bluuebunny/crossref_metadata_2025 huggingface dataset:
Anthropogenic Correlates of Species Richness in Southeastern Ontario Wetlands
Authors: Findlay C. Scott , Houlahan Jeff
Published: March 2003

We examined the relationship between the richness of four different wetland taxa (birds, mammals, herptiles, and plants) in 30 southeastern Ontario, Canada wetlands and two anthropogenic factors: road construction and forest removal/conversion on adjacent lands. Data were obtained from two sources: road densities and forest cover from 1:50,000 Government of Canada topographic maps and species lists and wetland areas from Ontario Ministry of Natural Resources wetland evaluation reports. Multiple regression analysis was used to model the relationships between species richness and wetland area, road density, and forest cover. Our results show a strong positive relationship between wetland area and species richness for all taxa. The species richness of all taxa except mammals was negatively correlated with the density of paved roads on lands up to 2 km from the wetland. Furthermore, both herptile and mammal species richness showed a strong positive correlation with the proportion of forest cover on lands within 2 km. These results provide evidence that at the landscape level, road construction and forest removal on adjacent lands pose significant risks to wetland biodiversity. Furthermore, they suggest that most existing wetland policies, which focus almost exclusively on activities within the wetland itself and/or a narrow buffer zone around the wetland perimeter, are unlikely to provide adequate protection for wetland biodiversity.
Checklists: An Under‐Used Tool for the Inventory and Monitoring of Plants and Animals
Authors: Droege Sam , Cyr André , Larivée Jacques
Published: March 2003

Checklists are widely used to catalog field observations of plants and animals. We used 25 years of bird checklist data from the Études des Populations d’Oiseaux du Quebec program to examine the ability of checklists to produce reliable conservation, management, and ecological information. We found that checklists can provide reliable information on changes in bird populations, phenology, and geographic and climate abundance patterns at local, regional, and continental scales. Professional and amateur conservation groups that need to develop extensive monitoring programs should take advantage of the fact that checklists, unlike other time‐consuming and expensive techniques, can be used to detect large‐scale changes in an entire community of species.

 Lastas de Chequeo: Una Herramienta Subutilizada en el Inventario y Monitoreo de Plantas y Animales 

Las listas de comprobación son ampliamente usadas para catalogar observaciones de plantas y animales en el campo. Utilizamos datos de listas de chequeo de aves de 25 años del programa de Estudios de Poblaciones de Aves de Quebec para examinar la habilidad de las listas para generar información confiable de conservación, manejo y ecología. Encontramos que las listas proveen información confiable sobre cambios en las poblaciones de aves, fenología y patrones de abundancia geográfica y climática a escala local, regional y continental. Grupos de conservacionistas profesionales y aficionados que necesitan desarrollar programas de monitoreo extensivos deberían tomar ventaja del hecho de que las listas, a diferencia de otras técnicas caras y de uso extensivo de tiempo, pueden ser usadas para detectar cambios de gran escala en una comunidad entera de especies.
An Evaluation and Modification of World Conservation Union Red List Criteria for Classification of Extinction Risk in Vascular Plants
Authors: Keith David A.
Published: March 2003

The World Conservation Union (IUCN) Red List criteria endorsed in 1994 consist of a set of decision rules based on quantitative thresholds of population size, distributional range, rates of decline, and extinction risk. I evaluated these criteria using data on 68 vascular plant taxa from southeastern Australia and found that deficiencies could be overcome with modifications that did not substantially alter the structure of the IUCN rule set. These modifications included smaller distributional thresholds appropriate to sessile organisms, inclusion of life‐history and land‐based attributes, an amendment to account for skewed metapopulation structure, and inclusion of a rule addressing number of populations and qualitatively defined classes of threatening processes. I reviewed the strengths and weaknesses of decision rules for risk classification such as those endorsed by the World Conservation Union compared with intuitively based qualitative schemes in traditional use. I concluded that explicit schemes foster greater accuracy and precision in risk classification, are more defensible in the face of challenges, and define an agenda for data collection that is essential for the ongoing assessment and management of threatened species.

 Evaluación y Modificación de los Criterios de Clasifícación de Riesgo de Extinción en Plantas Vasculares de la Lista Roja del IUCN 

