Risk Of Extirpation Research Articles

Abundance-dependent effects of neighbourhood dissimilarity and growth rank reversal in a neotropical forest

Why tropical forests harbour an exceptional number of species with striking differences in abundances remains an open question. We propose a theoretical framework to address this question in which rare species may have different extirpation risks depending on species ranks in tree growth and sensitivities to neighbourhood interactions. To evaluate the framework, we studied tree growth and its responses to neighbourhood dissimilarity (ND) in traits and phylogeny for 146 species in a neotropical forest. We found that tree growth was positively related to ND, and common species were more strongly affected by ND than rare species, which may help delay dominance of common species. Rare species grew more slowly at the community-wide average ND than common species. But rare species grew faster when common species tended to dominate locally, which may help reduce extirpation risk of rare species. Our study highlights that tree growth rank among species depends on their responses to neighbourhood interactions, which can be important in fostering diversity maintenance in tropical forests.

Chasing a changing climate: Reproductive and dispersal traits predict how sessile species respond to global warming

AbstractAimStudies of species' range shifts have become increasingly relevant for understanding ecology and biogeography in the face of accelerated global change. The combination of limited mobility and imperilled status places some species at a potentially greater risk of range loss, extirpation or extinction due to climate change. To assess the ability of organisms with limited movement and dispersal capabilities to track shifts associated with climate change, we evaluated reproductive and dispersal traits of freshwater mussels (Unionida), sessile invertebrates that require species‐specific fish for larval dispersal.LocationNorth American Atlantic Slope rivers.MethodsTo understand how unionid mussels may cope with and adapt to current and future warming trends, we identified mechanisms that facilitated their colonization of the northern Atlantic Slope river basins in North America after the Last Glacial Maximum. We compiled species occurrence and life history trait information for each of 55 species, and then selected life history traits for which ample data were available (larval brooding duration, host fish specificity, host infection strategy, and body size) and analysed whether the trait state for each was related to mussel distribution in Atlantic Slope rivers.ResultsBrooding duration (p < .01) and host fish specificity (p = .02) were significantly related to mussel species distribution. Long‐term brooders were more likely than short‐term brooders to colonize formerly glaciated rivers, as were host generalists compared to specialists. Body size and host infection strategy were not predictive of movement into formerly glaciated rivers (p > .10).Main conclusionsOur results are potentially applicable to many species for which life history traits have not been well‐documented, because reproductive and dispersal traits in unionid mussels typically follow phylogenetic relationships. These findings may help resource managers prioritize species according to climate change vulnerability and predict which species might become further imperilled with climate warming. Finally, we suggest that similar trait‐based decision support frameworks may be applicable for other movement limited taxa.

Will the California Current lose its nesting Tufted Puffins?

Tufted Puffin (Fratercula cirrhata) populations have experienced dramatic declines since the mid-19th century along the southern portion of the species range, leading citizen groups to petition the United States Fish and Wildlife Service (USFWS) to list the species as endangered in the contiguous US. While there remains no consensus on the mechanisms driving these trends, population decreases in the California Current Large Marine Ecosystem suggest climate-related factors, and in particular the indirect influence of sea-surface temperature on puffin prey. Here, we use three species distribution models (SDMs) to evaluate projected shifts in habitat suitable for Tufted Puffin nesting for the year 2050 under two future Intergovernmental Panel on Climate Change (IPCC) emission scenarios. Ensemble model results indicate warming marine and terrestrial temperatures play a key role in the loss of suitable Tufted Puffin nesting conditions in the California Current under both business-as-usual (RCP 8.5) and moderated (RCP 4.5) carbon emission scenarios, and in particular, that mean summer sea-surface temperatures greater than 15 °C are likely to make habitat unsuitable for breeding. Under both emission scenarios, ensemble model results suggest that more than 92% of currently suitable nesting habitat in the California Current is likely to become unsuitable. Moreover, the models suggest a net loss of greater than 21% of suitable nesting sites throughout the entire North American range of the Tufted Puffin, regardless of emission-reduction strategies. These model results highlight continued Tufted Puffin declines—particularly among southern breeding colonies—and indicate a significant risk of near-term extirpation in the California Current Large Marine Ecosystem.

