A beetle is a beetle is a beetle right? Not to a population biologist. This current epidemic contains millions of mountain pine beetles (MPB) spread across both Alberta and BC. Once beetles take flight each year in search of new trees, where do they go? Who is moving where? Is there anything different about beetles in different areas? These questions may prove crucial to our understanding of this and future outbreaks. However, before we can ask in depth questions we need a basic understanding of current beetle populations. Since we can’t just ask beetles these questions, we’re lucky that genomics offers tools which can help.

One of these tools has a name more suited to the exploration of outer space than of MPB, a microsatellite (no not that kind of satellite!!!). What is it and how is it used? Unless you happen to have an identical twin, variability in your DNA sequence can be used to distinguish you from the person next to you by looking at genetic markers. Microsatellites (one type of genetic marker) consist of tandem repeats of a specific nucleotide sequence present at fixed location in the genome (called a locus). These areas are prone to mutations which change to the number of repeats at that locus, altering its overall size. Over time, many different copies (alleles) of that locus are created and distributed throughout a population. When organisms reproduce, a single allele of the microsatellite locus is passed down from each parent to its offspring. Using the PCR reaction (another genetic tool), we can determine which alleles an individual has. The pattern of alleles they have creates a specific genetic signature called a genotype (you may also know this as a DNA fingerprint). When you compare the genotypes of different individuals, closely related individuals will have common alleles (e.g. mother/daughter). The more distant the relationship, the fewer common alleles there should be (e.g. fifth cousins).

If you’re thinking this is a forest based version of CSI, you’re not that far off. Like forensic science, population biologists use DNA sequence to help determine familial relationships and movement of individuals between populations. We can use microsatellites to provide basic information about the population structure of MPB in the present outbreak. They can also be used to tell when we are looking at something that is not a MPB as genetic markers can be created that are specific to the organism you’re looking at. Nice to have a backup when you’re looking at thousands of insects the size of a grain of rice.