bluuebunny/crossref_metadata_2025 huggingface dataset:
Implications of Hybridization between Introduced and ResidentOrconectesCrayfishes
Authors: Perry William L. , Feder Jeffrey L. , Lodge David M.
Published: March 2003

Abstract:One of the most imperiled taxonomic groups in North American freshwaters is that of crayfish ( Decapoda: Astacoidea): over 30% of the 390 species are threatened or endangered. This situation is globally significant because 80% of the world's crayfish species are North American. Few studies have examined the environmental changes that most threaten crayfish biodiversity, but competition and hybridization with non‐native crayfishes appear to be among the most important threats to native crayfishes. The rusty crayfish,Orconectes rusticus, native to southwestern Ohio has been introduced widely throughout the United States and is displacing two resident taxa,O. propinquusandO. virilis, in northern Wisconsin. Using morphological and allozyme comparisons of crayfish from allopatric and sympatric populations, we tested whetherO. rusticusis hybridizing with the resident crayfishes in northern Wisconsin. We found no evidence of hybridization betweenO. virilisand eitherO. rusticusorO. propinquus. In contrast, numerous morphologically intermediate crayfish betweenO. rusticusandO. propinquusoccurred at sympatric sites, and many of these individuals possessed allozymes diagnostic for both species in allopatry. Over 6% of the crayfish at one sympatric site were putative F1hybrids, 4% were putative F2individuals ( hybrid × hybrid origin), and 13% were putative backcrosses (  product of hybrid × parental matings). This is the first genetic documentation of hybridization between a resident and invading crayfish. Our results suggest that genetic mechanisms play a role in the extirpation ofO. propinquusbyO. rusticusand are consistent with observations of other researchers suggesting that hybridization with non‐native species is common among crayfishes at many other locations. High rates of endemism and widespread introductions of non‐native crayfish suggest that invasions and hybridization are a major threat to crayfish biodiversity.
Environmental Surrogates for Predicting and Conserving Adaptive Genetic Variability in Tree Species
Authors: Garnier‐Géré Pauline Hélène , Ades Peter Kevin
Published: March 2003

Abstract:Adaptive genetic variability within species is an essential component of biodiversity but has been largely ignored in studies aimed at assessing and predicting biodiversity of the forest environment. We used factorial regression and structuring models to test easily measured surrogates, such as ecological attributes, as predictors of adaptive genetic variation between populations of a tree species (Eucalyptus delegatensis). Adaptive variability was defined in terms of variation in average growth performance of 68 populations and of population‐by‐environment interaction across seven different environments. The best surrogates of genetic variability were measures of solar radiation and temperature range, each predicting more than 50% of the genetic variability within the species. Rock and understory types, when used either alone or in combination with other covariates, also were very efficient in discriminating between populations in groups showing similar adaptation. Significant relationships between particular surrogates and growth patterns of variation were attributed to effects of natural selection that had occurred in the population source locations. We recommend the development of studies focusing on the population level of biodiversity to improve the conservation of forest ecosystems in Australia.
Synergistic Effects of Subsistence Hunting and Habitat Fragmentation on Amazonian Forest Vertebrates
Authors: Peres Carlos A.
Published: March 2003

Abstract:Subsistence game hunting has profound negative effects on the species diversity, standing biomass, and size structure of vertebrate assemblages in Amazonian forests that otherwise remain largely undisturbed. These effects are likely to be considerably aggravated by forest fragmentation because fragments are more accessible to hunters, allow no (or very low rates of  ) recolonization from nonharvested source populations, and may provide a lower‐quality resource base for the frugivore‐granivore vertebrate fauna. I examined the likelihood of midsized to large‐bodied bird and mammal populations persisting in Amazonian forest fragments of variable sizes whenever they continue to be harvested by subsistence hunters in the aftermath of isolation. I used data from a comprehensive compilation of game‐harvest studies throughout Neotropical forests to estimate the degree to which different species and populations have been overharvested and then calculated the range of minimum forest areas required to maintain a sustainable harvest. The size distribution of 5564 Amazonian forest fragments—estimated from Landsat images of six regions of southern and eastern Brazilian Amazonia—clearly shows that these are predominantly small and rarely exceed 10 ha, suggesting that persistent overhunting is likely to drive most midsized to large vertebrate populations to local extinction in fragmented forest landscapes. Although experimental studies on this negative synergism remain largely unavailable, the prospect that increasingly fragmented Neotropical forest regions can retain their full assemblages of avian and mammalian species is unlikely.
Interagency Resource Teams: a Model for Collaborative Approaches to Environmental Education
Authors: Hancock Christine , Storey Annalisa , Downing James , Szewczak Susan May
Published: March 2003

