Steven M. Vamosi

In this study, we examined Pacific salmon decline and ecosystem function through Western science and Indigenous, Teslin Tlingit knowledge. We tested relationships of riparian tree growth and nitrogen composition at the limit of Pacific salmon distribution on the Teslin Tlingit Council (TTC) Traditional Territory in Southern Yukon, studied ecosystem roles of salmon and population declines in the area, and the interactions of these processes. Within sites, tree growth was positively related to salmon escapement at all salmon-bearing sites and not at the negative (salmon-free) control site. Mean δ15N was significantly higher at salmon-bearing sites compared to the negative control, showing similar patterns to comparable studies. Between sites, mean site tree growth did not show a clear response to salmon. Interviews conducted with Teslin Tlingit knowledge holders revealed measures of a healthy salmon run and large population declines that have negatively impacted local ecosystems (particularly bears, key to delivering salmon nutrients to terrestrial ecosystems) and human wellbeing on the Traditional Territory. Although this study was limited by available sites and data, we demonstrate that the health of salmon and riparian forests on the Traditional Territory are deeply linked, and the importance of considering multiple ways of knowing to improve ecological research.

Exotic species are one of the greatest threats to native species, communities, and ecosystems. Introductions of multiple exotic species into an environment may have different effects on native populations compared to when exotic species are introduced individually. Threespine stickleback species pairs ( Gasterosteus aculeatus ) and neighbouring solitary populations in southwestern British Columbia, a textbook example of an adaptive radiation, are now under threat from multiple exotic species. We assessed whether variation in morphological characters and body shape among solitary threespine stickleback populations was associated with different combinations of introduced smallmouth bass ( Micropterus dolomieu ) and signal crayfish ( Pacifastacus leniusculus ). We also examined morphological changes over time spans of 18-43 years to determine whether contemporary characteristics have responded to the presence of exotic species. We found clear differences in stickleback traits and body shape among exotic species combinations. Stickleback coexisting with bass and crayfish were highly armoured, whereas bass-only lakes contained stickleback with reduced armour. Two stickleback populations that coexist with signal crayfish showed significant increases in size over time. These patterns suggest that smallmouth bass and signal crayfish may have significant and different impacts on stickleback morphology.

Freshwater ecosystems are negatively impacted by a variety of anthropogenic stressors, with concomitant elevated rates of population decline for freshwater aquatic vertebrates. Because reductions in population size and extent can negatively impact genetic diversity and gene flow, which are vital for sustained local adaptation, it is important to measure these characteristics in threatened species that may yet be rescued from extinction. Across its native range, Bull Trout (Salvelinus confluentus) extent and abundance are in decline due to historic overharvest, invasive non-native species, and habitat loss. In Alberta's Eastern Slope region, populations at the range margin have progressively been lost, motivating us to better understand the amount and distribution of genetic variation in headwater habitats and some downstream sites where they continue to persist. Across this region, we sampled 431 Bull Trout from 20 sites in the Athabasca and Saskatchewan River basins and assayed 10 microsatellite loci to characterize within- and among-population genetic variation. The Saskatchewan and Athabasca River basins contained similar levels of heterozygosity but were differentiated from one another. Within the Athabasca River basin, five genetically differentiated clusters were found. Despite the evidence for genetic differentiation, we did not observe significant isolation-by-distance patterns among these sites. Our findings of ample genetic diversity and no evidence for hybridization with non-native Brook Trout in headwater habitats provide motivation to ameliorate downstream habitats and remove anthropogenic barriers to connectivity towards the goal of long-term persistence of this species.

Across its native range, Bull Trout ( Salvelinus confluentus ) extent and abundance are in decline due to historic overharvest and habitat degradation. Because Bull Trout are dependent on extensively connected, cold, clean headwater habitats, fragmentation from land use changes causes difficulty when determining the true extent and health of their populations, with Bull Trout of Alberta’s Eastern Slope region being no exception. Across this region, 431 Bull Trout from 20 sites were sampled from the Athabasca and Saskatchewan River basins and compared using 10 microsatellite loci to characterize within- and among-population genetic variation. The Saskatchewan and Athabasca River basins contained similar levels of heterozygosity but were differentiated from one another. Within the Athabasca River basin, five genetically differentiated clusters were found. Additionally, no isolation-by-distance pattern was observed between these sites. These results suggest these populations have ample genetic diversity, but genetic differentiation should be considered when deciding whether and how to alter connectivity between populations.

