Amanda E. Haponski

Signatures of vicariance, postglacial dispersal and spawning philopatry: population genetics of the walleye Sander vitreus

Population genetic relationships reveal the signatures of current processes such as reproductive behaviour and migration, as well as historic events including vicariance and climate change. We analyse population structure of native walleye Sander vitreus across North America, encompassing 10 nuclear DNA microsatellite loci, 26 spawning sites and 921 samples from watersheds across the Great Lakes, Lake Winnipeg, upper Mississippi River, Ohio River and Mobile Bay of the Gulf Coast. Geographical patterning is assessed using phylogenetic trees, pairwise FST analogues, hierarchical partitioning, Mantel regression, Bayesian assignment and Monmonier geographical networks. Results reveal congruent divergences among population groups, corresponding to historic isolation in glacial refugia, dispersal patterns and basin divisions. Broad‐scale relationships show genetic isolation with geographical distance, but reproductive groups within basins do not – with some having pronounced differences. Greatest divergence distinguishes outlying Gulf Coastal and northwest populations, the latter tracing to dispersal from the Missourian refugium to former glacial Lake Agassiz, and basin isolation ∼7000 ya. Genetic barriers in the Great Lakes separate groups in Lakes Superior, Huron’s Georgian Bay, Erie and Ontario, reflecting contributions from Mississippian and Atlantic refugia, and changes in connectivity patterns. Walleye genetic patterns thus reflect vicariance among watersheds and glacial refugia, followed by re‐colonization pathways and changing drainage connections that established modern‐day northern populations, whose separations are maintained through spawning site fidelity. Conservation management practices should preserve genetic identity and unique characters among these divergent walleye populations.

Molecular, morphological, and biogeographic resolution of cryptic taxa in the greenside darter Etheostoma blennioides complex

The systematic identity and genetic divergence of cryptic taxa and morphological subspecies in the Greenside Darter Etheostoma blennioides complex are analyzed from mitochondrial and nuclear DNA sequence data, along with morphological characters. We sequenced the mtDNA cytochrome b gene and control region and is the nuclear S7 intron 1 for 345 Greenside Darters from 19 locations across their distribution including areas of sympatry and allopatry, in comparison to putative sister species and relatives. Results provide the first genetic evidence that E. gutselli is a separate species and is the sister species of E. blennius, which together with E. rupestre comprise the sister group to the Greenside Darter complex; separating approximately 4.0 mya. MtDNA results show that the complex comprises 6 clades and supports only the morphological subspecies Etheostoma blennioides blennioides, distinguished by theta(ST)=0.94, approximately 1.7 my, scale counts, and ventral squamation. The former E. b. pholidotum and E. b. newmanii are polyphyletic and are invalid taxa, together comprising 5 differentiated clades that diverged approximately 0.90-1.7 mya. Nuclear DNA results recover some of the mtDNA clades, which are distinguished morphologically by subtle meristic count differences. Populations of E. b. blennioides genetically diverge, with diversity increasing to the southwest; attributed to restricted gene flow and genetic isolation with geographic distance. Samples of the former E. b. pholidotum from the Great Lakes/Wabash River clade are less divergent, with diversity increasing to the southwest, reflecting allopatric fragmentation and isolation by distance.

Genetic Divergence across a Low-head Dam: A Preliminary Analysis using Logperch and Greenside Darters

ABSTRACT Dams have been built on waterways for centuries, acting as barriers to fish migration and possible impediments to gene flow. We tested whether the Munroe Falls low-head dam, constructed in 1817 on the middle Cuyahoga River in the northeast Ohio portion of the Lake Erie watershed, formed a barrier for fish migration. Subsequent to our sampling, the dam was removed in fall 2005. The present study characterized the population genetic composition of two species of darters (Family Percidae), Etheostoma blennioides (greenside darter) and Percina caprodes (logperch darter), upstream and downstream from the dam in comparison with an outlying population from the Grand River, Ohio using mitochondrial DNA control region and cytochrome b gene sequences. Results found a single genotype in the greenside darter samples that was shared upstream and downstream from the dam, and thus no evidence for effect of the dam could be discerned. In contrast, samples of logperch darter differed in genotypic frequencies above and below the dam, with unique alleles occurring below the dam. It thus is possible that the Munroe Falls low-head dam acted as a one-way barrier to gene flow for logperch. Further genetic studies should test for possible after-effects of the dam removal on these darter populations, and relate these data to variation along and among river systems, including other potential barriers to gene flow.

Temporal and Spatial Genetic Consistency of Walleye Spawning Groups

Abstract Population genetic compositions of the three largest spawning groups of Lake Erie walleyes Sander vitreus (Maumee River, Sandusky River, and Van Buren Bay reefs) were tested for temporal and spatial consistency across 14 years using nine nuclear DNA microsatellite loci from 726 adult walleyes collected in 1995, 1998, 2003, 2007, and 2008. Previous genetic work focused on a one-time “snapshot”; an earlier study by our laboratory found genetic connectivity among the three spawning groups in 2003, whereas most other spawning runs across Lake Erie were genetically distinct. Present results show overall year-to-year genetic consistency of walleye spawning groups; no significant differences were found among collection dates within an annual run, between sexes, or among age-cohorts. Overall, walleyes spawning at the Van Buren Bay reefs were genetically divergent from those spawning in the Maumee and Sandusky rivers, reflecting geographic distance; the latter two groups were genetically closer, with slig...