Abstract: The Undergraduate Interagency Resource Teams at the White Mountain Research Station of the University of California were created in 1994 to support resource‐agency mandates and academic research objectives by providing qualified students who can learn, apply, and improve research and agency monitoring protocols. Drawing from documented elements of other successful internship programs, we identified four basic components that we believe may enhance the potential success of the interns: (1) self‐directed learning methodologies, (2) multidisciplinary approaches to science, (3) reflection on and documentation of intern learning, and (4) principles of a positive work environment, including teamwork, conflict resolution, and effective communication. During a 10‐week summer session, the Interagency Resource Teams expose approximately 17 students to the professional worlds of natural resource agencies and research scientists. In this environment, we have also observed that the internship program not only exposes students to resource management careers but may also help bridge the gap between resource agency specialists and academic researchers.
Plant‐Mammal Interactions in Tropical Bolivian Forests with Different Hunting Pressures
Authors: Roldán Alejandra I. , Simonetti Javier A.
Published: March 2003

Abstract: We studied plant‐animal interactions and vegetation structure in two geographically close tropical Bolivian forests subjected to different hunting intensities. We hypothesized that reduction of mammals openface> 1 kg in an “intensively hunted forest,” compared with an “occasionally hunted forest,” should correlate with decreased seed predation and seedling trampling, increased seedling survival and density, and decreased tree‐species diversity at the seedling stage in relation to the adult stage. The occasionally hunted forest held 1.7 times as many mammalian species as the intensively hunted forest. As predicted, predation of Astrocaryum murumuru seeds was 34.2% lower in the intensively hunted forest. Similarly, trampling of model seedlings was 5.4 times lower and seedling survival was 1.15 times greater in the intensively hunted forest than that in the occasionally hunted forest. But the intensively hunted forest displayed lower seedling densities and a higher ratio of seedling diversity to tree diversity than did the occasionally hunted forest. Reduction of peccaries from the intensively hunted forest may explain much of the between‐site differences in seed predation, trampling, and seedling survival. Lack of consistent differences in seedling density and diversity could mean that reduced granivory and trampling may be counteracted by reduced seed dispersal. The reduction of mammalian populations may produce a complex mosaic of forest patches with distinct degrees of structural change, depending on the intensity of defaunation.
Nest Poaching in Neotropical Parrots
Authors: Wright Timothy F. , Toft Catherine A. , Enkerlin‐Hoeflich Ernesto , Gonzalez‐Elizondo Jaime , Albornoz Mariana , Rodríguez‐Ferraro Adriana , Rojas‐Suárez Franklin , Sanz Virginia , Trujillo Ana , Beissinger Steven R. , A. Vicente Berovides , A. Xiomara Gálvez , Brice Ann T. , Joyner Kim , Eberhard Jessica , Gilardi James , Koenig S. E. , Stoleson Scott , Martuscelli Paulo , Meyers J. Michael , Renton Katherine , Rodríguez Angélica M. , Sosa‐Asanza Ana C. , Vilella Francisco J. , Wiley James W.
Published: March 2003

Abstract: Although the poaching of nestlings for the pet trade is thought to contribute to the decline of many species of parrots, its effects have been poorly demonstrated. We calculated rates of mortality due to nest poaching in 23 studies of Neotropical parrots, representing 4024 nesting attempts in 21 species and 14 countries. We also examined how poaching rates vary with geographic region, presence of active protection programs, conservation status and economic value of a species, and passage of the U.S. Wild Bird Conservation Act. The average poaching rate across all studies was 30% of all nests observed. Thirteen studies reported poaching rates of ≥20%, and four reported rates openface> 70%. Only six studies documented no nest poaching. Of these, four were conducted on islands in the Caribbean region, which had significantly lower poaching rates than the mainland Neotropics. The other two studies that showed no poaching were conducted on the two species with the lowest economic value in our sample ( U.S. retail price). In four studies that allowed direct comparison between poaching at sites with active nest protection versus that at unprotected sites, poaching rates were significantly lower at protected sites, suggesting that active protection efforts can be effective in reducing nest poaching. In those studies conducted both before and after the passage of the U.S. Wild Bird Conservation Act, poaching rates were found to be significantly lower following its enactment than in the period before. This result supports the hypothesis that the legal and illegal parrot trades are positively related, rather than inversely related as has been suggested by avicultural interests. Overall, our study indicates that poaching of parrot nestlings for economic gain is a widespread and biologically significant source of nest mortality in Neotropical parrots.
Consensus versus Conservation in the Upper Colorado River Basin Recovery Implementation Program
Authors: Brower Ann , Reedy Chanel , Yelin‐Kefer Jennifer
Published: March 2003

