One fly to rule them all: Flies are the key pollinators of the High Arctic

Date: September 28, 2016

Source: Swedish University of Agricultural Sciences (SLU)

Forget the view of the Arctic as an icy desert devoid of life. The Arctic summer is buzzing with insects -- and here as everywhere else, plants rely on them for pollination. But who are the insects driving the pollination services across the Arctic? A new study finds the biggest heroes among the most modest of animals: small flies related to our common house fly. This finding offers cause for concern, as arctic fly abundances are declining as the Arctic continues to warm.

Some flies are more important than others

Researchers from Finland, Sweden, Denmark and Canada have focused on a single but common arctic plant: the mountain avens (Dryas). They first recorded what insects visited the flowers of avens at 15 sites in northeast Greenland, then returned to score the seed set of these flowers. The results were clear: the more of the house fly -like flies (family Muscidae) that were present, the more flowers set seed. And even among these flies, a single super-hero emerged: what best explained seed set was the abundance of a single fly, Spilogona sanctipauli.

A new use for fly paper

To record the insects visiting a plant, the researchers invented a new solution. "Instead of staring on flowers for hours, waiting to see who sat down on them, we constructed self-trapping flowers," explains Mikko Tiusanen, lead author of the study. "For this, we used something very similar to fly paper -- the sticky traps used to catch e.g. insect pest in green houses. In our case, we cut this sticky paper into natural-looking flowers, and hid them among the real flowers."

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Canada’s High Arctic Is No Longer a Safe Haven for Polar Bears

As climate change has accelerated, scientists have long believed that Canada’s far north would serve as polar bears’ last sanctuary.

No longer. New research from the University of Alberta has found that as their ice habitat disappears, polar bear populations in the Canadian Arctic Archipelago might be no better off than their southern counterparts.

The entire region’s polar bear population could face starvation and reproductive failure by 2100, crossing the “point of no return,” according to the study.

“The previous work on the long-term trends in polar bear habitat indicated that the high Arctic was a likely refuge for polar bears,” Andrew Derocher, a biology professor and coauthor of the study, said in an email.

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Mammal and Bug Food Co-Op in the High Arctic

Apr. 24, 2013 — Who would have thought that two very different species, a small insect and a furry alpine mammal, would develop a shared food arrangement in the far North? 

University of Alberta researchers were certainly surprised when they discovered the unusual response of pikas to patches of vegetation that had previously been grazed on by caterpillars from a species normally found in the high Arctic. 

U of A biology researcher Isabel C. Barrio analyzed how two herbivores, caterpillars and pikas, competed for scarce vegetation in alpine areas of the southwest Yukon. The caterpillars come out of their winter cocoons and start consuming vegetation soon after the snow melts in June. Weeks later, the pika starts gathering and storing food in its winter den. For the experiment, Barrio altered the numbers of caterpillars grazing on small plots of land surrounding pika dens. 

"What we found was that the pikas preferred the patches first grazed on by caterpillars," said Barrio. "We think the caterpillar's waste acted as a natural fertilizer, making the vegetation richer and more attractive to the pika." 

U of A biology professor David Hik, who supervised the research, says the results are the opposite of what the team expected to find. 

"Normally you'd expect that increased grazing by the caterpillars would have a negative effect on the pika," said Hik. "But the very territorial little pika actually preferred the vegetation first consumed by the caterpillars." 

The researchers say it's highly unusual that two distant herbivore species -- an insect in its larval stage and a mammal -- react positively to one another when it comes to the all-consuming survival issue of finding food. 

Read on: http://www.sciencedaily.com/releases/2013/04/130424161114.htm

Climate Events Drive High-Arctic Vertebrate Community Into Synchrony: Extreme Weather Potent Force for Arctic Overwintering Populations

Jan. 17, 2013 — Climate change is known to affect the population dynamics of single species, such as reindeer or caribou, but the effect of climate at the community level has been much more difficult to document. Now, a group of Norwegian scientists has found that extreme climate events cause synchronized population fluctuations among all vertebrate species in a relatively simple high arctic community. These findings may be a bellwether of the radical changes in ecosystem stability that could result from anticipated future increases in extreme events.

The findings are published in the 18 January issue of Science.

The Norwegian scientists, with lead authors from the Centre for Conservation Biology at the Norwegian University of Science and Technology (NTNU), wanted to know how climate and weather events influenced an overwintering vertebrate community on the high arctic island of Spitsbergen, Svalbard, at 78 degrees N latitude.

They chose this simple ecosystem because it is composed of just three herbivores in the winter -- the wild Svalbard reindeer (Rangifer tarandus platyrhynchus), the Svalbard rock ptarmigan (Lagopus muta hyperborea), and the sibling vole (Microtus levis), and one shared consumer, the arctic fox (Vulpes lagopus).

The community's population fluctuations were mainly driven by rain-on-snow events, the researchers found. Rain-on-snow is an extreme climatic occurrence that causes icing on the deep-frozen arctic tundra. The ice keeps reindeer from grazing on their winter pastures and also reduces food accessibility for the rock ptarmigan and sibling vole populations, causing extensive simultaneous population crashes in all three species in the winter and spring after the extreme weather.

Read on: http://www.sciencedaily.com/releases/2013/01/130117142458.htm