bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Population Genetic Structure of the Rare Woodland Shrub Daviesia suaveolens and Its Common Congener D. mimosoides
Authors: Young A.G. , Brown A.H.D.
Published: March 2003

Genetic (allozyme) variation and population genetic structure of the rare shrub Daviesia suaveolens, found in only a few large populations on the eastern escarpment of the southern tablelands of New South Wales, were compared to those of its abundant and widespread relative D. mimosoides at both spatially equivalent and rangewide scales. We hypothesized that the rare species is genetically depauperate relative to the common one. We also generated baseline data on D. suaveolens to provide management recommendations for its conservation. Both species had high variation relative to other widespread woody angiosperms. Rangewide, the rare species exhibited lower species‐level genetic variation than its common relative but a similar level of variation to that found in D. mimosoides over an equivalent spatial scale. Population‐level genetic variation was similar for the two species. Over its small geographic range, D. suaveolens populations were three times as genetically differentiated as D. mimosoides over the same scale, showing a clear northsouth genetic disjunction and as much interpopulation divergence as the common species exhibited rangewide. These results confirm that not all types of rarity have the same genetic implications. Conservation strategies for D. suaveolens need not be concerned about low population‐level variation unless populations become significantly smaller than is currently typical. Of more importance is to maintain the high interpopulation differentiation by conserving populations from both the north and south of the species’ range.
Molecular Genetics of Pre‐1940 Red Wolves
Authors: Roy Michael S. , Geffen Eli , Smith Deborah , Wayne Robert K.
Published: March 2003

Conservation of the endangered red wolf (Canis rufus) has become a controversial issue because its genetic and morphological composition has been altered by hybridization with coyotes (C. latrans) and possibly gray wolves (C. lupus) making its evolutionary origins difficult to ascertain. The evolutionary hypothesis based on morphological data is that the red wolf had an Early Pleistocene origin and was the predecessor of both modern coyotes and gray wolves. After 1940 red wolves hybridized with coyotes as the species vanished from the wild. In contrast to this ancient origin‐recent introgression hypothesis, molecular data are more consistent with an origin through hybridization between gray wolves and coyotes. Interspecific hybridization may have occurred repeatedly over time prior to European settlement in the southcentral United States or may have been induced recently by anthropogenic changes. We review recent molecular evidence and present new results from the analysis of mitochondrial and nuclear DNA markers in pre‐1940 populations of red wolves. Our results are inconsistent with an ancient origin of the red wolf and support the hybridization model. We discuss possible hybridization scenarios and reasons for the red wolf reintroduction program to be concerned with the effects of genetic introgression from coyotes.
What is Good Ecological Restoration?
Authors: Higgs Eric S.
Published: March 2003

The rapid rise of ecological restoration is forcing consideration of what good restoration entails. Defining an end point for restoration is as much an ethical matter as a technical one, but scientifically trained restorationists have largely ignored the former issue. I argue that good restoration requires an expanded view that includes historical, social, cultural, political, aesthetic, and moral aspects. This expanded definition is necessary at a practical level to guide practitioners in the pursuit of excellence and at a conceptual level to prevent restoration from being swamped by technological activities and projects that veer away from ecological fidelity. Ecological fidelity is based on three principles: structural/compositional replication, functional success, and durability. These principles produce effective restoration, which is a necessary but not a sufficient condition of good restoration. An examination of characteristic problems that emanate from technological practices—reverse adaptation, an attention to product at the expense of process, and the separation of actions from consequences—leads directly to an expanded, inclusive framework for restoration. The results of an inclusive restoration process set up conditions necessary for restoration to achieve both ecological fidelity and harmonious human relationships within ecosystems.
The Rarest of Darwin’s Finches
Authors: Grant Peter R. , Grant B. Rosemary
Published: March 2003

The Mangrove Finch (Cactospiza heliobates) is unique among Darwin’s finches in its specialized habits and naturally fragmented distribution on individual islands. It has been reported to occupy six patches of mangroves separated to varying degrees on two of the Galápagos islands, Isabela and Fernandina. We present the results of a field study in three of the patches. The species appears to have become extinct on Fernandina and to be restricted now to a maximum of four habitat islands on Isabela. In one of them, Playa Tortuga Negra, we estimate the population of breeding adults to be 10–20 pairs. At another, west of Villamil, the population size is probably now small due to the cutting of mangroves. The other two populations, close to each other east of Punta Moreno, probably hold the largest demes. Their status is unknown. We estimate that the genetically effective size of the combined populations is 30–380 individuals. Because the populations are so small and restricted, they are vulnerable to any disturbance of the environment. This has probably been so throughout their history because they inhabit a fragmented habitat in a tectonically active region. New anthropogenic threats this century are an introduced wasp (Polistes versicolor), which may be a predator on a major food item (insect larvae) of the finches, and destruction of the habitat. Protection of the occupied habitat against human exploitation is required for the preservation of the species because no alternative habitat is known.
Influences of Egg Laying Behavior on Pathogenic Infection of Amphibian Eggs
Authors: Kiesecker Joseph M. , Blaustein Andrew R.
Published: March 2003

