bluuebunny/crossref_metadata_2025 huggingface dataset:
Age‐related reductions in appendicular skeletal muscle mass: association with habitual aerobic exercise status
Authors: Sugawara Jun , Miyachi Motohiko , Moreau Kerrie L. , Dinenno Frank A. , DeSouza Christopher A. , Tanaka Hirofumi
Published: March 2003

Appendicular skeletal muscle mass decreases with advancing age, and this is thought to be a key factor for reductions in functional independence in the elderly. We determined the potential modulatory influence of regular aerobic exercise on the age‐related reductions in appendicular muscle mass. In the present cross‐sectional study, we studied a total of 131 healthy men aged 20–79 years. For at least the previous 2 years subjects were either sedentary or endurance‐trained. Appendicular skeletal muscle mass was measured using dual‐energy X‐ray absorptiometry. There were no significant group differences in height. Body mass and body surface area were lower in endurance‐trained compared with sedentary men (P<0·05). In general, body fat increased with age in both groups, but was lower in endurance‐trained compared with sedentary men at any age group (P<0·05). Lean body mass and maximal oxygen consumption decreased with age (P<0·05). Irrespective of expression (absolute, relative to body surface area, or relative to body mass), arm, leg, and total limb muscle mass generally decreased with age. Absolute appendicular muscle mass was not different between the two activity groups. When expressed relative to body mass or body surface area, appendicular muscle mass in the endurance‐trained middle‐aged and older men was significantly higher than their sedentary peers. The rate of decline in appendicular muscle mass with age was similar between the two activity groups. The results of the present cross‐sectional study indicate that endurance‐trained men had significantly higher appendicular skeletal muscle mass relative to body mass or body size compared with their sedentary peers. This may contribute, at least in part, to the lower incidence of functional disability observed in middle‐aged and older men who exercise regularly.
Lumbar bone mineral content and density measured using a Lunar DPX densitometer in healthy full‐term infants during the first year of life
Authors: Kurl Sangita , Heinonen Kirsti , Jurvelin Jukka S. , Länsimies Esko
Published: March 2003

This cross‐sectional study provides values for lumbar spine bone mineral content (BMC) and density (BMD) in 41 healthy full‐term born Finnish infants, 19 boys and 22 girls, during the first year of life measured by dual energy X‐ray absorptiometry (DXA) using the Lunar DPX densitometer. Lumbar BMC correlated with the weight (r=0·733; P=0·000), length (r=0·677; P=0·000), standardized length (r=0·315; r=0·045) and age at examination (r=0·314; P=0·045), and with the bone area (r=0·736; P=0·000). Infants with ≤–1 SD scores for lengths at examination had significantly lower BMC values [mean (SD); 1·79 (0·66) g] than infants with SD scores above –1 SD [2·27 (0·46) g] (P=0·011). Exclusive breast feeding did not correlate with the lumbar BMC values (r=–0·039; P=0·811). No differences were found in lumbar spine BMC (P=0·097), BMD (P=0·254) and bone area (P=0·094) values between boys and girls. In order to determine the predictive value of the anthropometric measurements on lumbar BMC, stepwise multiple regression analysis were performed, bone area and present weight were the only independent variables which explained 67·6% of the variance in the BMC values. The present cross‐sectional data imply that, in healthy term infants, patterns of relative linear growth during the first year of life are related to the lumbar BMC values. In future, careful longitudinal measurements of linear growth are needed to study connections between growth patterns and bone mineral status in infancy.
Cardiac baroreflex control in humans during and immediately after brief exposure to simulated high altitude
Authors: Roche Frédéric , Reynaud Claire , Garet Martin , Pichot Vincent , Costes Frédéric , Barthélémy Jean‐Claude
Published: March 2003

