bluuebunny/crossref_metadata_2025 huggingface dataset:
The Ironwood Problem: (Mis)Management and Development of an Extractive Rainforest Product
Authors: PELUSO NANCY LEE
Published: March 2003

Abstract:This study explores the reasons that national and local forest management systems have failed to protect local supplies of ironwood occurring in the dipterocarp forests of West Kalimantan, Indonesia. Government management strategies have bypassed local people's claims to ironwood because customary forest management institutions have not been formally recognized and supported. Traditional ironwood management focused on the regulation of outsiders' access to the trees and an informal “ethic of access” guiding its use and distribution among village households. Kalimantan forest management is now dominated by industrial timber extraction. The government has given timber companies the rights to control all forest activities within their concession areas, but companies have little incentive or capacity to manage the activities of numerous villages within their concession territories. Yet the indirect effects of logging on village forest management have had a staggering impact on the social organization of forest use. The penetration of roads has facilitated outsiders' access to formerly remote areas. Chainsaws and logging roads have facilitated villagers' commercial harvest of ironwood and generated changes in the villagers' management of the wood. Private control has taken precedence over common (village) controls, and the ethic of access has been transformed. The article concludes that some traditional institutions could be empowered by the state to protect both forest resources and local claims in a joint forest management arrangement.
Conservation Genetics of Bull Trout in the Columbia and Klamath River Drainages
Authors: LEARY ROBB F. , ALLENDORF FRED W. , FORBES STEPHEN H.
Published: March 2003

Abstract:We used 51 isozyme loci to determine the population genetic structure of bull trout (Salvelinus confluentus) in the Columbia and Klamath River drainages. The sampled populations have little genetic variation within and significant genetic differences among themselves. Preserving the genetic diversity of bull trout will require the continued existence of many populations throughout this region. Bull trout from the Columbia and Klamath drainages would qualify as separate “species” under the United States Endangered Species Act according to criteria established for anadromous salmonid fishes. Genotype frequencies at the four variable loci in a group of bull trout used for artificial supplementation indicate an extremely small number of effective parents. The release of such fish into the wild could have harmful effects on native fish populations. Non‐native brook trout (Salvelinus fontinalis) have been introduced throughout the range of bull trout, and hybridization between these species has been reported. Protein and mitochondrial DNA genotypes collected from one stream in western Montana over an eight‐year period indicate the displacement of bull trout by brook trout. This rapid displacement was accompanied by extensive production of interspecific first‐generation hybrids by both reciprocal crosses.
Assessing Effects of Removals for Transplanting on a High‐Elevation Bighorn Sheep Population
Authors: STEVENS DAVID R. , GOODSON NIKE J.
Published: March 2003

Abstract: Transplanting Rocky Mountain bighorn sheep (Ovis canadensis canadensis) from established herds to initiate new populations or augment small herds is a common management practice. While transplant herds have frequently been studied, data on effects of removals on source herds are lacking. Assessment of these effects is necessary when removals are large relative to the size of the source population and when maintenance of a viable source population is a management goal. The Colorado Division of wildlife removed 53 bighorn sheep in three trapping operations during 1979–1984 from a bighorn herd estimated (in 1976) at 120 total sheep that ranges largely within Rocky Mountain National Park. The park, in cooperation with the Division of Wildlife initiated this study in 1986 to assess size and trend of the source population and to provide a basis for recommendations on future removals. We found that removals were made from a female‐juvenile subpopulation (the South Never Summer subpopulation) that used only part of the known bighhorn range. We estimated its size at 55–75 sheep and found it was increasing slowly. Recruitment levels indicated that seven years were required to replace ewes removed during one trapping operation. Bighorn ewes of this subpopulation raised lambs on an average of every other year, and maternal care of yearlings was common. Density‐independent factors such as the short growing season and severe winters experienced by bighorn sheep on this high elevation range limit their capability to respond to removals. Because female juveniles normally recruit into their mother's subpopulations and because interchange is rare among female‐juvenile subpopulations, removals may severely affect individual bighorn subpopulations. We recommend that removals be based on productivities of source herds rather than on assumed compensatory responses.
Estimating the Effective Population Size of Conserved Populations
Authors: Nunney Leonard , Elam Diane R.
Published: March 2003

