Savviness of prey to introduced predators.

The prey naivety hypothesis posits that prey are vulnerable to introduced predators because many generations in slow gradual coevolution are needed for appropriate avoidance responses to develop. It predicts that prey will be more responsive to native than introduced predators and less responsive to introduced predators that differ substantially from native predators and from those newly established. To test these predictions, we conducted a global meta-analysis of studies that measured the wariness responses of small mammals to the scent of sympatric mammalian mesopredators. We identified 26 studies that met our selection criteria. These studies comprised 134 experiments reporting on the responses of 36 small mammal species to the scent of six introduced mesopredators and 12 native mesopredators. For each introduced mesopredator, we measured their phylogenetic and functional distance to local native mesopredators and the number of years sympatric with their prey. We used predator and prey body mass as a measure of predation risk. Globally, small mammals were similarly wary of the scent of native and introduced mesopredators; phylogenetic and functional distance between introduced mesopredators and closest native mesopredators had no effect on wariness; and wariness was unrelated to the number of prey generations, or years, since first contact with introduced mesopredators. Small mammal wariness was associated with predator-prey body mass ratio, regardless of the nativity. The one thing animals do not seem to recognize is whether their predators are native.

La hipótesis de la ingenuidad de la presa plantea que ésta es vulnerable a los depredadores introducidos porque se requiere que muchas generaciones atraviesen una coevolución lenta y gradual para que se desarrollen las respuestas de evasión adecuadas. La hipótesis supone que la presa será más sensible a los depredadores introducidos que difieren notoriamente de los nativos y de aquellos recién establecidos. Realizamos un metaanálisis global de estudios que midieron las respuestas cautelosas de mamíferos pequeños ante el rastro de meso depredadores simpátricos para probar estas suposiciones. Identificamos 26 estudios que cumplieron con nuestro criterio de selección. Estos estudios estuvieron conformados por 134 experimentos que reportaban las respuestas de 36 especies de mamíferos pequeños ante el rastro de seis meso depredadores introducidos y 12 nativos. Medimos la distancia funcional y filogenética entre cada meso depredador introducido y los meso depredadores locales nativos y el número de años simpátricos con su presa. Usamos la masa corporal del depredador y la presa como medida del riesgo de depredación. A nivel mundial, los mamíferos pequeños compartieron la cautela ante el rastro de los meso depredadores nativos e introducidos; la distancia funcional y la filogenética entre los meso depredadores introducidos y el meso depredador nativo más cercano no tuvieron efecto sobre la cautela; y la cautela no estuvo relacionada con el número de generaciones de la presa, o años, desde el primer contacto con los meso depredadores introducidos. La cautela de los mamíferos pequeños estuvo asociada con las proporciones de masa corporal entre el depredador y la presa, sin importar el origen. Lo único que los animales parecen no reconocer es si el depredador es nativo o no.

Collapse of terrestrial mammal food webs since the Late Pleistocene.

Food webs influence ecosystem diversity and functioning. Contemporary defaunation has reduced food web complexity, but simplification caused by past defaunation is difficult to reconstruct given the sparse paleorecord of predator-prey interactions. We identified changes to terrestrial mammal food webs globally over the past ~130,000 years using extinct and extant mammal traits, geographic ranges, observed predator-prey interactions, and deep learning models. Food webs underwent steep regional declines in complexity through loss of food web links after the arrival and expansion of human populations. We estimate that defaunation has caused a 53% decline in food web links globally. Although extinctions explain much of this effect, range losses for extant species degraded food webs to a similar extent, highlighting the potential for food web restoration via extant species recovery.

A novel trophic cascade between cougars and feral donkeys shapes desert wetlands.

Introduced large herbivores have partly filled ecological gaps formed in the late Pleistocene, when many of the Earth's megafauna were driven extinct. However, extant predators are generally considered incapable of exerting top-down influences on introduced megafauna, leading to unusually strong disturbance and herbivory relative to native herbivores. We report on the first documented predation of juvenile feral donkeys Equus africanus asinus by cougars Puma concolor in the Mojave and Sonoran Deserts of North America. We then investigated how cougar predation corresponds with differences in feral donkey behaviour and associated effects on desert wetlands. Focusing on a feral donkey population in the Death Valley National Park, we used camera traps and vegetation surveys to compare donkey activity patterns and impacts between wetlands with and without cougar predation. Donkeys were primarily diurnal at wetlands with cougar predation, thereby avoiding cougars. However, donkeys were active throughout the day and night at sites without predation. Donkeys were ~87% less active (measured as hours of activity a day) at wetlands with predation (p < 0.0001). Sites with predation had reduced donkey disturbance and herbivory, including ~46% fewer access trails, 43% less trampled bare ground and 192% more canopy cover (PERMANOVA, R2  = 0.22, p = 0.0003). Our study is the first to reveal a trophic cascade involving cougars, feral equids and vegetation. Cougar predation appears to rewire an ancient food web, with diverse implications for modern ecosystems. Our results suggest that protecting apex predators could have important implications for the ecological effects of introduced megafauna.

