Botanical discoveries in northern B.C. alpine
This is one of a series of columns by specialists at the Royal B.C. Museum that explore the human and natural worlds of the province.
Have you ever wondered what B.C. looked like during the Pleistocene era, when the climate was generally colder and glaciers periodically advanced to cover the land and then melted, perhaps as many as five times? What did the land look like when the glaciers melted for the last time, about 14,000 years ago? Where did the species come from that now occur in B.C.?
Research often begins with a question. In our case the question is: What species of plants occur in the remote northern B.C. alpine (the land above the trees), where very little collecting has been undertaken?
Among other activities, museum-based taxonomists collect specimens to document the distribution of species at a particular place and time. Land managers depend upon knowledge of current and past distributions to evaluate the status of species — for example, to determine whether a species is invasive, or to assess whether it is rare and possibly needs protection. Species distributions also reflect something about landscape history.
Research sometimes begins by questioning a dogma. In our case, we are questioning the dogma that all of B.C. was covered by ice during the most recent ice advance.
I’ll illustrate a little about how we do our work and a couple of stories about what we have learned from our collections and from our DNA analysis, undertaken with a colleague at the University of Victoria.
In 2016, a group of Royal B.C. Museum scientists collected plant specimens in Sustut Provincial Park. The specific locations are identified by yellow triangles on the map. Our goal, when conducting fieldwork, is to collect specimens of every species we encounter. To do this, we try our best to visit all of the different habitats present, working as a team to divide up the landscape, being as efficient with our time as possible.
At each of the yellow triangles, we spent from a few minutes to two hours making collections and recording information about the location and habitat. At the end of each day, we pressed the specimens and put them in our portable plant dryer in order to preserve them to add to the museum’s collection.
After the specimens were identified from the fieldwork in Sustut, we provided B.C. Parks with a comprehensive list of species. We now have similar lists from many mountains in northern B.C., and are starting to do some preliminary analyses, comparing the lists from every mountain we’ve visited to determine which mountain ranges are most similar (in terms of the species that occur there) and which are most different.
This kind of geospatial analysis can inform larger questions about the history of the landscape, and provides very practical information. For example, it can identify areas of high species diversity and locations of rare species.
Here are a couple of examples of what we are learning.
In 2014, we collected a little gentian from Northern Rockies Provincial Park. At the time, I thought I had collected a different species, but when we returned from the field, using an identification guide written by a taxonomist who is a specialist in this genus, I realized that I had collected a really rare plant — one that I was vaguely aware of but had never seen before.
The nearest known location for this species is 1,000 kilometres south, in Cathedral Lakes Provincial Park, at the border between Washington and B.C. It has an astonishing global distribution, occurring in North America, Europe and Asia, as well as the Atlas mountains of Morocco.
There’s got to be an interesting story behind this distribution: How and when did it reach locations that are so far apart? Is the population that we discovered a remnant of a once much more widespread distribution? Did it survive here through the most recent ice advance? I chose to include this species in the Royal B.C. Museum’s Species at Risk mini-museum exhibition because it illustrates the need for additional fieldwork to learn more about the distribution of plants in B.C.
The second story is of a plant called Sibbaldia, a species that occurs throughout the northern hemisphere. This is one of the species for which we have used DNA analysis to trace its migration. Shown here is a summary of a whole lot of DNA-sequence data.
Each dot represents a location from which a sample was obtained. The red dots represent locations where fresh tissue was collected. The black dots are samples that were taken from specimens at the University of Colorado museum — important to include because they filled in some geographic gaps for places we could not reach ourselves.
Our results indicate that this species migrated into North America from Asia, some time during the past two million years. Once here, it spread southward through B.C. and into the U.S. along the Rocky Mountains and the Sierra Nevada of California. Long after it reached these southern locations and possibly before the most recent ice advance, it moved northward back through B.C. into the Arctic.
We think it moved from south to north (rather than the reverse) because most of the genetic diversity is present in the south. Each colour in the larger circles represents a different genetic type. As any species spreads from one location to the next, there is a loss of genetic diversity; this is because each time a new population is started by a few individuals, they bring with them only a portion of the genetic diversity of the parental population.
Our followup question is whether or not there is evidence that populations of this species existed within B.C.’s borders during the most recent ice advance. The yellow/green dots, marking the locations of the oldest genetic types, provide some insight into this. Their occurrence in northern B.C. is evidence that somewhere in this area there likely were places not covered by ice.
In conclusion, I ask you to consider the slender gentian again. We humans sometimes view other species in terms of their utility for us. It is known that some gentians have medicinal usages. This plant might also have medicinal uses — but it might not.
Does it, therefore, have no value, no purpose in its existence? Or does the knowledge of this little plant, growing in the heart of B.C.’s northern Rockies, inspire your own curiosity and wonder? Does this knowledge enhance your own humanity and sense of responsibility to care for the other organisms with which we share this very thin, spherical layer of life? What do you think?
Ken Marr, PhD, has been botany curator at the Royal B.C. Museum since 2001. He is especially interested in the classification, biogeography and conservation of terrestrial vascular plants, in particular the alpine flora of northern B.C.