TAXONOMIC AND POPULATION STATUS OF THE CLAYTON’S COPPER BUTTERFLY (LYCAENA DORCAS CLAYTONI)

TAXONOMIC AND POPULATION STATUS OF THE CLAYTON’S COPPER BUTTERFLY (LYCAENA DORCAS CLAYTONI)

By Emily S. Knurek

Thesis Co-Advisors: Dr. Judith Rhymer and Dr. Frank Drummond

An Abstract of the Thesis Presented

in Partial Fulfillment of the Requirements for the

Degree of Master of Science

(in Ecology and Environmental Science)

May, 2010

The Clayton’s copper butterfly was described as a distinct subspecies based on presumed physical differences with the closely-related Dorcas copper butterfly (Brower 1940). In 1997, Clayton’s copper was listed as endangered in Maine because it is known from few sites statewide, was thought to be abundant at only 1-2 sites, occurs in an uncommon habitat type, and its global range is nearly confined to Maine (Swartz et al. 2001). This research aimed to address fundamental questions about Clayton’s copper, specificallyto clarify its taxonomic status and to estimate size of subpopulations in Maine. These data aid in determining the global conservation status of Clayton’s copper and inform conservation efforts at the state level.

            Concern about whether Clayton’s copper is a valid subspecies was the impetus for exploring its taxonomic status in relation to the Dorcas copper as well as other closely-related butterfly subspecies and species. I conducted statistical comparisons of wing measurements detailed in original taxonomic descriptions and estimates of wing shape geometry. Additionally, two molecular genes were sequenced to explore genetic relationships among these closely-related butterflies.

Individual species and subspecies could be reliably identified in most cases, including Clayton’s copper, based on wing comparisons. There was little or no difference, however, among subspecies and species based on genetic relationships examined. These incongruent findings between wing characteristics and genetic data suggest that some taxonomic revision may be required, however, defining taxonomic boundaries is not clear-cut.

I conducted field studies in 2007 and 2008 to estimate the size of eight Clayton’s copper sub-populations. With the exception of Maine’s largest occurrence, counts to estimate population density had not previously been done (Webster and Swartz 2006). I quantified the area of shrubby cinquefoil habitat at each site, and estimated site-specific butterfly abundance with distance sampling methods.

Distance sampling was a useful method for calculating baseline density estimates. Estimates from distance sampling can also be back-calculated into Pollard indices if a simpler method is desired. Analysis of dispersion patterns indicated that butterflies aggregate in habitat patches. These results provide baseline information for future study of butterfly and host plant population dynamics at each site.