Scientists sound the alarm of next mass extinction

Scientists warn we are on the brink of the next major mass extinction event

Scientists warn we are on the brink of the next major mass extinction event

 

Biologists (yet again) sound the alarm in this latest article via Stanford News Service, warning that 16 to 33 percent of vertebrates are now endangered. Larger animals such as elephants, rhinos and polar bears face the highest decline rates, which follows in the pattern of past extinction events. The loss of such creatures would mean devastating trickle-down effects on the human population and other species.

[P]revious experiments conducted in Kenya have isolated patches of land from megafauna such as zebras, giraffes and elephants, and observed how an ecosystem reacts to the removal of its largest species. Rather quickly, these areas become overwhelmed with rodents. Grass and shrubs increase and the rate of soil compaction decreases. Seeds and shelter become more easily available, and the risk of predation drops.Consequently, the number of rodents doubles — and so does the abundance of the disease-carrying ectoparasites that they harbor.

“Where human density is high, you get high rates of defaunation, high incidence of rodents, and thus high levels of pathogens, which increases the risks of disease transmission,” said Dirzo, who is also a senior fellow at the Stanford Woods Institute for the Environment. “Who would have thought that just defaunation would have all these dramatic consequences? But it can be a vicious circle.”

Vertebrates aren’t the only species on a troubling path of defaunation. Over the last 35 years, while the human population has doubled, invertebrate numbers have plummeted by 45 percent.

Past mass extinctions were driven by planetary transformations or catastrophes, but the extinction we face today can be attributed to man-made causes.

This is far from the first time that scientists have cautioned us of the next looming mass extinction. Last month, The Week delivered a similar warning that we could be headed the way of the dinosaurs if we don’t address these crises immediately. In February, NPR concluded the mass extinction is already underway.

In the words of Neil deGrasse Tyson:

We just can’t seem to break our addiction to the kinds of fuel that will bring back a climate last seen by the dinosaurs, a climate that will drown our coastal cities and wreak havoc on the environment and our ability to feed ourselves. All the while, the glorious sun pours immaculate, free energy down upon us, more than we will ever need. Why can’t we summon the ingenuity and courage of the generations that came before us? The dinosaurs never saw that asteroid coming. What’s our excuse?

Source:  dailykos.com

Plants recognize their siblings

Plants recognize their siblings, biologists discover:

 

 

Plants recognize their siblings, biologists discover

Plants recognize their siblings, biologists discover

The next time you venture into your garden armed with plants, consider who you place next to whom. It turns out that the docile garden plant isn’t as passive as widely assumed, at least not with strangers. Researchers at McMaster University have found that plants get fiercely competitive when forced to share their pot with strangers of the same species, but they’re accommodating when potted with their siblings.

The study appears today in the Royal Society journal Biology Letters.

“The ability to recognize and favour kin is common in animals, but this is the first time it has been shown in plants” said Susan Dudley, associate professor of biology at McMaster University in Hamilton, Canada. “When plants share their pots, they get competitive and start growing more roots, which allows them to grab water and mineral nutrients before their neighbours get them. It appears, though, that they only do this when sharing a pot with unrelated plants; when they share a pot with family they don’t increase their root growth. Because differences between groups of strangers and groups of siblings only occurred when they shared a pot, the root interactions may provide a cue for kin recognition.”

Though they lack cognition and memory, the study shows plants are capable of complex social behaviours such as altruism towards relatives, says Dudley. Like humans, the most interesting behaviours occur beneath the surface.

Dudley and her student, Amanda File, observed the behavior in sea rocket (Cakile edentula), a member of the mustard family native to beaches throughout North America, including the Great Lakes.

So should gardeners arrange their plants like they would plan the seating at a dinner party?

“Gardeners have known for a long time that some pairs of species get along better than others, and scientists are starting to catch up with why that happens,” says Dudley. “What I’ve found is that plants from the same mother may be more compatible with each other than with plants of the same species that had different mothers. The more we know about plants, the more complex their interactions seem to be, so it may be as hard to predict the outcome as when you mix different people at a party.”

 

Source: phys.org