Cicada nymphs dominate American black bear diet in a desert riparian area.

American black bears are considered dependent on high-elevation forests or other montane habitats in the drylands of western North America. Black bear sign, including that of cubs, was observed throughout the summers of 2015, 2016, and 2018 along a perennial desert river in the Sonoran Desert of Arizona. We analyzed the contents of 21 black bear scats, collected from May to October of 2016 and 2018. Apache cicada nymphs (Diceroprocta apache) were the dominant food item, occurring in 90% of scats and comprising an average of 59% of scat contents. In the process of excavating these nymphs, bears created large areas of turned-over soil, a form of ecosystem engineering with potential implications for soils, vegetation, and fluvial geomorphology. Given that species distributions are shaped by physiological and ecological contexts, as well as anthropogenic legacies, it is possible that black bears once occurred more commonly in desert riparian systems prior to widespread agricultural development, hunting, and dewatering. Although more research is necessary, we suggest that desert riparian systems may be an alternative habitat for black bears. Better understanding the diet and habitat breadth of American black bears is important in the context of increasing landscape fragmentation and militarization in the U.S.-Mexican borderlands.

Functional traits of the world's late Quaternary large-bodied avian and mammalian herbivores.

Prehistoric and recent extinctions of large-bodied terrestrial herbivores had significant and lasting impacts on Earth's ecosystems due to the loss of their distinct trait combinations. The world's surviving large-bodied avian and mammalian herbivores remain among the most threatened taxa. As such, a greater understanding of the ecological impacts of large herbivore losses is increasingly important. However, comprehensive and ecologically-relevant trait datasets for extinct and extant herbivores are lacking. Here, we present HerbiTraits, a comprehensive functional trait dataset for all late Quaternary terrestrial avian and mammalian herbivores ≥10 kg (545 species). HerbiTraits includes key traits that influence how herbivores interact with ecosystems, namely body mass, diet, fermentation type, habitat use, and limb morphology. Trait data were compiled from 557 sources and comprise the best available knowledge on late Quaternary large-bodied herbivores. HerbiTraits provides a tool for the analysis of herbivore functional diversity both past and present and its effects on Earth's ecosystems.

Homogenization of carnivorous mammal ensembles caused by global range reductions of large-bodied hypercarnivores during the late Quaternary.

Carnivorous mammals play crucial roles in ecosystems by influencing prey densities and behaviour, and recycling carrion. Yet, the influence of carnivores on global ecosystems has been affected by extinctions and range contractions throughout the Late Pleistocene and Holocene (approx. 130 000 years ago to the current). Large-bodied mammals were particularly affected, but how dietary strategies influenced species' susceptibility to geographical range reductions remains unknown. We investigated (i) the importance of dietary strategies in explaining range reductions of carnivorous mammals (greater than or equal to 5% vertebrate meat consumption) and (ii) differences in functional diversity of continental carnivore ensembles by comparing current, known ranges to current, expected ranges under a present-natural counterfactual scenario. The present-natural counterfactual estimates current mammal ranges had modern humans not expanded out of Africa during the Late Pleistocene and were not a main driver of extinctions and range contractions, alongside changing climates. Ranges of large-bodied hypercarnivorous mammals are currently smaller than expected, compared to smaller-bodied carnivorous mammals that consume less vertebrate meat. This resulted in consistent differences in continental functional diversity, whereby current ensembles of carnivorous mammals have undergone homogenization through structural shifts towards smaller-bodied insectivorous and herbivorous species. The magnitude of ensemble structural shifts varied among continents, with Australia experiencing the greatest difference. Weighting functional diversity by species' geographical range sizes caused a threefold greater shift in ensemble centroids than when using presence-absence alone. Conservation efforts should acknowledge current reductions in the potential geographical ranges of large-bodied hypercarnivores and aim to restore functional roles in carnivore ensembles, where possible, across continents.

Position Paper: Recommendations for the Investigation, Diagnosis, and Certification of Deaths Related to Opioid and Other Drugs.