Tree genetic resources at risk in South America: A spatial threat assessment to prioritize populations for conservation

AbstractBackgroundHumans threat the populations of tree species by overexploitation, deforestation, land use change, and climate change. We present a novel threat assessment at intraspecific level to support the conservation of genetic resources of 80 socioeconomically viable tree species in South America. In this assessment, we evaluate the threat status of Ecogeographic Range Segments (ERSs). ERSs are groups of populations of a specific species in a certain ecological zone of a particular grid cell of a species’ geographic occupancy.MethodsWe used species location records to determine the species distributions and species‐specific ERSs. We distinguished eight threat situations to assess the risk of extirpation of the ERSs of all 80 species. These threat situations were determined by large or little tree cover, low or high human pressure, and low or high climate change impact. Available layers of tree cover and threats were used to determine the levels of fragmentation and direct human pressure. Maxent niche modelling with two Global Circulation Models helped determining climate change impact by the 2050s.ResultsWhen all 80 species are considered, in total, 59% of the ERSs are threatened by little tree cover or high human pressure. When climate change is also considered, then 71‐73% of the ERSs are threatened. When an increased risk of extirpation of populations outside protected areas is considered, then 84–86% of the ERSs are threatened. Seven species warrant special attention because all their ERSs are threatened across their whole distribution in South America: Balfourondendron riedelianum, Cariniana legalis, Dalbergia nigra, Handroanthus pulcherrimus, Pachira quintana, Prosopis flexuosa, and Prosopis pallida.ConclusionsOur results confirm the urgency to set up a regional action plan for the conservation of tree genetic resources in South America. With this threat assessment, we aim to support governments and organizations who are taking up this task.

Demographic and genetic viability of a medium-sized ground-dwelling mammal in a fire prone, rapidly urbanizing landscape.

The rapid and large-scale urbanization of peri-urban areas poses major and complex challenges for wildlife conservation. We used population viability analysis (PVA) to evaluate the influence of urban encroachment, fire, and fauna crossing structures, with and without accounting for inbreeding effects, on the metapopulation viability of a medium-sized ground-dwelling mammal, the southern brown bandicoot (Isoodon obesulus), in the rapidly expanding city of Perth, Australia. We surveyed two metapopulations over one and a half years, and parameterized the PVA models using largely field-collected data. The models revealed that spatial isolation imposed by housing and road encroachment has major impacts on I. obesulus. Although the species is known to persist in small metapopulations at moderate levels of habitat fragmentation, the models indicate that these populations become highly vulnerable to demographic decline, genetic deterioration, and local extinction under increasing habitat connectivity loss. Isolated metapopulations were also predicted to be highly sensitive to fire, with large-scale fires having greater negative impacts on population abundance than small-scale ones. To reduce the risk of decline and local extirpation of I. obesulus and other small- to medium-sized ground-dwelling mammals in urbanizing, fire prone landscapes, we recommend that remnant vegetation and vegetated, structurally-complex corridors between habitat patches be retained. Well-designed road underpasses can be effective to connect habitat patches and reduce the probability of inbreeding and genetic differentiation; however, adjustment of fire management practices to limit the size of unplanned fires and ensure the retention of long unburnt vegetation will also be required to ensure persistence. Our study supports the evidence that in rapidly urbanizing landscapes, a pro-active conservation approach is required that manages species at the metapopulation level and that prioritizes metapopulations and habitat with greater long-term probability of persistence and conservation capacity, respectively. This strategy may help us prevent future declines and local extirpations, and currently relatively common species from becoming rare.

Temporal changes in arthropod activity in tropical anthropogenic forests.

Arthropod communities in the tropics are increasingly impacted by rapid changes in land use. Because species showing distinct seasonal patterns of activity are thought to be at higher risk of climate-related extirpation, global warming is generally considered a lower threat to arthropod biodiversity in the tropics than in temperate regions. To examine changes associated with land use and weather variables in tropical arthropod communities, we deployed Malaise traps at three major anthropogenic forests (secondary reserve forest, oil palm forest, and urban ornamental forest (UOF)) in Peninsular Malaysia and collected arthropods continuously for 12 months. We used metabarcoding protocols to characterize the diversity within weekly samples. We found that changes in the composition of arthropod communities were significantly associated with maximum temperature in all the three forests, but shifts were reversed in the UOF compared with the other forests. This suggests arthropods in forests in Peninsular Malaysia face a double threat: community shifts and biodiversity loss due to exploitation and disturbance of forests which consequently put species at further risk related to global warming. We highlight the positive feedback mechanism of land use and temperature, which pose threats to the arthropod communities and further implicates ecosystem functioning and human well-being. Consequently, conservation and mitigation plans are urgently needed.

