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NYT and Science Daily, Nov 27 2017, 21:47 IST
A handout photo of differently-accented snapdragons observed in the study, in the Pyrenees Mountains between France and Spain. PHOTO CREDIT: John Innes Centre via NYT

A handout photo of differently-accented snapdragons observed in the study, in the Pyrenees Mountains between France and Spain. PHOTO CREDIT: John Innes Centre via NYT

MORE THAN ONE COLOUR

How snapdragons beckon bees

In the Pyrenees Mountains, between France and Spain, wild snapdragons bloom each spring. Their petals scream for pollination with colour. A bit of bright contrast brushed over the centre of the flower's lower lip advertises the nectar behind it. Bees follow the patterns and enter the mouths of the snapdragon. On one side of the mountainous landscape, one subspecies of snapdragon has magenta lips with yellow accents.

On the other, another offers the opposite: yellow lips with magenta accents. In the land between, hybrid flowers try it all. Researchers suspected colouration genes from the two subspecies were not mixing well, and that natural selection was favouring the survival of both magenta and yellow flowers independently, not the hybrids.

But how did the snapdragon cousins create accented patterns that appeared to be equally effective in the same environment? To find out how colour differences arose, scientists compared the genomes of the subspecies in a study published in Science.

They found that the magenta-yellow plants and their yellow-magenta mirrors shared most of the plant's genes - but not a handful related to colour. Bees favoured a couple of patterns and neglected plants with other colour schemes, the researchers believe, for certain genetic combinations.

LOSS IN GENETIC DIVERSITY

Birds that went extinct swiftly

A paper published in Science this month sheds light on why passenger pigeons went extinct so swiftly. Analysing the DNA of preserved birds, the researchers found evidence that natural selection was extremely efficient in passenger pigeons.

This might have made the pigeons particularly well-suited for living in dense flocks but unable to cope with living in sparse groups once their numbers started to plummet, the authors suggest. Biologists generally assume that a large population corresponds to high genetic diversity.

But passenger pigeons were so plentiful and so mobile that beneficial genetic mutations spread and detrimental ones disappeared very quickly. This caused a loss in overall genetic diversity. In the new study, researchers compared the genomes of four passenger pigeon specimens with those of two band-tailed pigeons, a close living relative, and saw signatures of efficient natural selection.

They also found typically high genetic diversity in regions of the genome that tend to get chopped up and rearranged between generations. Under strong natural selection, when beneficial mutations occur, large swaths of neutral or even slightly harmful DNA get fixed, suppressing genetic variation, said Beth Shapiro, an author of the study.

ACROBATIC MANOEUVRES

Blue whales shift directions

Blue whales are the largest animals in the world, with bodies that can weigh as much as 25 elephants and extend over the length of a basketball court. To support their hulking bodies, the whales use various acrobatic manoeuvres to scoop up many tiny prey, filtering the water back out through massive baleen plates. In most cases, the whales roll to the right as they capture their prey.

But, a new study published in Current Biology shows that the whales shift directions and roll left when performing 360 barrel rolls in shallow water. The findings offer the first evidence of 'handedness' in blue whales. The researchers also highlight the importance of studying animals in their natural environments for revealing phenomena that may be impossible to capture in a captive environment.

DOCUMENTARY

Chevron vs the Amazon

The oil industry giant Chevron began operating in Ecuador's Amazon rain forest in 1964. Over the course of the next 30 years, this majestic environmental wonder became the victim of unregulated corporate abuse and greed. By the time the corporation vacated the area in 1992, their toxic footprint had brought about 1,700 times more damage to the environment than the Exxon Valdez oil spill in USA.

Abby Martin, the director, visits the scene of the crime in Chevron vs
the Amazon: Inside the Killzone, and uncovers the extent to which the
industry has spoiled the riches of a tropical paradise. Thousands of
unique species of plant life, insects, animals, and an equally diverse
human population came under threat when Chevron established
operations in the region over 50 years ago. To watch the documentary, visit www.bit.ly/2cxKhmm.

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