Environmental Engineering Reference
In-Depth Information
up in Britain in 1996 and is now widespread in British wetlands. Should Brits be sending it home? Some
conservationists take Simberloff's zero-tolerance approach. But the bird conservationists at the Royal
Society for the Protection of Birds are welcoming. And if we should welcome the little egret, then why
not give a helping hand to other species in search of a haven?
Thomas has proposed Britain as a sanctuary for species at risk elsewhere. After all, it has no undis-
turbed terrain and no globally endangered species to lose. It would be an ideal refuge for lost species.
The Iberian lynx, the most endangered cat in the world, would love hunting British rabbits. Britain once
had lynx, and its rabbits originally came from Iberia. So why not?
5
When I visited Thomas in York in late 2013, however, he had a much more optimistic story to
tell—about nature's ability to bounce back from human threats. He was, he said, now convinced that
human activity, including human-caused climate change, could trigger an evolutionary explosion that
might counterbalance the extinctions and could leave us with more species than before. And alien spe-
cies were a big reason behind his new optimism. They were the dynamic element, the go-getters, sur-
vivors, gene-spreaders, and all-round carpetbagger colonists that could turn ecological disaster to evol-
utionary triumph. The thinking was simple. Extinctions would create the opportunity for evolution to go
into overdrive. Every species lost would create space for new species to move in. And the most invasive
of the aliens would be the ones best able to take advantage. The species that conservationists most fear
are precisely the ones that nature most needs.
Thomas had just published a short note in the science journal
Nature
titled “The Anthropocene
Could Raise Biological Diversity.” In it he said, “It is time to rethink our irrational dislike of invading
species.”
6
He told me: “We worry about the extinction of species in the era of humans. We are right to.
But the seeds of recovery are already visible. New species are beginning to emerge. Of course many of
the new species will fail. But others will become the new lineages of the future.” Nature as a dynamic
force will be reborn.
This is controversial stuff. The conventional narrative is that climate change may be leading the
world toward what some term the earth's sixth great extinction. One that is potentially as dramatic as
what happened when an asteroid hit the earth sixty-five million years ago and wiped out probably 50
percent of species, including the dinosaurs. Thomas's own research a decade before did much to make
the case for climate change as the prime cause of that extinction. Others stress the role of habitat loss
and the spread of alien species. The argument about aliens is that by extinguishing local endemics and
replacing them with global generalists they will reduce the world's overall stock of species. They will
cause the “homogenization” of nature. Niche players will be lost and the weedy generalists will spread
across the land.
Two questions are raised here. One is whether global biodiversity actually matters to nature. The
other is whether aliens will destroy it by accelerating extinctions or help nature recover from it by stim-
ulating evolutionary forces.
On the first question, there is actually no compelling evidence that the planet's total stock of species
is of any intrinsic importance to the functioning of nature. We know that local ecosystems may be more
resilient to change if they contain more species. That, incidentally, is another reason why alien species
that add to local biodiversity ought to be smiled on. But there is no research that I know of pointing
to such a value from global biodiversity. This suggests to me that our current preoccupation with how
Search WWH ::
Custom Search