Accurate estimation of effective population size is important in attempts to conserve small populations of animals or plants. We review the genetic and ecological methods that have been used to estimate effective population size in the past and suggest that, while genetic methods may often be appropriate for the estimation of Ne, and its monitoring, ecological methods have the advantage of providing data that can help predict the effect of a changed environment on Ne. Estimation of Ne, is particularly complex in populations with overlapping generations, and we summarize previous empirical estimates of Ne that used ecological methods in such populations. Since it is often difficult to assess what parameters and assumptions have been used in previous calculations, we suggest a method that provides a good estimate of Ne, makes clear what assumptions are involved, and yet requires a minimum of information. The method is used to analyze data from 14 studies. In 36% (5) of these studies, our estimate is in excellent agreement with the original, and yet we use significantly less information, in 21% (3) the original estimate is markedly lower, in 43% (6) it is markedly higher. Reasons for the discrepancies are suggested. Two of the underestimates involve a failure in the original to account for a long maturation time, and four of life overestimates involve problems in the original with the correction for overlapping generations.
Ecological Monitoring: A Vital Need for Integrated Conservation and Development Programs in the Tropics
Authors: Kremen Claire , Merenlender Adina M. , Murphy Dennis D.
Published: March 2003

The integration of conservation with rural economic development is the latest proposed means of preventing loss of the earth’s biodiversity and of solving the dilemma of “people versus parks.” International development agencies now recognize the need to preserve natural resources and biodiversity in concert with improving human well‐being; likewise, conservation agencies acknowledge that parks cannot be protected over the long term without the consent and support of local inhabitants. Nonetheless, of 36 integrated conservation and development projects (ICDPs) reviewed by us and others, only 5 demonstrate that they have positively contributed to the conservation of wildlife. In this paper we promote ecological monitoring to (1) evaluate the ICDP paradigm and specific ICDPs, (2) provide feedback to guide the future course of ICDPs, and (3) integrate information relevant to both conservation and development. Few ICDPs have included ecological monitoring programs to date, although several have plans to monitor in the future. We outline a flexible blueprint for ecological monitoring of ICDPs and provide an example from our ongoing work in Madagascar. To establish comprehensive ecological monitoring programs, we recommend that two types of monitoring be carried out at multiple levels of ecological organization and across diverse taxa. First, monitoring programs should assess the total effects of ICDPs on biodiversity and on overall ecosystem health by tracking indicator assemblages across space and through time (biodiversity monitoring). Second, ICDPs should monitor the resources and ecological processes that will be directly affected by changes in human activities due to implementation of ICDPs by comparing target species diversity and abundance in unregulated areas, managed buffer zones, and core protected areas through time (impact monitoring). Comprehensive ecological monitoring is critical in shaping ICDP management plans and in furthering the integration of conservation and development.
Low Genetic Variation but High Population Differentiation in a Common Tropical Forest Tree Species
Authors: Hall Pamela , Chase Michael R. , Bawa Kamaljit S.
Published: March 2003

Genetic variation and population differentiation were studied in an abundant, outcrossing tropical tree species, Pentaclethra macroloba, in Costa Rica. Population differentiation was analyzed on two spatial scales by collecting leaf material from 7 locations within a 1800‐ha biological reserve and from 11 additional sites up to 70 km from the reserve. Genetic differences between age classes were investigated by collecting leaves from adults and seedlings at six locations within the reserve. Measures of genetic variation were determined using protein electrophoresis of leaf material. Five polymorphic and nine monomorphic loci were identified. The mean heterozygosity of P. macroloba populations was 0.074. Heterozygosity varied among populations, ranging from 0.045 to 0.135, with the lowest value found in the reserve and the highest in a distant population. Low variation in the reserve was largely due to fixation at two loci that were polymorphic outside the reserve. Within the reserve, seedling populations were less differentiated than adult populations, with multilocus Fst, values of 0.0189 and 0.0384, respectively. On larger geographic scales, however, population differentiation accounted for 21.9% of the total genetic variation. Nm, calculated from multilocus Fsv was negatively correlated with geographic distance among pairs of populations within the reserve (r = 0.53) and among populations throughout Costa Rica (r = −0.47). In combination, these results suggest that while P. macroloba may be panmitic within the reserve, gene flow is relatively restricted among sites that are scattered over a deforested landscape. Furthermore, in spite of the abundance of this species, genetic neighborhoods may be small due to asynchronous reproduction and isolation by distance. Allelic diversity is higher outside the reserve, and continuing deforestation may result in loss of genetic diversity, greater genetic differentiation, and genetic isolation of these populations.
The Significance of Protected Areas for the Land Birds of Southern Finland
Authors: Virkkala Raimo , Rajasärkkä Ari , Väisänen Risto A. , Vickholm Markku , Virolainen Erkki
Published: March 2003

