SNIPPETS

Mite and ant locked together in amber

This ancient ant and its parasitic overlord were trapped together for eternity when they became engulfed in tree resin in the Baltic region, sometime between 49 million and 44 million years ago. This is only the second known example of a fossilised mite attached to its host. The 0.7mm-long mite and its victim are preserved in amber, which is fossilised tree resin.

The mite appears to be firmly attached to the ant’s head – a behaviour also seen in modern parasitic mites of the genus Varroa, which are often mentioned as possible culprits in the sudden collapse of honeybee colonies. Although it is difficult to say for sure, the ancient mite was probably a parasite, too, says Jason Dunlop, an arachnologist at the Leibniz Institute for Evolution and Biodiversity Science in Berlin.

“The amber mite looks very similar to modern mites, so we presume it had a similar mode of life and was parasitising the ant rather than attacking it directly,” he says. Dunlop and his collaborators identify the mite as belonging to the genus Myrmozercon, which includes numerous species still alive today.
An air bubble trapped between the two invertebrates hides some anatomical features, making it hard to identify the exact species. Mites are arachnids, a class of eight-legged arthropods that includes spiders and scorpions.“People who work on this group think that the mites suck the body fluids of the ants from time to time,” says Dunlop.

“The ant also carries the mite around, so that when baby mites hatch they can also crawl onto ants and be transported into the ant nest.” Dunlop received the specimen last year from Jörg Wunderlich, a German amateur arachnologist and former schoolteacher whose extensive amber collection is held in part by the Naturmuseum Senckenberg in Frankfurt. “When he buys amber, he examines it carefully for spiders, which he keeps for his own work,” Dunlop says. “But if he finds something like a mite or a harvestmen (another group of arachnids), he often sends it to me.”
Davide Castelvecchi


Warming trends of a heated planet
With high-level talks over a new international climate agreement beginning in Lima, Peru, it’s worth reviewing some basic points about climate change driven by the buildup of human-generated greenhouse gases. One, of course, is that the growing human influence on the system remains mixed in with a lot of natural variability in conditions.

At RealClimate, Stefan Rahmstorf of Potsdam University has written a fresh and detailed review of studies showing that global warming is still under way despite the recent pause in the planet’s mean temperature. The piece comes shortly after the World Meteorological Organization released its near-final analysis of 2014 climate conditions, noting that this year will likely end up the warmest since regular record-keeping back in the late 1800s.

Here’s the take-home section of Rahmstorf’s post: The warming since 1998 is not significantly less than the long-term warming. So while there has been a slowdown, this slowdown is not significant in the sense that it is not outside of what you expect from time to time due to year-to-year natural variability, which is always present in this time series.

Given the warm temperature of 2014, we already see the meme emerge in the media that “the warming pause is over”. That is doubly wrong – there never was a significant pause to start with, and of course a single year couldn’t tell us whether there has been a change in trend. Rahmstorf added another RealClimate post today on a new graph created by his colleagues at the German KlimaLounge blog as a visual rebuttal to a graph created in 2009 by Anthony Watts, the online aggregator of anything questioning the significance of global warming.

A graph posted by the RealClimate and KlimaLounge blogs tracks temperature, carbon dioxide levels and solar activity.

In the spirit of seeking clarity amid all the noise on such questions, it’s worth reposting the best animation I’ve seen explaining the difference between a trend and variation — in a way that even a member of Congress might grasp: There are critics of this approach. But I see it as a simple way to explore a really important concept.



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