Using the past to contextualize anthropogenic impacts on the present and future distribution of an endemic Caribbean mammal

Island species are difficult to conserve because they face the synergy of climate change, invasive species, deforestation, and increasing human population densities in areas where land mass is shrinking. The Caribbean island of Hispaniola presents particular challenges because of geopolitical complexities that span 2 countries and hinder coordinated management of species across the island. We employed species distribution modeling to evaluate the impacts of climatic change and anthropogenic activities on the distribution of an endemic mammal of conservation concern, the Hispaniolan solenodon (Solenodon paradoxus). We aggregated occurrence points for this poorly known species for the Last Glacial Maximum (LGM) and the present (1975–2016) based on museum collections, online biodiversity databases, and new field surveys. We quantified degree of overlap between periods and scenarios with Schoener's D. Through a conservation paleobiology lens, we found that over time humans played an increasing role in shaping the distribution of S. paradoxus, thus, providing a foundation for developing conservation strategies on appropriate spatiotemporal scales. Human population density was the single most important predictor of S. paradoxus occurrence. Densities >166 people/km² corresponded to a near-zero probability of occurrence. Models that accounted for climate but not anthropogenic variables falsely identified suitable habitat in Haiti, where on-the-ground surveys confirm habitat is unavailable. Climate-only models also significantly overestimated the potential for habitat connectivity between isolated populations. Our work highlights that alternative fates for S. paradoxus in the Anthropocene exist across the political border between the Dominican Republic and Haiti due to the fundamentally different economic and political realities of each country. Relationships in the fossil record confirm that Hispaniola's sociopolitical boundary is not biologically significant but instead represents one imposed on the island's fauna in the past 500 years by colonial activity. Our approach reveals how a paleontological perspective can contribute to concrete management insights.     

Factors influencing property selection for conservation revolving funds

Finding sustainable ways to increase the amount of private land protected for biodiversity is challenging for many conservation organizations. In some countries, organizations use revolving‐fund programs, whereby land is purchased and then sold to conservation‐minded owners under condition they enter into a conservation covenant or easement. The sale proceeds are used to purchase, protect, and sell additional properties, incrementally increasing the amount of protected private land. Because the effectiveness of this approach relies on selecting appropriate properties, we explored factors currently considered by practitioners and how these are integrated into decision making. We conducted exploratory, semistructured interviews with managers from each of the 5 major revolving funds in Australia. Responses indicated although conservation factors are important, financial and social factors are also highly influential. A major determinant was whether the property could be resold within a reasonable period at a price that replenishes the fund. To facilitate resale, often selected properties include the potential for the construction of a dwelling. Practitioners face with clear trade‐offs between conservation, financial, amenity, and other factors in selecting properties and 3 main challenges: recovering the costs of acquisition, protection, and resale; reselling the property; and meeting conservation goals. Our findings suggest the complexity of these decisions may constrain revolving‐fund effectiveness. Drawing from participant responses, we identified potential strategies to mitigate these risks, such as providing adequate recreational space without jeopardizing ecological assets. We suggest managers could benefit from a shared‐learning and adaptive approach to property selection given the commonalities between programs. Understanding how practitioners deal with complex decisions in the implementation of revolving funds helps identify future research to improve the performance of this conservation tool.     

The ethics of genetic engineering and gene drives in conservation

The ethical issues associated with using genetic engineering and gene drives in conservation are typically described as consisting of risk assessment and management, public engagement and acceptance, opportunity costs, risk and benefit distributions, and oversight. These are important, but the ethical concerns extend beyond them because the use of genetic engineering has the potential to significantly alter the practices, concepts, and value commitments of conservation. I sought to elucidate the broader set of ethical issues connected with a potential genetic engineering turn in conservation and provide an approach to ethical analysis of novel conservation technologies. The primary rationales offered in support of using genetic engineering and gene drives in conservation are efficiency and necessity for achieving conservation goals. The instrumentalist ethical perspective associated with these rationales involves assessing novel technologies as a means to accomplish desired ends. For powerful emerging technologies the instrumentalist perspective needs to be complemented by a form-of-life perspective frequently applied in the philosophy of technology. The form-of-life perspective involves considering how novel technologies restructure the activities into which they are introduced. When the form-of-life perspective is applied to creative genetic engineering in conservation, it brings into focus a set of ethical issues, such as those associated with power, meaning, relationships, and values, that are not captured by the instrumentalist perspective. It also illuminates why the use of gene drives in conservation is so ethically and philosophically interesting.     

