Predicting the Probability of Outbreeding Depression

Abstract: Fragmentation of animal and plant populations typically leads to genetic erosion and increased probability of extirpation. Although these effects can usually be reversed by re‐establishing gene flow between population fragments, managers sometimes fail to do so due to fears of outbreeding depression (OD). Rapid development of OD is due primarily to adaptive differentiation from selection or fixation of chromosomal variants. Fixed chromosomal variants can be detected empirically. We used an extended form of the breeders’ equation to predict the probability of OD due to adaptive differentiation between recently isolated population fragments as a function of intensity of selection, genetic diversity, effective population sizes, and generations of isolation. Empirical data indicated that populations in similar environments had not developed OD even after thousands of generations of isolation. To predict the probability of OD, we developed a decision tree that was based on the four variables from the breeders’ equation, taxonomic status, and gene flow within the last 500 years. The predicted probability of OD in crosses between two populations is elevated when the populations have at least one of the following characteristics: are distinct species, have fixed chromosomal differences, exchanged no genes in the last 500 years, or inhabit different environments. Conversely, the predicted probability of OD in crosses between two populations of the same species is low for populations with the same karyotype, isolated for <500 years, and that occupy similar environments. In the former case, we recommend crossing be avoided or tried on a limited, experimental basis. In the latter case, crossing can be carried out with low probability of OD. We used crosses with known results to test the decision tree and found that it correctly identified cases where OD occurred. Current concerns about OD in recently fragmented populations are almost certainly excessive.     

Field Evaluation of the PAS III Passive Alcohol Sensor

Passive alcohol sensors (PAS) are screening devices designed to sample nonintrusively the ambient air around a driver's mouth to determine the presence of alcohol. Studies have shown that PAS devices can aid police officers in the identification of unpaired drivers, particularly at sobriety checkpoints. Data from a 1996 nationwide survey, in which 5,392 drivers were evaluated for alcohol using both the PAS III (a passive sensor housed in a flashlight) and evidential breath test devices, have allowed the determination of appropriate criteria at various blood alcohol concentrations (BAC) for detecting impaired drivers in the field. Using the appropriate criteria, the PAS III can identify about 75% of the drivers with BACs at or above 0.10%, and 70% at or above 0.08%. This is a vast improvement over the 40-50% detection rate currently achieved by police officers at checkpoints not using sensors. Using the PAS III few drivers would be identified inappropriately. At the criterion recommended for detecting BACs at or above 0.08%, about 14% of drivers with BACs of 0.02-0.05% would be incorrectly identified as having a higher BAC. Field studies have shown that when police officers rely on observation alone about 20% of drivers with low BACs are detained for further evaluation. More widespread use of passive sensors by police officers would aid in the detection of drinking drivers. Sensors also could provide an additional deterrent to the general public if they believe that when stopped by the police after drinking they will be detained for further evaluation.     

Evaluating Biodiversity Conservation around a Large Sumatran Protected Area

Abstract:  Many of the large, donor-funded community-based conservation projects that seek to reduce biodiversity loss in the tropics have been unsuccessful. There is, therefore, a need for empirical evaluations to identify the driving factors and to provide evidence that supports the development of context-specific conservation projects. We used a quantitative approach to measure, post hoc, the effectiveness of a US$19 million Integrated Conservation and Development Project (ICDP) that sought to reduce biodiversity loss through the development of villages bordering Kerinci Seblat National Park, a UNESCO World Heritage Site in Indonesia. We focused on the success of the ICDP component that disbursed a total of US$1.5 million through development grants to 66 villages in return for their commitment to stop illegally clearing the forest. To investigate whether the ICDP lowered deforestation rates in focal villages, we selected a subset of non-ICDP villages that had similar physical and socioeconomic features and compared their respective deforestation rates. Village participation in the ICDP and its development schemes had no effect on deforestation. Instead, accessible areas where village land-tenure had been undermined by the designation of selective-logging concessions tended to have the highest deforestation rates. Our results indicate that the goal of the ICDP was not met and, furthermore, suggest that both law enforcement inside the park and local property rights outside the park need to be strengthened. Our results also emphasize the importance of quantitative approaches in helping to inform successful and cost-effective strategies for tropical biodiversity conservation.     