Decision‐making for mitigating wildlife diseases: From theory to practice for an emerging fungal pathogen of amphibians

Abstract Conservation science can be most effective in its decision‐support role when seeking answers to clearly formulated questions of direct management relevance. Emerging wildlife diseases, a driver of global biodiversity loss, illustrate the challenges of performing this role: in spite of considerable research, successful disease mitigation is uncommon. Decision analysis is increasingly advocated to guide mitigation planning, but its application remains rare. Using an integral projection model, we explored potential mitigation actions for avoiding population declines and the ongoing spatial spread of the fungus Batrachochytrium salamandrivorans (Bsal). This fungus has recently caused severe amphibian declines in north‐western Europe and currently threatens Palearctic salamander diversity. Available evidence suggests that a Bsal outbreak in a fire salamander (Salamandra salamandra) population will lead to its rapid extirpation. Treatments such as antifungals or probiotics would need to effectively interrupt transmission (reduce probability of infection by nearly 90%) in order to reduce the risk of host extirpation and successfully eradicate the pathogen. Improving the survival of infected hosts is most likely to be detrimental as it increases the potential for pathogen transmission and spread. Active removal of a large proportion of the host population has some potential to locally eradicate Bsal and interrupt its spread, depending on the presence of Bsal reservoirs and on the host's spatial dynamics, which should therefore represent research priorities. Synthesis and applications. Mitigation of Batrachochytrium salamandrivorans epidemics in susceptible host species is highly challenging, requiring effective interruption of transmission and radical removal of host individuals. More generally, our study illustrates the advantages of framing conservation science directly in the management decision context, rather than adapting to it a posteriori.

Impacts of long-term precipitation manipulation on hydraulic architecture and xylem anatomy of piñon and juniper in Southwest USA.

Hydraulic architecture imposes a fundamental control on water transport, underpinning plant productivity, and survival. The extent to which hydraulic architecture of mature trees acclimates to chronic drought is poorly understood, limiting accuracy in predictions of forest responses to future droughts. We measured seasonal shoot hydraulic performance for multiple years to assess xylem acclimation in mature piñon (Pinus edulis) and juniper (Juniperus monosperma) after 3+years of precipitation manipulation. Our treatments consisted of water addition (+20% ambient precipitation), partial precipitation-exclusion (-45% ambient precipitation), and exclusion-structure control. Supplemental watering elevated leaf water potential, sapwood-area specific hydraulic conductivity, and leaf-area specific hydraulic conductivity relative to precipitation exclusion. Shifts in allocation of leaf area to sapwood area enhanced differences between irrigated and droughted KL in piñon but not juniper. Piñon and juniper achieved similar KL under ambient conditions, but juniper matched or outperformed piñon in all physiological measurements under both increased and decreased precipitation treatments. Embolism vulnerability and xylem anatomy were unaffected by treatments in either species. Absence of significant acclimation combined with inferior performance for both hydraulic transport and safety suggests piñon has greater risk of local extirpation if aridity increases as predicted in the southwestern USA.