Protected areas (nature reserves) cover 0.7% of the land area in southern Finland (162,000 km2), which belongs to the south‐ and mid‐boreal coniferous forest zones. The value of these areas in preserving land birds was studied on the basis of quantitative censuses. The numbers of bird pairs were estimated in nature reserves and in the whole of southern Finland, and the significance of the reserves was evaluated based on how large a proportion of the total population in southern Finland was found in them. Forest habitat generalists and species of coniferous forests occurred in protected areas as expected by the proportion of these areas in southern Finland. Specimens of these species groups comprise two thirds of all the country’s land birds. Species of old‐growth forests and open peatlands clearly preferred protected areas, whereas species of bushes, and lush and deciduous forest were scarcer in protected areas than elsewhere in southern Finland. The latter fertile habitats are poorly represented in protected areas, even though due to their disappearance or alteration elsewhere several species confined to these habitats have declined and are even threatened. Drainage of open peatlands and clearcutting of old‐growth forests has caused a decrease in the area of these habitats in southern Finland during the past decades. Therefore, protected areas have a high significance in preserving bird species preferring these habitats. Protected areas are particularly important for decreased species of old‐growth forests, such as the Three‐toed Woodpecker Picoides tridactylus and the Siberian Jay Perisoreus infaustus, as about 10% of their total population in southern Finland was estimated to breed in protected areas. The future protection of both old‐growth and deciduous forests is important if we are to preserve bio‐diversity of land birds in Finland.
Postfledging Dispersal of White‐crowned Pigeons: Implications for Conservation of Deciduous Seasonal Forests in the Florida Keys
Authors: Strong Allan M. , Bancroft G. Thomas
Published: March 2003

From 1988 to 1991, we studied the postfledging dispersal of 31 radio‐tagged White‐crowned Pigeons (Columba leucocephala) from three natal keys in Florida Bay. Immature birds dispersed from the natal keys at 26–45 days after batching, and most young dispersed more than 20 km during the first 10 days postdispersal. Dispersing birds flew either north to the Florida mainland or east to northeast to the mainline Florida Keys. On the mainland, immature birds fed nearly exclusively within Everglades National Park or an adjacent state wildlife management area. On the mainline keys, White‐crowned Pigeons selectively used 5.01–20 ha forest fragments (p < 0.10) during the first 72 hours postdispersal. After this period, dispersing birds showed no preference among fragment size classes but used deciduous seasonal forests more frequently than suburban habitat(p < 0.10). The spatial pattern of dispersal on the mainline keys suggests that, during the first 72 hours postdispersal. White‐crowned Pigeons are not able to reach northern Key Largo, where 69% of the deciduous seasonal forests are protected in state or federal ownership. Protection of large forest fragments, especially on southern Key Largo, should be a priority for maintaining populations of White‐crowned Pigeons. These forests provide a series of “stepping stones” that enable dispersing immature White‐crowned Pigeons to fly to more distant areas where habitat availability is less restricted. This species is threatened in Florida and may play an important role in maintaining plant species diversity in the seasonal deciduous forests of south Florida by dispersing seeds of at least 37 species of trees and shrubs. Protection of sufficient habitat to allow successful postfledging dispersal of this important seed disperser will also protect the ecosystem’s biodiversity.
Potential Effects of a Forest Management Plan on Bachman’s Sparrows (Aimophila aestivalis): Linking a Spatially Explicit Model with GIS
Authors: Liu Jianguo , Dunning John B. , Pulliam H. Ronald
Published: March 2003

By combining a spatially explicit, individual‐based population simulation model with a geographic information system, we have simulated the potential effects of a U.S. Forest Service management plan on the population dynamics of Bachman’s Sparrow (Aimophila aestivalis) at the Savannah River Site, a U.S. Department of Energy facility in South Carolina. Although the Forest Service’s management plan explicitly sets management goals for many species, most of the prescribed management strategy deals with the endangered Red‐cockaded Woodpecker (Picoides borealis) because of legal requirements. We explored how a species (the sparrow) that is not the target of specific management strategies but that shares some habitat requirements with the woodpecker, would fare under the management plan. We found that the major components of the proposed management plan may allow the sparrow population to reach and exceed the minimum management goal set for this species, but only after a substantial initial decline in sparrow numbers and a prolonged transition period. In the model, the sparrow population dynamics were most sensitive to demographic variables such as adult and juvenile survivorship and to landscape variables such as the suitability of young clearcuts and mature pine stands. Using various assumptions about habitat suitability, we estimated that the 50‐year probability of population extinction is at least 5% or may be much higher if juvenile survivorship is low. We believe, however, that modest changes in the management plan might greatly increase the sparrow population and presumably decrease the probability of extinction. Our results suggest that management plans focusing on one or a few endangered species may potentially threaten other species of management concern. Spatially explicit population models are a useful tool in designing modifications of management plans that can reduce the impact on nontarget species of management concern.
Patch Isolation, Corridor Effects, and Colonization by a Resident Sparrow in a Managed Pine Woodland
Authors: Dunning John B. , Borgella Rene , Clements Krista , Meffe Gary K.
Published: March 2003