The Economic Value of Open Space: A Review and Synthesis

/ Communities increasingly face development pressures that can irreversibly alter open space lands. While the monetary costs and benefits of development are typically known, the corresponding values of natural lands are complex and difficult to measure. This paper reviews different concepts of economic value in relation to open space, describes methods for quantifying these values, and presents examples of each from published literature. Open space benefits accruing to citizens as market values or consumers' surplus include market and enhancement values, production values, natural systems value, use and nonuse values, and various intangible values. Economic impacts that open space lands have on local communities and economies include fiscal impacts on municipal budgets, expenditures from open space-related activities, and impacts from employment and tax revenues. These values are not universally present within a given community, nor are they quantitatively additive. However, a comprehensive consideration of the multiple values of open space will better inform community decisions about land conservation and development. KEY WORDS: Conservation; Economic value; Land use; Open space; Zoning     

Impact of Criticism of Null-Hypothesis Significance Testing on Statistical Reporting Practices in Conservation Biology

Abstract:  Over the last decade, criticisms of null-hypothesis significance testing have grown dramatically, and several alternative practices, such as confidence intervals, information theoretic, and Bayesian methods, have been advocated. Have these calls for change had an impact on the statistical reporting practices in conservation biology? In 2000 and 2001, 92% of sampled articles in Conservation Biology and Biological Conservation reported results of null-hypothesis tests. In 2005 this figure dropped to 78%. There were corresponding increases in the use of confidence intervals, information theoretic, and Bayesian techniques. Of those articles reporting null-hypothesis testing—which still easily constitute the majority—very few report statistical power (8%) and many misinterpret statistical nonsignificance as evidence for no effect (63%). Overall, results of our survey show some improvements in statistical practice, but further efforts are clearly required to move the discipline toward improved practices.     

Health Assessment of the 1985 Flood Disaster in Puerto Rico

In Puerto Rico, during October 1985, tropical storm Isabel caused widespread flooding, landslides, and collapsing of bridges. A maximum of 180 persons died, including an estimated 127 at a landslide where the majority (78%) of deaths resulted from traumatic injury. Approximately 3,000 homes were damaged with 4,400 persons temporarily displaced into 44 shelters. A shelter surveillance system was established to monitor 19 acute and chronic conditions in 28 shelters during a 5-week period. Trend analysis trends of selected reportable communicable diseases in the general community revealed no changes attributable to the disaster in the 12 most severely affected municipalities. In these municipalities, the number of persons using the scheduled outpatient clinics after the disaster decreased significantly, but the mean daily number of emergency room visits did not show significant change. Analysis of surveillance data showed that no infectious disease outbreaks had occurred in the shelters. The post-impact health consequences resulting from this widespread flooding were minimal. Even so, disease surveillance remains essential for efficacious resource allocation and prevention strategies.     

Environmental Determinants of Recent Endemism of Batrachochytrium dendrobatidis Infections in Amphibian Assemblages in the Absence of Disease Outbreaks

The inconsistent distribution of large‐scale infection mediated die‐offs and the subsequent population declines of several animal species, urges us to understand how, when, and why species are affected by disease. It is often unclear when or under what conditions a pathogen constitutes a threat to a host. Often, variation of environmental conditions plays a role. Globally Batrachochytrium dendrobatidis (Bd) causes amphibian declines; however, host responses are inconsistent and this fungus appears equally capable of reaching a state of endemism and subsequent co‐existence with native amphibian assemblages. We sought to identify environmental and temporal factors that facilitate host–pathogen coexistence in northern Europe. To do this, we used molecular diagnostics to examine archived and wild amphibians for infection and general linear mixed models to explore relationships between environmental variables and prevalence of infection in 5 well‐sampled amphibian species. We first detected infection in archived animals collected in 1999, and infection was ubiquitous, but rare, throughout the study period (2008–2010). Prevalence of infection exhibited significant annual fluctuations. Despite extremely rare cases of lethal chytridiomycosis in A. obstetricans, Bd prevalence was uncorrelated with this species’ population growth. Our results suggest context dependent and species‐specific host susceptibility. Thus, we believe recent endemism of Bd coincides with environmentally driven Bd prevalence fluctuations that preclude the build‐up of Bd infection beyond the critical threshold for large‐scale mortality and host population crashes. Determinantes Ambientales del Endemismo Reciente de Infecciones de Batrachochytrium dendrobatidis en Conjuntos de Anfibios en Ausencia de Brotes de Enfermedades Spitzen et al.