BBC Wildlife - UK (2020-04)

BBC Wildlife 75

EVOLUTION

April 2020

that pizzlies are breeding

and bringing up young. In

2010, when a pizzly bear

was shot in the Canadian

Arctic, genetic tests revealed

that the animal was, in

fact, a second-generation

individual with a grizzly

father and a pizzly mother – a grizzly

pizzly bear.

From the mules engineered by ancient

Greeks to the cattle-bison crosses or

‘beefalo’ produced in North America

today, humans have a long history of

creating hybrids. It’s another way that

our species influences evolution, and

the pizzly bear is just one example.

the temperature continues

to increase.

For those species that fail

to adapt, it is the end of the

road. Scientists estimate

that dozens of species

go extinct every day, and

that extinction rates are

a thousand times greater

than during pre-human

times. These losses are

our doing. Meanwhile,

the survivors are racing

to keep up with the pace

of environmental change.

Human activity is causing

evolution to speed up,

fuelling the emergence

of novel characteristics,

new species and bizarre hybrids.

Meeting in the middle

In the far north, as the sea-ice melts,

polar bears are moving southwards,

whilst grizzly bears are expanding their

range to the north. Somewhere in the

middle, the two species are meeting

and mating. The result is a hybrid with

characteristics of both parent species.

Left: the white-footed

mouse is adapting to

be better suited to a

New York diet. Above:

poaching is leading

to the decline of large

tusks in elephants.

Pizzly bears, as they are called, have
the slender neck of a polar bear but the
humped shoulders of a grizzly. They
have intermediate-coloured fur and
feet that, in appearance, fit somewhere
in-between the flat paddles of the Arctic
species and the clumpy stompers of its
North American relative.
No one knows how common or
otherwise this oddity is, but we do know
Narwhal: Dorling Kindersley/Getty; Darwin: GL Archive/Alamy; kakapo: Frans Lanting/FLPA; tusks: Christian Heinrich/Imagebroker/FLPA; mouse: Mark Mo

ett/Minden/Alamy

Positive change

Conservati ed to steer shaky

evolution onto positive

footings. T case in point.

Decimatedb pecies that plague

itsnative NewZealand,theflightless parrot hit

anall-time low in 1995 when just 51 remained.

Now,thanks to an intensive conservation

project that marries traditional techniques,

suchas habitat management, with innovative

technologies, such as assisted reproduction, the

population has grown to 211. Last year, scientists

finishedmapping the full genetic codes of all adult

individuals, and now the information will be used to

helpguide future matings to create the healthiest,

mostgenetically diverse group of birds possible.

he

ong

ed

byhumans.