived a disease outbreak and appears otherwise healthy, there are still lingering consequences of that disease months or years afterwards.

"If we really want to understand the full impact of wildlife diseases in nature we need to monitor disease-challenged populations over much longer timescales."

Ranavirus is believed to be spreading in the UK, and human activity such as movement of animals and soils is thought to be the major cause of this.

Amphibians are the most threatened group of vertebrates globally, and emerging infectious diseases play a large role in their continued population declines.

###

The paper, published in the journal PeerJ, is entitled: "An emerging viral pathogen truncates population age structure in a European amphibian and may reduce population viability."

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.



https://ift.tt/2KeNo4K

Comments

Post a Comment

Popular posts from this blog

All In The Family: Maine Mother & Son Charged in Massive Drug Bust

-
Image
corso dog :: Article Creator Woman Hospitalized After Attack By 2 Dogs At Same Edmonton Home Where Boy Died: Lawyer UPDATE: On April 15, 2024, the City of Edmonton provided an update on the fatal attack. It said that prior to the deadly incident on April 1, "the city had no lawful basis to remove the dogs from the home." The city added that "all prior complaints about the dogs involved in this incident were investigated thoroughly and appropriate action was taken in accordance with the applicable legislation." The city also said a review found that its staff "acted appropriately in accordance with our standard practices and in compliance with the relevant legal constraints given the nature of past complaints and reports." A woman was hospitalized after being attacked in February by two large Cane Corso dogs at the same home where an 11-year-old boy was killed last week, the woman's lawyer told Global News. "I...
Read more

Rare Frogs And Illegal Drugs - Palisades Hudson Financial Group

-
Image
Colombian conservationist Ivan Lozano has hit on a brilliantly promising strategy to protect his country’s rare and endangered amphibians. His plan: Flood the market with them. Lozano is not hunting rare frogs in Colombia’s Andean forests. He is raising them himself and selling them at prices designed to undercut poachers and smugglers. If he can raise the frogs cheaply enough, and in large enough numbers, he might manage to drive down the market price to the point that poachers no longer find it worthwhile to harvest and smuggle the creatures onto the black markets. Lozano told The Associated Press that his company also encourages collectors to breed their own frogs. Picture yourself as a poacher. If the government toughens the legal penalties and steps up enforcement, you will shrug your shoulders; legal risks are a basic cost of doing business. Since the demand for your product already exists among foreign collectors and other buyers, tougher enforcement merely reduces supply a...
Read more

Burn scars, winter storms threaten rare and endangered species in San Gabriel Mountains - The Bakersfield Californian

-
Image
LOS ANGELES — Up until a few weeks ago, the West Fork of the San Gabriel River was one of the most abundant wildlife habitats in Los Angeles County, a secluded and rugged area defined by its steep peaks, lush canyons and mixture of rare and endangered species. Recently however, a team of federal biologists and forest rangers was aghast when it visited the stream following the Bobcat fire, which has burned more than 115,000 acres in the heart of the San Gabriel Mountains National Monument. Terrain that once resembled a High Sierra granite gorge now looked like ground zero after a nuclear explosion, and the usually clean mountain air was sharp with the stench of smoke. Particularly unsettling were the bare and ashen slopes that were now primed to dissolve under pounding winter storms. A heavy mudslide, experts said, could reverse decades of conservation efforts by inundating the last outposts for such federally protected species as the Santa Ana sucker fish and Southern California m...
Read more