Amazonian frog has its own ant repellent

Chemicals presented on skin allow tiny frog to live and breed unhindered among leaf-cutting ants
 

Date: October 20, 2016

Source: Springer

Special chemicals covering the skin of a tiny yellow-striped Amazonian frog provide a protective shield that wards off leaf-cutting ants allowing it to live comfortably among them. "It helps the frog blend in, because it imitates the ants own chemical signals," says André Barros of the National Institute of Amazonian Research in Brazil. He led a study in Springer's journal Behavioral Ecology and Sociobiology. The ants do not give it even a single bite, but will quite aggressively attack all other types of frogs or other animals that cross their path.

This type of chemical-based mimicry and camouflage is often used by parasitic invertebrates and allows them to live unhindered within the protective confines of social insect-colonies. However, the strategy is not often seen in vertebrates, much less among frogs, and is only known in two other African frog species.

Lithodytes lineatus is a South American frog that is mainly found in the Amazon region. In Spanish the frog is known as "Sapito Listado." It shelters, breeds and builds its nest peacefully in the midst of leaf-cutting ants of the genus Atta without ever being attacked by them.

Leaf-cutting ants use chemical odors, such as pheromones, to recognize and communicate with members of their colony. Barros' team therefore speculated that the skin of Lithodytes lineatus must also be covered with a similar type of chemical that makes leaf-cutting ants recognize them as "friendly" and cheats them into allowing the frog into their midst.

They ran two sets of field experiments to test this. First Lithodytes lineatus frogs and four similar species were held in a glass vessel for ten minutes along with leaf-cutting ants. The Lithodytes lineatus frogs made no escape plans, in contrast with the members of the four other species that tried to jump or climb out and that were attacked by the ants.

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Genetic mutation in whale eyes may increase mortality risks

Date: October 24, 2016

Source: Florida Institute of Technology

Scientists have found that a genetic mutation in the eyes of right whales that hampers their ability to see in bright light may make them more susceptible to fatal entanglements in fishing gear, one of the major causes of death for this critically endangered mammal.

The study of this whale species, which numbers less than 500 individuals remaining in the Western Atlantic Ocean, may also help scientists better understand how vision works in other mammals, including people.

Florida Institute of Technology doctoral student Lorian Schweikert and her adviser, Michael Grace, professor of neuroscience and senior associate dean of science, worked with Jeffry Fasick, an assistant professor of biology at the University of Tampa, to characterize this newly discovered mutation in Northern right whales and Bowhead whales. Their results suggest that this mutation may seriously harm the whales' ability to visually avoid entanglement.

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Population analysis suggests Grauer's gorilla is Critically Endangered

Date: October 19, 2016

Source: PLOS

Grauer's gorilla, which is confined to the eastern Democratic Republic of Congo, is now Critically Endangered, according to a study published October 19, 2016 in the open-access journal PLOS ONE by Andrew Plumptre from Wildlife Conservation Society, USA, and colleagues.

This is the first analysis of the Grauer's gorilla population since civil war broke out in the region in 1996. Since the war, armed miners have hunted bushmeat including gorillas, but the presence of militia has complicated assessments of the gorilla population. Plumptre and colleagues assessed local community and ranger-collected data that included encounter rates at gorilla nests at 10 sites as well as spatial occupancy across the species' range.

Before the war, the population was estimated at 16,900 individuals. The researchers now estimate that there are only 3,800 Grauer's gorillas left in the wild, a 77% decline in a single generation. While this species was previously classified as Endangered, the gorillas are now listed as Critically Endangered on the IUCN Red List of Threatened Species based on this new population estimate. The new analysis also suggests that the gorilla's range is about 19,700 km2, and identified three key areas that are the most critical for the remaining population of this great ape.

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