BBC Wildlife - UK (2020-04)

76 BBC Wildlife April 2020

thesecouldbethefirstofmany

hybridisations that will threaten

polar biodiversity.

Going underground

Elsewhere, it’s not disappearance of

sea-ice but the emergence of cities that

is causing organisms to evolve. In the

mid-19th century, when workmen were

building the London Underground,

mosquitoes followed them down into

the fetid tunnels. The insects persisted

by feasting on the blood of rodents,

and of the poor London citizens who

sheltered on the platforms during the

Blitz. Then, 20 years ago, scientists

Katherine Byrne and Richard Nichols

analysed the insects’ DNA and found, to

their surprise, that mosquitoes from the

Central, Victoria and Bakerloo lines were

all genetically distinct.

As the scientists later explained, this

was because the different Tube line

populations were physically separate.

When the trains rumbled along, they

stirred up clouds of insects, but it was

almost impossible for the populations

to mix. The only way it could happen,

Byrne quipped, was if the insects

changed trains at Oxford Circus. Left to

their own devices, the insects had started

to evolve in subtly different directions.

In addition, the underground biters

were also genetically different to their

above-ground relatives, and in a nod

to their Blitz-biting shenanigans, the

subterranean strain was dubbed Culex

pipiens molestus. Now scientists

debate whether it is different

enough to be classified as a

separate species.

Similarly, in New York, the

growth of the Big Apple has fuelled

theevolution of the white-footed

mouse. A few hundred years ago,

thearea was covered in forests and

meadows, and the nimble rodents

that lived there formed one large

population. Then, as natural spaces

Humans might not have purposefully

forced the parent species together, but

we became their unwitting matchmaker

when we warmed the planet, melted the

sea-ice and caused their ranges to overlap.

The thawing Arctic is bringing other

species together, too. More than 30

possible hybridisations between discrete

populations and species of Arctic and

near-Arctic marine mammals have been

documented, including an apparent

bowhead-right whale hybrid and a

narwhal-beluga cross. At present, no one

knows what the long-term repercussions

of these clandestine trysts will be, but

it’s possible they will fuel the demise

ofalreadyvulnerablespecies,suchas

polarbear.Writinginthejournal

anKelly,AndrewWhiteley

n pointedoutthat

The beleaguered

black-footed ferret

may soon be more

resistant to disease.

Dabbling with DNA

Scientists are using molecular techniques to

alter the DNA of living things. For the most

part, this is done to aid medical research,

but now plans are afoot to deliberately

alter the DNA of certain wild species.

Researchers hope to edit the genome of the

black-footed ferret to make it resistant to a

deadly disease called the sylvatic plague.

Meanwhile, cloning has become

a tool of selective breeding. Argentine

polo player Adolfo Cambiaso, for

example, has made more

than a dozen copies of

his pony Cuartetera.