The isolation of habitat patches is often cited as having a major impact on the dynamics of small populations occupying patches in a complex landscape. Few studies, however, have provided field data demonstrating that isolation has an identifiable effect on specific populations independent of other factors such as local habitat quality or that landscape factors such as corridors can alleviate such effects. We conducted field surveys of Bachman’s Sparrow (Aimophila aestivalis) populations in regions, which we call linear landscapes, where suitable habitat patches were isolated to varying degrees from potential sources of dispersing birds. In these linear landscapes, isolated patches of habitat were less likely to be colonized than were nonisolated patches. We also found that corridor configurations of habitat patches improved the ability of sparrows to find and settle in newly created patches. These results suggest that, for species that do not disperse easily through inhospitable landscapes, habitat occupancy at a regional scale can be enhanced by careful landscape design and planning.
Mutation and Conservation
Authors: Lande Russell
Published: March 2003

Mutation can critically affect the viability of small populations by causing inbreeding depression, by maintaining potentially adaptive genetic variation in quantitative characters, and through the erosion of fitness by accumulation of mildly detrimental mutations. I review and integrate recent empirical and theoretical work on spontaneous mutation and its role in population viability and conservation planning. I analyze both the maintenance of potentially adaptive genetic variation in quantitative characters and the role of detrimental mutations in increasing the extinction risk of small populations. Recent experiments indicate that the rate of production of quasineutral, potentially adaptive genetic variance in quantitative characters is an order of magnitude smaller than the total mutational variance because mutations with large phenotypic effects tend to be strongly detrimental. This implies that, to maintain normal adaptive potential in quantitative characters under a balance between mutation and random genetic drift (or among mutation, drift, and stabilizing natural selection), the effective population size should be about 5000 rather than 500 (the Franklin‐Soulé number). Recent theoretical results suggest that the risk of extinction due to the fixation of mildly detrimental mutations may be comparable in importance to environmental stochasticity and could substantially decrease the long‐term viability of populations with effective sizes as large as a few thousand. These findings suggest that current recovery goals for many threatened and endangered species are inadequate to ensure long‐term population viability.
Introduction History and Invasion Patterns of Ammophila arenaria on the North Coast of California
Authors: Buell Ann C. , Pickart Andrea J. , Stuart John D.
Published: March 2003

European beachgrass (Ammophila arenaria [L] Link), introduced to stabilize sand, is fully naturalized in central and northern California and has supplanted populations of native dune plants in many areas, including the North Spit of Humboldt Bay. We interpreted air photos of the North Spit for the presence of Ammophila arenaria at three points in time: 1939/1942, 1962, and 1989. To quantify the spread and to detect invasion patterns of Ammophila, we then compiled maps using a geographic information system. We documented introduction dates and locations to improve the accuracy of our photo interpretation. Interpretation of the three photo series revealed invasion and expansion of Ammophila in both foredunes and inland dunes. The most dramatic increase in cover was found in the foredunes, whereas documented and presumed plantings were found mostly on inland dunes. Adjusting for intentional eradication, Ammophila cover on the North Spit was found to have increased between 1939 and 1989 by 574%. The square root of the area occupied by Ammophila on the North Spit increased linearly with time, conforming to biological invasion theory.
Localization of a Contact Zone between Two Highly Divergent Mitochondrial DNA Lineages of the Brown Bear Ursus arctos in Scandinavia
Authors: TABERLET PIERRE , SWENSON JON E. , SANDEGREN FINN , BJÄRVALL ANDERS
Published: March 2003

Abstract: In Europe the brown bear (Ursus arctos) is represented by two different mitochondrial DNA (mtDNA) lineages, which probably diverged about 0.85 million years ago. Scandinavia has been colonized by representatives of both lineages, from the north (eastern lineage) and from the south (western lineage), and now bears occur primarily in four main regions called female concentration areas. For management purposes the localization of the contact zone between these two genotypes is important. Using hairs as a source of DNA, 127 individual brown bears from throughout the Scandinavian populations were assayed for lineage assignment. A part of the mtDNA control region was amplified via the polymearase chain reaction, and the product was either sequenced (14 individuals) or digested with two diagnostic restriction endonucleases (113 individuals). Fifty‐six and 71 bears were assigned to the western and eastern lineages, respectively. The geographic distribution of the two genotypes allowed precise localization of the contact zone. Only two males from each lineage had crossed the border between the two lineages. We used dispersal data from bears radiomarked as yearlings to determine whether potential mtDNA introgressions agreed with the dispersal behavior of bears. The males in the “wrong” areas were all within the 95th‐percentile dispersal distance from the “correct” area. Females were more philopatric than males, and none were found in the wrong areas. The two female concentration areas flanking the contact zone were 134 km apart. Thus, radiotelemetry results on dispersal distances could explain the occurrence of the males in the wrong genetic area. In the absence of information concerning possible male‐mediated gene flow, a conservative management approach would be to consider the southern and the three northern female concentration areas as two distinct conservation units.

