Modern North American Research Articles

No relationship found between dental fluctuating asymmetry, birthweight, and birth term in two modern North American samples.

Deciduous dental crowns primarily develop during gestation and early infancy and embody early life stress exposures. Composite measures of dental fluctuating asymmetry (DFA) generated from the deciduous teeth may therefore indicate cumulative gestational stress in developmental origins of health and disease (DOHaD) studies. This study examines whether higher composite measures of deciduous DFA are associated with low birthweight and prematurity, two aspects of birth phenotype consistently associated with increased morbidity and mortality risks in adulthood. We evaluated associations between composite deciduous DFA, birthweight, and birth term in two contemporary North American samples: an autopsy sample from New Mexico (n = 94), and sample from a growth cohort study in Burlington, Ontario (n = 304). Dental metric data for each sample was collected from postmortem CT scans and dental casts, respectively. Composite DFA was estimated using buccolingual (BL) and mesiodistal (MD) crown diameters from paired deciduous teeth. Contrary to expectations, the results of linear regression indicated no significant relationship between birthweight and DFA, or birth term and DFA, in either sample. Deciduous DFA does not predict aspects of birth phenotype associated with gestational stress. Birthweight and birth term are plastic relative to the more developmentally stable deciduous dentition, which may only subtly embody early life stress. We suggest that deciduous DFA should be utilized with caution in DOHaD studies until its relationship with gestational stress is clarified.

Geometric morphometric assessment of the fossil bears of Namur, Belgium: Allometry and ecomorphology

The Namur area in Belgium is useful to study brown (Ursus arctos) and cave bears (Ursus spelaeus) as the assemblage contains little temporal and no geographical variation. Here, we aim to assess ontogenetic allometry within cave bears, as well as ecomorphological differences between adult brown bears (n = 9), adult cave bears (n = 5) and juvenile cave bears (n = 3). Landmarks for 3D digitization of the mandible were chosen based on the taphonomical damage of the specimens. Extant brown bears and extinct Pleistocene brown and cave bears were digitized with a Microscribe G2. Generalized Procrustes superimposition was performed on the coordinates. Allometry was studied using regression analysis. Principal component analysis (PCA) was conducted to assess ecomorphological differences between the groups. 61% of the shape variance within juvenile and adult cave bears was predicted by size (n = 8, p < 0.01). The juvenile cave bears have relatively deep horizontal rami. In adult cave bears, the horizontal ramus is much narrower dorsoventrally. Juvenile cave bears have a small masseteric fossa and a short coronoid process, whereas both are larger, relative to mandible size, in adult cave bears. This made juvenile cave bears likely less effective masticators than fully grown cave bears. In the PCA, principal component (PC) 1 accounts for 45.0% of the total variance and PC2 accounts for 27.6%. Fossil U. arctos from Namur fall within the 95% confidence interval of modern North American U. arctos on both PCs, but are more similar to cave bears than the average extant brown bear. From the similarity of fossil and modern brown bears, it can be deduced that the diet of fossil brown bears was probably also within the range of their modern North American conspecifics, although they might have been more efficient at masticating plant matter.

Early dispersal of domestic horses into the Great Plains and northern Rockies

The horse is central to many Indigenous cultures across the American Southwest and the Great Plains. However, when and how horses were first integrated into Indigenous lifeways remain contentious, with extant models derived largely from colonial records. We conducted an interdisciplinary study of an assemblage of historic archaeological horse remains, integrating genomic, isotopic, radiocarbon, and paleopathological evidence. Archaeological and modern North American horses show strong Iberian genetic affinities, with later influx from British sources, but no Viking proximity. Horses rapidly spread from the south into the northern Rockies and central plains by the first half of the 17th century CE, likely through Indigenous exchange networks. They were deeply integrated into Indigenous societies before the arrival of 18th-century European observers, as reflected in herd management, ceremonial practices, and culture.