The National Association of Medical Examiners convened an expert panel to update the association's evidence-based recommendations for investigating and certifying deaths associated with opioids and other misused substances to improve death certificate and mortality data for public health surveillance. The recommendations are as follows:1. Autopsy provides the best information on a decedent's medical condition for optimal interpretation of toxicology results, circumstances surrounding death, medical history, and scene findings. The panel considers autopsy an essential component of investigating apparent overdose deaths.2. Scene investigation includes reconciling prescription information and medication counts. Investigators should note drug paraphernalia or other evidence of using intoxicating substances.3. Retain blood, urine, and vitreous humor whenever available. Blood from the iliofemoral vein is preferable to blood from more central sites.4. A toxicological panel should be comprehensive, including potent depressant, stimulant, and antidepressant medications. Detecting novel substances present in the community may require special testing.5. When death is attributed to a drug or combination of drugs (as cause or contributing factor), the certifier should list the drugs by generic name in the autopsy report and death certificate.6. The best classification for manner of death in an overdose without any apparent intent of self-harm is "accident."

Introduced herbivores restore Late Pleistocene ecological functions.

Large-bodied mammalian herbivores dominated Earth's terrestrial ecosystems for several million years before undergoing substantial extinctions and declines during the Late Pleistocene (LP) due to prehistoric human impacts. The decline of large herbivores led to widespread ecological changes due to the loss of their ecological functions, as driven by their unique combinations of traits. However, recently, humans have significantly increased herbivore species richness through introductions in many parts of the world, potentially counteracting LP losses. Here, we assessed the extent to which introduced herbivore species restore lost-or contribute novel-functions relative to preextinction LP assemblages. We constructed multidimensional trait spaces using a trait database for all extant and extinct mammalian herbivores ≥10 kg known from the earliest LP (∼130,000 ybp) to the present day. Extinction-driven contractions of LP trait space have been offset through introductions by ∼39% globally. Analysis of trait space overlap reveals that assemblages with introduced species are overall more similar to those of the LP than native-only assemblages. This is because 64% of introduced species are more similar to extinct rather than extant species within their respective continents. Many introduced herbivores restore trait combinations that have the capacity to influence ecosystem processes, such as wildfire and shrub expansion in drylands. Although introduced species have long been a source of contention, our findings indicate that they may, in part, restore ecological functions reflective of the past several million years before widespread human-driven extinctions.

Trophic rewilding presents regionally specific opportunities for mitigating climate change.

Large-bodied mammalian herbivores can influence processes that exacerbate or mitigate climate change. Herbivore impacts are, in turn, influenced by predators that place top-down forcing on prey species within a given body size range. Here, we explore how the functional composition of terrestrial large-herbivore and -carnivore guilds varies between three mammal distribution scenarios: Present-Natural, Current-Day and Extant-Native Trophic (ENT) Rewilding. Considering the effects of herbivore species weakly influenced by top-down forcing, we quantify the relative influence keystone large-herbivore guilds have on methane emissions, woody vegetation expansion, fire dynamics, large-seed dispersal, and nitrogen and phosphorus transport potential. We find strong regional differences in the number of herbivores under weak top-down regulation between our three scenarios, with important implications for how they will influence climate change relevant processes. Under the Present-Natural non-ruminant, megaherbivore, browsers were a particularly important guild across much of the world. Megaherbivore extinction and range contraction and the arrival of livestock mean large, ruminant, grazers have become more dominant. ENT Rewilding can restore the Afrotropics and the Indo-Malay realm to the Present-Natural benchmark, but causes top-down forcing of the largest herbivores to become commonplace elsewhere. ENT Rewilding will reduce methane emissions, but does not maximize natural climate solution potential. This article is part of the theme issue 'Climate change and ecosystems: threats, opportunities and solutions'.

National Association of Medical Examiners position paper: Recommendations for the investigation and certification of deaths in people with epilepsy.

Sudden unexpected death of an individual with epilepsy can pose a challenge to death investigators, as most deaths are unwitnessed, and the individual is commonly found dead in bed. Anatomic findings (eg, tongue/lip bite) are commonly absent and of varying specificity, thereby limiting the evidence to implicate epilepsy as a cause of or contributor to death. Thus it is likely that death certificates significantly underrepresent the true number of deaths in which epilepsy was a factor. To address this, members of the National Association of Medical Examiners, North American SUDEP Registry, Epilepsy Foundation SUDEP Institute, American Epilepsy Society, and the Centers for Disease Control and Prevention constituted an expert panel to generate evidence-based recommendations for the practice of death investigation and autopsy, toxicological analysis, interpretation of autopsy and toxicology findings, and death certification to improve the precision of death certificate data available for public health surveillance of epilepsy-related deaths. The recommendations provided in this paper are intended to assist medical examiners, coroners, and death investigators when a sudden unexpected death in a person with epilepsy is encountered.

