Geography, environment, and colonization history interact with morph type to shape genomic variation in an Arctic fish.

Polymorphic species are useful models for investigating the evolutionary processes driving diversification. Such processes include colonization history as well as contemporary selection, gene flow, and genetic drift, which can vary between intraspecific morphs as a function of their distinct life histories. The interactive and relative influence of such evolutionary processes on morph differentiation critically informs morph-specific management decisions and our understanding of incipient speciation. We therefore investigated how geographic distance, environmental conditions, and colonization history interacted with morph migratory capacity in the highly polymorphic fish species, Arctic Charr (Salvelinus alpinus). Using an 87 k SNP chip we genetically characterized recently evolved anadromous, resident, and landlocked charr collected from 45 locations across a secondary contact zone of three charr glacial lineages in eastern Canada. A strong pattern of isolation by distance across all populations suggested geographic distance principally shaped genetic structure. Landlocked populations had lower genetic diversities and higher genetic differentiation than anadromous populations. However, effective population size was generally temporally stable in landlocked populations in comparison to anadromous populations. Genetic diversity positively correlated with latitude, potentially indicating southern anadromous populations' vulnerability to climate change and greater introgression between the Arctic and Atlantic glacial lineages in northern Labrador. Local adaptation was suggested by the observation of several environmental variables strongly associating with functionally relevant outlier genes including a region on chromosome AC21 potentially associated with anadromy. Our results demonstrate that gene flow, colonization history, and local adaptation uniquely interact to influence the genetic variation and evolutionary trajectory of populations.

New Geographic Records for Trichinella nativa and Echinococcus canadensis in Coyotes (Canis latrans) from Insular Newfoundland, Canada.

Coyotes (Canis latrans) rapidly expanded across North America during the 20th century and in 1987 colonized insular Newfoundland, Canada. Their arrival brought the potential for new predator-prey interactions and the potential for transmission of parasites to naïve populations. Trichinella spp. and Echinococcus spp. are zoonotic parasites not previously reported from the island of Newfoundland, Canada. Muscle samples (diaphragm and tongue) from 153 coyotes and feces from 35/153 coyotes were collected. Larvae of Trichinella spp. were recovered by muscle digestion from 6/153 coyotes (3.9%) and identified using multiplex PCR and Sanger sequencing as T. nativa. Fecal samples were screened for DNA of Echinococcus spp. using qPCR, and intestines from positive animals were examined for adult cestodes. No fecal samples were positive for DNA of E. multilocularis, and 2/35 (5.7%) samples were positive for E. canadensis, of which one was successfully genotyped as the G10 cervid strain. Echinococcus canadensis has not previously been reported on the island of Newfoundland, historically the only region of Canada where Echinococcus spp. was not known to occur. No species of Trichinella have previously been reported on the island. Both parasites are zoonotic, and hunters, trappers, dog owners, and the general public should be aware of these new risks for public health.