Localización de una zona de contacto entre dos linajes de ADN mitocondrial muy divergentes del oso pardo Ursus arctos en Escandinavia
Changes in Species Abundance, Distribution, and Diversity in a Central European Bird Community
Authors: Böhning‐Gaese Katrin , Bauer Hans‐Günther
Published: March 2003

We analyzed possible causes of changes in species abundance, range size, and diversity as well as extinctions and colonizations in a central European bird community. Using data from the semiquantitative “Lake Constance” breeding bird atlas, we demonstrated that changes in regional abundances from 1980–1981 to 1990–1992 of 151 coexisting bird species were influenced by breeding habitat and migratory status. Significant declines were found in populations of farmland species and long‐distance migrants. Farmland species lost parts of their ranges but hardly changed in local abundance in sites where they still occurred. In contrast, declines in long‐distance migrants were caused by significant declines in local abundance with only slight loss of occupied range. Regional extinctions and colonizations were predictable from overall population trends. For example, all species that went extinct were either farmland species or long‐distance migrants. Avian community composition was influenced by disproportionate declines of abundant species. This led to declines in the total number of breeding pairs and in community biomass and to increases in community evenness, but to only slight declines in species richness. Future conservation efforts in Europe need to focus more on farmland species and on understanding causes for the declines of long‐distance migrants.
Conservation Genetics of the Common Snapping Turtle (Chelydra serpentina)
Authors: Phillips Christopher A. , Dimmick Walter W. , Carr John L.
Published: March 2003

Previous studies of relationships among the subspecies of snapping turtles (Chelydra serpentina} based on morphological and osteological characters have been inconclusive. We investigated relationships among the four currently recognized subspecies using restriction endonuclease fragment patterns of mtDNA and protein electrophoresis. Sixteen six‐based recognizing restriction endonucleases yielded 90 variable fragments that define 11 different haplotypes. Individuals of the two North American subspecies, C. s. osceola and C. s. serpentina, are closely related, differing by a maximum of 0.5% sequence divergence. The Central American subspecies, C. s. rossignonii and C. s. acutirostris, are more distinct, both from each other (a minimum of 1.7% sequence divergence) and from the North American samples (an average of 4.45% sequence divergence). The degree of allozymic variation among the four subspecies was found to be limited and could not be used to diagnose the four recognized subspecies. The mtDNA data presented here support the species‐level distinctness of C. s. rossignonii and C. s. acutirostris from each other and from a C. s serpentina‐C. s. osceola complex. The recognition of three distinctive groups of Chelydra rather than one widespread polytypic species has important conservation implications because it focuses attention on the poorly known middle and South American species.
Population Declines, Viable Breeding Areas, and Management Options for Flamingos in Southern Africa
Authors: Simmons Robert E.
Published: March 2003

Habitat rehabilitation or intervention to prevent species declines are rarely employed in Africa. I argue that despite protection in national parks, active intervention is necessary to halt declines in southern Africa’s Greater (Phoenicopterus ruber) and Lesser (Phoeniconaias minor) Flamingo populations. Flamingos are long‐lived species that breed sporadically at only two localities in southern Africa: the Makgadikgadi Pans in Botswana and Etosha National Park in Namibia. Despite well‐publicized breeding on Etosha Pan, flamingos have experienced only three major breeding events in 40 years. Breeding failure occurs when high evaporation rates rapidly dry the pan, and up to 100,000 flightless chicks may starve. Consequently, pairs breeding in Etosha exhibit extraordinarily low recruitment (0.040 young pair/year) and extrapolations indicate that adults can replace themselves only if they breed for 38 to 50 years and all offspring survive. Because survival of offspring from fledging to adulthood (5 years) is about 46%, this breeding lifespan rises to an unrealistic 83 years, making Etosha a nonviable breeding site. Alternative, suitable flamingo habitats in Africa are being mined for soda‐ash, are damaged by pollution, or are unprotected. Accordingly, continent‐wide estimates and those from southern Africa alone suggest a population decline of about 40% in both species over the last 15 years. Because Namibia regularly supports 84% of the Greater and 93% of the Lesser Flamingos in southern Africa, conservation strategies are best focused there. Simple but effective management methods, based on those employed in western Europe, could reverse these downward trends. In Etosha a small island surrounded by a water‐filled depression would allow up to 4000 pairs to breed annually. The benefits of enhancing the breeding of flamingos in Etosha include research opportunities, tourism revenue, and a safe haven for two Red Data species.
Dances with Horses: Lessons from the Environmental Fringe
Authors: Symanski Richard
Published: March 2003