Heroin-related Deaths from the Hennepin County Medical Examiner's Office from 2004 Through 2015.

Over the past two decades, prescription and illicit opioid use has led to changes in public health policy to address the increasing number of opioid-related deaths. The purpose of this study was to review cases from Hennepin County Medical Examiner's Office between 2004 through 2015 where heroin was listed as a significant contributor or as the cause of death. We identified 322 heroin-related deaths, which were predominantly male (255; 79%). 6-Monoacetylmorphine (6-MAM) median (range) concentrations were as follows: blood (n = 7), 0.010 (0.006-0.078) mg/L; urine (n = 30), 0.359 (0.009-1.75) mg/L; and vitreous humor (n = 31), 0.034 (0.004-0.24) mg/L. Free morphine was measurable in 273 cases and the percent free morphine (range), when grouped by COD, was opioid (n = 124), 28% (2.2%-92%), and mixed drug toxicity (n = 135), 35.3% (1.5%-100%); (p < 0.01). Quantitation of 6-MAM in blood and vitreous humor, along with a free to total morphine ratio >26%, was useful in establishing heroin-related deaths.

National Association of Medical Examiners Position Paper: Recommendations for the Investigation and Certification of Deaths in People with Epilepsy.

Sudden unexpected death of an individual with epilepsy (SUDEP) can pose a challenge to death investigators, as most deaths are unwitnessed and the individual is commonly found dead in bed. Anatomic findings (e.g., tongue/lip bite) are commonly absent and of varying specificity, limiting the evidence to implicate epilepsy as a cause of or contributor to death. Thus, it is likely that death certificates significantly underrepresent the true number of deaths in which epilepsy was a factor. To address this, members of the National Association of Medical Examiners, North American SUDEP Registry, Epilepsy Foundation SUDEP Institute, American Epilepsy Society, and the Centers for Disease Control and Prevention convened an expert panel to generate evidence-based recommendations for the practice of death investigation and autopsy, toxicological analysis, interpretation of autopsy and toxicology findings, and death certification to improve the precision of death certificate data available for public health surveillance of epilepsy-related deaths. The recommendations provided in this paper are intended to assist medical examiners, coroners, and death investigators when a sudden, unexpected death in a person with epilepsy is encountered.

The Elephant in the Room: Outbreak of Carfentanil Deaths in Minnesota and the Importance of Multiagency Collaboration.

Over a three-month period in early 2017, the Hennepin County Medical Examiner's Office investigated nine apparent opioid toxicity deaths that occurred in three separate urban, suburban, and rural counties in our jurisdiction. All decedents were known substance abusers and had reportedly recently used heroin; most were found with drug paraphernalia. Complete autopsies variably showed classic stigmata of opioid overdose with no significant injury or natural disease to explain death. Initial toxicology screens failed to identify heroin or other narcotic substances. Several cases were presumptively positive for fentanyl by immunoassay, yet failed to confirm positive for fentanyl. Following American Board of Forensic Toxicology reporting standards, these cases were reported as negative for fentanyl by the laboratory. Due to the discrepant scene and toxicology findings suggestive of an opioid toxicity death, further discussion between the medical examiners and toxicologists prompted additional testing at a referral laboratory. This resulted in quantifiable blood carfentanil in all cases (mean 0.26 ng/mL, range 0.12 - 0.64 ng/mL). Cointoxicants included ethanol (n=2), methamphetamine (n=3), benzodiazepines (n=3), and cocaine (n=1). No case had definitive evidence of acute heroin intoxication, but two cases had low concentrations of morphine present (0.03 and 0.06 ng/mL), and two others had 6-monoacetyl morphine in the urine without morphine in the blood, suggesting recent use. All deaths were certified as accidental acute or mixed carfentanil toxicity. These cases present additional information about carfentanil-related deaths and highlight the importance of collaboration between forensic pathologists and toxicologists.

Superiority of postmortem liver fentanyl concentrations over peripheral blood influenced by postmortem interval for determination of fentanyl toxicity.

