Effects of Changes in Alternative Prey Densities on Predation of Drifting Lake Sturgeon Larvae (Acipenser fulvescens)

Predator–prey interactions including prey switching, predator swamping, and size-selectivity are important in maintaining multi-species systems. In fishes, early life stages are often recruitment bottlenecks due to high mortality partially caused by predation. High mortality is of particular concern for threatened species such as lake sturgeon (Acipenser fulvescens). Effects of different relative prey densities were examined using two predatory fishes [rock bass (Ambloplites rupestris) and hornyhead chub (Nocomis biguttatus)] and two density treatments of three prey [lake sturgeon, mayflies (Family: Heptageniidae), and suckers (Family: Catostomidae)]. Treatments consisted of prey introduced to predators in a series of pulses 30 min apart. In the initial low-density treatment, predators were offered prey at a pulse of prey at a 13:13:4 ratio of mayfly, suckers, and lake sturgeon, and a second pulse with a 1:1:1 prey ratio during the second pulse. In the equal-density treatment prey numbers were equivalent during both pulses. Larval sturgeon survival, predator preference, and size selection were measured for each trial. Lake sturgeon were the least preferred prey species while mayflies were positively selected. Hornyhead chub preference for lake sturgeon was higher in the equal-density treatment than in the low-density, indicating initial prey availability affected predator foraging behaviour. High densities of preferred macroinvertebrate prey could protect threatened lake sturgeon larvae from predation

Genetic Issues in Freshwater Turtle and Tortoise Conservation

Freshwater and terrestrial turtles are among the most imperiled biota on the planet, with nearly half of all extant taxa threatened with extinction. Active science-based management is required for the persistence of many species. Evolutionary genetic principles are often overlooked in the development of conservation and management plans, yet genetic data and theory can be critical to program success. Conservation biologists are encouraged to consider using genetic data and concepts when developing conservation strategies for turtles. We identify general areas where genetic principles and empirical data can be profitably used in conservation planning and provide examples from the turtle literature. Finally, we suggest important areas for future research in chelonian conservation genetics

Nesting by Canada Geese on Baffin Island, Nunavut

Outside of northern Quebec, there is little evidence to confirm reports of nesting by Canada Geese in Arctic habitats of North America, but they nest regularly in the Arctic tundra of West Greenland, from about 62˚ N to as far north as 76.96˚ N, 71.11˚ W. In 2013, we documented successful nesting by a pair of Canada Geese on northern Baffin Island (71.36˚ N, 79.59˚ W), approximately 1200 km north of the nearest known site of regular nesting by this species in northern Quebec. Photographs, egg measurements, and mitochondrial DNA evidence confirmed that these were Canada Geese. Egg laying began around 17 June, the nest of five eggs hatched on 18 July, and we determined that fledging should have occurred around 20 September. Daily mean temperatures on northern Baffin Island fell below freezing after 5 September 2013, and we suspect that the probability of recruitment for this brood was very low. Climate warming in the Arctic is likely to favor northward range expansion by Canada Geese.En dehors du nord du Québec, il existe peu de preuves permettant de confirmer des rapports selon lesquels la bernache du Canada nidifierait dans les habitats arctiques de l’Amérique du Nord. Cela dit, la bernache du Canada nidifie régulièrement dans la toundra arctique de l’ouest du Groenland, à partir d’environ 62˚ N et aussi loin qu’à 76,96˚ N, 71,11˚ O. En 2013, nous avons documenté la nidification réussie d’une paire de bernaches du Canada dans le nord de l’île de Baffin (71,36˚ N, 79,59˚ O), à environ 1 200 km au nord du site le plus près de nidification habituel connu de cette espèce dans le nord du Québec. Des photographies, la mesure des oeufs et des échantillons d’ADN mitochondrial ont permis de confirmer qu’il s’agissait effectivement de bernaches du Canada. La ponte a commencé vers le 17 juin, puis la couvée de cinq oeufs a éclos le 18 juillet. Nous avons ensuite déterminé que la prise des ailes aurait eu lieu vers le 20 septembre. Dans le nord de l’île de Baffin, les températures moyennes quotidiennes sont tombées sous le point de congélation après le 5 septembre 2013, si bien que nous estimons que pour cette nichée, la probabilité de recrutement était très faible. Le réchauffement climatique dans l’Arctique favorisera vraisemblablement l’expansion du parcours naturel de la bernache du Canada vers le nord.

