Naturebites

Naturebites

 Unique genetic variation

Once known for its green cover, Bengaluru has lost 78% of its green cover in the last two decades due to rapid urbanisation. The city's fig trees, however, have withstood the onslaught. Aiming to evaluate the loss of green cover, researchers from the Indian Institute of Science studied the genetic structure and diversity of the cluster fig tree population in Bengaluru. For the study, the researchers collected leaf samples from individual trees from different locations across the city. The study revealed that the population of cluster fig trees in Bengaluru has a fairly robust genetic structure, with no signs of inbreeding.

Inbreeding results in low genetic diversity that could cause loss of fitness and increase the risk of extinction for small population of individuals. However, in the case of the cluster fig trees, the credit for maintaining healthy population probably goes to their pollinator fig wasps, which live in a special mutualism with the fig. The DNA extracted from the collected leaves was used to conduct a genetic analysis called microsatellite analysis. "The fig-fig wasp mutualisms is especially helpful for the fig trees in maintaining a healthy population genetics even though trees occur at low densities, and is located far from each other," states Anusha Krishnan, an author of the study.

How a giant tortoise gets off its back

The giant tortoises of the Galápagos Islands have no natural predators, but their shells represent a mortal danger of their own. When flipped over, the animals — who regularly weigh in at more than 90 pounds — often struggle to find their feet. If they fail, they eventually die. And for a giant tortoise with one shell type, the saddleback, big spills are a regular part of life. “The saddlebacks live in places where you have a lot of lava rocks, so they should fall more often,” said Ylenia Chiari, a biologist at the University of South Alabama, USA, comparing them with domed tortoises, another type that lives on flatter terrain.

Domed tortoises have rounded shells, and saddleback tortoises have flatter shells with flared edges and a raised neck opening. Ylenia thought the shells on the saddlebacks had evolved to make it easier for these tortoises to get back up, and set out to test her hypothesis in a study that was published in the journal Scientific Reports. She was wrong, but her research offered additional insights into the anatomies of these tortoises and how they might have evolved to get back on their feet.

The larger size of the saddleback’s neck opening allows the saddleback to extend its longer neck farther, which biologists long assumed was a trait that helped the tortoise reach food in a drier climate. The shell’s larger front opening also allows the saddleback tortoises to use their long necks to help pick themselves up.

Birds that rapidly evolved bigger beaks

Conservationists have been warning of the damage invasive species can cause to habitats and native animals for years. The population of North American snail kites — birds that use curved beaks and long claws to dine on small apple snails in the Florida Everglades, USA — had been dwindling, from 3,500 in 2000 to just 700 in 2007. Things began to look particularly bleak in 2004, when a portion of the Everglades was invaded by a species of larger snail that the birds had historically struggled to eat.

But the number of snail kites in the Everglades grew during the decade after the invasion of the larger snails. The reason, according to a study published in Nature Ecology and Evolution, is that the snail kites have rapidly evolved larger beaks and bodies to handle the bulkier snails. The researchers found that beak and body sizes had grown greatly (about 8% on an average) since the invasion.

A Climate of Change

Produced as a prelude to the 2015 United Nations Framework Convention on Climate Change, the documentary A Climate of Change relies on the expert insights of several scientists to debunk the scepticism of global warming deniers and advocate for greater urgency in preventing further planetary abuse. Armed with easily understandable testimony and clear and concise evidence, the documentary hopes to put an end to the debate and begin the search for real solutions to an ever-worsening global crisis.

Each of the scientist interviewed in the documentary concurs that the entirety of the issue is not solely caused by humans, but further catastrophe can be avoided if we are willing to take the appropriate steps to act. The film makes great use of statistics to illustrate the extent of the crisis, but it realises this alone is not enough to affect real change. To watch the documentary, visit www.bit.ly/2k89ucN.

 

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