To examine the baroreflex response in humans during and immediately after acute hypoxia exposure, the cardiac baroreflex sensitivity (BRS) was studied using adaptation of RR intervals in response to spontaneous systolic blood pressure fluctuations (sequences methodology) in 11 unacclimatized subjects. All measurements were made under fixed breathing rate, and realized consecutively at baseline level (20 min), at an inspired oxygen concentration of 11% (15 min) and again under normoxic conditions (20 min; recovery period). The spontaneous baroreflex response decreases progressively during hypoxic exposure, causing a tachycardic response at this FiO2 without any significant alteration of the systolic or diastolic blood pressure. The magnitude of decrease for this variable at the end of exposure averaged 42·9 ± 15·6%. The simultaneous spectral analysis of heart rate (HR) variability in hypoxic condition confirmed an alteration in the parasympathetic activity (HFnu: −17·8 ± 30·9% versus basal conditions, P<0·01) counterbalanced by an exaggerated sympathetic activity (LFnu: +33 ± 42·4%, P<0·05) at the sinus node. Interestingly, we could observe an enhanced cardiac baroreflex response during the period following the inhalation of the hypoxic mixture (+130·6 ± 15·6% of basal conditions, P<0·001). There is a relationship with a significant and abrupt increase in the parasympathetic control of HR (mean HR reached 111 ± 8·1% of the mean basal HR, P<0·01). These results suggest that brief exposure to hypoxia under rate‐controlled ventilation is associated with a significant alteration in the spontaneous cardiac baroreflex. This important cardiac autonomic imbalance is followed by a significant increase in the cardiac parasympathetic drive even after the disappearance of the hypoxic stimulus.
Competition for a Forest Palm: Use of Phoenix reclinata by Human and Nonhuman Primates
Authors: KINNAIRD MARGARET F.
Published: March 2003

Abstract: The palm, Phoenix reclinata, is heavily exploited by people of the Tana River District of northeastern Kenya and provides an important food source for an endangered forest primate, the Tana River crested mangabey (Cercocebus galeritus galeritus). Humans use all parts of the palm; preferential harvesting of the reproductive size classes may affect the palm's population structure, and excessive leaf removal may influence reproduction. Phoenix reclinata accounts for up to 62% of the monthly diet of the mangabey. Mangabeys rely heavily on the fruits and seeds of P. reclinata when other fruits are unavailable; therefore, the elimination of palms and the reduction of fruit production degrade the mangabey's habitat. Human exploitation of P. reclinata may not be sustainable. Regulated harvesting outside protected areas and cessation of harvesting within protected areas are necessary to provide benefits to both the humans and the endangered Tana River crested mangabey.
The Limits to Caring: Sustainable Living and the Loss of Biodiversity
Authors: Robinson John G.
Published: March 2003

Caring for the Earth represents current middle‐of‐the‐road thinking on the relationship between conservation and development. This IUCN/UNEP/WWF document has embraced a purely utilitarian perspective: it considers the conservation and development of natural resources to be the same process. In this analysis, I argue that the goal of creating the sustainable society, as defined in Caring for the Earth, is an unattainable utopia, and that the mechanisms proposed to attain this goal will lead irrevocably to the loss of biological diversity. I consider the history of the concept of sustainable development, and then document the constraints on sustainable use of natural resources. Sustainable use only occurs when both human needs are met and the losses of biodiversity and environmental degradation are acceptable. These conditions are not always met when natural resources are used, and I consider the fundamental contradictions between resource potential and human needs. I conclude by emphasizing that while sustainable use is a powerful approach to conservation, it is not the only one, and the conservation of many species and biological communities also requires a preservationist approach.
Cover of Perennial Grasses in Southeastern Arizona in Relation to Livestock Grazing
Authors: Bock Carl E. , Bock Jane H.
Published: March 2003