Background: Tetrodotoxin (TTX) is a potent neurotoxin used in anti-predator defense by several aquatic species, including the rough-skinned newt, Taricha granulosa . While several possible biological sources of newt TTX have been investigated, mounting evidence suggests a genetic, endogenous origin. We present here a de novo transcriptome assembly and annotation of dorsal skin samples from the tetrodotoxin-bearing species T. granulosa , to facilitate the study of putative genetic mechanisms of TTX expression. Findings: Approximately 211 million read pairs were assembled into 245,734 transcripts using the Trinity de novo assembly method. Of the assembled transcripts, we were able to annotate 34% by comparing them to databases of sequences with known functions, suggesting that many transcripts are unique to the rough-skinned newt. Our assembly has near-complete sequence information for an estimated 83% of genes based on Benchmarking Universal Single Copy Orthologs. We also utilized other comparative methods to assess the quality of our assembly. The T. granulosa assembly was compared with that of the Japanese fire-belly newt, Cynops pyrrhogaster , and they were found to share a total of 30,556 orthologous sequences (12.9% gene set). Conclusions: We provide a reference assembly for Taricha granulosa that will enable downstream differential expression and comparative transcriptomics analyses. This publicly available transcriptome assembly and annotation dataset will facilitate the investigation of a wide range of questions concerning amphibian adaptive radiation, and the elucidation of mechanisms of tetrodotoxin defense in Taricha granulosa and other TTX-bearing species.

Traditionally, entomologists have used morphological characteristics for mosquito taxonomy and systematics. However, this approach does not take into consideration the genetic relatedness of species. In 2000, the Aedes genus of mosquitoes in the tribe Aedini was split into two genera ( Aedes and Ochlerotatus ), thereby elevating Ochlerotatus from subgenus to genus rank, strictly based on morphology of adults. Herein, we use the genetic barcoding marker COI to generate a phylogeny of 65 species of Aedes, Ochlerotatus , and Anopheles outgroup from almost 900 sequences downloaded from BOLD systems. Our results reveal evidence of non-random, but polyphyletic clustering of Aedes and Ochlerotatus species, with a monophyletic outgroup. We do find support for the validity of Ochlerotatus as an evolutionary unit, although we find insufficient evidence to support its retention as a genus. We suggest that mosquito phylogenetic analyses incorporate a greater number of genetic markers to help clarify our understanding of Aedini species classifications, but caution that recent assessments based solely on morphology may be insufficient.

Interspecific resource competition is expected to select for divergence in resource use, weakening interspecific relative to intraspecific competition, thus promoting stable coexistence. More broadly, because interspecific competition reduces fitness, any mechanism of interspecific competition should generate selection favoring traits that weaken interspecific competition. However, species also can adapt to competition by increasing their competitive ability, potentially destabilizing coexistence. We reared two species of bean beetles, the specialist Callosobruchus maculatus and the generalist C. chinensis, in allopatry and sympatry on a mixture of adzuki beans and lentils, and assayed mutual invasibility after four, eight, and twelve generations of evolution. Contrary to the expectation that coevolution of competitors will weaken interspecific competition, the rate of mutual invasibility did not differ between sympatry and allopatry. Rather, the invasion rate of C. chinensis, but not C. maculatus, increased with duration of evolution, as C. chinensis adapted to lentils without experiencing reduced adaptation to adzuki beans, and regardless of the presence or absence of C. maculatus. Our results highlight that evolutionary responses to interspecific competition promote stable coexistence only under specific conditions that can be difficult to produce in practice.

Investigating the consequences of landscape features on population genetic patterns is increasingly important to elucidate the ecological factors governing connectivity between populations and predicting the evolutionary consequences of landscapes. Small prairie lakes in Alberta, Canada, and the brook stickleback (Culaea inconstans) that inhabit them, provide a unique aquatic system whereby populations are highly isolated from one another. These heterogeneous and extreme environments are prone to winterkills, an event whereby most of the fish die and frequent bottlenecks occur. In this study, we characterized the genetic population structure of brook stickleback among several lakes, finding that the species is hierarchically influenced by within‐lake characteristics in small‐scale watersheds. Landscape genetic analyses of the role of spatial features found support for basin characteristics associated with genetic diversity and bottlenecks in 20% of the sampled lakes. These results suggest that brook stickleback population genetic patterns may be driven, at least in part, by ecological processes that accelerate genetic drift and landscape patterns associated with reduced dispersal. Collectively, these results reinforce the potential importance of connectivity in the maintenance of genetic diversity, especially in fragmented landscapes.