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Posts Tagged ‘lag time’

As Climate Change Bears Down, Do We Relocate Threatened Species?

Posted by Richard Conniff on December 26, 2017

(Photo: Frans Lanting)

by Richard Conniff/Scientific American

On a knob of rock in New Zealand’s Cook Strait known as North Brother Island, a population of the lizard-like creature called the tuatara is quickly becoming all male. When scientists first noticed the imbalance in the late 1990s, the sex-ratio was already 62.4 percent male, and it has rapidly worsened since then, to more than 70 percent. Researchers say climate change is the cause: ground temperature determines the sex of tuatara embryos, with cooler temperatures favoring females and warmer ones favoring males.  When climate pushes the sex ratio to 85 percent male, the North Brother Island tuataras will slip inescapably into what biologists call the extinction vortex.

So what should conservationists do? For the tuatara and many other species threatened by climate change, relocating them to places they have never lived before–a practice known as assisted colonization—is beginning to seem like the only option. “We’d prefer to do something a little more natural,” says Jessica Hellman, a lepidopterist at Notre Dame, who was among the first researchers to put the assisted colonization idea up for discussion. That is, it would be better for species to shift their ranges on their own, using natural corridors to find new homes as their old ones become less habitable. But for many island and mountain species, long distance moves were never an option in the first place, says Hellman. In other cases, old corridors no longer exist, because human development has fragmented them.

The idea of assisted colonization as a conservation tactic has elicited fierce criticism, however, because of its potential Read the rest of this entry »

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