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Plants care more about kin than strangers

Like humans, plants also pay more attention to their closest relatives than strangers.
When an insect bites a leaf, many plants release volatile chemicals to warn their neighbours for attack.

While some plants respond by attracting predatory insects that eat the herbivores, others make themselves less tasty. 

Richard Karban of the University of California, Davis, has now suggested that for the sagebrush, responses to these warning signals may vary with relatedness, according to New Scientist.

Karban's team exposed different branches of the same plants to volatile chemicals at the start of three growing seasons. The substances came from relatives of the same species whose leaves had been clipped to trigger chemical release.

By the end of the seasons, the researchers found that herbivores had done less damage to the branches exposed to chemicals from close relatives than to those receiving signals from more distant relatives. 

High calcium doubles risk of cardiovascular death in women

High intakes of calcium in women is associated with a higher risk of death from all causes - cardiovascular disease in particular- a study has suggested. Experts recommend a high calcium intake and as such, more than 60 per cent of middle-aged and older women in the US now take supplements.

Researchers from Uppsala University in Sweden studied 61,443 Swedish women (born between 1914 and 1948) for an average of 19 years to test if the intake had connection to higher risk of ischemic heart disease and stroke. Data was taken from the Swedish Cause of Death Registry and information on diet was taken from the Swedish Mammography Cohort.

Information was obtained from the women on their menopausal status, postmenopausal oestrogen therapy, parity information, weight and height, smoking habits, leisure-time physical activity and educational level.

Sparrows use threatening signals against threats

Territorial song sparrows have a hierarchical warning scheme in place when they need to ward off trespassing rivals, according to a new study.

First an early warning that matches the intruder’s song, then wing waving – a bird’s version of “flipping the bird” – as the dispute heats up, and finally, if all other signals have failed, attack.

“This is one of the most complicated communication systems outside of human language,” said lead author Çaglar Akçay, who did the study as a UW graduate student. He is now a postdoctoral researcher at Cornell University.

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