Abstract: We examined consensus‐based management through the lens of the Colorado River Recovery Implementation Program, a consensus‐based plan that attempts to develop the Colorado River's water while protecting its endangered fishes. Because this management model has been touted as a preferred substitute to government‐imposed regulation, we analyzed the recovery implementation program to determine its strengths and weaknesses. By reviewing secondary information and interviewing members of the diverse groups involved in the program, we gathered detailed information about the program's history, implementation, and progress. Our investigation revealed that the recovery implementation program has allowed development of the Colorado River's water and incorporated more voices into the decision‐making process. But the program circumvented federal authority over endangered species conservation, which has proved detrimental to the fishes. Furthermore, we learned that the consensus‐based model is vulnerable to control by special‐interests and may be driven by bureaucratic procedural goals rather than species recovery. To ameliorate these concerns, (1) program success should be judged by species recovery, rather than political achievements, (2) the federal government should retain the power of issuing statutory sanctions in the event of continued population decline, and (3) funding should be provided by an agency with a clear species‐protection agenda to reduce the disproportionate power of utilitarian interest groups. By incorporating these recommendations, conservation programs can better realize the benefits of a consensus‐based approach without sacrificing species recovery.
Transfer of a Pathogen from Fish to Amphibians
Authors: Kiesecker Joseph M. , Blaustein Andrew R. , Miller Cheri L.
Published: March 2003

Abstract:Ecological studies of exotic species focus primarily on how invaders directly affect particular resident species. In contrast, little is known about the indirect effects of introduced species on native communities, including how pathogens may be spread by introduced species. We provide evidence suggesting that introduced fish may serve as a vector for a pathogenic oomycete,Saprolegnia ferax, that has been associated with embryonic mortality of amphibians in the Cascade Mountains of Oregon, U.S.A. In laboratory experiments, mortality induced byS. feraxwas greater in western toad (  Bufo boreas) embryos exposed directly to hatchery‐reared rainbow trout (Oncorhynchus mykiss) experimentally infected withS. feraxand hatchery‐reared trout not experimentally infected than in control embryos. Embryos also developed significantS. feraxinfections when raised on soil that was exposed to trout experimentally infected withS. ferax. Furthermore, toad embryos exposed toS. feraxisolated from sites whereSaprolegniaoutbreaks are common experienced higher mortality than embryos exposed toS. feraxisolated from sites whereSaprolegniaoutbreaks have not occurred. Given the widespread practice of introducing hatchery‐reared fishes, we suggest that fish used in stocking programs could be an important vector for diseases responsible for amphibian losses.
Conservation Genetics, Extinction, and Taxonomic Status: a Case History of the Regal Fritillary
Authors: Williams Barry L.
Published: March 2003

Abstract: I investigated the phylogeography of mitochondrial DNA haplotypes in the regal fritillary (  Speyeria idalia  ) to determine the conservation status of isolated populations in light of alternative definitions of species, subspecies, and evolutionarily significant units. A total of 1441 bases of partial cytochrome oxidase I and II genes were sequenced from 115 individuals in 18 populations located throughout the range of the species. A relatively disjunct population was differentiated with five synapomorphies, whereas all other populations had little haplotype variation and no apparent association between geographic and genetic distance. The divergence of the disjunct population may be due to either historical isolation among populations or extinction of intermediate populations within a cline. Genetic divergence due to the extinction of populations in fragmented habitat, termed “anthrovicariance,” may be a generalizable phenomenon. Similar cases in insects have been described previously. If more cases can be elucidated, taxonomists will need to consider whether allopatry achieved through a natural vicariant event should be treated differently than that achieved via human‐induced habitat loss. Mitochondrial DNA sequence divergence, along with ecological and natural‐history data, suggest that the disjunct population of  S. idalia is a distinct evolutionary lineage. Although taxonomic designation is not a simple task, the data indicate that the disjunct population is clearly of conservation concern.
Selection in Captivity during Supportive Breeding May Reduce Fitness in the Wild
Authors: Ford Michael J.
Published: March 2003

Abstract: I used a quantitative genetic model to explore the effects of selection on the fitness of a wild population subject to supportive breeding. Supportive breeding is the boosting of a wild population's size by breeding part of the population in captivity and releasing the captive progeny back into the wild. The model assumes that a single trait is under selection with different optimum trait values in the captive and wild environments. The model shows that when the captive population is closed to gene flow from the wild population, even low levels of gene flow from the captive population to the wild population will shift the wild population's mean phenotype so that it approaches the optimal phenotype in captivity. If the captive population receives gene flow from the wild, the shift in the wild population's mean phenotype becomes less pronounced but can still be substantial. The approach to the new mean phenotype can occur in less than 50 generations. The fitness consequences of the phenotypic shift depend on the details of the model, but a>30% decline in fitness can occur over a broad range of parameter values. The rate of gene flow between the two environments, and hence the outcome of the model, is sensitive to the wild environment's carrying capacity and the population growth rate it can support. The results have two important implications for conservation efforts. First, they show that selection in captivity may significantly reduce a wild population's fitness during supportive breeding and that even continually introducing wild individuals into the captive population will not eliminate this effect entirely. Second, the sensitivity of the model's outcome to the wild environment's quality suggests that conserving or restoring a population's habitat is important for preventing fitness loss during supportive breeding.
Modeling Problems in Conservation Genetics withBrassica rapa:Genetic Variation and Fitness in Plants under Mild, Stable Conditions
Authors: Wise Carla A. , Ranker Tom A. , Linhart Yan B.
Published: March 2003