Mass mortality of developing amphibian eggs and larvae from pathogenic infection has been recently documented in some amphibian populations. For example, the pathogenic fungus, Saprolegnia ferax, has been linked with amphibian embryo mortality in the Pacific Northwest. Continued mortality in early life history stages may ultimately contribute to a population decline. We document the prevalence of S. ferax on embryos of three anuran species (   Bufo boreas, Rana cascadae, and Hyla regilla) common to the Pacific Northwest. These species differ in key aspects of their behavior and ecology, and these differences may lead to differential susceptibility to S. ferax. R. cascadae often lays its eggs communally and B. boreas usually deposits its eggs communally. We observed embryos at natural oviposition sites. Eggs laid communally had higher mortality than those laid away from other egg masses. Field experiments that manipulated both the spatial position and timing of egg laying demonstrated that eggs laid later and in closer proximity to communal masses had higher mortality. Our results suggest that eggs in communal masses are highly susceptible to infection with S. ferax.
The Use of Bushland, Corridors, and Linear Remnants by Birds in Southeastern Queensland, Australia
Authors: Bentley Jocelyn M. , Catterall Carla P.
Published: March 2003

Within the southeastern region of Queensland, Australia, native forest cover ( bushland) has been greatly reduced and fragmented, and clearing is still occurring. Many of the region’s bird species are being increasingly restricted to isolated habitat remnants. However, little is known about the habitat value of these remnants and whether their value is influenced by their degree of connection. We investigated bird use of riparian corridors in pastoral and urban surroundings and riparian linear remnants within an urban context. We compared the avifauna of these remnants with dryland and riparian sites within continuous bushland. We also assessed their use by previously derived response‐guilds of birds to bushland clearing. We counted 3567 individuals of 102 bird species. Riparian bushland supported more species and had greater bird abundances than dryland bushland. Corridors and linear remnants supported densities of many bushland‐dependent species similar to those in bushland; this varied with species’ patterns of large‐scale migration and residency. Bushland‐dependent winter migrants used both corridors and linear remnants extensively. Bushland‐dependent residents were most abundant in continuous bushland and least abundant in linear remnants, possibly reflecting the constraints of central place foraging. Effects of isolation were only evident in resident bushland‐dependent species. Local habitat variables were significantly associated with variation in abundance of some types of birds within corridors and linear remnants; however, the differences in bird abundances attributable to spatial characteristics were greater than those attributable to habitat characteristics. The effects of bushland fragmentation and isolation were mediated by the extent to which species are dependent upon bushland and their patterns of large‐scale migration or residency. Local habitat, and possibly more importantly altitude, may influence site use by winter migrants and generalist species.
Effects of Population Size on Seed Production and Germinability in an Endangered, Fragmented Grassland Plant
Authors: Morgan John W.
Published: March 2003

Abstract:
Fragmentation and isolation of plant populations are thought to affect demographic processes such as seed production and cause reductions in fitness. I followed seed set over a 3‐year period in eight populations of the endangered Rutidosis leptorrhynchoides (Asteraceae) that differed in population size from 13 to over 5000 flowering plants. Germinability of the resultant seed was also examined to determine whether small populations had lower fitness than large populations. Seed set was significantly associated with population size in 2 of the 3 years. Small populations (<30 flowering plants) produced significantly fewer seeds per head in 1994 and 1995 than did large populations (500 to over 5000 flowering plants), which did not differ significantly from one another. There was, however, substantial variation within populations. In 1993 seed production did not follow any simple relationship with population size, possibly because environmental stress from low rainfall had an overriding impact. Differences in seed germinability between populations were largely not evident, suggesting that this aspect of fitness has not declined substantially in small populations relative to large populations. This study suggests that nongenetic, demographic factors are of immediate importance to the persistence of small populations of R. leptorrhynchoides because of their potential impacts on seedling recruitment.
Molecular Systematics and the Conservation of Rare Species
Authors: Soltis Pamela S. , Gitzendanner Matthew A.
Published: March 2003