Effectiveness of Panama as an intercontinental land bridge for large mammals

Habitat fragmentation is a primary driver of wildlife loss, and establishment of biological corridors is a common strategy to mitigate this problem. A flagship example is the Mesoamerican Biological Corridor (MBC), which aims to connect protected forest areas between Mexico and Panama to allow dispersal and gene flow of forest organisms. Because forests across Central America have continued to degrade, the functioning of the MBC has been questioned, but reliable estimates of species occurrence were unavailable. Large mammals are suitable indicators of forest functioning, so we assessed their conservation status across the Isthmus of Panama, the narrowest section of the MBC. We used large-scale camera-trap surveys and hierarchical multispecies occupancy models in a Bayesian framework to estimate the occupancy of 9 medium to large mammals and developed an occupancy-weighted connectivity metric to evaluate species-specific functional connectivity. White-lipped peccary (Tayassu pecari), jaguar (Panthera onca), giant anteater (Myrmecophaga tridactyla), white-tailed deer (Odocoileus virginianus), and tapir (Tapirus bairdii) had low expected occupancy along the MBC in Panama. Puma (Puma concolor), red brocket deer (Mazama temama), ocelot (Leopardus pardalis), and collared peccary (Pecari tajacu), which are more adaptable, had higher occupancy, even in areas with low forest cover near infrastructure. However, the majority of species were subject to ≥1 gap that was larger than their known dispersal distances, suggesting poor connectivity along the MBC in Panama. Based on our results, forests in Darien, Donoso–Santa Fe, and La Amistad International Park are critical for survival of large terrestrial mammals in Panama and 2 areas need restoration.     

A strategy for wildlife management in depopulating rural areas of Japan

Former ranges of wild animals have been reestablished in many developed countries. However, this reestablishment has led to increasing human–wildlife conflict in agroforest ecosystems. In Japan, human–wildlife conflict, such as crop raiding by and ecological impacts of wild ungulates and primates, is a serious problem in depopulated rural areas due to these animal range expansions and increased abundances. Japan's human population is predicted to decline by 24% by 2050, and approximately 20% of agricultural settlements will become completely depopulated. In this scenario, anthropogenic pressures on wildlife (e.g., hunting and habitat alteration) will continue to decrease and human–wildlife conflict will increase due to increasing wildlife recovery. Japan's local governments plan to slow range recovery, prevent species reestablishment, or remove recolonizing large mammals through lethal control. This strategy, however, is not cost-effective, and workforce shortages in depopulated communities make it infeasible. Moreover, the suppression of wildlife prevents the recovery of ecological functions and thus would degrade regional biodiversity. The declining pressure on wildlife that accompanies human depopulation will prevent the restoration of any past states of human–wildlife interaction. We suggest human-used areas in rural landscapes be aggregated in compact cities and that in transition zones between human settlements and depopulated lands that land-sharing approaches be applied. Concentrating management efforts in compact cities may effectively decrease human–wildlife conflict, rather than intensifying human pressures. Reforestation of depopulated lands may lead to recovery of wildlife habitats, their ecosystem functions, and regional biodiversity due to minimization of negative anthropogenic effects (land-sparing approach). Balancing resolution of human–wildlife conflict and ecological rewilding could become a new, challenging task for regional wildlife managers.     

When all life counts in conservation

Conservation science involves the collection and analysis of data. These scientific practices emerge from values that shape who and what is counted. Currently, conservation data are filtered through a value system that considers native life the only appropriate subject of conservation concern. We examined how trends in species richness, distribution, and threats change when all wildlife count by adding so-called non-native and feral populations to the International Union for Conservation of Nature Red List and local species richness assessments. We focused on vertebrate populations with founding members taken into and out of Australia by humans (i.e., migrants). We identified 87 immigrant and 47 emigrant vertebrate species. Formal conservation accounts underestimated global ranges by an average of 30% for immigrants and 7% for emigrants; immigrations surpassed extinctions in Australia by 52 species; migrants were disproportionately threatened (33% of immigrants and 29% of emigrants were threatened or decreasing in their native ranges); and incorporating migrant populations into risk assessments reduced global threat statuses for 15 of 18 species. Australian policies defined most immigrants as pests (76%), and conservation was the most commonly stated motivation for targeting these species in killing programs (37% of immigrants). Inclusive biodiversity data open space for dialogue on the ethical and empirical assumptions underlying conservation science.     

