NatureWrap: These guys mess with killer whales

Long-finned pilot whales (Globicephala melas) off southern Australia mimic the calls of killer whales – their natural predator and food rival – as a possible ploy to outsmart them, a new study shows.

Researchers from Curtin University also found evidence of duetting – coordinated and patterned singing related to social bonding and coordination of behaviour – which is common in birds and primates but very rarely reported in aquatic mammals.

This suggests, they say, that the whales’ acoustic communication system is even more complex and sophisticated than previously thought.

Rachael Courts and colleagues analysed calls recorded in the Great Australian Bight between 2013 and 2017, publishing their findings in the journal Scientific Reports.

Courts says some calls were remarkably similar to those of the same species in the Northern Hemisphere, which is surprising as non-equatorial aquatic mammals are not expected to cross the equator for large-scale migrations, meaning the last contact between the two populations would have been more than 10,000 years ago.

Co-author Christine Erbe says the team recorded three unique vocalisations which had not previously been reported for the species.

“These were very complex multi-component calls much like killer whale calls, but given this is the first Southern Hemisphere study, we don’t know how common the calls might be in other Southern Hemisphere pilot whales.”

How insects got their wings

Insect wings likely evolved from an outgrowth or lobe on the legs of an ancestral crustacean, according to scientists from the Marine Biological Laboratory at Woods Hole, US.

After the marine animal moved onto land 300 million years ago, the leg segments closest to its body became incorporated into the body wall during embryonic development, the researchers say, perhaps to better support its weight. The leg lobes then moved up onto the insect’s back, and those later formed the wings.

The findings are based on old scientific papers, new genomic approaches, and the realisation a decade ago that insects are most closely related to crustaceans within the arthropod phylum, as revealed by genetic similarities.

“Prior to that, based on morphology, everyone had classified insects in the myriapod group, along with the millipedes and centipedes, and if you look in myriapods for where insect wings came from, you won’t find anything,” says Heather Bruce, co-lead author of a paper in Nature Ecology & Evolution.

“So insect wings came to be thought of as novel structures that sprang up in insects and had no corresponding structure in the ancestor – because researchers were looking in the wrong place for the insect ancestor.”

The source of sorghum

Wild cousins of sorghum, the fifth-most important cereal crop globally, are most concentrated in Australia, despite having been domesticated in Africa.

Researchers from Australia, Colombia and the US, who previously investigated the relatives of chilli peppers, zucchini, carrots, potatoes and sweet potatoes, analysed millions of data points to predict the global distributions of a crop grown on every inhabited continent.

Sorghum is more drought- and heat-tolerant than maize and can grow without fertiliser. In parts of Africa and Asia, it is a critically important crop for food and nutrition security.

However, most wild species are found in northern and western Australia and Queensland; one is found in the Americas, and five in Africa and Asia.

“The most widespread species extends 34,403,804 square kilometres from Japan to Pakistan; the least widespread extends 400 square kilometres across the remote Katherine region in Australia,” says Harry Myrans, from Australia’s Monash University.

The concern, he adds, is that many wild species are “not sufficiently safeguarded” in protected areas, natural habitats or genebanks. “Habitat destruction, invasive species and climate change itself all threaten their existence.”

The findings are published in the journal Diversity and Distributions.

“This critical research has enabled us to process more data than ever before, and it will allow us to create a methodology to understand the distributions and conservation of other crops,” says co-author Maria Diaz from the International Center for Tropical Agriculture in Colombia.

Old guys of the ocean

An 81-year-old midnight snapper found off the coast of Western Australia has taken the title of the oldest tropical reef fish recorded anywhere in the world.

It was caught at the Rowley Shoals, about 300 kilometres west of Broome, and is in good company. A research team led by the Australian Institute of Marine Science (AIMS) identified 11 individual fish more than 60 years old, including a 79-year-old red bass.

The study covered four locations along the WA coast, as well as the protected Chagos Archipelago in the central Indian Ocean.

“Until now, the oldest fish that we’ve found in shallow, tropical waters have been around 60 years old,” says AIMS’s Brett Taylor. “We’ve identified two different species here that are becoming octogenarians, and probably older.”

Marine scientists can accurately determine the age of a fish by studying their ear bones, or otoliths, which have annual growth bands that can be counted in much the same way as tree rings.

The research is published in the journal Coral Reefs.