Los criterios de la lista roja del IUCN establecidos en 1994 constituyen un juego de reglas de decisión basadas en límites cuantitativos de tamaño poblacional, rango de distribución, tasas de declive y riesgo de extinción. Evaluamos estos criterios usando datos de 68 taxa de plantas vasculares del sureste de Australia y encontramos que ciertas deficiencias pueden ser resueltas con modificaciones que no alteran sustancialmente la estructura del juego de reglas del IUCN. Estas modificaciones incluyen límites de distribución más pequeños apropiados para organismos sésiles, inclusión de atributos de la historia de vida y en base al terreno, una enmienda que considere estructucturas metapoblacionales sesgadas y la inclusión de una regla que considere el número de poblaciones y clases cuantitativamente definidas de los procesos de amenaza. Revisamos la fortaleza y debilidad de las reglas de decisión para clasificación de riesgos como lo son las reglas del IUCN comparadas con esquemas cualitativos con bases intuitivas de uso tradicional. Concluimos que los esquemas explícitos amplían la precisión y exactitud de las clasifcaciones de riesgo, son más defensivas en presencia de desafios y definen una agenda para la colección de datos que es esencial para la evaluación en curso y manejo de especies amenazadas.
Number of Censuses Required for Demographic Estimation of Effective Population Size
Authors: Vucetich John A. , Waite Thomas A.
Published: March 2003

Adequate population viability assessment may require estimation of effective population size (  Ne ). But failure to take into account the effect of temporal fluctuation in population size (FPS) on Ne may routinely lead to unrealistically optimistic viability assessments. We thus evaluate a technique that accounts for the effect of FPS on Ne. Using time series of annual counts of 48 free‐ranging animal populations, we show that Ne is dependent on timescale: as more census records are incorporated, estimates of FPS tend to increase, and thus estimates of Ne tend to decrease. Estimates based on, say, 10 annual counts tend to grossly underestimate the influence of FPS on estimates of long‐term Ne, often by more than 100%. Moreover, a newly derived expression for the confidence intervals of Ne /N (in which N is population size) reveals that estimates of Ne based on only a few annual counts are quite unreliable. Our work thus emphasizes the need for long‐term population monitoring and provides a framework for interpreting Ne estimates calculated from limited census data.

 Número de Censos Requeridos para una Estimación Demográfica Efectiva de Tamaño Poblacional  

Evaluaciones adecuadas de viabilidad poblacional pueden requerir estimaciones de tamaño poblacional efectivo (  Ne ). Sin embargo, omisiones en la consideración del efecto de la fluctuación temporal del tamaño poblacional (FPS) en Ne pueden conducir rutinariamente a estimaciones de viabilidad irrealmente optimistas. Es por ello que evaluamos una técnica que toma en consideración el efecto de FPS en Ne. Utilizamos series de tiempo de conteos anuales de 48 poblaciones de animales de rango libre, mostramos que Ne es dependiente de la escala temporal: mientras más registros de censos son incorporados, las estimaciones de FPS tienden a incrementar y por lo tanto las estimaciones de Ne tienden a disminuir. Estimaciones basadas, en por ejemplo, 10 conteos anuales tienden a subestimar la influencia de FPS en las estimaciones de largo plazo de Ne (frecuentemente por más de un 100%). Mas aún, una nueva expresión derivada para intervalos de confianza de Ne  / N (en la cual N es el tamaño poblacional) revela que las estimaciones de Ne basadas en solo unos cuantos conteos anuales son poco confiables. Nuestro trabajo hace énfasis en la necesidad de monitoreos poblacionales a largo plazo y provee un marco de trabajo para interpretar estimaciones de Ne calculadas a partir de datos de censos limitados.
Protected Areas and Conservation of Biodiversity in the Tropics
Authors: Sánchez‐Azofeifa G. Arturo , Quesada‐Mateo Carlos , Gonzalez‐Quesada Pablo , Dayanandan S. , Bawa Kamaljit S.
Published: March 2003

Abstract:
We compared deforestation rates and the extent of fragmentation inside and outside protected areas in the Sarapiquí region of Costa Rica. We determined deforestation rates using remotely sensed images with supervised classification. We georeferenced the processed images and then transformed them to vector format for final mapping and parameter quantification. The deforestation rate in protected areas was low and declined sharply from 0.56% annually between 1976 and 1986 to 0.16% from 1991 to 1995. Outside the protected areas, the rate decreased from 3.6% in 1976–1986 to 2.8% in 1986–1991, but it increased again to 3.2% in 1991–1995. Fragmentation outside the protected areas increased considerably: the number of patches increased from 537 in 1976 to 1231 in 1996, while during the same period the average size of patches decreased from 0.95 to 0.25 km2. Forest landscapes in the Sarapiquí region are likely to lose considerable biodiversity because of the past forest loss and fragmentation even without further increases in deforestation and fragmentation.
Effects of Landscape Disturbance on Animal Communities in Lake Tanganyika, East Africa
Authors: Alin Simone R. , Cohen Andrew S. , Bills Roger , Gashagaza Masta Mukwaya , Michel Ellinor , Tiercelin Jean‐Jacques , Martens Koen , Coveliers Peter , Mboko Sima Keita , West Kelly , Soreghan Michael , Kimbadi Sona , Ntakimazi Gaspard
Published: March 2003