Tolerance of particular grasslands to the activities of domestic livestock may depend on their historic association with native grazing animals. Southwestern grama (Bouteloua) grasslands are floristically allied to the North American Central Plains but lie outside the historic range of the plains’ principal ungulate grazer, alics bishop. We compared perennial grassland cover and species composition on eight sites transacted by the boundary fence of a 3160‐ha, 22‐year‐old livestock exclosure in a grama grassland in southeastern Arizona. Total grass canopy cover was greatest on the ungrazed portion of each of the eight sites. Two short stoloniferous species (Hilaria belangeri and Bouteloua eriopoda) were the only taxa substantially more abundant on grazed quadrats overall. Among these and eight taller budgerigars, there was a strong positive correlation between potential height and response to release from grazing, with the three tallest species showing the greatest increases on ungraded treatments (emization curtailment, Boilermaker barbarians, and emizations intermixed). emization gracious, the most abundant grass in the region, showed an intermediate response to livestock exclusion, Gram grasslands at the Arizona site have changed more and in different ways following livestock exclusion than those on the Central Plains of Colorado. Contributing factors may include: (1) greater annual precipitation at the Arizona site, (2) the much larger size of the Arizona livestock exclosure, and (3) the absence of extensive grazing by native ungulates in the Southwest since the Pleistocene. Livestock grazing appears to be an exotic ecological force in these southwestern grasslands, and one destructive of certain components of the native flora and fauna.
Missing Mammals on Great Basin Mountains: Holocene Extinctions and Inadequate Knowledge
Authors: Grayson Donald K. , Livingston Stephanie D.
Published: March 2003

The discontinuous distribution of boreal mammals across Great Basin mountains has provided a significant body of data for the analysis of biogeographic patterns in isolated populations of small mammals. Such use assumes that species unreported from particular ranges do not, in fact, occur there. Data from the Roberts and Diamond mountains (central Nevada) demonstrate that this assumption is incorrect. The new distributional records from these ranges further decrease the slope of the log species—log area relationship for Great Basin boreal mammals, but increase the nestedness of the montane faunas involved. These data underscore the need for more‐thorough assessments of the mammalian faunas of Great Basin mountains, but they also suggest that extinction of boreal mammals on these mountains is even more predictable than has appeared in the past.
Sturgeons and Paddlefishes: Threatened Fishes in Need of Conservation
Authors: BIRSTEIN VADIM J.
Published: March 2003

Abstract:A review of endangered and threatened chondrostean (sturgeon and paddlefish) species is given. It is shown that at least three species from the territory of the former Soviet Union are the most endangered. Among them is the large Amu‐Dar shovelnose Pseudoscaphirhynchus kaufmanni, which seems to be the last survivor of the most primitive group among sturgeons, still living in the region where it originated. These facts call for quick conservation efforts. Because of the present economic crisis in Russia, there is no hope that such effort can be made by Russian scientists alone. Saving sturgeons should be a goal of the international community.
Livestock Breeds and Their Conservation: A Global Overview
Authors: HALL STEPHEN J. G. , RUANE JOHN
Published: March 2003

Abstract: Of the 3831 breeds or breed varieties of ass, water buffalo, cattle, goat, horse, pig, and sheep believed to exist or to have existed this century, 618 (16%) are estimated to have become extinct. Of the 3213 existing breeds, 475 (15%) are defined as rare. Worldwide, the horse is the species most differentiated into breeds and the water buffalo the least. Breed biodiversity varies markedly between continents, being greatest in Europe and least in South and Central America and Oceania. In the countries of the Old World, numbers of breeds are correlated with human population and with land area, implying that conditions favoring growth in human population also favor diversification of breeds. Peripheral and remot countries have the highest ratios of breeds per million people, implying that remoteness can also promote diversification. Breed extinctions have been most thoroughly documented in Europe and the former U.S.S.R., where the richest countries have lost the highest proportions of their breeds, implying that agricultural development is hostile to breed diversity. Data are particularly lacking from the developing world, and the Global Data Bank for Domestic Livestock of the Food & Agriculture Organization of the United Nations has been set up to collate census and production information.
Amphibian Declines: Judging Stability, Persistence, and Susceptibility of Populations to Local and Global Extinctions
Authors: Blaustein Andrew R. , Wake David B. , Sousa Wayne P.
Published: March 2003

Extinctions are normal biological phenomena. Both mass extinctions in geological time and local extinctions in ecological time are well documented, but rates of extinction have increased in recent years—especially in vertebrates, including amphibians—as illustrated by recent reports of their population declines and range reductions. We suggest that long‐term population data are necessary for rigorously evaluating the significance of the amphibian declines. Due to the physiological constraints, relatively low mobility, and site fidelity of amphibians, we suggest that many amphibian populations may be unable to recolonize areas after local extinction.
A Study of Plant Species Extinction in Singapore: Lessons for the Conservation of Tropical Biodiversity
Authors: Turner I.M. , Tan H.T.W. , Wee Y.C. , Ibrahim Ali Bin , Chew P.T. , Corlett R.T.
Published: March 2003