Osteology and neuroanatomy of a phasianid (Aves: Galliformes) from the Miocene of Nebraska

AbstractTetraoninae (grouse) and Meleagridinae (turkeys) are conspicuous representatives of the modern North American avifauna. The pre-Pleistocene fossil record of these clades has historically been limited to fragmentary remains, in some cases contributing to confusion rather than improving our understanding of how these charismatic landfowl evolved. We report an exquisitely preserved partial skeleton representing a new species of Late Miocene phasianid from the Ash Hollow Formation of Nebraska.Centuriavis lioaen. gen. n. sp. is a phasianid species close in size to modern sage-grouse that diverged prior to the grouse-turkey split, and thus offers insight into the early history of this radiation. The cranial endocast resembles other North American phasianids and differs from odontophorids in exhibiting a strongly projected Wulst bordered by a well-defined vallecula. Phylogenetic analyses indicate thatCenturiavis lioaeforms a clade with Tetraoninae, Meleagridinae, andPucrasia macrolopha(Koklass pheasant). The new fossil species provides a Late Miocene minimum calibration for the divergence of these extant taxa from other Galliformes and supports the hypothesis of a single dispersal from Asia to North America by a lineage that later gave rise to grouse and turkeys.UUID:https://zoobank.org/34ecda2f-f2f2-4c92-a82f-292e23cf2da1

Genomic evaluation of hybridization in historic and modern North American Bison (Bison bison)

During the late nineteenth century North American bison underwent a significant population bottleneck resulting in a reduction in population size of over 99% and a species-level near-extinction event. Factors responsible for this destruction included indiscriminate killing, loss of access to suitable habitat, and diseases. At the nadir of this population crash, very few wild plains bison survived and were restricted to Yellowstone National Park, USA and a small number of wild wood bison remained in Wood Buffalo National Park, Canada. However, most surviving bison in the late 1800’s were maintained by cattle ranchers in private herds where hybridization between bison with various breeds of domestic cattle was often encouraged. Over the last 20 years, the legacy of this introgression has been identified using mitochondrial DNA and limited nuclear microsatellite analyses. However, no genome-wide assessment has been performed, and some herds were believed to be free of introgression based on current genetic testing strategies. Herein, we report detailed analyses using whole genome sequencing from nineteen modern and six historical bison, chosen to represent the major lineages of bison, to identify and quantitate signatures of nuclear introgression in their recent (within 200 years) history. Both low and high coverage genomes provided evidence for recent introgression, including animals from Yellowstone, Wind Cave, and Elk Island National Parks which were previously thought to be free from hybridization with domestic cattle. We employed multiple approaches, including one developed for this work, to identify putative cattle haplotypes in each bison genome. These regions vary greatly in size and frequency by sample and herd, though we detected domestic cattle introgression in all bison genomes tested. Since our sampling strategy spanned across the diversity of modern bison populations, these finding are best explained by multiple historical hybridization events between these two species with significant genetic recombination over the last 200 years. Our results demonstrate that whole genome sequencing approaches are required to accurately quantitate cattle introgression in bison.

Ancient roots of tungsten in western North America

Abstract The highly irregular and localized distribution of tungsten deposits worldwide constitutes a supply challenge for basic industries such as steel and carbides. Over Earth's history, tungsten has preferentially accumulated at paleocontinental margins formed during the breakup of supercontinents. Later crustal thickening of these paleogeographic regions and the magmas they produce are associated with large tungsten districts. However, all of the largest tungsten deposits in the modern North American Cordillera, which preserves over 3 b.y. of geologic record in a paleocontinental margin with abundant crustal magmatism, are limited to the narrow Canadian Tungsten Belt in northwestern Canada. We use neodymium isotopic compositions of scheelite (CaWO4) from the Canadian Tungsten Belt and the paleogeographic distribution of tungsten deposits in the North American Cordillera to constrain the factors that control tungsten distribution. We document that tungsten is specifically associated with materials that, on average, were derived from the mantle during the Mesoarchean to Paleoproterozoic. Weathering and erosion of the supercontinents Columbia and Rodinia favored pre-enrichment of tungsten in sediments. The orogenic heating of pre-enriched sediments produced reduced melts that were capable of efficiently scavenging tungsten and formed the largest deposits in North America.