Estimating the normal background rate of species extinction

A key measure of humanity's global impact is by how much it has increased species extinction rates. Familiar statements are that these are 100–1000 times pre‐human or background extinction levels. Estimating recent rates is straightforward, but establishing a background rate for comparison is not. Previous researchers chose an approximate benchmark of 1 extinction per million species per year (E/MSY). We explored disparate lines of evidence that suggest a substantially lower estimate. Fossil data yield direct estimates of extinction rates, but they are temporally coarse, mostly limited to marine hard‐bodied taxa, and generally involve genera not species. Based on these data, typical background loss is 0.01 genera per million genera per year. Molecular phylogenies are available for more taxa and ecosystems, but it is debated whether they can be used to estimate separately speciation and extinction rates. We selected data to address known concerns and used them to determine median extinction estimates from statistical distributions of probable values for terrestrial plants and animals. We then created simulations to explore effects of violating model assumptions. Finally, we compiled estimates of diversification—the difference between speciation and extinction rates for different taxa. Median estimates of extinction rates ranged from 0.023 to 0.135 E/MSY. Simulation results suggested over‐ and under‐estimation of extinction from individual phylogenies partially canceled each other out when large sets of phylogenies were analyzed. There was no evidence for recent and widespread pre‐human overall declines in diversity. This implies that average extinction rates are less than average diversification rates. Median diversification rates were 0.05–0.2 new species per million species per year. On the basis of these results, we concluded that typical rates of background extinction may be closer to 0.1 E/MSY. Thus, current extinction rates are 1,000 times higher than natural background rates of extinction and future rates are likely to be 10,000 times higher. Estimación de la Tasa Normal de Extinción de Especies     

Impact of conservation areas on trophic interactions between apex predators and herbivores on coral reefs

Apex predators are declining at alarming rates due to exploitation by humans, but we have yet to fully discern the impacts of apex predator loss on ecosystem function. In a management context, it is critically important to clarify the role apex predators play in structuring populations of lower trophic levels. Thus, we examined the top‐down influence of reef sharks (an apex predator on coral reefs) and mesopredators on large‐bodied herbivores. We measured the abundance, size structure, and biomass of apex predators, mesopredators, and herbivores across fished, no‐take, and no‐entry management zones in the Great Barrier Reef Marine Park, Australia. Shark abundance and mesopredator size and biomass were higher in no‐entry zones than in fished and no‐take zones, which indicates the viability of strictly enforced human exclusion areas as tools for the conservation of predator communities. Changes in predator populations due to protection in no‐entry zones did not have a discernible influence on the density, size, or biomass of different functional groups of herbivorous fishes. The lack of a relationship between predators and herbivores suggests that top‐down forces may not play a strong role in regulating large‐bodied herbivorous coral reef fish populations. Given this inconsistency with traditional ecological theories of trophic cascades, trophic structures on coral reefs may need to be reassessed to enable the establishment of appropriate and effective management regimes. El Impacto de las Áreas de Conservación sobre las Interacciones Tróficas entre los Depredadores Dominantes y los Herbívoros en los Arrecifes de Coral     

Identification of policies for a sustainable legal trade in rhinoceros horn based on population projection and socioeconomic models

Between 1990 and 2007, 15 southern white (Ceratotherium simum simum) and black (Diceros bicornis) rhinoceroses on average were killed illegally every year in South Africa. Since 2007 illegal killing of southern white rhinoceros for their horn has escalated to >950 individuals/year in 2013. We conducted an ecological–economic analysis to determine whether a legal trade in southern white rhinoceros horn could facilitate rhinoceros protection. Generalized linear models were used to examine the socioeconomic drivers of poaching, based on data collected from 1990 to 2013, and to project the total number of rhinoceroses likely to be illegally killed from 2014 to 2023. Rhinoceros population dynamics were then modeled under 8 different policy scenarios that could be implemented to control poaching. We also estimated the economic costs and benefits of each scenario under enhanced enforcement only and a legal trade in rhinoceros horn and used a decision support framework to rank the scenarios with the objective of maintaining the rhinoceros population above its current size while generating profit for local stakeholders. The southern white rhinoceros population was predicted to go extinct in the wild <20 years under present management. The optimal scenario to maintain the rhinoceros population above its current size was to provide a medium increase in antipoaching effort and to increase the monetary fine on conviction. Without legalizing the trade, implementing such a scenario would require covering costs equal to approximately $147,000,000/year. With a legal trade in rhinoceros horn, the conservation enterprise could potentially make a profit of $717,000,000/year. We believe the 35‐year‐old ban on rhinoceros horn products should not be lifted unless the money generated from trade is reinvested in improved protection of the rhinoceros population. Because current protection efforts seem to be failing, it is time to evaluate, discuss, and test alternatives to the present policy.