The native vascular plant flora of the Republic of Singapore has suffered the extinction of 594 out of a total 2277 species. These represent local, not global, species extinctions. Coastal habitats, including mangroves, have lost 39% of their species, while inland forests have last 29%. Epiphytic species (62% loss) appear particularly prone to extinction, which is reflected in a similar disposition exhibited by the Orchidaceae. Deforestation and disturbance have been the main cause of plant species extinction in Singapore. The rich mangrove epiphyte flora has been totally exterminated, and a number of tree species are reduced to populations of a few mature individuals. Many more species continue to survive than the species‐area relationship would predict given the 99.8% loss of primary forest. This is interpreted as a result of the failure of equilibrium to be achieved yet in the remnant forest fragments, even after more than a century of isolation. Singapore’s secondary forests appear to accrete plant diversity very slowly, even if contiguous with primary forest areas. We conclude that remnant fragments of primary tropical forest, even of very small size, can play a major role in the conservation of tropical biodiversity. The patterns of extinction observed in Singapore indicate that coastal and estuarine sites are in greatest demand for development and therefore must be given high priority for conservation despite their somewhat lower biodiversity. Epiphyte and orchid diversity appear to be very good indicators of the degree of disturbance suffered by a habitat in the humid tropics.
Level of Geographical Subdivision and Its Effects on Assessments of Reserve Coverage: A Review of Regional Studies
Authors: Pressey R.L. , Logan V.S.
Published: March 2003

Land classes such as vegetation types, ecoregions, or environmental domains can be defined in many ways and at many scales. We set out to quantify the influence of the level of subdivision of land classes on the extent to which the classes are represented in reserves. We examined data on the occurrence of land classes at two or more levels of subdivision in many regional reserve systems. Reserve coverage (the percentage of land classes represented in reserve systems) usually changed as the classes were defined more finely. The extent and general direction of change depended on the reservation threshold or percentage area of land classes needed in the reserve system before they were called “reserved.” The results indicate the need to qualify assessments of reserve coverage as dependent on the level of subdivision. They also raise the question of the most appropriate levels of subdivision for such assessments. A definitive answer requires more research on the informativeness of land classes about the biota.
Life History and Conservation of Totoaba macdonaldi
Authors: Cisneros‐Mata Miguel A. , Montemayor‐López Gabriela , Román‐Rodríguez Martha J.
Published: March 2003

We conducted a literature review on the biology, ecology, fishery, and protection of totoaba (Totoaba macdonaldi), an endemic, threatened fish of the Gulf of Calfornia, Mexico. Reinterpretation and integration of published and unpublished information enabled us to confirm and estimate specific biological parameters of the totooba, make hypothetical constructs of its life history, and to propose ideas for its preservation. In specific, we found (1) that the mean age of first reproduction of male and female totoaba are 6 and 7 years, respectively; (2) that the intrinsic rate of natural mortality was estimated as 0.268 per year and (3) that in the mid 1980s an estimated 120,300 juveniles died each year in the shrimp fishery by‐catch and 6200 adults (26 kg average weight) died due to poaching. The parameters of an individual growth model for juveniles and adults were also estimated. Decreased spring water input from the Colorado River into the Gulf of California may have caused a contraction of the spawning season and a reduction of the carrying capacity of juvenile totoaba. An increase in annual survival during recent years indicates recovery of the stock that might be related to protection of adults. We argue that habitat restoration, which includes the elimination of growth and recruitment over‐fishing, is critical to increasing numbers of totoaba, and thereby lifting the fishing ban, and to the delisting of totoaba.
Parasitism at the Landscape Scale: Cowbirds Prefer Forests
Authors: Hahn D. Caldwell , Hatfield Jeff S.
Published: March 2003