A Creature Without a Cave

This article analyses prominent examples of the Wendigo myth in modern North American horror media and the implications of misappropriation by non-Indigenous creators for non-Indigenous audiences. This article’s cross-media analysis covers television, film and game media; Teen Wolf (2011–17), Supernatural (2005–20), Bruce Wemple’s The Retreat (2020) and SuperMassive Games’ Until Dawn (2015). This analysis will trace the process of these media, made by non-Indigenous white creators, removing the Wendigo’s indigeneity and placing it within fictional settings as an antagonist. I have named this observation of the Wendigo the ‘Caveless Creature’ phenomenon. The paper concludes that employing the Wendigo as a caveless creature is a common practice within horror as it easily creates a villain for white protagonists to defeat repeatedly. This construction is problematic in the horror genre as it presents an Indigenous antagonist that poses a threat to white culture for its otherness and indigeneity – while at the same time, misappropriating, discarding and demonising the Indigenous culture the myth comes from, at whim. Although this article is specifically observing the Wendigo, I argue that it is one of many caveless creatures, and the treatment of them by creators of non-Indigenous horror genre should be analysed in the future.

Dietary niches of creodonts and carnivorans of the late Eocene Cypress Hills Formation.

Modern North American carnivorous mammal assemblages consist of species from a single clade: the Carnivora. Carnivorans once coexisted with members of other meat-eating clades, including the creodonts (Hyaenodontida and Oxyaenida). Creodonts, however, went extinct in North America during the late Eocene and early Oligocene, potentially due to niche overlap and resource competition with contemporary carnivorans. In this study, we employ a community ecology approach to understand whether the dietary niches of coexisting creodonts and carnivorans overlapped during the late Eocene (Chadronian North American Land Mammal Age), a time when creodonts were dwindling and carnivorans were diversifying. We quantify niche overlap based on inferences of diet from carnassial tooth shape estimated using Orientation Patch Count, Dirichlet’s Normal Surface Energy, and linear dental measurements as well as from body mass for all species in the Calf Creek Local Fauna of Cypress Hills, Saskatchewan (Treaty 4 land). Although creodonts and carnivorans shared characteristics of their carnassial tooth shape, suggesting similar chewing mechanics and feeding habits, we find that marked differences in body size likely facilitated niche partitioning, at least between the largest creodonts and carnivorans. Calculations of prey focus masses and prey mass spectra indicate that only the smallest creodont may have experienced significant competition for prey with the coeval carnivorans. We suggest that the ultimate extinction of creodonts from North America during the late Eocene and Oligocene was unlikely to have been driven by factors related to niche overlap with carnivorans.

Regulating Death: A Brief History of Medical Assistance in Dying.

Unique reports of suicide and euthanasia date back more than 2 millennia, reflecting evolving philosophies of death and dying as expressions of the mores dominating a given era. One longstanding theme in the history of decisions to die has been staunch opposition founded in religious claims that one’s body is a trust from the divine (and therefore not wholly in their ownership). The role of the physician has also been traditionally estranged from participation in such decisions, dating back to rudimentary conceptions of medical ethics in the Hippocratic notion primum non nocere (‘first, do no harm’). However, fundamental principles in the modern philosophy of medicine lend support to the idea that physicians can be justified in actions which cause some harm, in so far as they are acting to fulfil a greater ethical imperative. This brief historical review explores the inception of modern North American medical assistance in dying (MAiD) policy through a series of critical case studies in the unfolding of its practice. Medically assisted dying has presently been legalised in Canada and some United States jurisdictions, but with critical caveats surrounding circumstances of mature minors, advance directives and mental illness as participants’ sole underlying medical condition. While the modern regulations surrounding MAiD continue to take shape, the palliative care community is well-positioned to both guide and scrutinise the ethics of this practice.