Catch-effort estimation of white-tailed deer population size

Estimation of population size is important for most research in population biology and in the management of game species. Using a stochastic, catch-effort, competing risks model (Dupont 1983), we estimated the population size of the Savannah River Site white-tailed deer (Odocotleus virginianus) herd for 1965-86. Population size varied markedly in response to changes in both hunting method and pressure. Still hunters preferentially harvested older animals compared to dog hunters. Deer were 2.37 times more susceptible to harvest from dog hunting than from still hunting. Hunter-induced mortality was estimated as 1.73 and 4.10 times as large as nonhunting mortality for still and dog hunting, respectively. The temporal pattern of estimated prehunt population sizes was significantly correlated with the temporal pattern of car-deer accidents recorded on the site during the same time period, suggesting that the temporal pattern of the population estimates is accurate. If the number of cohorts is large and an accurate estimate of hunter effort can be obtained, this technique may provide more reliable population estimates than previously available techniques because it imposes fewer and less stringent biological assumptions

Methodological Bias in Estimates of Strain Composition and Straying of Hatchery‐Produced Steelhead in Lake Michigan Tributaries

Steelhead Oncorhynchus mykiss were first introduced into the Great Lakes in the late 1800s. Subsequently, natural recruitment of steelhead from spawning runs in streams across the basin has been regularly supplemented by hatchery production of strains derived from widely dispersed locales within the species’ native range. Estimates of hatchery contributions to the spawning runs of naturalized populations may be underrepresented by observations of marked fish, as not all hatchery fish are marked prior to release. To assess the potential bias in estimates of the hatchery contribution to steelhead spawning runs in four major rivers in Michigan, we used scale pattern analysis (SPA) to identify nonmarked hatchery fish and multilocus genotypes to estimate the proportional contributions of each hatchery strain to spawning runs. The four hatchery strains currently stocked are significantly genetically distinct (mean FST = 0.077), making it possible to identify specific strains by use of likelihood‐based assignment tests. The differences between direct (mark observations) and indirect (SPA and genetic analysis) estimates of hatchery contribution were mainly due to variations in the percentage of hatchery fish marked by states prior to release and the potential for confusion between certain marks and injuries. By combining direct and indirect assessment methodologies, we estimated that the percentage of hatchery fish returning to the four rivers ranged from 13% to 31% of total spawning runs. The large contribution of hatchery fish to nonstocked rivers differed significantly from expectations of strain‐specific stocking rates across the Lake Michigan basin and for individual streams, indicating high amounts of straying into Michigan streams.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141020/1/nafm1288.pd

Application of Large-Scale Parentage Analysis for Investigating Natal Dispersal in Highly Vagile Vertebrates: A Case Study of American Black Bears (\u3ci\u3eUrsus americanus\u3c/i\u3e)

Understanding the factors that affect dispersal is a fundamental question in ecology and conservation biology, particularly as populations are faced with increasing anthropogenic impacts. Here we collected georeferenced genetic samples (n=2,540) from three generations of black bears (Ursus americanus) harvested in a large (47,739 km2), geographically isolated population and used parentage analysis to identify mother-offspring dyads (n=337). We quantified the effects of sex, age, habitat type and suitability, and local harvest density at the natal and settlement sites on the probability of natal dispersal, and on dispersal distances. Dispersal was male-biased (76% of males dispersed) but a small proportion (21%) of females also dispersed, and female dispersal distances (mean ± SE = 48.9±7.7 km) were comparable to male dispersal distances (59.0±3.2 km). Dispersal probabilities and dispersal distances were greatest for bears in areas with high habitat suitability and low harvest density. The inverse relationship between dispersal and harvest density in black bears suggests that 1) intensive harvest promotes restricted dispersal, or 2) high black bear population density decreases the propensity to disperse. Multigenerational genetic data collected over large landscape scales can be a powerful means of characterizing dispersal patterns and causal associations with demographic and landscape features in wild populations of elusive and wide-ranging species

Management Implications of Molt Migration by the Atlantic Flyway Resident Population of Canada Geese, Branta canadensis

We used satellite-tracked transmitters in 2001 and 2003 to document the timing, location, and extent of molt migrations by female Canada Geese (Branta canadensis) affiliated with the Atlantic Flyway Resident Population (AFRP) of Canada Geese that breed in the temperate region of eastern North America. Twenty-seven adult females were captured during the nesting period in late May and fitted with a satellite transmitter mounted either on a plastic neck collar or backpack harness. Nests of 24 birds were destroyed late in incubation to prevent renesting and ensure nest failure; three females did not have nests. Twelve of the 27 birds (44%) made a northward migration to molt in northern Quebec, Canada: seven to the eastern coast of Hudson Bay (58°12'N, 76°60'W), three to lowland areas east of James Bay (53°30'N, 79°02'W), and two to interior locations south of Ungava Bay (55°54'N, 68°24'W). Molt migrants were present in northern Quebec from June to September, a period that coincides with breeding ground aerial surveys and banding operations conducted for Atlantic Population (AP) Canada Geese that breed in this same region of northern Quebec. With >1 million AFRP geese estimated in the Atlantic Flyway, the potential exists for substantial numbers of yearling, sub-adult, and nest-failed or non-breeding adults to molt migrate to northern breeding areas and bias efforts to survey and mark AP geese. Within AFRP breeding areas, many local flocks have reached nuisance levels. We hypothesized that by inducing molt migration in breeding adults, through destruction of nests late in incubation, we would lessen recruitment, reduce numbers of summer resident adults with young, and increase adult mortality from hunting. However, molt migration behavior was not uniform throughout our study area. Molt migrants were from rural areas in New York, Pennsylvania, and Vermont, whereas marked birds that did not make molt migrations were from more coastal regions of the flyway. The 14 birds that did not make a molt migration remained within 60 km of their banding site. A genetic comparison of these two groups revealed no detectable differences. We conclude that failure to undergo a molt migration is likely attributed to the historical origin of captive-reared birds of mixed subspecies that comprise AFRP flocks in the eastern regions of the flyway and the availability of quality local habitat, distinct from brood-rearing areas, for molting