Abstract:Rare species are frequently genetically depauperate compared with widespread species, but the degree to which low genetic variation affects short‐term viability is still unresolved. We examined the relationship between population‐level genetic variation and fitness in small, experimental populations ofBrassica rapa(a Eurasian annual) in a stable, mild environment. We used allozyme and morphological markers to create populations with either high or low levels of genetic variation. We then grew three high‐variation and three low‐variation populations for six generations under benign growing conditions, with consistent levels of light, nutrients, and water. We measured fitness components and genetic variation throughout the experiment. All populations were maintained at equal sizes (n= 100 seeds to start each generation), and plants were mass‐pollinated to avoid differential inbreeding. Under mild conditions, high‐variation plants did not have consistently higher fitness than low‐variation plants. In generation three, plants in low‐variation populations outperformed high‐variation plants. In generation four, however, which was subjected to unplanned heat stress, high‐variation plants had higher values for many of the fitness components measured, suggesting that, under stress, genetic variation may be associated with a fitness advantage. No differences in multiplicative fitness were found in any generation, indicating that high‐ and low‐variation populations did not differ significantly in overall population viability. Our results indicate that when degree of inbreeding and population size are held constant, genetic variation per se does not increase fitness under benign conditions. As theory predicts, the role of population‐level genetic variation may instead be in enhancing the ability of small populations to remain viable under fluctuating, stressful, or novel conditions.
Planning to Save a Species: the Jaguar as a Model
Authors: Sanderson Eric W. , Redford Kent H. , Chetkiewicz Cheryl‐Lesley B. , Medellin Rodrigo A. , Rabinowitz Alan R. , Robinson John G. , Taber Andrew B.
Published: March 2003

Abstract: International conservation planning at the end of the twentieth century is dominated by coarse‐filter, supra‐organismal approaches to conservation that may be insufficient to conserve certain species such as the jaguar (   Panthera onca). If we are to retain broadly distributed species into the next century, we need to plan explicitly for their survival across their entire geographic range and through political boundaries while recognizing the variety of ecological roles the species plays in different habitats. In March 1999 the Wildlife Conservation Society sponsored a priority‐setting and planning exercise for the jaguar across its range, from northern Mexico to northern Argentina. Field scientists from 18 countries reached consensus on four types of information: (1) the spatial extent of their jaguar knowledge, (2) the known, currently occupied range of jaguars, (3) areas with substantial jaguar populations, adequate habitat, and a stable and diverse prey base, and (4) point localities where jaguars have been observed during the last 10 years. During the exercise, these experts also conducted a range‐wide assessment of the long‐term survival prospects of the jaguar and developed an algorithm for prioritizing jaguar conservation units occurring in major habitat types. From this work, we learned that the known, occupied range of the jaguar has contracted to approximately 46% of estimates of its 1900 range. Jaguar status and distribution is unknown in another 12% of the jaguar's former range, including large areas in Mexico, Colombia, and Brazil. But over 70% of the area where jaguars are thought to still occur was rated as having a high probability of supporting their long‐term survival. Fifty‐one jaguar conservation units representing 30 different jaguar geographic regions were prioritized as the basis for a comprehensive jaguar conservation program.
Rarity and Conservation Planning across Geopolitical Units
Authors: Rodrigues Ana S. L. , Gaston Kevin J.
Published: March 2003

Abstract: Conservation planning is usually done within geopolitical units that tend to encompass only part of the geographic range of most species. Consequently, the relative rarity of a species within the study area considered does not necessarily reflect its relative global rarity or its conservation relevance. We investigated the implications of species' rarity in complementary reserve selection across geopolitical boundaries based on data on the distribution of birds in southern Africa. Our results demonstrate that restricted‐range species have a disproportionate effect on the number and identity of the cells selected by complementarity. The most extreme situation occurs when species whose ranges occupy single cells impose the selection of those particular sites as irreplaceable cells. Not all restricted‐range species are equally important. Some are “apparent rarities” in the study area because they are vagrants, occur very marginally to their range, or have been introduced, and these are mainly irrelevant to conservation planning in a region. Filtering rare nontarget species from the data before reserve selection results in a significant increase in the efficiency of minimum complementary sets. It is particularly recommended for taxa with high mobility, in which vagrancy is more likely. Dividing the study area into geopolitical units has a profound effect on the sites selected by complementarity. It results in loss of overall efficiency, in a tendency for selection of sites at the periphery of the units, and in some species receiving more protection at the edge of their ranges than at the center. Geopolitical coordination in conservation planning may not only result in improved overall efficiency but also a better allocation of resources that improves the long‐term robustness of reserve networks.
Integrating Epidemiology into Population Viability Analysis: Managing the Risk Posed by Rabies and Canine Distemper to the Ethiopian Wolf
Authors: Haydon D. T. , Laurenson M. K. , Sillero‐Zubiri C.
Published: March 2003