Lesser prairie‐chicken population forecasts and extinction risks: An evaluation 5 years post–Catastrophic drought

ABSTRACTThe lesser prairie‐chicken (Tympanuchus pallidicinctus) is a species of conservation concern resulting from long‐term declines in abundance due in part to loss and fragmentation of habitat. Habitat loss can affect landscape carrying capacity, and may exacerbate otherwise normal fluctuations in populations during periods of drought, anomalous weather, or other stochastic events. Previous work provided a unified long‐term (1965–2012) assessment of lesser prairie‐chicken population dynamics and projections of persistence in the Southern Great Plains. Despite the final year of data collection coinciding with a record‐setting drought, lesser prairie‐chicken populations exhibited reasonable probabilities of persistence for 3 of the 4 ecoregions in which they occur. Our objective was to validate previous population forecasts with 4 years of additional data (post‐drought). We assessed long‐term (1964–2016) changes in lesser prairie‐chicken populations, using reconstructed population abundances from lek count and aerial survey data, and projected likely future probabilities of persistence. Based on our validations, model forecasts appear to provide a reasonable ability to project population abundance in the near term (∼5 yr). Population abundances have largely edged upward since the extreme drought conditions of 2011–2012. Additionally, near‐term extirpation risks have been reduced measurably for 3 of the 4 ecoregions and the range‐wide population as a result of increased annual growth rates. Meta‐population analysis indicated that each ecoregion had similar likelihoods of persistence as estimated independently for each single population, (i.e., without gene flow), but the longest term probability of extinction for the range‐wide meta‐population (i.e., with gene flow) was reduced by half as compared to the range‐wide population modeled with disconnected subpopulations (i.e., ecoregions). Regardless, our results continue to support the importance of maintaining connectivity between ecoregions and core areas therein. © 2017 The Wildlife Society.

The Effects of a Prolonged Drought on Southern Steelhead Trout (Oncorhynchus mykiss) in a Coastal Creek, Los Angeles, California

Long-term lifecycle monitoring of federally endangered southern steelhead trout (Oncorhynchus mykiss) in Topanga Creek provides a unique opportunity to examine the health and abundance of a steelhead population before (2008--2011) and during (2012--2016) a prolonged drought. We found that the five-year drought resulted in a substantial and significant decline in available wetted habitat suitable for rearing and upstream migratory access for anadromous adults. The response of the steelhead population has been a significant reduction in anadromous spawning, distribution of rearing, and abundance of all life stages of anadromous and resident steelhead. After five years of drought a population that exceeded 325 individuals in 2008, now numbers fewer than 50 fish, and appears to be at extremely high risk of extirpation. Acknowledging the possibility of increased drought regionally and globally, the need to bolster southern steelhead resiliency to additional disturbance is paramount.

Patterns and drivers of fish extirpations in rivers of the American Southwest and Southeast.

Effective conservation of freshwater biodiversity requires spatially explicit investigations of how dams and hydroclimatic alterations among climate regions may interact to drive species to extinction. We investigated how dams and hydroclimatic alterations interact with species ecological and life history traits to influence past extirpation probabilities of native freshwater fishes in the Upper and Lower Colorado River (CR), Alabama-Coosa-Tallapoosa (ACT), and Apalachicola-Chattahoochee-Flint (ACF) basins. Using long-term discharge data for continuously gaged streams and rivers, we quantified streamflow anomalies (i.e., departure "expected" streamflow) at the sub-basin scale over the past half-century.Next, we related extirpation probabilities of native fishes in both regions to streamflow anomalies, river basin characteristics, species traits, and non-native species richness using binomial logistic regression. Sub-basin extirpations in the Southwest (n=95 Upper CR, n=130 Lower CR) were highest in lowland mainstem rivers impacted by large dams and in desert springs. Dampened flow seasonality, increased longevity (i.e., delayed reproduction), and decreased fish egg sizes (i.e., lower parental care) were related to elevated fish extirpation probability in the Southwest. Sub-basin extirpations in the Southeast (ACT n=46, ACF n=22) were most prevalent in upland rivers, with flow dependency, greater age and length at maturity, isolation by dams, and greater distance upstream. Our results confirm that dams are an overriding driver of native fish species losses, irrespective of basin-wide differences in native or non-native species richness. Dams and hydrologic alterations interact with species traits to influence community disassembly, and very high extirpation risks in the Southeast are due to interactions between high dam density and species restricted ranges. Given global surges in dam building and retrofitting, increased extirpation risks should be expected unless management strategies that balance flow regulation with ecological outcomes are widely implemented.