Effects of Chronic Wasting Disease on Reproduction and Fawn Harvest Vulnerability in Wisconsin White-Tailed Deer

Chronic wasting disease (CWD) is a fatal, transmissible spongiform encephalopathy that affects free-ranging and captive North American cervids. Although the impacts of CWD on cervid survival have been documented, little is known about the disease impacts on reproduction and recruitment. We used genetic methods and harvest data (2002–04) to reconstruct parentage for a cohort of white-tailed deer (Odocoileus virginianus) fawns born in spring 2002 and evaluate the effects of CWD infection on reproduction and fawn harvest vulnerability. There was no difference between CWD-positive and CWD-negative male deer in the probability of being a parent. However, CWD-positive females were more likely to be parents than CWD-negative females. Because our results are based on harvested animals, we evaluated the hypothesis that higher parentage rates occurred because fawns with CWD-positive mothers were more vulnerable to harvest. Male fawns with CWD-positive mothers were harvested earlier (.1 mo relative to their mother’s date of harvest) and farther away from their mothers than male fawns with CWDnegative mothers. Male fawns with CWD-positive mothers were also harvested much earlier and farther away than female fawns from CWD-positive mothers. Most female fawns (86%) with CWD-positive mothers were harvested from the same section as their mothers, while almost half of male and female fawns with CWD-negative mothers were farther away. We conclude that preclinical stages of CWD infection do not prohibit white-tailed deer from successfully reproducing. However, apparently higher harvest vulnerability of male fawns with CWD-positive mothers suggests that CWD infection may make females less capable of providing adequate parental care to ensure the survival and recruitment of their fawns

A New GTSeq Resource to Facilitate Multijurisdictional Research and Management of Walleye Sander Vitreus

Conservation and management professionals often work across jurisdictional boundaries to identify broad ecological patterns. These collaborations help to protect populations whose distributions span political borders. One common limitation to multijurisdictional collaboration is consistency in data recording and reporting. This limitation can impact genetic research, which relies on data about specific markers in an organism\u27s genome. Incomplete overlap of markers between separate studies can prevent direct comparisons of results. Standardized marker panels can reduce the impact of this issue and provide a common starting place for new research. Genotyping-in-thousands (GTSeq) is one approach used to create standardized marker panels for nonmodel organisms. Here, we describe the development, optimization, and early assessments of a new GTSeq panel for use with walleye (Sander vitreus) from the Great Lakes region of North America. High genome-coverage sequencing conducted using RAD capture provided genotypes for thousands of single nucleotide polymorphisms (SNPs). From these markers, SNP and microhaplotype markers were chosen, which were informative for genetic stock identification (GSI) and kinship analysis. The final GTSeq panel contained 500 markers, including 197 microhaplotypes and 303 SNPs. Leave-one-out GSI simulations indicated that GSI accuracy should be greater than 80% in most jurisdictions. The false-positive rates of parent-offspring and full-sibling kinship identification were found to be low. Finally, genotypes could be consistently scored among separate sequencing runs \u3e94% of the time. Results indicate that the GTSeq panel that we developed should perform well for multijurisdictional walleye research throughout the Great Lakes region

Current challenges in glioblastoma : intratumour heterogeneity, residual disease and models to predict disease recurrence

Glioblastoma (GB) is the most common malignant primary brain tumour, and despite the availability of chemotherapy and radiotherapy to combat the disease, overall survival remains low with a high incidence of tumour recurrence. Technological advances are continually improving our understanding of the disease and in particular our knowledge of clonal evolution, intratumour heterogeneity and possible reservoirs of residual disease. These may inform how we approach clinical treatment and recurrence in GB. Mathematical modelling (including neural networks), and strategies such as multiple-sampling during tumour resection and genetic analysis of circulating cancer cells, may be of great future benefit to help predict the nature of residual disease and resistance to standard and molecular therapies in GB