Abstract:Despite the tradition of systematic biology as the science of diversity, systematics has until recently contributed relatively little to the theory and practice of conservation biology. We identify four areas in which systematics could contribute to the conservation of rare plant species: (1) species concepts, (2) the identification of lineages worthy of conservation, (3) the setting of conservation priorities, and (4) the effects of hybridization on the biology and conservation of rare species. Species concepts that incorporate history and reflect phylogeny ultimately will be more useful for preserving biodiversity than those that do not. Phylogenetic analyses involving conspecific populations often reveal multiple lineages that may warrant protection as evolutionarily distinct units. Phylogenetic information also should be considered in setting priorities for conservation. Systematics provides the tools for inferring relationships among organisms and, in conjunction with biogeography, for identifying those areas that harbor many actively speciating groups. Hybridization may lead to the extinction of a rare species, but in other cases, ironically, artificial hybridization with a more widespread congener may be the only way to preserve the gene pool of a rare species. We appeal to systematists to contribute actively to both conservation theory and practice, and we call for the integration of systematics in the establishment of conservation priorities and the development of strategies to preserve Earth’s biota.
High Rates of Extinction and Threat in Poorly Studied Taxa
Authors: McKinney Michael L.
Published: March 2003

Abstract:Mass extinctions in the past have been characterized by abnormally high species extinction rates within almost all taxa. Attempts to estimate relative rates of extinction and threat among modern taxa, such as insects, plants, and vertebrates, are impeded by differences in the quality of information about each group. Insects and marine groups, for example, have much smaller percentages of known threatened species but also have many more undescribed species than do plants or vertebrates. I tested the possibility that all major groups have equally high rates of extinction and threat. The first test was a model assuming that differences in apparent global extinction and threat rate are caused by two sampling biases that produce artificially low rates in understudied taxa: (1) a common‐species bias in which taxonomists tend to record common (more extinction‐resistant) species first and (2) evaluative neglect, which is a tendency to spend relatively less effort evaluating the extinction and threat status of recorded species in understudied taxa. Global extinction and threat data from a number of groups generally follow the pattern predicted by this model. The second test shows that in direct measurements of extinction and threat between taxa in well‐studied regions, such as the United States and United Kingdom, the apparent global disparity among taxa is greatly reduced. Indeed, many globally understudied taxa, such as insects and other invertebrates, have higher rates of threat than many other taxa, including mammals, in these well‐studied areas. These two tests provide quantitative support for previous suggestions that the wide disparity in rates of species extinction and threat among groups represents an artifactual distortion of the actual rates. Specific suggestions for improved estimates of actual threat include (in order of increasing accuracy): use of well‐studied proxy taxa such as mammals; comparison of threat data among taxa only in well‐studied regions; and, especially important, increased efforts to evaluate the threat status of recorded species of understudied taxa.
Decline of a Native Mussel Masked by Sibling Species Invasion
Authors: Geller Jonathan B.
Published: March 2003

Abstract:
The European blue mussel ( Mytilus galloprovincialis) has extensively invaded southern California, whereas a native species, M. trossulus, is abundant in northern California and further north. In this study, a portion of the 16S ribosomal RNA gene was sequenced from mussels collected in southern and central California in the nineteenth century. I aligned these sequences with 22 sequences representing modern M. galloprovincialis, M. edulis, and M. trossulus. Phylogenetic analysis using parsimony identified the nineteenth‐century mussels as M. trossulus. Because mussel populations have been continuously present in this region since the time these mussels were collected, these data indicate that M. trossulus were present during the initial invasion of M. galloprovincialis, but, due to the morphological similarity of the two species, declined without notice.
Fragmentation Effects on Forest Birds: Relative Influence of Woodland Cover and Configuration on Landscape Occupancy
Authors: Villard Marc‐André , Trzcinski M. Kurtis , Merriam Gray
Published: March 2003

Abstract: Habitat fragmentation has been shown to influence the abundance, movements, and persistence of many species. We asked the following questions: (1) Do species respond mainly to habitat loss or to the changes in habitat configuration resulting from this loss? (2) Do species exhibit sharp thresholds in their response to forest cover or configuration? We compared the relative influence of forest cover and configuration on 15 bird species in 33 landscapes (6.25 km2) in eastern Ontario, Canada. Forest cover in these landscapes varied between 3.4% and 66.8%. The metrics we used to quantify forest configuration were correlated to forest cover, so we regressed these configuration metrics against cover and used the residuals in logistic regression models. Of the 15 forest bird species included in the analyses, the presence of only 3 (Downy Woodpecker [  Picoides pubescens], Brown Creeper [Certhia americana], and White‐breasted Nuthatch [ Sitta carolinensis]) was not significantly related to either cover or configuration of woodland. Forest cover and configuration each were significant predictors of the presence of 6 species in landscapes occupied in both years, and 3 species responded both to cover and configuration. Models based on single years showed variability in the landscape characteristics that were significant predictors of the presence of each species. These results indicate that (1) landscape structure was an important predictor of bird distribution, (2) both forest cover and configuration were important predictors of species presence, and (3) responses were species‐specific. Effects of forest cover and configuration on species presence generally were not characterized by sharp thresholds, preventing the application of simple management rules. Although forest cover is an important feature of landscape structure, our results indicate that woodland configuration is a far from negligible component that should also be incorporated in conservation strategies.
Conservation Priorities for Chukar Partridge in Israel Based on Genetic Diversity across an Ecological Gradient
Authors: Kark Salit , Alkon Philip U. , Safriel Uriel N. , Randi Ettore
Published: March 2003