Allelic Variation at the Vernalization Response (Vrn-1) and Photoperiod Sensitivity (Ppd-1) Genes and Their Association With the Development of Durum Wheat Landraces and Modern Cultivars.

Wheat adaptability to a wide range of environmental conditions is mostly determined by allelic diversity within genes controlling vernalization requirement (Vrn-1) and photoperiod sensitivity (Ppd-1). We characterized a panel of 151 durum wheat Mediterranean landraces and 20 representative locally adapted modern cultivars for their allelic composition at Vrn-1 and Ppd-1 gene using diagnostic molecular markers and studied their association with the time needed to reach six growth stages under field conditions over 6 years. Compared with the more diverse and representative landrace collection, the set of modern cultivars were characterized by a reduction of 50% in the number of allelic variants at the Vrn-A1 and Vrn-B1 genes, and the high frequency of mutant alleles conferring photoperiod insensitivity at Ppd-A1, which resulted on a shorter cycle length. Vrn-A1 played a greater role than Vrn-B1 in regulating crop development (Vrn-A1 > Vrn-B1). The results suggest that mutations in the Vrn-A1 gene may have been the most important in establishing the spring growth habit of Mediterranean landraces and modern durum cultivars. The allele Vrn-A1d, found in 10 landraces, delayed development. The relative effects of single Vrn-A1 alleles on delaying the development of the landraces were vrn-A1 = Vrn-A1d > Vrn-A1b > Vrn-A1c. Allele vrn-B1 was present in all except two landraces and in all modern cultivars. The null allele at Ppd-A1 (a deletion first observed in the French bread wheat cultivar ‘Capelle-Desprez’) was found for the first time in durum wheat in the present study that identified it in 30 landraces from 13 Mediterranean countries. Allele Ppd-A1a (GS105) was detected in both germplasm types, while the allele Ppd-A1a (GS100) was found only in modern North American and Spanish cultivars. The relative effect of single Ppd-A1 alleles on extending phenological development was Ppd-A1(DelCD) > Ppd-A1b > Ppd-A1a (GS105) > Ppd-A1a (GS100). Sixteen Vrn-1+Ppd-1 allelic combinations were found in landraces and six in modern cultivars, but only three were common to both panels. Differences in the number of days to reach anthesis were 10 days in landraces and 3 days in modern cultivars. Interactive effects between Vrn-1 and Ppd-1 genes were detected.

Drivers of Holocene palsa distribution in North America

Palsas and peat plateaus are climatically sensitive landforms in permafrost peatlands. Climate envelope models have previously related palsa/peat plateau distributions in Europe to modern climate, but similar bioclimatic modelling has not been attempted for North America. Recent climate change has rendered many palsas/peat plateaus in this region, and their valuable carbon stores, vulnerable. We fitted a binary logistic regression model to predict palsa/peat plateau presence for North America by relating the distribution of 352 extant landforms to gridded modern climate data. Our model accurately classified 85.3% of grid cells that contain observed palsas/peat plateaus and 77.1% of grid cells without observed palsas/peat plateaus. The model indicates that modern North American palsas/peat plateaus are supported by cold, dry climates with large seasonal temperature ranges and mild growing seasons. We used palaeoclimate simulations from a general circulation model to simulate Holocene distributions of palsas/peat plateaus at 500-year intervals. We constrained these outputs with timings of peat initiation, deglaciation, and postglacial drainage across the continent. Our palaeoclimate simulations indicate that this climate envelope remained stationary in western North America throughout the Holocene, but further east it migrated northwards during 11.5–6.0 ka BP. However, palsa extents in eastern North America were restricted from following this moving climate envelope by late deglaciation, drainage and peat initiation. We validated our Holocene simulations against available palaeoecological records and whilst they agree that permafrost peatlands aggraded earliest in western North America, our simulations contest previous suggestions that late permafrost aggradation in central Canada was climatically-driven.