When environmental activists disregard or show contempt for facts and the rules of evidence, their intrusion into environmental issues may be perversely counterproductive. Using field and telephone interview data and unpublished and published documents, including court briefs, I show that certain activists misrepresented the Nevada Bureau of Land Management in its custodial role for the nation’s wild horses. The core of the misrepresentation was an independent census of Nevada’s wild horses conducted by the Public Lands Resource Council, an ad hoc association. These census data differ dramatically from those produced by the Bureau of Land Management. The latter data were confirmed, in part, by Bureau of Land Management roundups in northcentral Nevada. The Animal Rights Law Clinic at the Rutger’s School of Law joined forces with the Public Lands Resource Council and used the council’s questionable census results in an attack on the Bureau of Land Management’s horse program. A careful probing of environmentalist agendas and data is at least as important as careful scientific design, execution, and display of results. Saving species and ecosystems is, then, as much an exercise in human psychology and the politics and sociology of advocacy groups as it is in conservation biology.
A Science for Survival: Values and Conservation Biology
Authors: Barry Dwight , Oelschlaeger Max
Published: March 2003

Practice of conservation biology that does not actively and continuously question the values that shape it is self‐defeating: Conservation biology is inescapably normative. Advocacy for the preservation of biodiversity is part of the scientific practice of conservation biology. If the editorial policy of or the publications in Conservation Biology direct the discipline toward an “objective, value‐free” approach, then they do not educate and transform society but rather narrow the focus to the “object of knowledge” (be this species, gene pools, landscapes, or ecosystems). To pretend that the acquisition of “positive knowledge" alone will avert mass extinctions is misguided. Conservation biologists should reflect on the constitutive values (especially contextual, but also methodological and bias) underlying their research programs and policy recommendations. Such reflection is itself an inherent element of scientific objectivity and takes into account the social nature of scientific knowledge. Without openly acknowledging such a perspective, conservation biology could become merely a subdiscipline of biology, intellectually and functionally sterile and incapable of averting an anthropogenic mass extinction.
Genetic Introgression of Endemic Taxa by Non‐natives: A Case Study with Leon Springs Pupfish and Sheepshead Minnow
Authors: Echelle Anthony A. , Echelle Alice F.
Published: March 2003

Genetic studies of a pupfish (Cyprinodon bovinus) endemic to a small, spring‐fed system in west Texas illustrate the potential for small introductions of non‐native species to cause large‐scale genetic changes through hybridization and genetic introgression. We performed a genetic survey (allozymes and RFLP analysis of mtDNA) of four samples of C. bovinus representing all wild populations of the species and a captive population maintained since 1976 at Dexter, New Mexico. The results indicate genetic introgression of the entire wild population by sheepshead minnow (C. variegatus), a coastal species with a history of introductions in west Texas. Frequencies of foreign genetic elements averaged across four diagnostic allozyme loci and mtDNA varied from 6.1 to 15.1%. The captive population appears free of foreign genetic material. Comparisons with past studies of C. bovinus indicate the present situation is largely due to a recent introduction of C. variegatus, not to an introduction in the mid‐1970s; however, residual effects from the earlier introduction cannot be completely discounted. Genetic analysis indicates that the source of introduced C. variegatus in Diamond Y Draw is the nearest known population, an introduced stock in Lake Balmorhea approximately 90 km away. The results demonstrate the value of maintaining imperiled species in captivity. Captive C. bovinus provide an opportunity to restore the genetic integrity of wild populations.
Population Constraints Associated with the Use of Black Rhinos as an Umbrella Species for Desert Herbivores
Authors: Berger Joel
Published: March 2003

The numerous tactics used to conserve biodiversity include the designation of protected areas, political change, and research and education, the latter involving paradigms such as insular biogeography and the “umbrella species concept.” In Namibia lands removed from national park status in 1970 and currently under the jurisdiction of indigenous people now contain one of the few unfenced populations of black rhinos (Diceros bicornis) remaining in Africa. Theory predicts that the protection of umbrella species will ensure the survival of other biota that require(s) less space. To gauge how well biodiversity might be retained by examining the spatial needs of a small population of black rhinos, I used data gathered under various ecological conditions to estimate mean and minimum population sizes of six large herbivores of the Namib Desert ranging in size from giraffe (Giraffa camelopardalis) to springbok (Antidorcas marsupialis) and ostrich (Struthio camelus). My results indicate that annual differences in rainfall, both within and between seasons, resulted in wide fluctuations in herbivore population sizes for all species except rhino. Although other herbivores switched to areas of higher rainfall, rhinos did not. The data suggest that under conditions of extreme environmental variance the space used by rhinos alone was unlikely to assure the existence of populations of other species in excess of 250 individuals. Fifty percent of the species failed to exceed 150 individuals 50% of the time and one third of the species never attained populations in excess of 50 individuals. However, by employing assumptions about the spatial needs of rhino populations numbering up to 100 individuals, the mean minimum population sizes attained by any of four desert herbivores is 535. A future challenge in using rhinos and other large‐bodied species as umbrellas for organisms of either similar or dissimilar trophic levels will be the refinement of estimates of population viability.
Mass Mortality and Population Declines of Anurans at an Upland Site in Western Panama
Authors: Lips Karen R.
Published: March 2003