Abstract:
Recent studies suggest that patterns of genetic diversity significantly influence the viability and persistence of local populations. Revealing and mapping spatial patterns of genetic diversity within species’ ranges may be vital when defining criteria and prioritizing areas for conservation. Chukar Partridges (Alectoris chukar) in Israel occur along a steep ecogeographical gradient extending from mesic Mediterranean zones in the north to steppe and desert regions in the south. To test the hypothesis that the most genetically diverse populations within a species’ range occur within the ecotone, an area of transition between ecosystems where a sharp environmental gradient exists, we examined the allozyme diversity of chukars collected at five locations within the species’ continuous range in each of 2 years. Based on 32 allozyme loci, the genetic diversity of chukars increased significantly along a gradient from populations in Mediterranean regions to those at the ecotone in the northern Negev desert, despite close geographical proximity among populations. Genetic diversity as estimated by percent polymorphic loci, observed and expected heterozygosity, and mean number of alleles was not homogeneous among sampling localities: single and multilocus Hardy‐Weinberg and linkage disequilibria increased along the gradient toward the ecotone. Populations exhibited some isolation by distance effects in the face of substantial gene flow. We therefore recommend that higher conservation priority be assigned to the Mediterranean‐Negev ecotone area. For Chukar Partridges, it supports the highest overall genetic diversity as well as unique alleles. Priorities for other populations, moreover, can also be set based on their genetic diversity across ecological gradients. Rapid urbanization of Israeli landscapes threatens to disrupt unique and perhaps essential genetic connections among chukar populations, and management of chukars in Israel within a metapopulation context is an urgent requirement.
Using Presence‐Absence Data to Build and Test Spatial Habitat Models for the Fisher in the Klamath Region, U.S.A.
Authors: Carroll Carlos , Zielinski William J. , Noss Reed F.
Published: March 2003

Abstract: Forest carnivores such as the fisher ( Martes pennanti) have frequently been the target of conservation concern because of their association in some regions with older forests and sensitivity to landscape‐level habitat alteration. Although the fisher has been extirpated from most of its former range in the western United States, it is still found in northwestern California. Fisher distribution, however, is still poorly known in most of this region where surveys have not been conducted. To predict fisher distribution across the region, we created a multiple logistic regression model using data from 682 previously surveyed locations and a vegetation layer created from satellite imagery. A moving‐window function in a geographic information system was used to derive landscape‐level indices of canopy closure, tree size class, and percent conifer. The model was validated with new data from 468 survey locations. The correct classification rate of 78.6% with the new data was similar to that achieved with the original data set (80.4%). Whereas several fine‐scale habitat attributes were significantly correlated with fisher presence, the multivariate model containing only landscape‐ and regional‐scale variables performed as well as one incorporating fine‐scale data, suggesting that habitat selection by fishers may be dominated by factors operating at the home‐range scale and above. Fisher distribution was strongly associated with landscapes with high levels of tree canopy closure. Regional gradients such as annual precipitation were also significant. At the plot level, the diameter of hardwoods was greater at sites with fisher detections. A comparison of regional fisher distribution with land‐management categories suggests that increased emphasis on the protection of biologically productive, low‐ to mid‐elevation forests is important to ensuring the long‐term viability of fisher populations.
Mitochondrial DNA Variability in Italian and East European Wolves: Detecting the Consequences of Small Population Size and Hybridization
Authors: Randi Ettore , Lucchini Vittorio , Christensen Mads Fjeldsø , Mucci Nadia , Funk Stephan M. , Dolf Gaudenz , Loeschcke Volker
Published: March 2003

Abstract: The Italian wolf (Canis lupus) population has declined continuously over the last few centuries and become isolated as a result of the extermination of other populations in central Europe and the Alps during the nineteenth century. In the 1970s, approximately 100 wolves survived in 10 isolated areas in the central and southern Italian Apennines. Loss of genetic variability, as suggested by preliminary studies of mitochondrial DNA (mtDNA) sequences, hybridization with feral dogs, and the illegal release of captive, non‐native wolves are considered potential threats to the viability of the Italian wolf population. We sequenced 546 base pairs of the mtDNA control region in a comprehensive set of Italian wolves and compared them to those of dogs and other wolf populations from Europe and the Near East. Our data confirm the absence of mtDNA variability in Italian wolves: all 101 individuals sampled across their distribution in Italy had the same, unique haplotype, whereas seven haplotypes were found in only 26 wolves from an outbred population in Bulgaria. Most haplotypes were specific either to wolves or dogs, but some east European wolves shared haplotypes with dogs, indicative of hybridization. In contrast, neither hybridization with dogs nor introgression of non‐native wolves was detected in the Italian population. These findings exclude the introgression of dog genes via matings between male wolves and female dogs, the most likely direction of hybridization. The observed mtDNA monomorphism is the possible outcome of random drift in the declining and isolated Italian wolf population, which probably existed at low effective population size during the last 100–150 years. Low effective population size and the continued loss of genetic variability might be a major threat to the long‐term viability of Italian wolves. A controlled demographic increase, leading to recolonization of the historical wolf range in Italy, should be enforced.
Effect of Hunting in Source‐Sink Systems in the Neotropics
Authors: Novaro Andres J. , Redford Kent H. , Bodmer Richard E.
Published: March 2003

