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Data from: A portrait of a sucker using landscape genetics: how colonization and life history undermine the idealized dendritic metapopulation
Salisbury, Sarah J.; McCracken, Gregory R.; Keefe, Donald; Perry, Robert; Ruzzante, Daniel E. — 2016-07-08 Dendritic metapopulations have been attributed unique properties by in silico studies, including an elevated genetic diversity relative to a panmictic population of equal total size. These predictions have not been rigorously tested in nature, nor has there been full consideration of the interacting effects among contemporary landscape features, colonization history and life history traits of the target species. We tested for the effects of dendritic structure as well as the relative importance of life history, environmental barriers and historical colonization on the neutral genetic structure of a longnose sucker (Catostomus catostomus) metapopulation in the Kogaluk watershed of northern Labrador, Canada. Samples were collected from eight lakes, genotyped with 17 microsatellites, and aged using opercula. Lakes varied in differentiation, historical and contemporary connectivity, and life history traits. Isolation by distance was detected only by removing two highly genetically differentiated lakes, suggesting a lack of migration–drift equilibrium and the lingering influence of historical factors on genetic structure. Bayesian analyses supported colonization via the Kogaluk's headwaters. The historical concentration of genetic diversity in headwaters inferred by this result was supported by high historical and contemporary effective sizes of the headwater lake, T-Bone. Alternatively, reduced allelic richness in headwaters confirmed the dendritic structure's influence on gene flow, but this did not translate to an elevated metapopulation effective size. A lack of equilibrium and upstream migration may have dampened the effects of dendritic structure. We suggest that interacting historical and contemporary factors prevent the achievement of the idealized traits of a dendritic metapopulation in nature. https://creativecommons.org/publicdomain/zero/1.0/
Université de Montréal Dataverse Logo
Rocky Mountain alpine lake brook trout census and effective sizes [2017-2019]
Borealis
Clarke, Shannon H.; McCracken, Gregory R.; Humphries, Shelley; Ruzzante, Daniel E.; Grant, James W.A.; Fraser, Dylan J. — 2022-04-20 Data were collected each year during the summer from 2017 to 2019. Census size (Nc) estimates were generated using mark-recapture methods involving multiple recapture events, and estimated using the Schnabel method. Effective number of breeder (Nb) estimates were generated using the Linkage Disequilibrium Method in the NeEstimator V2 software, from genotypes of year 0+ individuals. Three of these lakes were subjected to size-selective harvesting beginning in the fall of 2017, and were harvested each proceeding fall.
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Limited genetic parallelism underlies recent, repeated incipient speciation in geographically proximate populations of an Arctic fish (Salvelinus alpinus)
Dryad
Salisbury, Sarah J.; McCracken, Gregory R.; Perry, Robert; Keefe, Donald; K. S. Layton, Kara; Kess, Tony; Nugent, Cameron M.; Leong, Jong S.; Bradbury, Ian R.; Koop, Ben F.; Ferguson, Moira M.; Ruzzante, Daniel E. — 2020-09-30 <p>The genetic underpinnings of incipient speciation, including the genomic mechanisms which contribute to morphological and ecological differentiation and reproductive isolation, remain poorly understood. The repeated evolution of consistently, phenotypically distinct morphs of Arctic Charr (<i>Salvelinus alpinus</i>) within the Quaternary period offer an ideal model to study the repeatability of evolution at the genomic level. Sympatric morphs of Arctic Charr are found across this species' circumpolar distribution. However, the specific genetic mechanisms driving this morph differentiation are largely unknown despite the cultural and economic importance of the anadromous morph. We used a newly designed 87k SNP chip to investigate the character and consistency of the genomic differences among sympatric morphs within three recently deglaciated and geographically proximate lakes in Labrador, Canada. We found genetically distinct small and large morph Arctic Charr in all three lakes consistent with resident and anadromous morphs, respectively. A degree of reproductive isolation among sympatric morphs is likely given genome-wide distributions of outlier SNPs and high genome-wide <i>F</i><sub>ST</sub>s. Across all lakes, outlier SNPs were largely non-overlapping suggesting a lack of genetic parallelism driving morph differentiation. Alternatively, several genes and paralogous copies of the same gene consistently differentiated morphs across multiple lakes suggesting their importance to the manifestation of morphs. Our results confirm the utility of Arctic Charr as a model for investigating the predictability of evolution and support the importance of both genetic parallelism and non-parallelism to the incipient speciation of Arctic Charr morphs.</p>

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(Author: McCracken, Gregory R.)

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