An undergraduate research study has found that a threatened type of beetle found in Saskatchewan and Colorado is in fact made up of two genetically distinct subspecies. The discovery has important implications for conservation efforts for the insects, and shows that both populations of Gibson’s big sand tiger beetle are more threatened than previously thought.
“In this study, we analyzed genetic relatedness to determine that Gibson’s big sand tiger beetle is made up of two subspecies rather than one,” said lead author Rowan French, who conducted the research during her undergraduate studies in the University of Alberta’s Department of Biological Sciences. “Our findings mean that both subspecies may be vulnerable to extinction due to their highly restricted ranges.”
Gibson’s big sand tiger beetle is a nationally threatened subspecies in Canada with an unusual geographic distribution. It is found almost exclusively in southern Saskatchewan, where it is found on pale-coloured sand dunes. Similar beetles also live in northwestern Colorado. The two regions are separated by more than 1,100 kilometres, but in spite of their separation, adult beetles from both areas are nearly identical in colour pattern and other traits.
In conservation biology, genetically discrete groupings are populations that may be in the early stages of evolving into separate species, and merit separate monitoring and conservation management, French explained.
“Across genetic data types and analyses, the Colorado populations were consistently distinguishable from Canadian populations,” said French. “This suggests that Cicindela formosa gibsoni is restricted to Canada, while the new subspecies—Cicindela formosa gaumeri—is restricted to Colorado. Thus, populations from those two regions are more genetically unique than previously recognized and may have independently evolved similar colour patterns.”
Solving a 50-year-old puzzle
This puzzle is almost 50 years old, first theorized in the unpublished 1977 PhD thesis of Grant Gaumer, who left academia soon after completing his PhD. As the team’s study was inspired by Gaumer’s thesis, they named the new subspecies Cicindela formosa gaumeri after him to honour his outstanding contributions to tiger beetle research.
French’s research was supervised by two experts in the field who are co-authors on the study: Felix Sperling, professor in the Department of Biological Sciences, and John Acorn in the Faculty of Agricultural, Life & Environmental Sciences’ Department of Renewable Resources.
The research team was also joined by co-authors Aaron Bell and Kiara Calladine from the University of Saskatchewan, who recently conducted the first population study of Cicindela formosa gibsoni in Saskatchewan and, before COVID-19, conducted a 6,400-kilometre trip across the United States and Canada to collect the necessary specimens for the genetic analysis.
“The Committee on the Status of Endangered Wildlife in Canada is in the process of reassessing the conservation status of the Canadian populations of these beetles,” said French. “We hope that our work will contribute to this reassessment and to management plans that aim to protect this unique subspecies.”
The study,“Genomic distinctness despite shared color patterns among threatened populations of a tiger beetle,” was published in Conservation Genetics.