Abstract:Watershed deforestation, road building, and other anthropogenic activities result in sediment inundation of lacustrine habitats. In Lake Tanganyika, this threatens the survival of many rock‐dwelling species by altering the structure and quality of rocky habitats. We investigated the relationship between habitat quality, as related to watershed disturbance intensity, and the biodiversity of faunal communities at three rocky littoral sites of low, moderate, and high disturbance. Turbidity measurements and other environmental observations confirmed that our lake sites represented a gradient of disturbance conditions. We documented differences in species density (number of species per constant area or time), species richness, abundance, and trophic ecology for fishes, molluscs, and ostracods. Fish censuses were performed by scuba divers at 1–20 m and by remotely operated vehicle (ROV) at 40–80 m. In the fish surveys, abundance, species density and richness, and herbivory reached their maxima at intermediate water depths. The depth range of herbivores, however, was restricted at higher‐disturbance sites. The ROV fish surveys at the high‐disturbance site showed high species richness despite low species density and abundance, and piscivores were proportionally more prevalent than in all other surveys. Molluscs censused by diver quadrats and sieve samples showed decreasing species richness and species density (sieve samples only) with increasing disturbance and no significant abundance trend. Ostracod species richness was similar between low‐ and moderate‐disturbance sites but was markedly lower at the high‐disturbance site (species density and abundance data were not available). Our faunal analyses suggest that all three taxonomic groups are negatively affected by sediment inundation but may have varying response thresholds to disturbance. Further, this study emphasized the utility of using complementary survey techniques to monitor and ultimately manage biodiversity in complex freshwater ecosystems.
Molecular Variation and Evolutionarily Significant Units in the Endangered Gila Topminnow
Authors: Parker Karen M. , Sheffer Ruby J. , Hedrick Philip W.
Published: March 2003

Determining evolutionarily significant units in endangered species is one of the most significant challenges facing conservation biology. Often genetic information has been used as the primary basis of recommendations for evolutionarily significant units, but these data should be evaluated carefully and used in conjunction with other information. The endangered Gila topminnow (Poeciliopsis. o. occidentalis) has been the subject of extensive conservation biology research and genetic investigation. We extended these data to highly variable genetic markers, examined variation in microsatellite loci, and compared it with previous measures of genetic diversity for the Gila topminnow from the four watersheds in Arizona in which they are still naturally extant. Fish from Monkey Spring were the most highly differentiated from the other populations. Overall, the amounts and patterns of genetic variation were consistent with known historical and physical differences among sites. The four watersheds are highly physically isolated from one another and differ in a number of important factors in their physical habitat, biota, and the life‐history of the topminnows. Based on these geographic patterns and the genetic results, we recommend that the four watersheds all be managed and conserved separately.
Using Taxonomy to Predict Success among Introduced Avifauna: Relative Importance of Transport and Establishment
Authors: Lockwood Julie L.
Published: March 2003

Abstract:
For invasion ecology to become a quantitative approach to conservation, robust predictors of success must be identified. Taxonomy, although often casually mentioned, has never been thoroughly assessed as an agent of prediction. I used binomial probabilities to identify taxonomic patterns in establishment success among global avifauna. At most, 2.54% of all avian species are considered successfully established exotics somewhere in the world. The distribution of these species among higher taxa is far from random. Seven families contained more successfully established exotic species than expected by chance: Anatidae (ducks and geese), Phasianidae (pheasants), Passeridae (sparrows and estrildid finches), Psittacidae (parrots and allies), Columbidae (pigeons and doves), Rheidae (rheas), and Odontophoridae (New World quails). Human influence on probability of transport appears to drive this taxonomic pattern. Anatidae, Odontophoridae, and Phasianidae hold far more species than expected that arrived in their invasive range for exploitation (i.e., hunting or game). Passeridae and Sturnidae (starlings and mynahs) have more pet species than expected by chance. Thus, traits that enhance probability of purposeful transport exhibit a taxonomic pattern. This human influence on probability of transport increases the quantity of species introduced but does not increase the proportion of species that successfully become established. When invasion risk is assigned, it is vital to understand the interaction between species‐specific attributes that influence establishment and transportation.
Habitat Loss and Changes in the Species‐Area Relationship
Authors: Ney‐Nifle Muriel , Mangel Marc
Published: March 2003

