Hot ice crawlers

I enjoy reading older literature for many reasons. I love the “time capsule” aspect of it, as I get a glimpse into what people were thinking in decades (or centuries) past. I also enjoy finding little bits of information that have served as part of the foundation for ongoing current study – or that could spark new inquiry.

As editor of the Journal of the Entomological Society of British Columbia, I am often on the journal website taking care of journal business. While there I sometimes delve into the archives and see what I can find.

(The archives, by the way, are almost complete thanks to the tireless work of Alex Chubaty and a small army of other volunteers. Only a bit more work, and we’ll have the entire century-plus natural history record of JESBC online. Exciting!)

While poking around the archives recently I came across this little gem of an article, written in 1945 by George Spencer and entitled “On the incidence, density, and decline of certain insects in British Columbia.” Since part of the research in my lab is on outbreaking insects – bark beetles – this title caught my eye.

Further reading brought me to this paragraph:

About 1937, J. D. Gregson found Grylloblatta campodeiformis Walk. at Kamloops in the talus slope of Mount Paul, at an elevation of 1,400 feet only. The face of this slope is one of the hottest spots in the Dry Belt and Grylloblatta seems to retreat into the cold interior of the rock pile during summer, coming out to the surface only when November cools down the countryside with sharp frosts. Its previous records were from Lakes Louise and Agnes and on Rundle Mountain, in the Rockies, Alberta, and in British Columbia, a reported record from Forbidden Plateau near Courtenay on Vancouver Island and at the top of Grouse Mountain near Vancouver. To find it in numbers at 1,400 feet at Kamloops, provides a most remarkable record of discontinuous distribution. It is probable that further collecting in this Province, in late autumn will show that Grylloblatta is widely distributed in locations similar to those occurring at Kamloops. The insect must have followed the skirts of the receding ice sheet 15,000 years ago and persisted in situations where it could retreat in summer time to near frozen spots deep in rock piles.

Grylloblattids have always fascinated me, although I have yet to see one alive in its natural habitat. It’s on my bucket list. Entomologists have strange bucket lists.

These creatures – often called ice crawlers – are a small group consisting of around three dozen known species. They live mainly in alpine regions and they are best suited to a narrow range of temperatures a bit above the freezing mark. They eat insects or other food items that are blown into their cold habitat from lower, warmer, and less desolate elevations. They do not do well at high temperatures – temperatures that you and I would think of as a nice day – so it was quite surprising to find these creatures in such a blazing hot location.

A bit of further digging in the JESBC archives pulled up a 1938 article by Gregson (“Notes on the Occurrence of Grylloblatta campodeiformis Walker in the Kalmoops District”) which provides great detail on the natural history and some of the early collections of this insect near to Kamloops. It makes for a fairly short, but fascinating and instructive read, giving some details on how this population may be able to survive summer surface temperatures above 40ºC.

So what has become of this information in the almost eighty years since Gregson’s description? As luck would have it, there are two very recent pieces reviewing what is known about grylloblattids. In one article, Schoville and Graening (2013) have developed an updated checklist of ice crawlers (and there have been some good collections made in the recent past), with copious information on their natural history. If you take a look at Figure 1 in their paper, you can see two lonely triangles near to Kamloops. In other words, over the decades the Mt. Paul population still seems to be rather isolated in its one little hot island.

In another recent (2014) paper by Schoville [“Current status of the systematics and evolutionary biology of Grylloblattidae (Grylloblattodea)”], you can see a photograph of G. campodeiformis (Figure 1) along with the known worldwide distribution of all species (Figure 2). Schoville also describes “a glacially driven alpine species pump within the Sierra Nevada mountains” and speculates as to whether it’s possible that past climate change explains the distribution of species in other parts of North America.

So, the Mt. Paul ice cralwers seem to constitute quite an interesting little population. Besides behavioral (and physiological?) adaptations to their harsh habitat, they are also seemingly quite isolated from any other populations. Can understanding why this is the case help us to understand past speciation events? Perhaps someone has done further research on this overall situation, and if so, I’d love to hear about it. But there seem to be a number of obvious questions here regarding the relationship of this population to other G. campodeiformis populations. And, of course, there are all sorts of other evolutionary, behavioral, physiological, and ecological questions to be considered as well.

As I wrote above, perhaps this has been studied in further depth, or perhaps studies are ongoing. If so, please point me in the right direction because I’d love to read further.

If not, it’s just another one of those zillions of projects out there waiting for someone to take it on.

And in either case, it outlines the value of an ongoing commitment to natural history research to uncover interesting situations and point to new research directions.