Potential loss of cold-water stenothermal diatoms (Bacillariophyta) from their southern refugia in the western United States

A large number of cold-water stenothermal diatom taxa live between 39 and 49°N latitude at the southern limits of their respective ranges in the mountainous northwest sector of the United States. These taxa are either endemics, alpine taxa with disjunct populations in Europe and Asia, or boreal taxa that are more common at higher latitudes. The southern populations are vulnerable to extirpation from the effects of climate change and other stressors. A simple model was created to assess relative risk of extirpation from the northwest United States for a subset of 35 cold-water stenothermal taxa. The model has five input variables: number of populations south of 49°N latitude, mean population size, distance of the southernmost population from 49°N, mean water temperature at the time of sampling, and lowest elevation of a refugium population. Nine taxa, including three local endemics, were found to be at a high risk of extirpation or extinction resulting from climate change. Eight taxa were rated at a low risk of extirpation and risk to the remaining 18 taxa was rated as moderate. Type localities, images of voucher specimens, and latitudinal spectra are provided for each of the 35 selected taxa. The fate of rare and sensitive diatoms will depend on how the global community addresses (or does not address) climate change and how the lands and habitats that support these species are managed (or not managed) to protect larger and more charismatic species.

Use of the productivity and susceptibility analysis and a rapid management-risk assessment to evaluate the vulnerability of sharks caught off the west coast of Baja California Sur, Mexico

Quantitative assessments of shark populations are difficult to undertake due to the scarcity of studies focusing on species identification and landings. We used the productivity and susceptibility analysis and a rapid management-risk assessment (M-risk) method to examine the impact of the artisanal fishery on 29 shark species captured and landed off the west coast of Baja California Sur. We also examined the regulatory measures currently applied to shark fisheries in Mexico to assess their efficacy in mitigating the impact on fishing mortality. Twenty-eight species had low productivity; only Mustelus californicus was placed in the moderate productivity category. Seventeen species had high susceptibility while 12 were placed in the moderate category. Twenty species were placed in the high vulnerability category, and nine in the moderate category. The five most vulnerable species were Sphyrna zygaena, Squatina californica, Heterodontus francisci, Isurus oxyrinchus, and Carcharhinus falciformis. The management-risk is high for all species; artisanal fisheries have a significant impact particularly on coastal shark species, which can be very sensitive to overfishing as well as large species that use the coastal area during the early stages of their development. Research priorities should include studies assessing the elasticity and demographic aspects of S. zygaena and I. oxyrinchus. Squatina californica and T. semifasciata require urgent attention due to the risk of extirpation. New regulations and improvements to existing legislation in Mexico may have a positive impact in shark populations, which can be examined in future assessments.

Floaters may buffer the extinction risk of small populations: an empirical assessment.

The high extinction risk of small populations is commonly explained by reductions in fecundity and breeder survival associated with demographic and environmental stochasticity. However, ecological theory suggests that population extinctions may also arise from reductions in the number of floaters able to replace the lost breeders. This can be particularly plausible under harsh fragmentation scenarios, where species must survive as small populations subjected to severe effects of stochasticity. Using a woodpecker study in fragmented habitats (2004-2016), we provide here empirical support for the largely neglected hypothesis that floaters buffer population extirpation risks. After controlling for population size, patch size and the intrinsic quality of habitat, populations in patches with floaters had a lower extinction probability than populations in patches without floaters (0.013 versus 0.131). Floaters, which often replace the lost breeders, were less likely to occur in small and low-quality patches, showing that population extirpations may arise from unnoticed reductions in floater numbers in poor-quality habitats. We argue that adequate pools of the typically overlooked floaters may buffer extirpation risks by reducing the detrimental impacts of demographic and environmental stochasticity. However, unravelling the influence of floaters in buffering stochastic effects and promoting population stability require additional studies in an ample array of species and stochastic scenarios.