Abstract: The species‐area relationship (SAR) has been used successfully to predict extinction from extent of habitat reduction. These extinction estimates assume that species have uniformly distributed range requirements and a minimum abundance level required for persistence; how many species are lost depends solely on how much habitat is removed, not on where it is removed. We consider another limiting case in which range requirements, rather than abundances, determine extinctions. We used a new method for constructing SARs based on assumptions about geographic ranges of species. Our results show that habitat destruction can change the SAR and consequently the number of species predicted to be lost due to habitat destruction. Our method generates SARs that vary in shape according to the specific distributions of geographic range and occupancy but that have the common feature of being described by a power law with an exponent of <1. When the geographic range of species was included in the SAR, the way habitat was lost became important. Although the SAR before habitat destruction is often used to predict species loss after habitat destruction, assumptions must be clearly stated. To predict the damage caused by habitat loss with our model, it is necessary to know the fraction of aggregated species, the distribution of geographic ranges, the form of habitat destruction, and the sampling protocol. The remaining theoretical challenge is to develop a full theory that links abundance and range.
Inbreeding Depression in the Speke's Gazelle Captive Breeding Program
Authors: Kalinowski Steven T. , Hedrick Philip W. , Miller Philip S.
Published: March 2003

Abstract: The Speke's gazelle (Gazella spekei) captive breeding program has been presented as one of the few examples of selection reducing the genetic load of a population and as a potential model for the captive breeding of endangered species founded from a small number of individuals. In this breeding program, three generations of mate selection apparently increased the viability of inbred individuals. We reanalyzed the Speke's gazelle studbook and examined potential causes for the reduction of inbreeding depression. Our analysis indicates that the decrease in inbreeding depression is not consistent with any model of genetic improvement in the herd. Instead, we found that the effect of inbreeding decreased from severe to moderate during the first generation of inbreeding, and that this change is responsible for almost all of the decline in inbreeding depression observed during the breeding program. This eliminates selection as a potential explanation for the decrease in inbreeding depression and suggests that inbreeding depression may be more sensitive to environmental influences than is usually thought.
Managing Boreal Forest Landscapes for Flying Squirrels
Authors: Reunanen Pasi , Mönkkönen Mikko , Nikula Ari
Published: March 2003

Abstract: Flying squirrel (Pteromys volans) populations have declined severely during the past few decades, and the species has become a focal species in forest management and the conservation debate in Finland. We compared landscape structure around known flying squirrel home ranges with randomly chosen forest sites to determine which landscape patterns characterize the areas occupied by the species in northern Finland. We sought to identify the key characteristics of the landscape that support the remaining flying squirrel populations. We analyzed landscape structure within circular areas with 1‐ and 3‐km radii around 63 forest sites occupied by flying squirrels, and around 96 random sites. We applied stepwise analysis of the landscape structure where landscapes were built up step‐by‐step by adding patch types in order of their suitability for the flying squirrel. The land‐use and forest‐resource data for the analysis were derived from multisource national forest inventory and imported to a geographical information system. Landscape patch types were divided into three suitability categories: breeding habitat (mixed spruce‐deciduous forests); dispersal habitat ( pine and young forests); and unsuitable habitat ( young sapling stands, open habitats, water). Flying squirrel landscapes contained more suitable breeding habitat patches and were better connected by dispersal habitats than random landscapes. Our results suggest that for the persistence of the flying squirrel, forest managers should 1) maintain a deciduous mixture, particularly in spruce‐dominated forests; 2) maintain physical connectivity between optimal breeding habitats; and 3) impose coarse‐grained structures on northeastern Finnish landscapes at current levels of habitat availability.
Effects of Selective Logging on the Butterflies of a Bornean Rainforest
Authors: Willott S. J. , Lim D. C. , Compton S. G. , Sutton S. L.
Published: March 2003

Abstract: Selective logging has been the main cause of disturbance to tropical forests in Southeast Asia, so the extent to which biodiversity is maintained in selectively logged forest is of prime conservation importance. We compared the butterfly assemblages of Bornean primary rainforest to those of rainforest selectively logged 6 years previously. We sampled by means of replicated transects stratified into riverine and ridge forests and we included roads in the logged forest. There was a three‐fold variation in species richness and abundance over the 8‐month sampling period. More species and individuals were observed in the logged forest, although between‐replicate variability was high. Rarefied species richness was positively correlated with canopy openness within the range of disturbance levels encountered at our forest sites. Within families, there was no significant difference in the number of species between primary and logged forest. There was a significant difference in the relative abundance of species, but this was due largely to the abundance of one or two species. Community ordination separated the sites along a gradient of disturbance and revealed strong differences between riverine and ridge‐forest butterfly assemblages in primary forest that were obscured in logged forest. There was no evidence that logging has resulted in a change in the composition of the butterfly assemblages from species with a local distribution to more widespread species. We conclude that at a logged forest site in close proximity to primary forest, low intensities of logging do not necessarily reduce the species richness or abundance of butterflies, although assemblage composition is changed.
Will Observation Error and Biases Ruin the Use of Simple Extinction Models?
Authors: Meir Eli , Fagan William F.
Published: March 2003