Abstract:Previous studies of the sustainability of wildlife hunting in the Neotropics have not considered the potential dispersal of animals into hunted areas. A literature review of studies of subsistence hunting in the Neotropics suggests that hunting is often conducted in areas adjacent to relatively undisturbed habitat that may act as sources of animals for the hunted sites. We compared studies of tapir (  Tapirus terrestris) hunting at different sites to illustrate the potential bias of sustainability evaluations based on local productivity. The limited information available suggests that dispersal could have a key role in rebuilding animal populations depleted by hunting. Thus, factors that strongly affect dispersal—such as spatial distribution and size of areas with and without hunting, population size in source areas, and social behavior—should be considered when the sustainability of hunting is evaluated in areas with heterogeneous hunting pressure. We suggest the application of two models that use spatial controls (recognizing the potential source‐sink nature of some hunted systems and protecting unhunted refugia) to avoid wildlife overexploitation when biological data and enforcement capabilities to regulate harvests are limited. This approach may produce more reliable evaluations of sustainability, provide information on the dynamics of hunting systems, and help local communities and policymakers conserve key areas (including protected areas) that may act as game sources.
Reproductive Success in Reestablished versus Natural Populations of a Threatened Grassland Daisy (Rutidosis leptorrhynchoides)
Authors: Morgan John W.
Published: March 2003

Abstract: Populations of the endangered Rutidosis leptorrhynchoides (Asteraceae) have been reestablished in conservation reserves to reduce their risk of extinction in the wild. The reproductive success (number of seeds per inflorescence, percent seed set, germinability) of five small reestablished populations (at 5–10 years after establishment) was compared to that of two large natural remnant populations from which they were derived. Initial growth rates under glasshouse conditions were compared for seedlings derived from seed from remnant and reestablished populations. Seed set per inflorescence in all five reestablished populations was equal to or greater than seed set in remnant population plants. The resulting seed was as germinable, and in some cases more germinable, than seed derived from remnant populations; the seedlings then grew as large or larger than remnant population seedlings grown under glasshouse conditions. Fitness reductions in small reestablished populations of R. leptorrhynchoides are not evident at the reproductive stage. Hence, these populations have some potential to maintain natural regeneration processes and might therefore positively contribute to the conservation of this species.
Iberian Lynx in a Fragmented Landscape: Predispersal, Dispersal, and Postdispersal Habitats
Authors: Palomares F. , Delibes M. , Ferreras P. , Fedriani J. M. , Calzada J. , Revilla E.
Published: March 2003

Abstract: Applied conservation biology must provide solutions for the conservation of species in modern landscapes, where prime habitats are being continuously fragmented and altered and animals are restricted to small, nonviable populations. We studied habitat selection in a fragmented population of endangered Iberian lynx (  Lynx pardinus) by examining 14 years of radiotracking data obtained from lynx trapped in two different source areas. Habitat selection was studied independently for predispersal lynx in the source areas, for dispersing individuals through the region, and for postdispersing animals, most of which settled far from their point of origin. A multivariate analysis of variance showed that habitat use differed significantly among these phases and between area of origin, but not between sexes. The habitat type most used, and best represented within home ranges, was the mediterranean scrubland. Pine plantations were also important during and after dispersal. The rest of the habitats were either avoided (open habitats) or used according to availability ( pine and eucalyptus plantations) by dispersing lynx. Differences due to lynx origin were detected only during predispersal and dispersal and were observed because animals from each area had different habitat availability. Lynx with established territories did not use areas at random. They occupied patches of mediterranean scrubland more often than would be expected from scrubland availability during predispersal; the rest of the habitats were included within home ranges less than would be expected from their availability in the landscape. Results indicate that dispersing animals may use habitats of lower quality than habitats used by resident individuals, which suggests that conservation strategies applied across regions might be a viable objective.
Avifaunal Use of Wooded Streets in an Urban Landscape
Authors: Fernández‐Juricic Esteban
Published: March 2003