An Evaluation of the Modern North American Bariatric Surgery Landscape: Current Trends and Predictors of Procedure Selection.

The last 5years have produced a dramatic transformation in the landscape of bariatric and metabolic surgery. Yet, while the landscape of bariatric procedures is changing, little is known about these trends or which factors are responsible for their evolution. All primary elective laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG) cases were extracted from the comprehensive Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) data registry from 2015 to 2018. A total of 590,971 patients were identified, with 79.6% being female. Overall, 73.4% of patients underwent LSG. The mean age was 44.5 ± 12.0years and mean BMI was 45.3 ± 7.9kg/m2. An increase in proportion of LSG cases was observed and associated with a decrease in LRYGB cases from 2015 to 2018. Multivariable analysis identified dialysis dependence as the greatest predictor of LSG (OR 2.67; 95% CI 2.34-3.04), whereas insulin-dependent diabetes (OR 2.27; 95% CI 2.23-2.32) and gastroesophageal reflux disease (OR 1.52; 95% CI 1.51-1.55) were the two greatest predictors of LRYGB, respectively. Patients offered LSG in 2018 had a near 1.3-fold increase in odds of receiving sleeve gastrectomy vs. those offered surgery in 2015. The overall numbers of bariatric cases have increased from 2015 to 2018 and are associated with an increase in proportion of LSG cases and a decrease in proportion of LRYGB cases over time. Factors other than patient comorbidities alone are responsible for the current trends and modern landscape of bariatric surgery.

Adapting Fitness Age Calculations to Suit a Modern North American Female Population, Regardless of Age, Race, or Ability Level

Objectives: Fitness Age (FA) has been reported in Japan and South Korea as one way to assess an individual’s overall health. To date, this method has not been used in North America. The objective of the current study was to assess the applicability of existing Fitness Age calculations for North American women. Methods: Thirty-seven North American working women aged 18 to 67 years completed a fitness test battery, as described by previous studies. The fitness test results were used with published regression equations to estimate each woman’s FA which was subsequently adjusted to correct for biases in the data. Results: The data from the fitness tests were similar to those presented in the previously published literature with the exception of grip strength, trunk flexion, and body fat percentage which differed significantly compared to the populations assessed previously. These population differences appear to have impacted the applicability of the published methods for this population. Discussion: Because the FA estimates must be corrected according to a theoretical “ideal” to address population biases before they can be used, the authors propose using the deviation from this theoretical ideal rather than raw FA in future aging studies, as this is where the interesting inter-personal differences lay.

Radon exposure is rising steadily within the modern North American residential environment, and is increasingly uniform across seasons

Human-made buildings can artificially concentrate radioactive radon gas of geologic origin, exposing occupants to harmful alpha particle radiation emissions that damage DNA and increase lung cancer risk. We examined how North American residential radon exposure varies by modern environmental design, occupant behaviour and season. 11,727 residential buildings were radon-tested using multiple approaches coupled to geologic, geographic, architectural, seasonal and behavioural data with quality controls. Regional residences contained 108 Bq/m3 geometric mean radon (min < 15 Bq/m3; max 7,199 Bq/m3), with 17.8% ≥ 200 Bq/m3. Pairwise analysis reveals that short term radon tests, despite wide usage, display limited value for establishing dosimetry, with precision being strongly influenced by time of year. Regression analyses indicates that the modern North American Prairie residential environment displays exceptionally high and worsening radon exposure, with more recent construction year, greater square footage, fewer storeys, greater ceiling height, and reduced window opening behaviour all associated with increased radon. Remarkably, multiple test approaches reveal minimal winter-to-summer radon variation in almost half of properties, with the remainder having either higher winter or higher summer radon. This challenges the utility of seasonal correction values for establishing dosimetry in risk estimations, and suggests that radon-attributable cancers are being underestimated.

