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Little is known about exotic earthworms (Oligochaeta: Lumbricidae) in Alaska outside its southeastern panhandle. This study documents the distribution of exotic earthworms in the relatively undisturbed Kenai National Wildlife Refuge (KNWR), a large, primarily wilderness refuge in southcentral Alaska. We sampled 69 sites near boat launches, along road corridors, and in low human impact areas > 5 km from the road, finding three species of earthworms (Dendrobaena octaedra, Dendrodrilus rubidus, and Lumbricus terrestris). Most road sites (90%) and boat launches (80%) contained earthworms; half (50%) of low human impact sites contained earthworms. Distance to roads was the only significant factor in predicting earthworm occurrence; soil pH, soil moisture, leaf litter depth, and vegetation cover were not. The disparate distributions of these three species suggest that within the KNWR road construction and vehicle traffic played a role in dispersal of the widespread, abundant Dendrobaena octaedra and uncommon Dendrodrilus rubidus; bait abandonment appeared to be the primary method of introduction of Lumbricus terrestris. While the distribution of harmful anecic earthworms in KNWR is currently limited, the prohibition of Lumbricus spp. as bait within conservation units in Alaska may be warranted. [ABSTRACT FROM AUTHOR]

We investigated the genetic makeup of Lutz spruce, a natural hybrid between white and Sitka spruce on the Kenai Peninsula, Alaska. Microsatellites indicate 72% of individuals sampled had predominantly white spruce ancestry, whereas 14% had predominantly Sitka spruce ancestry; some individuals classified as white spruce had Sitka spruce plastid genotypes. As Picea mitochondria are maternally inherited and plastids are paternally inherited, it appears that white spruce was the ancestral seed parent of nearly all spruce on the western peninsula, whereas Sitka spruce alleles originated from pollen. Pollen records show that white spruce colonized the western peninsula ∼8500 YBP from glacial refugium, whereas Sitka spruce arrived on the eastern peninsula ∼4000 YBP after migrating up the Pacific coast. Our data suggest that Sitka spruce colonization west of the Kenai Mountains may have occurred not via seed dispersal but by long distance transport of wind-borne pollen and subsequent hybridization with established white spruce populations. Hybridization was an important mechanism that allowed Sitka spruce to expand the leading edge of its range in response to historical climate change. As the climate continues to warm, climate envelope modeling suggests Lutz spruce may ultimately displace white spruce on the western peninsula even as Sitka spruce is constrained to the eastern peninsula where it will continue to hybridize. [ABSTRACT FROM AUTHOR]