POST-GLACIAL DISTRIBUTION PATTERNS

There is no fossil record of Lepidoptera from glacial or post-glacial times in the Mixedwood Plains Ecozone, and few Lepidoptera fossils from these times are known from anywhere in North America. As a result, our knowledge of glacial and post-glacial distribution patterns must be deduced from what is known from the botanical record and by determining whether or not the present day patterns suggest that the Lepidoptera have tracked the botanical patterns. For example, a post-glacial warming trend that reached its peak about 7000 years ago and resulted in the expansion of the prairie into northeastern North America (Lafontaine, 1982). Disjunct remnants of this "prairie peninsula" persist across northeastern United States and southern Ontario. Collections of Lepidoptera from relict prairie in southern Ontario (e.g. Windsor Prairie, Pinery Provincial Park) demonstrate prairie species followed this post-glacial expansion and occur in these areas today. This assumption is more reasonable than proposing that prairie species have dispersed from the west and colonized these habitats more recently since even small patches of habitat will support small populations of Lepidoptera that are unlikely to have found these areas through dispersal. Most moths that are associated with prairie habitats and occur in southern Ontario are in the family Noctuidae is much more diverse in aridlands in central and western North America than are other groups of Lepidoptera and makes up the majority of the relict praririe species in the Ecozone. Many of these prairie species persist in dune habitats; the best collected of these are in the vicinity of Pinery Provincial Park near Port Franks on Lake Huron and near Port Colborne on Lake Erie but dune species are also known to occur at Presqu'ile Provincial Park and Sandbanks Provincial Park on Lake Ontario. Prairie species of Cutworms (Noctuidae) in dune habitats near Port Colborne and Port Franks are listed in Table2.

TABLE 2. NOCTUIDAE OF RELICT PRAIRIE DUNES

SPECIES	PORT COLBORNE	PINERY PROV. PK.
Abagrotis orbis *		X
Anathix aggressa		X
Eucoptocnemis fimbriaris		X
Euxoa manitobana		X
Euxoa aurulenta	X	X
Oligia obtusa	X	X
Oncocnemis riparia	X	X
Papaipema aweme		X
Protorthodes incincta		X
Schinia gloriosa		X
Trichoclea artesta	X	X

* Also in dunes at Presqu'ile Provincial Park on Lake Ontario





Several Pyralidae (Loxocrambus awemensis, Thaumatopsis pectinifer, and Macalla zelleri) are also associated with these two dune areas.

Another example of post-glacial relict distributions is the occurrence of boreal zone species in the southern part of the Ecozone. Most of southern Ontario was covered with boreal forest following deglaciation; this habitat moved northwards as the climate ameliorated and was replaced by mixed and deciduous forests that moved into the area from the south. Disjunct remnants of these boreal plant communities, and their associated Lepidoptera species, persisted in the south, usually in bogs. Examples are Bog Copper (Lycaena epixanthe), Dorcas Copper (Lycaena dorcas), and Pink-edged Sulphur (Colias interior) in southern Ontario, Chryxus Arctic (Oeneis chryxus) in the Ottawa Valley and Frontenac Axis in eastern Ontario, and Jutta Arctic (Oeneis jutta), and the noctuids Syngrapha montana and Anarta luteola in the Mer Bleue Bog near Ottawa.

The Olive Hairstreak (Callophrys gryneus) is an example of a species that has probably moved into the Ecozone both in post-glacial times and in recent times. This butterfly occurs in Red Juniper stands on the north shore of Lake Erie (mainly at Pt. Pelee), in southeastern Ontario (Gananoque to Belleville), and in the Ottawa Valley in western Quebec. In western Quebec it is associated with a disjunct population of Red Juniper believed to be a relict stand dating from the post-glacial climatic optimum when the Champlain Sea occupied most of the Ottawa Valley (Brunton and Lafontaine, 1967). Its occurrence in southeastern Ontario, however, is probably a more recent event associated with the spread of Red Juniper in the area as forests were cleared for farming. Most Red Juniper in this area, and the colonies of Olive Hairstreak, are on abandoned farmland.

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