Costa Rican frogs, new species discovery


A male Warszewitsch's frog in its natural habitat (El Valle de Antón, Panama). Credit: Dr Robert Puschendorf

From ScienceDaily:

The truth about a true frog: Unknown Costa Rican frog hidden amongst a widespread species

The discovery highlights the urgent need of modern DNA tools when studying rapidly declining animal groups like amphibians

April 11, 2019

Known to science since 1857, a common species of true frog (a “true frog” is one assigned to the family Ranidae), found from north-eastern Honduras, through Nicaragua and Costa Rica to central Panama, turns out to have been keeping its “multiple identities” a secret all along.

According to British and Costa Rican herpetologists, who recently used DNA barcoding to study the species in question, what we currently call Warszewitsch’s frog is in fact a group of “cryptic” species. The study, conducted in the Área de Conservación Guanacaste (ACG), Costa Rica, by James Cryer, Dr Robert Puschendorf, Dr Felicity Wynne from the University of Plymouth, and Dr Stephen Price, UCL, is published in the open-access journal ZooKeys.

In their paper, the authors suggest that the well-known Central American frog species, commonly known as the Warszewitsch’s frog, may in fact consist of multiple different “cryptic” species. This phenomenon is well documented among tropical amphibian fauna, where high levels of genetic variation within populations of a single species surpass levels found between different, classified species.

By utilizing a technique known as DNA barcoding, which compares short snippets of DNA sequences between individuals sampled, the scientists analysed specimens from three different geographic areas within Costa Rica and Panama. In this case, the researchers used sequences derived from mitochondria, the energy-producing “power houses” found in animal cells. Their results indicated there was enough genetic variation to suggest cryptic species are indeed present.

The team chose this particular species because cryptic species were previously identified at two Panamanian sites. Now, the samples from Costa Rica broaden the study area, suggesting that there could be multiple species going by the name Warszewitsch’s frog all across its known distribution.

Conservation biologist and lead author James Cryer says:

“The next step will be to gather more samples throughout the full range of the species. Additionally, if we are to fully discern one species variant from another, further studies that compare the physical, behavioural and ecological characteristics of the frogs, alongside more genetic testing is needed.”

Overall, findings like these are important to help improve our understanding of amphibian biodiversity and, thus, work towards its conservation.

“If indeed there are multiple species, it may be that they have different ecological requirements, and therefore different approaches to their conservation are needed.” Cryer says. “This study further reinforces the power of DNA barcoding for rapid, preliminary species identification. Especially in the tropics, where habitat loss, climate change and infectious disease continually threaten many undescribed amphibian species.”

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Saving baby sloths, birds in Costa Rica


This 2 April 2019 video says about itself:

Rehabilitating Baby Sloths in Costa Rica – 360 | National Geographic

Witness the recovery and release of wildlife at the Toucan Rescue Ranch in Costa Rica.

Splendid leaf frog in Costa Rica, video


This 31 March 2019 video says about itself:

On this episode of Breaking Trail, the Brave Crew is in location in Costa Rica, and they FINALLY find a very special frog… the Splendid Leaf Frog! This is one RARE frog!

Get ready, you’re about to meet a rare frog that leaps back!

Breaking Trail leaves the map behind and follows adventurer and animal expert Coyote Peterson and his crew as they encounter a variety of wildlife in the most amazing environments on the planet!

Costa Rican singing mice, new study


This 2013 video says about itself:

Singing Mouse Serenades The Sky. Really.

Move over Celine Dion. Alston’s singing mouse (Scotinomys teguina) emits sopranino trills to mark its boundaries deep in mountain cloud forests. [The little vocalist even takes a bow.]

From the NYU Langone Health / NYU School of Medicine in the USA:

Study of singing mice suggests how mammalian brain achieves conversation

Research may lead to future solutions to speech problems

February 28, 2019

By studying the songs of mice from the cloud forests of Costa Rica, researchers have discovered a brain circuit that may enable the high-speed back and forth of conversation.

Males of the study species, Alston’s singing mouse (Scotinomys teguina), produce songs with nearly a hundred audible notes. They challenge competitors by singing in turns, alternating like talking humans, say the study authors. In contrast, standard laboratory mice produce ultrasonic sounds without evident exchanges.

Thus, the new study, led by researchers at NYU School of Medicine, launches a new field by employing a novel mammalian model to examine brain mechanisms behind the sub-second precision of vocal turn-taking.

“Our work directly demonstrates that a brain region called the motor cortex is needed for both these mice and for humans to vocally interact,” says senior study author Michael Long, PhD, an associate professor of neuroscience at NYU School of Medicine.

“We need to understand how our brains generate verbal replies instantly using nearly a hundred muscles if we are to design new treatments for the many Americans for whom this process has failed, often because of diseases such as autism or traumatic events, like stroke,” says Long.

Published online as the cover story of Science on March 1, the study found that, along with brain areas that tell muscles to create notes, separate circuits in the motor cortex enable the fast starts and stops that form a conversation between vocal partners.

“By segregating sound production and control circuits, evolution has equipped the brains of singing mice with the tight vocal control also seen in cricket exchanges, bird duets, and possibly, human discussion,” adds study co-first author Arkarup Banerjee, PhD, a post-doctoral scholar in Long’s lab.

Despite the ubiquity of vocal exchanges in the natural world, he says, there are no suitable mammalian models in neuroscience for their study. Before the new report, the leading model for studying this back-and-forth was the marmoset, a primate whose conversational turns are considerably slower than human speech, and unlikely to result from the fast muscle response to sensory cues (e.g. motor cortical circuitry).

