PERSISTENCE OF BRANCHINECTA PALUDOSA (ANOSTRACA) IN SOUTHERN WYOMING, WITH NOTES ON ZOOGEOGRAPHY

Abstract

The fairy shrimp Branchinecta paludosa is a persistent resident of aestival ponds at high elevation in the Medicine Bow Mountains of southern Wyoming. These populations are far removed from the Arctic tundra habitat that typifies the distribution of the species, and appear to represent the southern margin of the range in North America. All of the records for the northern United States and southern Canada appear to lie along the Central Flyway that is a major migration route for waterfowl and shorebirds that nest in the Arctic. Passive dispersal probably provides for frequent colonization of marginal habitats and gene flow to established populations.