Abstract: Infectious disease constitutes a substantial threat to the viability of endangered species. Population viability analysis (PVA) can be a useful tool for directing conservation management when decisions must be made and information is absent or incomplete. Incorporating epidemiological dynamics explicitly into a PVA framework is technically challenging, but here we make a first attempt to integrate formal stochastic models of the combined dynamics of rabies and canine distemper into a PVA of the Ethiopian wolf ( Canis simensis), a critically endangered canid. In the absence of disease, populations in habitat patches of every size were remarkably stable and persistent. When rabies virus was introduced, epidemics, assumed to arise from sporadic dog‐to‐wolf transmission, caused extinction probabilities over 50 years to rise linearly with the force of infection from the dog reservoir and particularly steeply in smaller populations. Sensitivity analysis revealed that although the overall pattern of results was not altered fundamentally by small to moderate changes in disease‐transmission rates or the way in which interpack disease transmission was modeled, results were sensitive to the process of female recruitment to male‐only packs. Completely protecting wolf populations from rabies through vaccination is likely to be impractical, but the model suggested that direct vaccination of as few as 20–40% of wolves against rabies might be sufficient to eliminate the largest epidemics and therefore protect populations from the very low densities that make recovery unlikely. Additional simulations suggested that the affect of periodic epidemics of canine distemper virus on wolf population persistence was likely to be slight, even when modeled together with rabies. From a management perspective, our results suggest that conservation action to protect even the smallest populations of Ethiopian wolves from rabies is both worthwhile and urgent.
Quantitative Changes in Forest Quality in a Principal Overwintering Area of the Monarch Butterfly in Mexico, 1971–1999
Authors: Brower Lincoln P. , Castilleja Guillermo , Peralta Armando , Lopez‐Garcia Jose , Bojorquez‐Tapia Luis , Diaz Salomon , Melgarejo Daniela , Missrie Monica
Published: March 2003

Abstract:Degradation of the oyamel fir‐pine forest ecosystem in central Mexico is a threat to the overwintering and migratory phenomenon of the eastern North American population of the monarch butterfly (   Danaus plexippus). Because a lack of quantitative data has hindered effective conservation policy, we photogrammatically analyzed the changing state of a major overwintering forest area. We analyzed stereographic aerial photographs of a 42,020‐ha area taken in 1971, 1984, and 1999 with GRASS, a geographic information system. What in 1971 was a nearly continuous high‐quality forest is now fragmented and severely degraded. Between 1971 and 1999, 44% of conserved forest (  forest with>80% cover) was degraded, and the largest patch of high‐quality forest was reduced from 27,115 ha to 5827 ha. The annual rate of degradation from 1971 to 1984 was 1.70%, and this increased to 2.41% during the next 15 years. At the latter rate, <10,000 ha of high‐quality forest will remain in 20 years and <4,500 ha in 50 years. A subset of the analysis quantified changes in a 6596‐ha area on the Sierra Chincua, Sierra Campanario, and Cerro Chivati Huacal massifs that were declared protected by presidential decree in 1986. Corresponding rates of degradation of these reserves more than tripled, from approximately 1.0% between 1971 and 1984 to more than 3% between 1984 and 1999. Passage of the 1986 decree failed to protect the forest. Our data provide irrefutable evidence that successful implementation of a more inclusive presidential decree issued in November 2000 will require (1) effective enforcement against logging within the oyamel‐pine forest ecosystem and (2) restoration of areas that have been degraded. All indications are that the rate of logging is increasing throughout the area. The grandeur of the monarch butterfly overwintering phenomenon in this tiny area of Mexico is too great a cultural and biological treasure for this rampantly destructive process to continue.
Detecting Wildlife Poaching: Identifying the Origin of Individuals with Bayesian Assignment Tests and Multilocus Genotypes
Authors: Manel Stéphanie , Berthier Pierre , Luikart Gordon
Published: March 2003

Abstract: Illegal harvesting is a serious threat to the persistence of many plant and animal taxa. The combination of highly polymorphic DNA markers and new statistical methods called “assignment tests” can potentially help detect and thereby reduce poaching. Assignment tests can identify the population of origin of individuals if populations are genetically differentiated. We evaluated the usefulness of two assignment tests to wildlife forensics by applying them to large empirical (microsatellite DNA) data sets from 10 species. We also conducted computer simulations to assess the influence of genetic polymorphism ( heterozygosity) and population differentiation (   FST ) on the performance of the tests. The fully Bayesian assignment test of Pritchard et al. (2000) performed better than the partially Bayesian exclusion test of Cornuet et al. (1999), but the fully Bayesian method requires the assumption that the true population of origin was sampled. The median percentage of individuals correctly assigned for the 10 empirical data sets was 61% and 36% for the assignment and exclusion tests, respectively. Both the empirical and simulated data sets suggest that nearly all individuals can be assigned with high statistical certainty (99.9%) for two highly differentiated populations (    FST≈ 0.15–0.2) when 10 loci (  H> 0.6) and samples of 30–50 individuals are used per population. We recommend using both tests when the true population of origin might not have been sampled in the data set.
Using Spatially Explicit Data to Evaluate Marine Protected Areas for Abalone in Southern California
Authors: Rogers‐Bennett Laura , Haaker Peter L. , Karpov Konstantin A. , Kushner David J.
Published: March 2003