Comparative Genetic Diversity, Population Structure, and Adaptations of Walleye and Yellow Perch Across North America

The yellow perch Perca flavescens and the walleye Sander vitreus are native North American percid fishes, which have considerable fishery and ecological importance across their wide geographic ranges. Over the past century, they were stocked into new habitats, often with relative disregard for conserving local genetic adaptations. This chapter focuses on their comparative population structure and genetic diversity in relationship to historical patterns, habitat connectivity, dispersal ability, distributional abundances, and reproductive behavior. Both species possess considerable genetic structure across their native ranges, exhibiting similar patterning of discontinuities among geographic regions. The two species significantly differ in levels of genetic diversity, with walleye populations possessing overall higher genetic variability than yellow perch. Genetic divergence patterns follow the opposite trend, with more pronounced differences occurring among closely spaced spawning aggregations of yellow perch than walleye. Results reveal broad-scale correspondence to isolation by geographic distance, however, their fine-scale population structures show less relationship, often with pronounced genetic differences among some nearby reproductive groups. Genetic composition of spawning groups is stable from year to year in walleye, according to two decades of data, and is less consistent in yellow perch. These patterns appear to reflect fundamental behavioral differences between the two species.

Genetic History of Walleyes Spawning in Lake Erie's Cattaraugus Creek: a Comparison of Pre- and Poststocking

AbstractFish stocking (artificial supplementation) has been used to augment populations and angling opportunities. However, genetic composition and adaptations of native fish populations may be affected, raising management concerns. From 1995 to 2000, the New York State Department of Environmental Conservation stocked Walleye Sander vitreus fry and fingerlings from the Maumee River (western Lake Erie) into Cattaraugus Creek (eastern Lake Erie). We analyzed nuclear microsatellite (sat) DNA and mitochondrial DNA (mtDNA) variation in Cattaraugus Creek Walleyes for comparisons between prestocking and poststocking groups, among annual spawning runs (1998–2011), among age cohorts, and between sexes. Results for genetic differentiation (index FST) were not significant between prestocking and poststocking groups (sat: FST = 0.003; mtDNA: FST < 0.001), and the two groups did not resemble stocked Maumee River fingerlings (sat: FST = 0.003–0.012; mtDNA: FST = 0.076–0.090). Tests for differentiation were not signific...

Taxonomy, Distribution, and Evolution of the Percidae

The family Percidae exclusively is native to freshwaters of the Northern Hemisphere, with just two of its genera divided between Eurasia and North America. Percidae comprises 11 genera and an estimated 266–275 species, reaching tremendous species richness in the North American darters. We provide an up-to-date account relating the results of the latest DNA sequence and morphological analyses to resolve the relationships of the family Percidae, including its component genera and species. We provide newly assembled distribution maps for the taxa, and summarize their primary distinguishing morphological characters and life history. For each genus, the latest phylogenetic tree of species relationships is shown and explained. We relate these findings to historic biogeography and contemporary distributions. Just recently, tremendous inroads have been made using new molecular tools and analyses that allow us to begin to understand the tremendous evolutionary diversification of the Percidae, as well as the landscape and climate factors that have shaped these patterns. This information may provide an important indication of the future responses of percid taxa to continued anthropogenic influences.

Moorean and Tahitian Partula tree snail survival after a mass extinction: New genomic insights using museum specimens

Natural history museum collections provide a biodiversity window into the past and are of particular importance to the study of extinction-impacted clades such as the Pacific Island tree snail family Partulidae. Deliberate introduction of the predatory rosy wolf snail Euglandina rosea in the late 20th century led to the extinction/extirpation of 55/61 Society Island Partulidae species. In this study, we phylogenomically investigated the inter-relationships of the three surviving Society Island valley Partula species: P. taeniata (Moorea), P. clara and P. hyalina (Tahiti). All three formed a distinct clade in earlier mitochondrial phylogenies. Using Next Generation Sequencing (NGS) double digested Restriction Associated DNA sequencing (ddRADseq), we found that 46-year-old lyophilized museum specimens produced similar numbers of reads, sequencing depth, and loci as 10-year old ethanol-preserved collections. Phylogenomic trees indicated that Tahitian P. clara and P. hyalina are the result of a single founding lineage from Moorea, contrasting previous mitochondrial results and clarifying the enigmatic taxonomic status of P. c. incrassa. Our study highlights the utility and viability of NGS techniques for museum specimens and their increased resolution of evolutionary patterns. Sampling will be expanded to include the remaining Society Island partulid taxa to further explore the evolutionary history of this radiation.