I report an episode of anuran mortality and decline in the Reserva Forestal Fortuna, Chiriquí, Panama. The symptoms of decline at this site include population reductions, the presence of dead or dying adults, and tadpole abnormalities. Streamside anurans were abundant and diverse in 1993–1995, were restricted to a few streams in December 1996–January 1997, and then became rare throughout the reserve in July–August 1997. Between December 1996 and January 1997, I found 54 dead or dying frogs belonging to 10 species, and 12% of tadpoles had abnormalities of the oral disc. In July–August 1997 I monitored nine streams 37 times and captured only six individuals, whereas 13 terrestrial surveys along five trails resulted in 18 captured individuals. No dead or dying animals were found during those two months, but 11% of tadpoles had mouthpart abnormalities. Necropsies revealed that 18 of 18 dead anurans had a fungal infection of the skin; because this fungus was the only infection shared among all dead frogs, I suggest that it killed them and contributed to the decline of these populations. The presence of mouthpart abnormalities during a period of adult mortality suggests that this symptom may also be linked to the fungus infection. Clinical signs of decline in the anurans of Fortuna are similar to those found in the anurans of Monteverde and Las Tablas, Costa Rica, and I hypothesize that this pathogen was involved in the declines at all three sites.
Predictions of Mammal Diversity on Four Land Masses
Authors: Medellín Rodrigo A. , Soberón Jorge
Published: March 2003

Knowledge about the number of living species is fundamental to the practice of conservation biology, but we are far from knowing the number of species even for relatively well‐known groups such as mammals. We analyzed a database that contained information on the year of description, distribution, size class, and taxonomic order of each known mammalian species. Our goal was to predict the size class, order, and number of mammalian species on each of four land masses—America, Eurasia, Africa, Oceania. We constructed cumulative functions of species described versus year of description, and we fitted a logarithmic model to calculate instantaneous rates of species description in 1992 and 2032 and to estimate the number of species to be described in each group in the 40‐year interval. Africa and Eurasia had the highest absolute number of species today and the greatest number of species expected to be described in species‐rich orders (except for Rodentia, in which the highest number of known and expected species was in the American land mass). Per unit area, Oceania had the highest number of known species and the greatest number of species expected to be described. Our estimates, based on the historical patterns of species accumulation, place the total number of mammalian species in the year 2032 at 4875, which is 247 more than in 1992. The majority of the new species will be small (<100 g) and will be in the orders Insectivora, Chiroptera, and Rodentia. Our analyses will help identify particular groups and land masses for which field surveys, conservation efforts, and taxonomic study deserve particular attention.
Impoundments and the Decline of Freshwater Mussels: a Case Study of an Extinction Gradient
Authors: Vaughn Caryn C. , Taylor Christopher M.
Published: March 2003

Abstract: One major factor leading to the imperilment of freshwater mussels ( Bivalvia, Unionidae) has been the large‐scale impoundment of rivers. We examined the distribution and abundance of mussels at 37 sites along a 240‐km length of the Little River in southeastern Oklahoma, U.S.A., which is affected by both mainstem and tributary reservoirs. We observed a mussel extinction gradient downstream from impoundments in this river: with increasing distance from the mainstem reservoir there was a gradual, linear increase in mussel species richness and abundance. Mussel species distributions were significantly nested, with only sites furthest from the impoundment containing relatively rare species. Below the confluence with the inflow from the second reservoir these same trends were apparent but much weaker, and overall mussel abundance was greatly reduced. Our results suggest that considerable stream lengths are necessary to overcome the effects of impoundment on mussel populations, and such information should be considered in conservation and management plans.
The Appropriateness of Puppet‐Rearing Birds for Reintroduction
Authors: Valutis Laura L. , Marzluff John M.
Published: March 2003

Abstract:
Captive propagation and reintroduction programs for rare and endangered species rarely include testing of techniques prior to initiation of recovery efforts. To experimentally test the effects of rearing social, altricial birds with or without a conspecific, parental model (a puppet), we used Common Ravens (Corvus corax) in southwestern Idaho as surrogates for the endangered Hawaiian Crow (Corvus hawaiiensis) and Mariana Crow (Corvus kubaryi). A puppet is believed to reduce sexual and filial imprinting on human caretakers. We raised 49 ravens without a puppet and 25 ravens with a puppet. We initiated puppet‐rearing when birds were 7 days of age and continued until 60 days of age, when nestlings could eat well on their own. The influence of puppet‐rearing was tested as part of a factorial design that also tested for the effects of conspecific tutoring and age at release. Rearing ravens with a puppet did not affect social behaviors prior to release, dispersal from the release area, or integration with wild birds after release. Ravens raised with a puppet, however, were more fearful of caretakers and more vigilant prior to release, characteristics that may have improved their chances for survival after release. It is important for researchers to consider the species and the desired pre‐ and post‐release behaviors to determine if rearing with a puppet is appropriate for their recovery efforts. These considerations can be taken into account by using a surrogate species prior to recovery efforts and creative management approaches in the initial phases of an endangered species recovery program.
Targeting Ecosystem Features for Conservation: Standing Crops in the Florida Everglades
Authors: Turner Andrew M. , Trexler Joel C. , Jordan C. Frank , Slack Sarah J. , Geddes Pamela , Chick John H. , Loftus William F.
Published: March 2003