Abstract: Abalone populations have declined dramatically in southern California. The white abalone (   Haliotis sorenseni) is now (  2001) on the federal endangered species list. To aid in the restoration of white, pink (  H. corrugata), and green abalone (  H. fulgens), productive marine protected areas need to be selected. We used spatially explicit fishery data (1950–1995) to identify the most productive marine areas in southern California. To assess the role of existing marine protected areas we compared fishery‐independent data (1983–2001) inside protected and fished areas. San Clemente Island produced the greatest cumulative catches of white, pink, and green abalone, the most white abalone per hectare of deep reef (25–65 m), and the most green abalone per kilometer of rocky shoreline. Santa Barbara Island, however, produced 10 times more pink abalone per hectare of kelp canopy, making this area an excellent candidate for restoration and protection. Pink abalone surveyed in the Kelp Forest Monitoring Program were most abundant at three sites surrounding Anacapa Island: (1) protected, (2) protected but less visible, and (3) fished. The protected sites, despite having lower abundances of pink abalone initially (1983), had significantly more abalone (   H = 9.0; df = 2; p = 0.011) than the nearby fished site over time. Size‐frequency distributions revealed that the protected site had more (30%) commercial‐size abalone (≥158 mm shell length) than the less visable site (6%) or the fished site (2%). Mean size was significantly larger at the protected site, yielding the highest estimate of biomass and potential egg production (2555 million eggs/site/year) of all the sites. Marine protected areas need to be selected and enforced so that abalone‐restoration efforts can be enacted before remnant populations die. Restoration sites for a wide variety of depleted species can be selected based on previous levels of productivity identified by spatially explicit data.
Sexual Selection and Life‐History Decisions: Implications for Supportive Breeding and the Management of Captive Populations
Authors: Wedekind Claus
Published: March 2003

Abstract:Natural breeding systems and various kinds of mate‐choice or sperm‐choice rules (e.g., as proposed in the “good genes” models of sexual selection) are expected to have important implications for the genetics of the next generation. Moreover, mate‐choice decisions may be connected to life‐history decisions about current and future parental effort. Considering these genetic and conditional aspects of free mating could improve the long‐term success of breeding programs in conservation. In some cases, free mate choice might be more genetically advantageous than random mating because it may promote offspring health and enable host populations to react to coevolving pathogens. However, breeding systems are not evolved to avoid extinction. In small and endangered populations, some forms of natural breeding systems and mate preferences need to be carefully manipulated to avoid an extensive reduction of the effective population size (   Ne  ). In general, supportive breeding should minimize the variance in reproductive success that is not linked to viability traits. However, minimizing reproductive skew might not be the best conservation strategy if potential mates differ in their heritable viability. If a reproductive skew can be positively linked to heritable viability or increased parental effort, there might be a way to optimize this skew with respect to the survival prospects of a population.
Incorporating Landscape Attributes into Models for Migratory Grassland Bird Conservation
Authors: Bakker Kristel K. , Naugle David E. , Higgins Kenneth F.
Published: March 2003

Abstract:We evaluated the influence of local and landscape attributes on the occurrence and density of seven passerine species in grasslands (n =380) throughout eastern South Dakota ( U.S.A.). Landscape composition and land cover were quantified at three spatial scales: 400‐, 800‐, and 1600‐m radii from the transect center. Separate habitat models were generated for mixed‐grass and tallgrass prairie regions to depict the way birds respond to geographic variation in local and landscape structure. Sedge Wrens ( Cistothorus platensis) and Clay‐colored Sparrows ( Spizella pallida) in the mixed‐grass and tallgrass regions used both large and small patches if they were embedded in a landscape with a high proportion of grassland habitat. Occupancy rates for these species were higher in small patches within landscapes with high grassland abundance than in large patches within low grassland landscapes. Grasshopper Sparrows (Ammodramus savannarum) and Dickcissels ( Spiza americana) in the mixed‐grass region and Savannah Sparrows (   Passerculus sandwichensis) in the tallgrass region were area‐sensitive species that used large grassland patches regardless of landscape configuration. The occurrence of Savannah Sparrows in both regions and Sedge Wrens, Grasshopper Sparrows, and Western Meadowlarks ( Sturnella neglecta) in the mixed‐grass region was negatively associated with an increase in patch edges with trees. Explained variation in density estimates was associated only with local patch and vegetation variables. Individual species demonstrated scale‐dependent differences in the way they perceived habitat and in their response to regional landscape structure. These findings provide evidence that results from one region may not be extrapolated to others because they may vary with species distribution, vegetation structure, and landscape composition. Assessments of regional grassland bird habitat must be conducted at multiple scales because some species respond only to local conditions within grasslands, whereas others respond to habitat structure at landscape scales.
Effects of Habitat Fragmentation by Damming on the Persistence of Stream‐Dwelling Charr Populations
Authors: Morita Kentaro , Yamamoto Shoichiro
Published: March 2003

