I was giving a tour of the museum last week to some alumni who were back on campus for Homecoming and somebody asked me that question. The Lyman Museum has in the neighborhood of three million specimens, but we have nowhere near three million species. So why do we have hundreds of specimens of a little black milichiid fly called Paramyia nitens? Why do we have drawers full of Monarch butterflies? We have long series of many of the insects represented in our collection, from grasshoppers and ground beetles to bumble bees and ladybird beetles. But WHY? It’s a question that museum scientists and staff hear a lot, especially when somebody wonders why those museums take up so much space. Well, here’s why . . .
Every specimen in a natural history collection is unique. It carries its own characteristic traits, its own DNA, its own label with data about where and when and how it was collected. Each insect in a collection is a unique, irreplaceable volume of biodiversity information. Just as each human is different and distinct, each Bombus affinis (that’s a bumble bee for the non-entomologists out there) is unique and distinct. So by having more than one specimen of a given species, we have the ability to address all sorts of questions about insects and their environment.
1. We can analyse traits of multiple specimens within a species to determine the range of variation in particular characteristics. This allows us not only to get a better picture of differences between and within species, but also to plot out variation in size, colour and shape across the geographic range of a species. This gives us a more complete picture of what each of these species really “is”.
2. Methods for extracting DNA from museum specimens are improving all the time, such that we can now study differences in DNA sequence data from specimens in widespread or variable species. Such studies can often open a window into the presence of closely-related cryptic species within an otherwise externally similar “species”. Beyond this, genetic evidence can give us valuable information about the time and place of origin of particular populations. In a place such as Canada, where just about every species came from somewhere else following the retreat of the glaciers 10,000 years ago, and where more species are coming in all the time, those are very relevant questions.
3. We can use museum specimens for ecological analyses that incorporate the abundance of species. With a good insect collection, we can reconstruct changes in the insect community of habitats and sites that have been altered drastically (by humans or by natural processes) since the first historical collections were made there. In our collection, for example, we have specimens collected in the 1800s from fields and forests that are now part of downtown Montreal.
4. Using collection dates from specimen labels we can monitor the decline of threatened and endangered species. We have lots of specimens of the aforementioned Bombus affinis from southern Quebec in the 1960s, but no recently collected specimens at all. In fact, Bombus affinis has declined dramatically in southern Canada in recent years to the point that it now listed as Endangered. At the same time, we can monitor the spread and increasing abundance of introduced and invasive species. Some of the first records of many well-known invasive species are specimens in insect collections. We can walk through the collection, pull out drawers and see the Cabbage White butterfly arrive in Quebec from Europe in the 1860s, or see new European ladybird beetles move up the St-Lawrence River over the past few decades. At the same time we can track the decline of the American Burying Beetle or the Giant Lacewing, represented now by a few old specimens and nothing new.
An insect collection is far from a static thing. It’s a picture of change.