Abstract: The Everglades in southern Florida, U.S.A., is a major focus of conservation activities. The freshwater wetlands of the Everglades do not have high species richness, and no species of threatened aquatic animals or plants live there. We have, however, identified a distinctive ecological feature of the Everglades that is threatened by canal construction, draining, and nutrient enrichment from agricultural runoff. Compared to values reported from other freshwater systems, standing stocks of periphyton in relatively undisturbed areas of the Everglades were unusually high, and standing stocks of invertebrates and fish were unusually low. Averaging data gathered from nine sites and five sampling periods spanning 1 year, we found that periphyton standing crop was 88.2 g/m2 (ash‐free dry mass), invertebrate standing stock was 0.64 g/m2 (dry mass), and fish standing stock was 1.2 g/m2 (dry mass of large and small species combined). We found that fish standing stocks were much higher in phosphorus‐enriched sites than in nearby reference sites but that invertebrate standing stocks were similar in enriched and reference sites. Our results support the notion that oligotrophy is at least partially responsible for the low standing stocks of fish, but they also suggest that species interactions and a paucity of deep‐water refugia are important. Anthropogenic eutrophication in Everglades marshes will lead to the loss of distinctive ecosystem features. A focus on species richness and “hot spots” of threatened species provides no basis for conservation of ecosystems like the Everglades. If oligotrophic ecosystems often have low species richness, they will be underrepresented in preservation networks based on some common criteria for establishing conservation priorities.
Marine Protected Area Design and the Spatial and Temporal Distribution of Cetaceans in a Submarine Canyon
Authors: Hooker Sascha K. , Whitehead Hal , Gowans Shannon
Published: March 2003

Abstract:The Gully, the largest submarine canyon off the coast of eastern Canada, is currently under consideration as a marine conservation area, primarily because of the increasing interest in oil and gas production on the Scotian Shelf. Cetaceans, as a guild of abundant, large organisms that are relatively sensitive to such threats, provide a reliable means to determine the boundaries for a conservation area in this region. We compared the abundance of cetaceans between the Gully and other parts of the Scotian Shelf and Slope and found that abundance was higher in the Gully. We also assessed cetacean distribution and relative abundance within the Gully relative to search effort for several spatial and temporal parameters: depth, slope, sea surface temperature, and month. Distribution within the Gully was most strongly correlated with depth, but was also significantly correlated with sea surface temperature and month. Five of the 11 cetacean species commonly found in the Gully, and all those for which the Gully formed significant habitat on the Scotian Shelf, were concentrated in the deep (200–2000 m) mouth of the canyon. We suggest that a year‐round marine protected area is necessary for the Gully. A core protection zone should be defined in the Gully based on depth and bounded by the 200‐m isobath. A buffer zone around the core zone should be defined to provide protection from activities with further‐reaching effects, such as noise, dredging, and chemical pollution.
Unprecedented Low Levels of Genetic Variation and Inbreeding Depression in an Island Population of the Black‐Footed Rock‐Wallaby
Authors: Eldridge Mark D. B. , King Juliet M. , Loupis Anne K. , Spencer Peter B. S. , Taylor Andrea C. , Pope Lisa C. , Hall Graham P.
Published: March 2003

Abstract:
It has been argued that demographic and environmental factors will cause small, isolated populations to become extinct before genetic factors have a significant negative impact. Islands provide an ideal opportunity to test this hypothesis because they often support small, isolated populations that are highly vulnerable to extinction. To assess the potential negative impact of isolation and small population size, we compared levels of genetic variation and fitness in island and mainland populations of the black‐footed rock‐wallaby (Petrogale lateralis[Marsupialia: Macropodidae]). Our results indicate that the Barrow Island population of P. lateralis has unprecedented low levels of genetic variation ( He= 0.053, from 10 microsatellite loci) and suffers from inbreeding depression (reduced female fecundity, skewed sex ratio, increased levels of fluctuating asymmetry). Despite a long period of isolation (∼1600 generations) and small effective population size ( Ne∼15), demographic and environmental factors have not yet driven this population to extinction. Nevertheless, it has been affected significantly by genetic factors. It has lost most of its genetic variation and become highly inbred ( Fe= 0.91), and it exhibits reduced fitness. Because several other island populations of P. lateralis also exhibit exceptionally low levels of genetic variation, this phenomenon may be widespread. Inbreeding in these populations is at a level associated with high rates of extinction in populations of domestic and laboratory species. Genetic factors cannot then be excluded as contributing to the extinction proneness of small, isolated populations.