Abstract: Dam construction has serious consequences for aquatic ecosystems, and one of the most serious is the “barrier effect,” the prevention of organism migration throughout a system. We assessed the effect of habitat fragmentation by damming on the population persistence of a stream‐dwelling fish, the white‐spotted charr (Salvelinus leucomaenis), in streams of southwestern Hokkaido, Japan. We sampled for charr at 52 dammed‐off sites by electrofishing or snorkeling and measured five habitat characteristics: isolation period, watershed area, gradient, elevation, distance from sea. Of the 52 study sites above dams, white‐spotted charr were absent at 17 sites and were present at 35 sites. Because the charr occupied all undammed upstream reaches, the damming would cause the absence of charr upstream. Among five habitat characteristics examined, stepwise logistic‐regression analysis showed that disappearance was promoted with increasing isolation period, with decreasing watershed area (i.e., habitat size), and with decreasing gradient. The resulting logistic model explained 82.7% of the present white‐spotted charr occurrence and forecasted that 12 of 35 extant populations will disappear after 50 years. Our findings imply that extirpation of small, dammed‐off populations is inevitable unless efficient fish ladders are installed or dams are removed.
Effects of Roads and Human Disturbance on Amur Tigers
Authors: Kerley Linda L. , Goodrich John M. , Miquelle Dale G. , Smirnov Evgeny N. , Quigley Howard B. , Hornocker Maurice G.
Published: March 2003

Abstract: Understanding the effects of human disturbance on endangered wildlife populations is critical to their conservation. We examined the effects of roads and human disturbance on the survivorship and foraging efficiency of Amur tigers (  Panthera tigris altaica) on and near Sikhote‐Alin State Biosphere Zapovednik, Primorye Krai ( province), Russia. To evaluate the effects of roads, we estimated survivorship of radiocollared tigers and their cubs living in three types of areas: (1) areas with primary roads, (2) areas containing secondary roads, and (3) areas with minimal or no road access. We classified a tiger into one of these three treatments based on which types of roads bisected their 50% minimum convex polygon home ranges. Over a 9‐year period (1991–2000), adult female survival was greatest (χ 2 = 12.2, df = 2, p = 0.002) for radiocollared tigers in roadless areas. All adult female tigers in roadless areas survived their tenure in those locations (n = 2), whereas all died or disappeared prematurely from areas with primary roads (n = 6). Cub survival was lower in areas with primary and secondary roads than in roadless areas (χ 2 = 10.9, df = 1, p < 0.009). We evaluated the effects of human disturbance at kill sites by examining 86 kills made by 15 tigers determining whether human disturbance had occurred at the kill site, and examining prey carcasses after tigers left, to estimate the percent meat eaten and whether the tiger abandoned the kill following human disturbance. Tigers undisturbed at kills consumed more meat (  Z = 3.71, p = 0.0002) from each kill than disturbed tigers did. Undisturbed tigers also spent more time at each kill site than disturbed tigers did (  Z = 2.3; p = 0.02). Abandonment of kills occurred in 63% of 24 instances when tigers were disturbed by people. Because roads decrease the survivorship and reproductive success of tigers, we recommend that in habitats managed for tigers, construction of new roads should be prohibited wherever possible and access to secondary roads (e.g., logging roads) should be reduced or prevented wherever possible. Protected areas seem to cease functioning as source populations where road access exists, and unprotected areas—the majority of Amur tiger range—cannot sustain stable populations with the increasing threat of human access to tiger habitat.
Nonindigenous Species: Ecological Explanation, Environmental Ethics, and Public Policy
Authors: Lodge David M. , Shrader‐Frechette Kristin
Published: March 2003