Introgression of novel genetic diversity to improve soybean yield.

Exotic soybean germplasm can be used to increase novel genetic diversity and yield potential of cultivars. Modern North American soybean (Glycine max [L.] Merr.) cultivars have been derived from only a few ancestors. The objectives of this research were to develop breeding lines with novel genetic diversity that were equivalent to the yield of a commercial cultivar parent and within those lines identify regions of novel genetic diversity that were not present in the Corteva Agriscience elite soybean germplasm pool. Nine lines created from diverse germplasm (USDA-ARS breeding program at the University of Illinois) were crossed to a RM34Elite parent to develop populations and sublines for yield testing. Across yield tests at 30 locations conducted between 2014 and 2016, eleven breeding lines were identified that were equivalent to or significantly higher in yield when compared to the RM34Elite parent. Among the eleven final lines, the introgressed novel haplotypes that were not present in current Corteva Agriscience soybean germplasm occupied an estimated 0.8-10.0% of the genome. JH-2665, the highest yielding line across 3years of testing, yielded 280kg/ha more than the RM34Elite parent and had an estimated 8.6% of the genome containing novel diversity haplotypes. JH-2665 had 96 regions of novel diversity introgression ranging from 1 to 12cM in size, with six regions over 6cM in length. The methods reported demonstrate how high-yielding lines with novel genetic diversity can be developed. This material will be useful for expanding the genetic diversity needed to improve genetic gain in future soybean cultivar development.

Sex estimation from the calcaneus and talus using discriminant function analysis and its possible application in fossil remains

Foot bones have been shown to be sexually dimorphic and they are frequently used for sex estimation. In this study, we estimated the sex based on the calcaneus and the talus of a modern North American population obtained from the Hamann-Todd Osteological Collection, housed at the Cleveland Museum of Natural History (Ohio, USA). A total of 164 calcanei (84 males and 80 females) and 162 tali (83 males and 79 females) were studied. Several univariate discriminant functions were obtained, with accuracy ranging from 70.2 to 90.2%. The best variable for sex estimation in this sample is the talar length. Multivariate discriminant functions were also obtained. The accuracy (83.3 to 96.4%) was generally higher than that obtained with the univariate discriminant functions. The best multivariate equation is the one that uses all the variables measured in the talus. Discriminant functions previously reported in other studies were tested on the Hamann-Todd collection to verify their validity outside the population for which they were made. In addition, together with the equations reported here, they were applied on data from fossil remains belonging to three different groups (Homo neanderthalensis, hominins from the Sima de los Huesos, and anatomically modern Homo sapiens) in order to find some discriminant functions that allow for a valid determination of sex in this type of fossil populations. Several equations yielded good correct allocation percentages in fossil populations thus facilitating the estimation of sex for 16 fossil specimens of previously unknown sex.

Perilous Empathy on the Early Modern Frontier

Abstract The captivity narratives produced in New England in the late seventeenth and early eighteenth centuries are rich and complex sources in which to discover early modern attitudes towards empathy. Contemporary scholars including Sara Ahmed and Carolyn Pedwell have argued that empathy can be problematic, reifying and reproducing various forms of injustice under the guise of fellow feeling. On the early modern North American frontier, empathy was understood as problematic for other reasons, an undesirable response to both the captors and the captive that was often diverted, displaced, or denied in captivity narratives. By situating the captivity narratives of Hannah Swarton, Hannah Dustan, Mary Rowlandson and Elizabeth Hanson within their initial cultural contexts and contemporary theories of empathy and emotions, this essay contributes to an alternative history of empathy.

Evaluation of Major Ancestors of North American Soybean Cultivars for Resistance to Three Pythium Species that Cause Seedling Blight.

