Sharks, sheep and viruses

Three recent conservation biology-type papers worth a look:

Do shark declines creat fear-released systems?
A model sugesting that if you take pacific sleeper sharks out of the ocean, seals swim deeper, and eat more pollock - which live deep - and fewer herring.

Are cattle, sheep, and goats endangered species?
The "rise of the breed" 200 years ago, followed by more recent selection for increased productivity has led to a dangerous drop in the genetic diversity of domestic animals. "Many industrial breeds now suffer from inbreeding, with effective population sizes falling below 50... It is therefore important to take measures that promote a sustainable management of these genetic resources; first, by in situ preservation of endangered breeds; second, by using selection programmes to restore the genetic diversity of industrial breeds; and finally, by protecting the wild relatives that might provide useful genetic resources."

(Andrew Marr says that whenever you see a newspaper headline ending in a question mark (Is this the most evil man in Britain?; Are working mothers poisoning their children? and so on) you should answer 'no'. I'm not sure if the same applies for the scientific literature.)

Barley yellow dwarf viruses (BYDVs) preserved in herbarium specimens illuminate historical disease ecology of invasive and native grasses
Invasive species are often thought to thrive because they escape all the diseases and predators that keep them in check back home. But this study suggests that the diseases that invaders bring with them are just as important as the ones they leave behind.

In California, over the past two centuries European grasses have almost completely displaced the native prairie. Carolyn Malmstrom and her colleagues think that one factor in their success was the viruses they brought with them. For example, they have previously shown that native grasses growing alongside exotics have higher levels of cereal yellow dwarf viruses.

But this doesn't put the viruses at the scene of the crime. Now they've taken a step towards that (although how you ever prove such an idea, I don't know). Using herbarium specimens from 1917, they have recovered some of the oldest plant viral sequences so far and, by comparing them with European relatives, show that the disease probably showed up along with the plants — and also hopped from California to Australia in the late nineteenth century — and may have been a useful ally in the invaders battle against the natives.