Abstract: The public is getting a mixed message from ecologists, other scholars, and journalists on the topic of nonindigenous species. Misunderstandings and tension exist regarding the science, values, environmental ethics, and public policy relevant to invasive species, which are the subset of nonindigenous species that cause economic or environmental damage. Although there is a natural background rate at which species invasions occur, it is much lower than the current human‐induced rates at which species are being moved around the globe. Contrary to some recently voiced opinions , the fact that some species invasions occur without human assistance does not confer acceptability on all species invasions. Also, despite claims to the contrary, the reductions of native biodiversity caused by nonindigenous species are large and well documented. Even if that were not true, an emphasis on species numbers alone as a metric for the impact of nonindigenous species does not adequately incorporate the high value many humans place on the uniqueness of regional biota. Because regional biota are being homogenized by species invasions, it has become an appropriate and official public policy goal in the United States to reduce the harm done by invasive species. The goal is not, however, a reduction of numbers of nonindigenous species per se, as recently claimed by some authors, but a reduction in the damage caused by invasive species, including many sorts of environmental and economic damage. A major challenge remaining for ecology, environmental ethics, and public policy is therefore the development of widely applicable risk‐assessment protocols that are acceptable to diverse constituencies. Despite apparent disagreements among scholars, little real disagreement exists about the occurrence, effects, or public‐policy implications of nonindigenous species.
Prenatal Smoking Cessation Counseling by Texas Obstetricians
Authors: Mullen Patricia Dolan , Pollak Kathryn I. , Titus Jyothi P. , Sockrider Marianna Martin , Moy Julie Graves
Published: March 2003

Background:

Smoking during pregnancy causes 20 to 30 percent of low birthweight and 10 percent of infant mortality in the United States. Brief counseling can reduce rates of smoking. The study objectives were to describe Texas obstetricians' pregnancy smoking cessation counseling activity and to identify attributes associated with consistent, effective counseling.

Methods:

A survey was mailed to a random sample of Texas obstetricians.

Results:

A response rate of 44 percent (n=204) was attained. A counseling coverage‐effectiveness index was created based on the percentage of smokers counseled and use of specific techniques. Almost all respondents reported asking about smoking; fewer, however, reported counseling smokers. Physicians with low index scores, indicating inconsistent coverage, ineffective counseling, or both were dissatisfied with their current counseling, did not perceive counseling to decrease smoking, were not aware of the risks of smoking, and were unfamiliar with expert reports and recommendations for prenatal care.

Conclusions:

Obstetricians who are not reached by expert reports and guidelines from groups outside their specialty or who do not perceive the seriousness of maternal smoking are less likely to counsel consistently and to use the most effective techniques. Continuing medical education at local, state, and national levels should be directed toward increasing knowledge and skills about smoking cessation counseling of pregnant women. (BIRTH 25:1, March 1998)
Maternity Care in The Netherlands: The Changing Home Birth Rate
Authors: Wiegers Therese A. , Van Der Zee Jouke , Keirse Marc J. N. C.
Published: March 2003

In 1965 two‐thirds of all births in The Netherlands occurred at home. In the next 25 years, that situation became reversed with more than two‐thirds of births occurring in hospital and fewer than one‐third at home. Several factors have influenced that change, including the introduction of short‐stay hospital birth, hospital facilities for independent midwives, increased referral rates from primary to secondary care, changes in the share of the different professionals involved in maternity care, medical technology, and demographic changes. After a decline up to 1978 and a period of relative stability between 1978 and 1988, the home birth rate started to decline further, to the extent that it might destabilize the Dutch maternity care system and the role of midwives in it. The Dutch maternity care system depends heavily on primary caregivers, midwives and general practitioners who are responsible for the care of women with low‐risk pregnancies, and on obstetricians who provide care for high‐risk pregnancies. Its preservation requires a high level of cooperation among the different caregivers, and a functional selection system to ensure that all women receive the type of care that is best suited to their needs. Preserving the home birth option in the Dutch maternity care system necessitates the maintenance of high training and postgraduate standards for midwives, the continued provision of maternity home care assistants, and giving women with uncomplicated pregnancies enough confidence in themselves and the system to feel safe in choosing a home birth. (BIRTH 25:3 September 1998)
Knee‐Chest Postural Management for Breech at Term: A Randomized Controlled Trial
Authors: Smith Caroline , Crowther Caroline , Wilkinson Chris , Pridmore Brian , Robinson Jeffrey
Published: March 2003

Background: In 3 to 4 percent of all term births, the fetus presents as a breech. The objectives of this trial were to assess if assuming the knee‐chest position reduced the frequency of breech presentation at delivery, increased the success of the subsequent external cephalic version, or both, and to determine if this management plan reduced the need for cesarean delivery. Methods: A randomized clinical trial recruited 100 women from two hospitals in Adelaide, South Australia, with a singleton breech presentation and a gestational age equal to or more than 36 weeks. Women in the treatment group were advised to assume the knee‐chest position for 15 minutes three times a day for one week. Women in the control group did not perform postural management. All participants were reviewed one week later, and women whose baby remained as a breech presentation were offered an external cephalic version. Results: Postural management did not increase the success of the external cephalic version, reduce the frequency of breech presentation at delivery, or reduce the need for cesarean delivery in women with a breech presentation at term. Conclusions: Findings from this trial included in a meta‐analysis of postural management for breech presentation at term suggested that this is not an effective form of care to be offered routinely to women with a breech presentation at term.