Abstract: Birds in urban landscapes primarily occupy parks (  forest fragments), wooded streets ( linear strips connecting fragments), or the urban matrix. I studied the effects of street location in the landscape, vegetation structure, and human disturbance ( pedestrian and automobile load) within wooded streets on bird species richness, temporal persistence, and density of feeding and nesting guilds, and on the probability of street occupation by individual species in Madrid during two consecutive breeding seasons. The number of species recorded increased from the least suitable (control streets without vegetation) to the most suitable habitats (urban parks), with wooded streets being intermediate landscape elements. Fourteen species, belonging to four of the eight guilds identified in this system, were recorded in wooded streets in both years. Streets that connected urban parks, along with vegetation structure, positively influenced the number of species within wooded streets, species persistence, guild density, and probability of occupation of streets by individual species. Human disturbance exerted a negative influence on the same variables. Wooded streets potentially could function as corridors, allowing certain species—particularly those feeding on the ground and breeding in trees or tree holes—to fare well by supporting alternative habitat for feeding and nesting. Local improvements in corridor quality, through increased vegetation complexity and reduced human disturbance, could exert a positive influence on the regional connectivity of the system. Because of differential use of corridors by species with different habitat requirements, however, corridor implementation should also take into account the target species of management.
Seed Removal and Fate in Two Selectively Logged Lowland Forests with Constrasting Protection Levels
Authors: Guariguata Manuel R. , Adame Jesús J. Rosales , Finegan Bryan
Published: March 2003

Abstract: We evaluated seed removal by terrestrial mammals and the fate of removed, threaded seeds (as a measure of dispersal) in two neighboring tropical rain forest sites in the Caribbean lowlands of Costa Rica. Both sites have been selectively logged but differ in their degree of protection from human intrusion and habitat connectivity: La Selva is protected from hunting and connected to a national park, whereas Tirimbina remains unprotected and is not connected to a park. The two study sites are similar in logging intensity, elevation, and canopy tree structure and composition. We predicted that rates of seed removal and seed dispersal would be higher at the connected and protected site. For seven tree species (six of which are timber species), we determined that patterns of seed removal under an exclusion experiment (semipermeable cages vs. uncaged) varied both within species across sites and within sites across species, suggesting site differences in abundance, degree of animal activity, or presence of particular mammal seed consumers. Rates of seed removal and dispersal were largely species‐specific. Most of the study species showed neither site nor treatment effect, whereas others had disproportionately higher removal rates at La Selva. For all species combined (covering a 6‐month period due to phenological differences among the study species; n = 920 seeds per site), twice as many removed seeds were dispersed at La Selva (5.3%) than at Tirimbina (2.2%). Only one timber species, Pentaclethra macroloba, did not appear sensitive to site differences in rates of seed removal, most likely because its seeds are toxic to animals. Two timber species, Carapa nicaraguensis and Lecythis ampla, whose seeds are consumed by large scatterhoarding rodents, had 2.5% and 13%, respectively, of their removed seeds dispersed at La Selva, whereas no seeds were dispersed at Tirimbina. In northeastern Costa Rica, where forest cover is fragmented and selective logging is currently underway, the biological sustainability of timber species dispersed by terrestrial mammals may be more likely in sites protected from hunting and/or adjacent to protected areas than in forested patches subjected to hunting.
A Framework for Prioritizing Domestic Animal Breeds for Conservation Purposes at the National Level: a Norwegian Case Study
Authors: Ruane John
Published: March 2003

Abstract: Although encompassing only a handful of species, domestic animals have had profound effects on food production for humankind and on human societies. On a global basis, a large proportion of breeds are currently in danger of becoming extinct in the near future. At this critical time, resources are limited and only a selected number of breeds may be supported by concrete conservation programs. I present a framework to facilitate decision making on a national level as to which breeds to support for conservation. These decisions should be made by a national committee of experts experienced with the different breeds and species. First, they must define the species of interest. Second, they should collate as much data as possible and score each breed for key criteria: degree of endangerment, presence of traits of current economic value, presence of traits of current scientific value, agroecological value in a special landscape, cultural‐historical value, and genetic uniqueness. The degree of endangerment is the most important criterion because great uncertainty about the future means that all breeds may have traits of future economic or scientific value, so the main aim should therefore be to minimize loss of breeds. To illustrate use of the framework, I considered breed prioritization in Norway. I compared and scored 45 breeds from 17 domestic animal species for these key criteria and thus identified Norwegian breeds of high priority for conservation.
Amazonian Tree Mortality during the 1997 El Niño Drought
Authors: Williamson G. Bruce , Laurance William F. , Oliveira Alexandre A. , Delamônica Patricia , Gascon Claude , Lovejoy Thomas E. , Pohl Luciano
Published: March 2003

