History of the northern silvery blue (Glaucopsyche lygdamus couperi) (Lepidoptera: Lycaenidae) in southern Ontario, Canada: separating range expansion from original populations and other subspecies.

Layberry, R.A., Catling, P.M., and Schmidt, B.C. (2015). "History of the northern silvery blue (Glaucopsyche lygdamus couperi) (Lepidoptera: Lycaenidae) in southern Ontario, Canada: separating range expansion from original populations and other subspecies.", The Canadian Entomologist, 147(1), pp. 59-70. doi : 10.4039/tce.2014.26  Access to full text

Abstract

The historical distribution of Glaucopsyche lygdamus (Doubleday) (Lepidoptera: Lycaenidae) in southern Ontario, Canada was analysed using three major databases. In southern Ontario, G. lygdamus includes (1) subspecies G. lygdamus couperi Grote that has expanded its range from the north since the 1940s and 1950s reaching Hamilton, Ontario, Canada in 2012; (2) a non-expanding population on the Norfolk Sand Plain, Ontario, Canada that appears phenotypically closest to G. lygdamus couperi, but with some wing marking characters that are transitional to the more southern subspecies G. lygdamus lygdamus; and (3) rare and local pre-expansion populations referable to G. lygdamus couperi that occurred in the Ottawa Valley and Bruce Peninsula, Ontario, Canada in alvar woodlands, and possibly also on lakeshore dunes. The very rare and local occurrences of silvery blue in southern Ontario in the past is in direct contrast to its increasing abundance in the area in present times, but the genetic and phenotypic diversity of silvery blue may be declining due to genetic mixing with and/or to the effect of increasing parasitoids from the expanding race.

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