Abstract: Estimating the risk of extinction for populations of endangered species is an important component of conservation biology. These estimates must be made from data that contain both environmental noise in the year‐to‐year transitions in population size (so‐called “process error”), random errors in sampling, and possible biases in sampling ( both forms of observation errors). To determine how much faith to place in estimated extinction rates, it is important to know how sensitive they are to observation error. We used three simple, commonly employed models of population dynamics to generate simulated population time series. We then combined random observation error or systematic biases with those data, fit models to the time series data, and observed how close the extinction dynamics of the fitted models compared with the dynamics of the underlying models. We found that systematic biases in sampling rarely affected estimates of extinction risk. We also found that even moderate levels of random observation error do not significantly affect extinction estimates except over a small range of process errors, corresponding to the region where extinction risk is most uncertain. With more substantial sampling error, estimates of extinction risk degraded rapidly. Field census techniques for a variety of taxa often involve observation errors within ±32% of actual population sizes. For typical time series used in conservation, therefore, we often may not need to be overly concerned about observation errors as an extra source of imperfection in our estimated extinction rates.
Making the Leap from Researcher to Planner: Lessons from Avian Conservation Planning in the Dominican Republic
Authors: Latta Steven C.
Published: March 2003

Abstract: As research biologists move into conservation biology, especially in foreign countries, providing support for conservation planning efforts presents unique challenges. Published accounts of national, multidisciplinary planning efforts and priority setting for avian conservation are not common. I describe the process and results of a broad‐based, grassroots‐oriented avian conservation planning workshop held in the Dominican Republic in which we designed a coordinated strategy for avian conservation in the country. The planning process sought to (1) increase communication and cooperation among conservationists; (2) familiarize participants with resources pertinent to avian conservation; (3) encourage the transfer of information between researchers and managers; (4) promote the concepts of long‐term avian monitoring, avian conservation plans, and species management plans; and (5) develop a common, multidisciplinary strategy to promote the conservation of birds in the Dominican Republic. The workshop highlighted group discussions among research biologists, managers, educators, and public policy specialists to assess avian conservation needs and priorities with respect to each discipline and has since galvanized a significant portion of the conservation community around several cooperative projects involving diverse segments of the community. Avian biologists can play a significant role in conservation efforts through a willingness to work with key players in diverse fields and to envision holistic, multidisciplinary approaches to conservation issues.
Conservation and Management of Anacapa Island Deer Mice
Authors: Pergams Oliver R. W. , Lacy Robert C. , Ashley Mary V.
Published: March 2003

Abstract: We investigated the genetic and morphological status of an endemic subspecies of deer mice (  Peromyscus maniculatus anacapae) on Anacapa Island of California through mitochondrial DNA (mtDNA) analysis, morphometric discriminant function analysis, and population viability analysis. We sought to assist the development of a management plan that may include captive breeding, reintroduction, or translocation of mice following eradication of introduced rats. The genetic and morphological data were used to investigate whether the subspecies or populations on each of the three islets of Anacapa represent evolutionarily significant units for conservation. The status of the East Anacapa population was of particular concern because deer mice have recently been caught there following more than 15 years of no records of deer mice. Sequences of the mtDNA cytochrome oxidase c subunit II gene (COII ) indicated that the Anacapa subspecies had unique haplotypes not found on neighboring islands or the mainland and thus represents a distinct unit for conservation. Further, one of these haplotypes was shared among the islets, including most of the East Anacapa mice, suggesting that the East Anacapa population had either recovered from a severe bottleneck or had been recolonized by P. m. anacapae, but that it was not derived from other subspecies. Discriminant function analysis of morphological data also supported classification of the East Anacapa mice as P. m. anacapae. The mitochondrial mtDNA sequence data yielded estimates of two to seven migrants per generation among the Anacapa islets, suggesting a functioning metapopulation. Incorporating these data and information available on the life history and demographics of deer mice, we used a novel type of population viability analysis to develop a captive breeding and reintroduction plan for Anacapa deer mice should they be eradicated along with the rats. A sine wave was incorporated into the population viability analysis to simulate population size cyclicity. Our study provides baseline information needed for developing a comprehensive conservation and management plan for a threatened island endemic.
Role of Propagule Size in the Success of Incipient Colonies of the Invasive Argentine Ant
Authors: Hee Jason J. , Holway David A. , Suarez Andrew V. , Case Ted J.
Published: March 2003

Abstract: Factors that contribute to the successful establishment of invasive species are often poorly understood. Propagule size is considered a key determinant of establishment success, but experimental tests of its importance are rare. We used experimental colonies of the invasive Argentine ant (  Linepithema humile) that differed both in worker and queen number to test how these attributes influence the survivorship and growth of incipient colonies. All propagules without workers experienced queen mortality, in contrast to only 6% of propagules with workers. In small propagules (10–1,000 workers), brood production increased with worker number but not queen number. In contrast, per capita measures of colony growth decreased with worker number over these colony sizes. In larger propagules ( 1,000–11,000 workers), brood production also increased with increasing worker number, but per capita brood production appeared independent of colony size. Our results suggest that queens need workers to establish successfully but that propagules with as few as 10 workers can grow quickly. Given the requirements for propagule success in Argentine ants, it is not surprising how easily they spread via human commerce.
Black Rats, Island Characteristics, and Colonial Nesting Birds in the Mediterranean: Consequences of an Ancient Introduction
Authors: Martin Jean‐Louis , Thibault Jean‐Claude , Bretagnolle Vincent
Published: March 2003