Social Songs Different

The research team found that S. teguina songs — series of notes that evolve predictably as the song goes on — changed in social situations as the mice had to “bend and break the songs” to converse. The tight connection between song patterns and readings taken by electromyography, which captures electrical signals as the brain generates muscle contractions, enabled the team to determine the relationships between brain centers and song musculature while two mice coordinated their responses.

In contrast to the findings of past studies, the researchers found that a functional “hotspot” located at the front of the motor cortex to one side — the orofacial motor cortex or OMC — regulated song timing.

To study the contributions of these specialized brain circuits to social singing, the team interfered with cortical regions in the mice using a number of techniques, including devices that cooled the OMC during songs. Long has helped to pioneer the cooling technique in the study of human brain circuits related to speech.

Called focal cooling, it is a safe way to slow the pace of vocalizations without changing the pitch, tone, or duration of individual notes, say the study authors. They argue that the observed, functional separation in the brain between sound generation and timing functions, this hierarchy, is what makes socially relevant exchanges possible.

Moving forward, the researchers are already using their mouse model to guide related exploration of speech circuits in human brains. By understanding the activity that helps to engage two brains in conversation, they can look for the processes that go awry when disease interferes with communication, potentially spurring the development of new treatments for many disorders.

Along with Long, study authors from the NYU Neuroscience Institute and Department of Otolaryngology at NYU School of Medicine were co-first authors Arkarup Banerjee and Daniel Okobi Jr, as well as Andrew Matheson. The work was done in collaboration with Steven Phelps, PhD, director of the Center for Brain, Behavior and Evolution at the University of Texas at Austin, whose lab pioneered the study of the singing mouse in the lab and field. Some of the authors are also members of the Center for Neural Science at New York University.

This research was supported by the New York Stem Cell Foundation, the Simons Foundation Society of Fellows, and the Simons Collaboration on the Global Brain.

How hermit crabs get new shells


This 25 February 2019 video says about itself:

Hermit crabs are drawn to smell of flesh torn from their kin | Science News

Within three minutes on a beach at Osa Peninsula, Costa Rica, land hermit crabs (Coenobita compressus) crowd a tube containing flesh bits of their own kind. Researchers say the smell signals that an empty shell may be available for the taking.

By Yao-Hua Law, 8:00am, February 25, 2019:

Hermit crabs are drawn to the smell of their own dead

Competition for abandoned shells turns into a lively gathering

The death of a millionaire with no heir draws an opportunistic crowd. So, too, does the demise of a land-dwelling hermit crab. Researchers working in Costa Rica found that the curious crabs are drawn to the smell of flesh torn from one of their own.

Dartmouth College biologist Mark Laidre, along with undergraduate student Leah Valdes, set out 20 plastic tubes on a beach, each holding bits of hermit crab flesh. Within five minutes, almost 50 hermit crabs (Coenobita compressus) swarmed around each sample, the pair reports online February 10 in Ecology and Evolution. “It’s almost like they were celebrating a funeral,” Laidre says.

The reality, however, is more macabre. That scent of flesh is a signal that a fellow land hermit crab has been eaten, and that its empty shell is available for the taking, Laidre says. The crabs “are all in an incredible frenzy to try to move into that leftover shell.”

None of the roughly 850 known hermit crab species, most of which live in the sea and some on land, can grow their own shells. Instead, the crabs occupy shells originally left behind by dead snails. A hermit crab grows to the size of its shell, but to grow further, the creature must find and occupy a larger shell.

For the roughly 20 or so species of land hermit crabs, finding a suitable shell can be especially challenging. Big shells with lots of extra room to grow may be too heavy in the short term for a hermit crab to tote around on land without the buoyancy of water to help lighten the load, and lighter shells may be too small.

Land hermit crabs can remodel their shells, making them bigger, Laidre reported in 2012. The animals use corrosive secretions and scraping to widen a shell’s opening, remove the internal spiral and reduce wall thickness. Remodeling can double the available space while trimming one-third the weight. But remodeling is taxing and slow. It’s much faster to take over an already remodeled shell of another land hermit crab, alive or dead. Hence the strong attraction of land hermit crabs toward smells that suggest another is dead, Laidre says.

The researchers also found that land hermit crabs approached bits of snail flesh, though the scent appears to be far less alluring than that of their own species. Sea hermit crabs, however, didn’t find the smell of another hermit crab’s corpse more attractive than those of snails.

That makes sense to Laidre. For sea hermit crabs, upsizing to bigger and heavier shells is relatively easy, thanks to water’s buoyancy that helps the crabs support a shell that’s a little too big at first. That, combined with the fact that there are also many more empty shells in the sea than on land, means that sea hermit crabs face less competition when looking for a home, he says.

By highlighting that shell availability is limited for land hermit crabs, the study makes an important point for conservation, says ecologist Chia-Hsuan Hsu, who studies hermit crabs at National Taiwan University in Taipei and wasn’t involved in the research. “We can tell the public: ‘Don’t take shells from the beach’, ” he says.

Resplendent quetzal in Costa Rica in 4K


This 18 December 2018 video says about itself:

The resplendent quetzal bird from the trogon family calls home the mountain range of Talamanca in Costa Rica. This stunning looking bird feeds off wild avocado among other fruits. Footage was filmed in the wild in the San Gerardo de Dota area of the Talamanca.

I was privileged to also see resplendent quetzals at their nest there.