Abstract: In 1997, the Amazon Basin experienced an exceptionally severe El Niño drought. We assessed effects of this rare event on mortality rates of trees in intact rain forest based on data from permanent plots. Long‐term (5‐ to 13‐year) mortality rates averaged only 1.12% per year prior to the drought. During the drought year, annual mortality jumped to 1.91% but abruptly fell back to 1.23% in the year following El Niño. Trees dying during the drought did not differ significantly in size or species composition from those that died previously, and there was no detectable effect of soil texture on mortality rates. These results suggest that intact Amazonian rainforests are relatively resistant to severe El Niño events.
A Critique of the Recovery of Greenback Cutthroat Trout
Authors: Young Michael K. , Harig Amy L.
Published: March 2003

Abstract: There are no examples of recovery of fish listed under the U.S. Endangered Species Act, but the number of federally threatened greenback cutthroat trout ( Oncorhynchus clarki stomias) populations is approaching the delisting goal. We evaluated recovery of this subspecies in light of developing theory in conservation biology and with regard to recovery of other salmonids in the inland western United States. Four of the five criteria used to define populations that would count toward delisting appeared to underestimate the risk of extinction of those populations. Typically, recovery goals for numbers of greenback cutthroat trout populations were less stringent than those for other inland salmonids petitioned for listing or listed as threatened under the Endangered Species Act and were comparable to those for a federally endangered species. Before delisting is considered, we propose that historical populations be replicated in additional waters to protect genetic diversity and that existing populations be enlarged to reduce their vulnerability to demographic variation, to increase their access to refugia, and to permit reestablishment of mobile life histories. Existing stocks should also be evaluated to determine whether they represent distinct population segments.
Captive Breeding and Reintroduction Evaluation Criteria: a Case Study of Peninsular Bighorn Sheep
Authors: Ostermann Stacey D. , Deforge James R. , Edge W. Daniel
Published: March 2003

Abstract:Captive breeding and reintroduction programs are rarely evaluated, and assessment criteria vary widely. We used the following criteria to evaluate a bighorn sheep (Ovis canadensis) augmentation program: (1) survival and recruitment rates in the captive population, (2) survival of released animals, (3) recruitment of released animals, (4) growth rate of the reintroduced or augmented population, and (5) establishment of a viable wild population. Captive bighorn survival and recruitment was high, averaging 0.98 (SD = 0.05) and 71.0% (SD = 19.4), respectively. Annual survival of free‐ranging captive‐reared bighorn (n= 73, x = 0.80, SD = 0.11) did not differ (  Z= −0.85,p= 0.40;n= 14) from survival of wild‐reared bighorn (n= 43, x = 0.81, SD = 0.12). Recruitment was unusually low for both captive‐reared (  x = 13.7%, SD = 0.24) and wild‐reared ewes (  x = 13.7%, SD = 0.20). Although reintroduction did not result in population growth or establishment of a viable population, it helped prevent extirpation of the reinforced deme, preserved metapopulation linkage, and aided habitat preservation. Chronic low recruitment and low adult survivorship precluded achievement of criteria 3–5. Environmental conditions in the release area also appeared to hinder program success. Standard evaluation criteria for ongoing reintroductions allow for informative assessments and facilitate comparisons needed to refine reintroduction science as a recovery tool for threatened or endangered populations.
Tracking Fragmentation of Natural Communities and Changes in Land Cover: Applications of Landsat Data for Conservation in an Urban Landscape (Chicago Wilderness)
Authors: Wang Yeqiao , Moskovits Debra K.
Published: March 2003

Abstract: Greater Chicago is home to a surprisingly high concentration of globally significant natural communities. Within the metropolis survive some of the world's best remaining examples of eastern tallgrass prairie, oak savanna, open oak woodland, and prairie wetland. Chicago Wilderness is more than 81,000 ha of protected areas in the urban and suburban matrix. It also is the name of the coalition of more than 110 organizations committed to the survival of these natural lands. The long‐term health of these imperiled communities depends on proper management of the more extensive, restorable lands that surround and connect the patches of high‐quality habitat. Information critical to the success of conservation efforts in the region includes (1) a current vegetation map of Chicago Wilderness in sufficient detail to allow quantitative goal setting for the region's biodiversity recovery plan; (2) quantified fragmentation status of the natural communities; and (3) patterns of land‐cover change and their effects on the vitality of communities under threat. We used multispectral data from the Landsat thematic mapper (October 1997) and associated ground truthing to produce a current vegetation map. With multitemporal remote‐sensing data (acquired in 1972, 1985, and 1997), we derived land‐cover maps of the region at roughly equivalent intervals over the past 25 years. Analyses with geographic information system models reveal rapid acceleration of urban and suburban sprawl over the past 12 years. Satellite images provide striking visual comparisons of land use and health. They also provide banks of geographically referenced data that make quantitative tracking of trends possible. The data on habitat degradation and fragmentation are the biological foundation of quantitative goals for regional restoration.
Searching for a Predictive Model for Species Richness of Iberian Dung Beetle Based on Spatial and Environmental Variables
Authors: Lobo Jorge M. , Martín‐Piera Fermín
Published: March 2003