Abstract: The devastation of island faunas by alien species has been instrumental in raising concerns about the global threat to biological diversity. Colonial nesting species, often restricted to islands, have been affected severely. Eradication of introduced species as a means to alleviate the problem is usually done with little or no understanding of the mechanisms governing interactions between introduced and native species. Such an understanding could help target management action. We analyzed how island area, rock substrate, bird species biology, and presence of an introduced species, the black rat (  Rattus rattus), interact to explain the distribution and abundance of colonial nesting birds on a set of 72 islands from six archipelagos in the western Mediterranean. Rats were introduced to this region over 2000 years ago, and these communities have had time to reach an equilibrium. Using general linear models, we show that rats have affected species distributions more on the smaller islands and on islands with an acidic or neutral rock substrate; larger bird species are more resistant. On the smaller islands, where rat densities are highest, larger colonial birds are negatively affected. On larger islands, where rat densities are lower and fluctuate form year to year, larger colonial birds can maintain healthy populations despite the presence of rats. Although rats caused local extinction or reduction in bird abundance, the presence of islands varying in size and/or substrate allowed most archipelagos to retain their suite of colonial nesting bird species, despite a presumably reduced abundance for most species.
Stress Resistance and Environmental Dependency of Inbreeding Depression in Drosophila melanogaster
Authors: Dahlgaard Jesper , Hoffmann Ary A.
Published: March 2003

Abstract: Both inbreeding and environmental stress can have adverse effects on fitness that affect the conservation of endangered species. Two important issues are whether stress and inbreeding effects are independent as opposed to synergistic, and whether inbreeding effects are general across stresses as opposed to stress‐specific. We found that inbreeding reduced resistance to acetone and desiccation in adult Drosophila melanogaster, whereas resistance to knockdown heat stress was not affected. Inbred flies, however, experienced a greater proportional decrease in productivity than outbreds following heat stress. Correlations using line means indicated that all resistance traits were uncorrelated in the inbred as well as in the outbred flies. Recessive, deleterious alleles therefore did not appear to have any general deleterious effects on stress resistance. Inbreeding within a specific environment and selection for resistant genotypes may therefore purge a population of deleterious genes specific to only one environmental stress.
Managing the Abundance and Diversity of Breeding Bird Populations through Manipulation of Deer Populations
Authors: McShea William J. , Rappole John H.
Published: March 2003

Abstract: Deer densities in forests of eastern North America are thought to have significant effects on the abundance and diversity of forest birds through the role deer play in structuring forest understories. We tested the ability of deer to affect forest bird populations by monitoring the density and diversity of vegetation and birds for 9 years at eight 4‐ha sites in northern Virginia, four of which were fenced to exclude deer. Both the density and diversity of understory woody plants increased following deer exclosure. The numerical response of the shrubs to deer exclosure was significantly predicted by the soil quality (ratio of organic carbon to nitrogen) at the sites. Bird populations as a whole increased following exclosure of deer, particularly for ground and intermediate canopy species. The diversity of birds did not increase significantly following exclosure of deer, however, primarily because of replacement of species as understory vegetation proceeded through successional processes. Changes in understory vegetation accounted for most of the variability seen in the abundance and diversity of bird populations. Populations of deer in protected areas are capable of causing significant shifts in the composition and abundance of bird communities. These shifts can be reversed by increasing the density and diversity of understory vegetation, which can be brought about by reducing deer density.
War and Peace and Conservation Biology
Authors: Ehrenfeld David
Published: March 2003

