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Science In Action: Fungal Threat to World’s Favourite Banana

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23/08/2018 GMT

Fungal Threat to World’s Favourite Banana

BBC World Service - Science In Action, Fungal Threat to World’s Favourite Banana

The Cavendish banana is globally threatened by a fungal disease. Can genetics save it?

What no bananas?; Hominim Hybrids; How a volcanic eruption led to a deluge that stopped Napoleon’s men at Waterloo; How bats and fireflies fight it out.

The Cavendish banana is the favourite variety for much of the world – it’s big and seedless, accounts for 47% of the global production market and nearly all global trade in bananas are Cavendish. But it’s under attack. It’s a vegetative clone (i.e. all genetically identical) and a fungus which kills it and a variety of other bananas is spreading across the world. Can genetics save it?

Hominim Hybrids
Denisovans are an extinct group of hominins that separated from Neanderthals more than 390,000 years ago. Scant remains of only a handful of individuals of these early people, were described in 2010, after they were found in the Denisova Cave in the Altai Mountains in Siberia (a cave that has also been inhabited by Neanderthals and modern humans over thousands of years). We don’t know what the Denisovans looked like, or much about how they lived. But from the DNA extracted from the handful of bone fragments we know a lot about their ancestry. And now, genomic analysis of the bones of one of the individuals, shows that she was around 13 years old and her mother was a Neanderthal and her father was a Denisovan - proving interbreeding between these two hominin lineages. 

Volcanic Lightning and Charged Ash
How could a volcanic eruption in Indonesia have contributed to the defeat of Napoleon at the Battle of Waterloo? Recent findings show that the ash from a large volcanic eruption can reach heights in the atmosphere twice as high as previously thought, because the negatively charged particles experience electrostatic repulsion. If the charged particles of volcanic dust propel themselves into the ionosphere - the ionised upper level of the atmosphere that is responsible for cloud formation - they can effectively ‘short-circuit’ this layer and prevent clouds forming. This effect can spread around the globe within 100 seconds. Once the ionosphere has recovered, clouds form and release the built up moisture as rain. So the large April 1815 eruption of Indonesia’s Mount Tambora may well have caused the unseasonably wet weather that made the fields too muddy for Napoleon’s cavalry, half way across the world in Europe. 

Bats and Fireflies 
A new study shows that the flashing green lights of fireflies aren’t just for attracting a mate. Researchers discovered that this bioluminescence acts as a warning signal to bats of the firefly’s awful taste. The study also revealed that the fireflies have another way to tell the bats to stay away: a very relaxed flight path. Bats can use both the fireflies’ three-dimensional flight pattern and light flashes to learn and remember to stay away from the noxious species, but learn most quickly when both signals are available. This is the first time multi-sensory signalling has been shown in a natural predator-prey system. Furthermore, the results suggest that, in fireflies, bioluminescence for bats came before bioluminescence for lovers! 

Picture: Bananas, Credit: Bebenjy/Getty Images

Presenter: Roland Pease
Producer: Fiona Roberts

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