Not many insects inhabit Antarctica. To put in perspective, while over one million insect species have been described, only a couple of hundred occur in the southernmost continent.

In the 1960s, Eretmoptera murphyi, which another terrestrial chironomid, was accidentaly introduced to Signy Island (part of the Maritime zone) (Cranston 1985). Over the next few decades, the Signy population exploded and now they contribute more to the soil nitrate than all invertebrate species combined (Hughes et al., 2013). Although this would typically be a benefit, a rich-nutrient soil may facilitate biological invasions, which is an alarming concern in the Antarctic fragile ecosystems (Frenot et al., 2008).  

Maritime Antarctica is arguably more environmentally challenging relative to sub-Antarctic islands. However, some studies suggest that E. murphyi's stress tolerance limits are inconsistent with the environmental conditions that it experiences in its native habitats, and so its impressive ability to tolerate environmental stress probably played an important role in permitting its establishment in Signy. 

Map of the Northern portion of the Antarctic Peninsula and Southern portion of the Atlantic showing E. murphyi and B. antarctica distribution ranges (grey and black circles, respectively). A) Eretmoptera murphyi larvae, photo courtesy of the British Antarctic Survey. B) Eretmoptera murphyi female adult, photo courtesy of the British Antarctic Survey. C) Belgica antarctica larva. Photo: John-Michael Watson. D) Belgica antarctica adult male. Photo: Jack Devlin.

This is one of the projects I am most excited about, which is essentially trying to understand why chironomids are so tough

Eretmoptera murphyi and B. antarctica share many aspects of their biology, both are terrestrial, wingless, live two year life cycles, most of which is spent in the larval stage. Both species are also extremophiles, and so they can tolerate extreme levels of stress. Interestingly, they present stress limits that are inconsistent with the environmental conditions to which they are exposed to in a daily basis. 

While one would propose that this is due to their distribution ranges (ie they are became adapted to these extreme environments over their evolutionary history), chironomids hardly respect this "norm". For example, Frouz and Matěna (2015) have studied the desiccation tolerance of 6 aquatic and terrestrial chironomid species and found that they the aquatic ones could survive at least 50% of water loss. The terrestrial species were able to tolerate up to 86% of water loss before perishing.

Going back to E. murphyi and B. antarctica, these species have diverged at least 30 Mya (Allegrucci et al., 2012). In other words, B. antarctica is isolated in Antarctica for at least 30 Mya. So, I was curious about whether their environmental stress tolerance is a product of environmental adaptation or if the mechanisms allowing this impressive environmental physiology is actually conserved within the family.

The first step is to confirm my assumptions of the similar stress tolerance limits, so one of my dissertation chapters was on the following question: 

What are the limits of environmental stress tolerance for these midge species, and are these limits consistent with current range limits?

I hypothesized that environmental stress tolerance limits should be similar between them, but E. murphyi would present a higher ability to cope with heat stress due to its northern distribution range while B. antarctica would present a higher ability to cope with cold stress given its southward extending range.

This part of the project is completed, written up and in review. hopefully will be ready for public access soon! stay tuned!!