Abstract:Since its inception, conservation biology has been, like medicine, a mission‐oriented field, its mission being to preserve the Earth's biodiversity. Unlike medicine, however, conservation biology has no regular, systematically employed mechanisms in place for monitoring the success or failure of its efforts. My appraisal of papers published in the first three issues of volume 13 ofConservation Biologyindicates that the majority of research in the discipline yields more descriptions and recommendations than actual conservation achievements. This does not appear to be a problem of motivation or the quality of our science. We have made undeniable advances in our understanding of conservation biology, but this has not produced comparable conservation results, in part because the forces causing the extinction of species and the disruption of ecosystems often have little to do with biology. Have we undertaken a task whose completion lies beyond the power of our science and technology? InWar and Peace, Leo Tolstoy used the failure of Napoleon's invasion of Russia to examine the idea that science (expertise) and reason simply cannot control the great events of the world, which are inherently too complex to be managed by these methods. The twentieth‐century philosopher Isaiah Berlin largely agrees but takes a more moderate position: he explains why it is sometimes possible to apply reason to the vast problems that confront us and achieve the desired results. By analogy, in conservation biology we can achieve conservation objectives, but we must give up the self‐serving belief that an increase in our scientific knowledge by itself will always move us toward effective conservation. To help identify the conservation strategies that work, conservation biology must close critical feedback loops by emulating medicine and regularly monitoring the effectiveness of its research and recommendations and by understanding the place of its work in the life of the community.
Interdisciplinary Guidelines for Developing Effective Koala Conservation Policy
Authors: Clark Tim W. , Mazur Nicole , Begg Robert J. , Cork Steven J.
Published: March 2003

Abstract: Adequacy of the ongoing koala policy process and whether it can conserve koalas is currently in dispute. To address this issue, interdisciplinary guidelines are available to improve koala policy and management and to find consensus. These guidelines focus attention on five policy elements. The first three are rational, political, and moral perspectives on koala policy; the fourth the standpoint of a participant, and the fifth is knowledge integration for practical action. We discuss and illustrate these elements with koala case material. Rationality in policy is addressed through problem orientation, which requires participants to clarify goals, identify problems, and create alternatives in an iterative way. We examined the political dynamics—value clashes—in decision processes. A decision process ideally clarifies and secures common interests. We provide standards for each decision function, such as reliability, comprehensiveness, timeliness. Morality rests on basic premises that are used to justify policy positions. Clarification of the participant's standpoint addresses differing personalities, epistemologies, disciplines, and organizational and parochial biases. Integrating knowledge for practical policy action requires a conceptual framework that is up to the demands of the task. Together the five policy elements make up a logically comprehensive set of interrelated concepts for koala policy development, implementation, and appraisal. Many opportunities exist to use these guidelines skillfully in on‐the‐ground koala conservation efforts to improve koala policy outcomes.
Local Population Dynamics in Metapopulation Models: Implications for Conservation
Authors: Lopez Jorge E. , Pfister Catherine A.
Published: March 2003

Abstract: Habitat fragmentation and the division of populations into spatially separated units have led to the increasing use of metapopulation models to characterize these populations. One prominent model that has served as a heuristic tool was introduced by Levins and is based on a collection of simplifying assumptions that exclude information on the dynamics and spatial distribution of local populations. Levins's and similar models predict the proportion of occupied habitat patches at equilibrium and the conditions needed to avoid total extinction. There are many obvious concerns about using such models, including how realistic alterations might change the predictions and whether occupancy has any relationship to population‐level processes. Although many of the assumptions of these simple models are known to be unrealistic, we do not know how the assumptions affect model predictions. We simulated a metapopulation, and our results show that assumptions such as homogeneity of habitat patches, random migration among patches, equivalent extinction probabilities in all patches, and a large number of patches can lead to large overestimations of habitat occupancy. But when we explicitly modeled the underlying population dynamics within each patch, we found (1) that there was a strong correlation between proportion of occupied patches and total metapopulation size and (2) that the distribution of individuals among patches was relatively insensitive to model assumptions. Thus, our results show that although realistic modifications will change model predictions for occupancy, occupancy and population trends will be correlated. These correlations between occupancy and population size suggest that occupancy models may have some utility in conservation applications.
Indirect Benefits of Marine Protected Areas for Juvenile Abalone
Authors: Rogers‐Bennett Laura , Pearse John S.
Published: March 2003

Abstract: Marine protected areas ( MPAs) designed to provide harvest refugia for red sea urchins (  Strongylocentrotus franciscanus) offer a unique opportunity to study the indirect effects of urchin fishing on subtidal communities. Sea urchins may provide important cryptic microhabitat for juvenile abalone sheltering beneath urchin spines in shallow habitats worldwide. We investigated the abundance of juvenile (3–90 mm) red abalone, (   Haliotis rufescens) and the rare flat (<90 mm) abalone (   H. walallensis) on protected and fished rocky reefs in California. Abalone abundance surveys were conducted inside 24× 30 m plots on three protected reefs with red sea urchins present and three fished reefs where red sea urchins were removed by commercial or experimental fishing. Significantly more juvenile abalone were found in 1996 and 1997 on protected reefs with urchins present than on fished reefs ( χ  2 = 188, df = 1, p < 0.001). Juvenile red abalone abundance was not correlated with local adult red abalone abundance or habitat rugosity. One‐third of the juveniles inside the MPAs were found under the urchins' spine canopy, as were a suite of unfished marine organisms. In the laboratory, juvenile abalone survived better ( χ  2 = 7.31, df = 1, p < 0.01) in crab predation experiments in which red sea urchins were available as shelter. Fishing red urchins reduced structural complexity, potentially decreasing microhabitat available for juvenile abalone. This example demonstrates how MPAs designed for one fished species may help other species, illustrating their usefulness for ecosystem‐based fishery management and marine conservation.
Extraterritorial Movements of a Forest Songbird in a Fragmented Landscape
Authors: Norris D. Ryan , Stutchbury Bridget J. M.
Published: March 2003