Persistence of greater sage‐grouse in agricultural landscapes

ABSTRACTLocal extirpations influence species’ range contractions and are often precursors of range‐wide extinction. Understanding extinction dynamics is important for devising effective management strategies to protect threatened and endangered species. The greater sage‐grouse (Centrocercus urophasianus) is an example of a species undergoing range contraction, and has been extirpated from nearly half its historically occupied habitat. We used species distribution modeling to quantify environmental variables constraining a threatened sage‐grouse population inhabiting an agricultural landscape in Washington, USA. Fields planted to perennial vegetation as part of the Conservation Reserve Program (CRP) were important in providing year‐round habitat for sage‐grouse but only when intermixed with native sagebrush‐steppe vegetation. Without the CRP, we estimate 66% of sage‐grouse habitat in the study area would become unsuitable. Conversely, if CRP allotments were concentrated near occupied native sagebrush‐steppe, we estimate the area of sage‐grouse habitat could be increased by up to 63%. In addition to the area of native sagebrush‐steppe and CRP lands, we also found that climate variability, the patch configuration of sagebrush‐steppe, and proximity to major roads and transmission lines constrain the distribution of occupied habitat within the study area. Our study demonstrates how conservation programs such as CRP may be used as a management tool to reduce the risk of extirpation in agricultural areas, and to facilitate species range shifts in response to climatic changes in the sagebrush biome. © 2017 The Wildlife Society.

A General Framework for Setting Quantitative Population Objectives for Wildlife Conservation

Author(s): Dybala, Kristen E.; Clipperton, Neil; Gardali, Thomas; Golet, Gregory H.; Kelsey, Rodd; Lorenzato, Stefan; Melcer, Jr., Ronald; Seavy, Nathaniel; Silveira, Joseph G.; Yarris, Gregory S. | Abstract: Quantitative population objectives are necessary to successfully achieve conservation goals of secure or robust wildlife populations. However, existing methods for setting quantitative population objectives commonly require extensive species-specific population viability data, which are often unavailable or are based on estimates of historical population sizes, which may no longer represent feasible objectives. Conservation practitioners require an alternative, science-based method for setting long-term quantitative population objectives. We reviewed conservation biology literature to develop a general conceptual framework that represents conservation biology principles and identifies key milestones a population would be expected to pass in the process of becoming a recovered or robust population. We then synthesized recent research to propose general hypotheses for the orders of magnitude at which most populations would be expected to reach each milestone. The framework is structured as a hierarchy of four population sizes, ranging from very small populations at increased risk of inbreeding depression and extirpation (l 1,000 adults) to large populations with minimized risk of extirpation (g 50,000 adults), along with additional modifiers describing steeply declining and resilient populations. We also discuss the temporal and geographic scales at which this framework should be applied. To illustrate the application of this framework to conservation planning, we outline our use of the framework to set long-term population objectives for a multi-species regional conservation plan, and discuss additional considerations in applying this framework to other systems. This general framework provides a transparent, science-based method by which conservation practitioners and stakeholders can agree on long-term population objectives of an appropriate magnitude, particularly when the alternative approaches are not feasible. With initial population objectives determined, long-term conservation planning and implementation can get underway, while further refinement of the objectives still remains possible as the population’s response to conservation effort is monitored and new data become available.

Vitals rates and seasonal movements of two isolated greater sage-grouse populations in Utah's West Desert

Declines in greater sage-grouse (Centrocercus urophasianus; hereafter, sagegrouse) populations in Utah over the last century parallel range-wide trends. However, little is known about the ecology of sage-grouse populations that inhabit Utah’s naturally fragmented habitats. Utah’s West Desert sage-grouse populations occupy sagebrush (Artemisia spp.) habitats that are geographically separated by the Great Salt Lake, and largely confined to the Sheeprock and Deep Creek watersheds. From 2005 to 2006, we monitored sagegrouse that were radio-collared in each watershed to determine the factors affecting the vital rates in these isolated populations. Livestock grazing by domestic cattle was the dominate land use, and mammalian predator control for livestock protection was conducted in both watersheds. Corvid control was conducted only in the Sheeprock watershed. During the study, we identified 6 leks that had not been previously documented. Seasonal migration patterns for individual radio-collared sage-grouse in both watersheds varied across the sites. Habitat structure metrics were similar at brood-rearing and random sites for both areas. Nesting and brood success and the ratio of chicks per successful brood were higher for both populations in 2005 than 2006. We attributed these annual differences in vital rates to seasonal variation in precipitation. Spring precipitation in 2005 was twice the 30-year average following a 5 year drought. However, chick recruitment estimates for both populations regardless of year were lower than reported in the published literature. Adult sage-grouse survival rate estimates in Sheeprock and Deep Creek watersheds were lower and higher, respectively, than published reports indicated. These differences may reflect a difference in meso-predators communities. Sage-grouse conservation strategies in both areas should continue to emphasize protection of brood-rearing and seasonal habitat, but the risk of population extirpation as a consequence of extended droughts predicted by climate change models and the invasion of small mesopredators may remain problematic for these populations.