Pythium seedling blight, which can be caused by a number of Pythium spp., is a disease that affects soybean (Glycine max) in the United States and Canada. Pythium ultimum var. ultimum, one of the most common pathogenic species, is favored by cool, wet conditions in early spring and causes seed decay, root rot, and seedling damping-off. In all, 102 major ancestors of modern North American cultivars and "first progeny" cultivars developed directly from ancestral lines were evaluated for resistance to P. ultimum var. ultimum and two other species of Pythium in greenhouse assays. Several ancestors and first progeny cultivars, as well as the resistant check Archer, had varying levels of partial resistance to an Illinois isolate of P. ultimum var. ultimum. In a subsequent experiment, four of the most resistant lines (PI 84637, Maple Isle, Fiskeby III, and Fiskeby 840-7-3) and the susceptible cultivar Kanro were screened for resistance against isolates of P. irregulare and P. sylvaticum, and resistance to P. ultimum var. ultimum was confirmed. The lines that were partially resistant to P. ultimum var. ultimum in the first experiment were also partially resistant to P. irregulare and P. sylvaticum. The P. ultimum var. ultimum isolate was the most aggressive of the three isolates, followed by the P. irregulare and P. sylvaticum isolates. Modern cultivars descended from the soybean lines with partial resistance to these pathogens could be useful sources of resistance to Pythium seedling blight if they are found to have similar levels of resistance.

Aortic root replacement with cryopreserved homograft for infective endocarditis in the modern North American opioid epidemic

ObjectiveTo study mid-term survival in patients with infective endocarditis as a result of IV drug use undergoing aortic root replacement with cryopreserved aortic homograft. MethodsPatients undergoing aortic root homograft replacement from 2011-2017 were studied retrospectively. Aortic root replacement was performed using a modified Bentall technique. Primary outcomes included both short-term and mid-term survival. Secondary outcomes included immediate postoperative complications. ResultsA total of 138 patients underwent cryopreserved homograft replacement of the aortic root for aortic root abscesses. Eighty-five patients (61.6%) underwent reoperative sternotomy, and 12 patients (8.7%) underwent second or third reoperative sternotomy. Sixty-seven (48.5%) patients had severe aortic insufficiency preoperatively. Operative mortality was 12.3% (17 patients). Five patients (3.6%) sustained a permanent stroke. Twenty-one patients (15.2%) required dialysis for renal failure, and 21 patients (15.2%) had complete heart block necessitating a permanent pacemaker. Estimated 5-year mortality for the cohort was 43%. ConclusionsCryopreserved homograft replacement is a safe and desirable option for high-risk patients with infective endocarditis and aortic root abscess. Homograft accommodation for a widely debrided aortic annular bed provides a reasonable surgical strategy for patients needing aortic root replacement with annular abscess.

Parallel evolution of site-specific changes in divergent caribou lineages.

The parallel evolution of phenotypes or traits within or between species provides important insight into the basic mechanisms of evolution. Genetic and genomic advances have allowed investigations into the genetic underpinnings of parallel evolution and the independent evolution of similar traits in sympatric species. Parallel evolution may best be exemplified among species where multiple genetic lineages, descended from a common ancestor, colonized analogous environmental niches, and converged on a genotypic or phenotypic trait. Modern North American caribou (Rangifer tarandus) originated from three ancestral sources separated during the Last Glacial Maximum (LGM): the Beringian–Eurasian lineage (BEL), the North American lineage (NAL), and the High Arctic lineage (HAL). Historical introgression between the NAL and the BEL has been found throughout Ontario and eastern Manitoba. In this study, we first characterized the functional differentiation in the cytochrome‐b (cytB) gene by identifying nonsynonymous changes. Second, the caribou lineages were used as a direct means to assess site‐specific parallel changes among lineages. There was greater functional diversity within the NAL despite the BEL having greater neutral diversity. The patterns of amino acid substitutions occurring within different lineages supported the parallel evolution of cytB amino acid substitutions suggesting different selective pressures among lineages. This study highlights the independent evolution of identical amino acid substitutions within a wide‐ranging mammal species that have diversified from different ancestral haplogroups and where ecological niches can invoke parallel evolution.