Abstract: In Mediterranean countries, inventories of many animal groups, particularly insects, are incomplete or nonexistent. Hence, a feasible spatial picture of unequally surveyed areas is required to ascertain which faunistic surveys are good enough to produce reliable estimates of species richness. We used generalized linear models to build a multiple‐regression function through which we predicted the distribution of Iberian dung beetle species richness. Given the scarcity and unevenness of the species‐richness spatial distribution, the number of records of a dung beetle database ( BANDASCA ), falling within each of the 50 × 50 km grid squares, was chosen as a measure of the sampling effort for that square. Examining the asymptotic relationship between the number of dung‐beetle species and database records for each physioclimatic Iberian subregion, we found that 82 grid squares (32% of the total) were adequately sampled. Dung‐beetle species richness was related in each of these 82 cells to 24 explanatory variables. Curvilinear functions, interaction terms, and the significant third‐degree polynomial terms of latitude and longitude were included to model species‐richness distribution. The final model accounted for 62.4% of the total deviance after we eliminated seven outlier squares, with maximum elevation, grassland area, land‐use diversity, forest area, geological diversity, interaction of terrestrial area and maximum elevation, and interaction between calcareous rock and geological diversity and latitude being the most significant independent variables. The residuals of the function were not spatially autocorrelated, and we validated the final model by a jackknife procedure. Large and environmentally complex hotspots in the Iberian Central, Baetic, and Subbaetic mountain ranges stand out from the emerging map of species richness. Further detailed research is required to determine the complementarity of the faunas of these two main hotspots, the key question in conservation planning for a dung‐feeding beetle.
Extirpations of Grizzly Bears in the Contiguous United States, 1850 –2000
Authors: Mattson David J. , Merrill Troy
Published: March 2003

Abstract: We investigated factors associated with the distribution of grizzly bears (   Ursus arctos horribilis) in 1850 and their extirpation during 1850–1920 and 1920–1970 in the contiguous United States. We used autologistic regression to describe relations between grizzly bear range in 1850, 1920, and 1970 and potential explanatory factors specified for a comprehensive grid of cells, each 900 km2 in size. We also related persistence, 1920–1970, to range size and shape. Grizzly bear range in 1850 was positively related to occurrence in mountainous ecoregions and the ranges of oaks ( Quercus spp.), piñon pines (  Pinus edulis and P. monophylla), whitebark pine (   P. albicaulis), and bison (   Bos bison) and negatively related to occurrence in prairie and hot desert ecoregions. Relations with salmon ( Oncorynchus spp.) range and human factors were complex. Persistence of grizzly bear range, 1850–1970, was positively related to occurrence in the Rocky Mountains, whitebark pine range, and local size of grizzly bear range at the beginning of each period, and negatively related to number of humans and the ranges of bison, salmon, and piñon pines. We speculate that foods affected persistence primarily by influencing the frequency of contact between humans and bears. With respect to current conservation, grizzly bears survived from 1920 to 1970 most often where ranges at the beginning of this period were either larger than 20,000 km 2 or larger than 7,000 km2 but with a ratio of perimeter to area of < 2. Without reductions in human lethality after 1970, there would have been no chance that core grizzly bear range would be as extensive as it is now. Although grizzly bear range in the Yellowstone region is currently the most robust of any to potential future increases in human lethality, bears in this region are threatened by the loss of whitebark pine.
Evaluating the Extinction Risk of a Perennial Herb: Demographic Data versus Historical Records
Authors: Lindborg Regina , Ehrlén Johan
Published: March 2003

Abstract: Demographic information is frequently used to project the long‐term extinction risk of endangered species, but the limitations of this approach have not been extensively discussed. We examined demographic data for the endangered perennial herb Primula farinosa with matrix models to assess population growth rates and extinction risks. The data came from six populations in contrasting habitats followed over a 4‐year period. The results of these demographic models were compared to the results of experimental manipulations and to the actual change in occurrence of P. farinosa over a 70‐year period in different habitat types. According to demographic models, all managed populations had a projected negative population growth rate and experienced a high extinction risk in 100 years, whereas unmanaged populations had increasing population sizes. In contrast, experiments and historical records suggested that continuous grazing is positively correlated with population persistence. Our results thus show that demographic studies done during a transient phase of population growth after management cessation may not capture the long‐term changes. In such cases, projections of population growth rates may give misleading guidance for conservation. Short‐term demographic studies are in many cases unlikely to correctly assess the survival probability of a species. We therefore argue that complementary information, such as long‐term historical data or experimental manipulations of the environment, should be used whenever possible.