Refrigeration and the Reduction of the Takeoff Rate of Bushmeat

Rising incomes in the developing world has led to increased consumption of bushmeat as a luxury good with a mounting risk of species extirpation. In a two-period model with stochastic supply, this article shows that the simple expedient of introducing refrigeration to the bushmeat markets can lead to the reduction of harvest rates. In the absence of refrigeration, all bushmeat brought to the market must be sold immediately, putting downward pressure on price and sending the incorrect signal to hunters that everything they kill can and will be sold. With refrigeration, it is possible to carry over inventory from one period to the next, which in turn limits harvests. Although harvest rates fall unequivocally, there may be no incentive for market participants to introduce refrigeration. This last result is explained through the use of the economists’ notion of economic welfare as measured by consumer and producer surplus. Achieving the socially desirable goal of lower harvest rates may require third-party intervention in the market.

Climatic microrefugia under anthropogenic climate change: implications for species redistribution

The role of modern climatic microrefugia is a neglected aspect in the study of biotic responses to anthropogenic climate change. Current projections of species redistribution at continental extent are based on climatic grids of coarse (≥ 1 km) resolutions that fail to capture spatiotemporal dynamics associated with climatic microrefugia. Here, we review recent methods to model the climatic component of potential microrefugia and highlight research gaps in accounting for the buffering capacity due to biophysical processes operating at very fine (< 1 m) resolutions (e.g. canopy cover) and the associated microclimatic stability over time (i.e. decoupling). To overcome this challenge, we propose a spatially hierarchical downscaling framework combining a free‐air temperature grid at 1 km resolution, a digital elevation model at 25 m resolution and small‐footprint light detection‐and‐ranging (LiDAR) data at 50 cm resolution with knowledge from the literature to mechanistically model sub‐canopy temperatures and account for microclimatic decoupling. We applied this framework on a virtual sub‐canopy species and simulated the impact of a warming scenario on its potential distribution. Modelling sub‐canopy temperatures at 50 cm resolution and accounting for microclimatic stability over time enlarges the range of temperature conditions towards the cold end of the gradient, mitigates regional temperature changes and decreases extirpation risks. Incorporating these spatiotemporal dynamics into species redistribution models, being correlative, mechanistic or hybrid, will increase the probability of local persistence, which has important consequences in the understanding of the capacity of species to adapt. We finally provide a synthesis on additional ways that the field could move towards effectively considering potential climatic microrefugia for species redistribution.

The problem of estimating recent genetic connectivity in a changing world.

Accurate understanding of population connectivity is important to conservation because dispersal can play an important role in population dynamics, microevolution, and assessments of extirpation risk and population rescue. Genetic methods are increasingly used to infer population connectivity because advances in technology have made them more advantageous (e.g., cost effective) relative to ecological methods. Given the reductions in wildlife population connectivity since the Industrial Revolution and more recent drastic reductions from habitat loss, it is important to know the accuracy of and biases in genetic connectivity estimators when connectivity has declined recently. Using simulated data, we investigated the accuracy and bias of 2 common estimators of migration (movement of individuals among populations) rate. We focused on the timing of the connectivity change and the magnitude of that change on the estimates of migration by using a coalescent-based method (Migrate-n) and a disequilibrium-based method (BayesAss). Contrary to expectations, when historically high connectivity had declined recently: (i) both methods over-estimated recent migration rates; (ii) the coalescent-based method (Migrate-n) provided better estimates of recent migration rate than the disequilibrium-based method (BayesAss); (iii) the coalescent-based method did not accurately reflect long-term genetic connectivity. Overall, our results highlight the problems with comparing coalescent and disequilibrium estimates to make inferences about the effects of recent landscape change on genetic connectivity among populations. We found that contrasting these 2 estimates to make inferences about genetic-connectivity changes over time could lead to inaccurate conclusions.