OBJECTIVE: The current study was undertaken to determine the relationship between postmortem (PM) peripheral blood (PB) and liver fentanyl concentrations and the role of measuring liver fentanyl concentrations in cause of death investigations in medical examiner cases in which fentanyl was identified. DESIGN AND METHODS: FB and liver tissue were routinely collected at autopsy from 4 Minnesota medical examiners' offices in 2010-2011. Samples were analyzed by gas chromatography-mass spectrometry (GC-MS). RESULTS: PB fentanyl ranged from <2-15µg/L in non-drug related deaths (n=5), <2-22µg/L from mixed drug toxicity (n=26) and 3.7-56µg/L from fentanyl toxicity (n=33). Liver fentanyl ranged from 11 to 104µg/kg, 6 to 235µg/kg, and 18 to 365µg/kg, respectively. PB and liver fentanyl showed a modest correlation (r=0.67). PM interval to the liver/blood ratio showed a decreasing ratio over increasing PM interval in cases from fentanyl and mixed drug toxicity. Liver fentanyl concentrations best define therapeutic use at <23µg/kg and fatal toxicity at >56µg/kg, without substantial overlap as found in blood fentanyl concentrations. CONCLUSION: Discriminatory liver fentanyl concentrations suggestive of therapeutic or toxic drug levels may better assist cause of death determination in cases of suspected fentanyl toxicity than postmortem PB concentrations. Peripheral blood fentanyl concentrations appear to undergo postmortem redistribution, associated with an increasing PM interval.

Suicide by gabapentin overdose.

Gabapentin is an antiepileptic drug that is prescribed for both FDA-approved and multiple off-label conditions, and has a relatively safe side-effect profile. Rare cases of overdose-related adverse effects have been reported in the literature. Described herein are the circumstances and autopsy findings of a 62-year-old woman with a history of depression, whose death was caused by intentional ingestion of excess gabapentin. The postmortem peripheral blood gabapentin concentration as determined by high-performance liquid chromatography/tandem mass spectroscopy was 88 µg/mL. Previously reported cases of individuals surviving gabapentin overdoses are discussed and compared with this case. Based on a review of the available literature, this appears to be the first published report of a death due solely to gabapentin toxicity.

Postmortem redistribution of fentanyl in blood.

Fentanyl concentrations were measured in postmortem specimens collected in 20 medical examiner cases from femoral blood (FB), heart blood (HB), heart tissue, liver tissue, and skeletal muscle. Unique was a subset of 7 cases in which FB was obtained at 2 postmortem intervals, shortly after death (FB1) and at autopsy (FB2). The mean collection times of FB1 and FB2 after death were 4.0 and 21.6 hours, respectively. Fentanyl concentrations for FB1 and FB2 ranged from undetectable to 14.6 microg/L (mean, 4.6 microg/L) and 2.0 to 52.5 microg/L (mean, 17.3 microg/L), respectively. Corresponding mean HB, liver tissue, and heart tissue fentanyl concentrations were 29.8 microg/L, 109.7 mg/kg, and 103.4 mg/kg, respectively. The fentanyl HB/FB1 ratio (mean, 8.39) was higher compared with the corresponding HB/FB2 ratio (mean, 3.48). These results suggest that postmortem redistribution of fentanyl can occur in FB.

Check Sample Abstracts.

The following abstracts are compiled from Check Sample exercises published in 2008. These peer-reviewed case studies assist laboratory professionals with continuing medical education and are developed in the areas of clinical chemistry, cytopathology, forensic pathology, hematology, microbiology, surgical pathology, and transfusion medicine. Abstracts for all exercises published in the program will appear annually in AJCP.

Fentanyl postmortem redistribution: preliminary findings regarding the relationship among femoral blood and liver and heart tissue concentrations.

Postmortem redistribution refers to the process of drugs diffusing from tissues into blood along a concentration gradient between death and time of specimen collection at autopsy. Anatomical site-to-site variation can exist for drug concentrations. The purpose of this study was twofold. First femoral blood, liver, and heart fentanyl concentrations were compared in medical examiner cases to assist in determining which specimen most appropriately should be used for interpretation. Nine fentanyl-positive cases were identified by history of drug use over a 15-month period (2007-2008). Femoral blood fentanyl concentrations (n = 9) ranged from 2.7 to 52.5 microg/L, liver fentanyl tissue (n = 9) ranged from 37.0 to 179 microg/kg, and heart fentanyl tissue (n = 3) ranged from 52.8 to 179 microg/kg. Liver tissue to femoral blood ratios ranged from 0.85 to 35.8, and heart tissue to femoral blood ratios ranged from 1.9 to 5.4. Second, utilizing a published compendium of multiple postmortem drugs, liver and heart tissues to femoral blood drug ratios were compared to known volumes of distribution, solubilities, and pKa. No significant relationships were observed. In conclusion, establishing a larger evidence-based database using liver fentanyl concentrations may be more optimal than blood concentrations for interpretation of postmortem fentanyl concentrations in medical examiner and coroner cases.