Abstract: Forest isolation resulting from fragmentation is thought to impede the movement of forest songbirds. Because of the difficulty of tracking birds continuously, however, few data exist documenting the influence of isolation and landscape features on avian movements. During the breeding season, male Hooded Warblers (   Wilsonia citrina ) leave their small (<2.5 ha), isolated forest patches to travel between forest fragments. We documented a total of 106 forays ( n = 20 males) and found that individuals traveled up to 2.5 km away from their resident forest patch, primarily to solicit covert extra‐pair copulations. Forays occurred despite the absence of forested corridors connecting fragments; even when corridors were present, males most often chose to fly directly across open fields. Resident patch size and distance to forests visited were not correlated with the frequency of forays. The maximum distance males flew over open fields did not exceed 465 m, and longer distances likely inhibit males from traveling outside their woodlots. If territorial establishment depends on the availability of extra‐pair partners, then higher degrees of isolation between forests could explain why some species avoid settling in extremely fragmented landscapes. Conservation efforts should limit isolation between forest stands, thereby preserving the ability of animals to move within fragmented landscapes during the breeding season.
Phylogenetic Reanalysis of the Saudi Gazelle and Its Implications for Conservation
Authors: Hammond Robert L. , Macasero William , Flores Benito , Mohammed Osama B. , Wacher Tim , Bruford Michael W.
Published: March 2003

Abstract: The identification of taxonomically appropriate populations of endangered species for captive breeding and reintroduction programs is fundamental to the success of those programs. The Saudi gazelle (  Gazella saudiya) was endemic to the Arabian peninsula but is now considered extinct in the wild and is potentially a candidate for captive breeding and reintroduction. Using 375 base pairs of mitochondrial DNA (mtDNA) cytochrome b gene derived from museum samples collected from the wild prior to the presumed extinction of this species, we show that G. saudiya is the sister taxon of the African dorcas gazelle ( G. dorcas). Reciprocal monophyly of G. saudiya mtDNA haplotypes with G. dorcas, coupled with morphological distinctiveness, suggests that it is an evolutionarily significant unit. These data indicate that captive populations identified previously as potential sources of G. saudiya for captive breeding appear incorrectly designated and are irrelevant to the conservation of G. saudiya. The polymerase chain reaction–restriction fragment length polymorphism ( PCR‐RFLP) analysis of several private collections of living gazelles in Saudi Arabia provides no evidence for the survival of G. saudiya. We recommend that field surveys be undertaken to establish whether G. saudiya is indeed extinct in the wild and that other private collections within the Arabian peninsula be screened genetically. We urge caution when captive animals of unknown provenance are used to investigate the phylogenetics of cryptic species groups.
Amphibian Declines and Environmental Change: Use of Remote‐Sensing Data to Identify Environmental Correlates
Authors: Carey Cynthia , Heyer W. Ronald , Wilkinson John , Alford Ross A. , Arntzen J. W. , Halliday Tim , Hungerford Laura , Lips Karen R. , Middleton Elizabeth M. , Orchard Stan A. , Rand A. Stanley
Published: March 2003

Abstract: Populations of many amphibian species are declining worldwide, and a few species appear to have become extinct. In an attempt to evaluate the potential usefulness of remote‐sensing techniques as a tool for identifying the causes of these declines, we compiled a database that contains descriptions of 120 localities, both at which declines have been documented and at which no declines are yet known. The number of species involved, dates and degree of declines, habitat characteristics, and other factors are provided for each locality. Four relatively undisturbed areas in northeastern Australia, Costa Rica–Panama, central Colorado, and Puerto Rico were chosen for examination of environmental correlates coincident with mass mortalities at these localities. We used data predicted by models or collected by satellites, airplanes, or direct sampling on the ground to evaluate variations over time in temperature, precipitation, wind direction, UV‐B radiation, and concentrations of certain contaminants at these sites. We asked whether unusual changes in these environmental variables occurred either just in advance of or concurrent with dates of amphibian mass mortalities. The variation in certain environmental variables documented by others (Alexander & Eischeid 2001; Middleton et al. 2001; Stallard 2001 [all this issue]) appears unlikely to have directly caused amphibian deaths. But correlations between these environmental changes and the occurrence of amphibian die‐offs invite further investigation into synergistic interactions among environmental variables and possible indirect causal relationships.