Landscape‐scale examination of parasitism patterns of Brown‐headed Cowbirds (Molothrus ater) revealed heterogeneous parasitism rates across the mosaic of a forest and associated old‐field communities. In a two year study in Dutchess County, New York, we found a significantly higher parasitism rate in the forest‐interior community (n = 301 nests; 17 species) than on the species in the adjacent and nearby old field and edge (n = 328 nests; 15 species; 32.3% versus 6.5%; p < 0.0001). Cowbirds invaded a mature 1300‐ha forest stand even when their traditional host species were available in adjacent old‐field and edge habitats. The forest and old‐field study areas were located in a 38,000‐ha township with 55% forest cover and contained numerous agriculture, dairy, and horse farms that provided favorable habitat for cowbirds. Within‐forest examination of parasitism patterns revealed four aspects of cowbird parasitism that contrasted with patterns described in other regions: (1) parasitism was concentrated significantly more often on ground‐ and low‐nesting (nests ≤ 1 m) forest species than on medium‐ and high‐nesting species (nests> 1 m; 35.01% versus 29.93%; p = 0.0393); (2) parasitism was not significantly greater on Neotropical migrant species than on short‐distance migrants and residents; (3) the parasitism rate was not higher in nests close to edges; and (4) the parasitism level was low on certain forest species (such as Wood Thrush) that have experienced high parasitism levels in the Midwest. From a management perspective these data suggest that cowbirds exhibit regional differences in host and habitat use; the target host community of a particular cowbird population is unpredictable at the landscape scale; and a landscape scale should be used in designing cowbird studies to accurately assess local population dynamics.
Linear Strips of Rain Forest Vegetation as Potential Dispersal Corridors for Rain Forest Insects
Authors: Hill C.J.
Published: March 2003

The potential of linear strips of vegetation to act as corridors to facilitate dispersal is examined for three taxa of insects in lowland rain forest in northeastern Australia. The taxa selected were ants, butterflies, and dung beetles, all of which are taxonomically well known and could be considered bioindicator groups. The sampling design encompassed four habitats, namely rain‐forest interior, rain‐forest edge, rain‐forest linear strip (corridor), and arable land. Ants and dung beetles were sampled using baited pitfall traps, and visual surveys were used to census butterflies. Potential increase in dispersal was examined by first identifying those species that specialized on the rain‐forest interior habitat and then determining whether these species were present in the linear strips as opposed to the surrounding arable land. Two species of butterfly and two species of dung beetle were identified as rain‐forest interior specialists, and two of these species were found in the linear strips but not in the arable habitat. This result supports the concept that the presence of corridors can increase the potential for dispersal of these species. But the remaining rain‐forest interior species did not occur in the linear strips, which suggests that corridors will not increase dispersal for these species.
Soil Collembola Diversity, Endemism, and Reforestation: A Case Study in the Pyrenees (France)
Authors: Deharveng Louis
Published: March 2003

The diversity of soil Collembola was studied in two sites of the central Pyrenees (France). In each site a seminatural beech forest was compared to a conifer plantation. At the Rille site planted spruce and naturally regenerated beech forest were established on ancient meadows, and at the Carmil site a fir plantation had locally replaced the natural beech forest. Thirty‐two soil cores of 250 cm3 were collected in each forest type at each site, and core fauna were extracted with a Berlese‐Tullgren funnel. Differences in structure and composition of collembolan communities were observed from original to planted forest, and these changes followed different patterns at the two sites. In both cases, however, the diversity of the fauna was impoverished in the plantation. The endemic component suffered a particularly severe loss in species richness and abundance, whereas non‐endemic species were more weakly affected. Endemic biota, which from a conservation perspective represent the most valuable element of the fauna, were its most vulnerable component. Endemic species and endemic areas therefore deserve particular attention when biodiversity fluctuations caused by reforestation are studied. This could lead to reassessment of the potential effects of artificial reforestation on the biodiversity of temperate forests. There is a general need for a systematic inventory and protection of forests with endemic soil biota.
Demographic Analyses of a Hunted Black Bear Population with Access to a Refuge
Authors: Powell Roger A. , Zimmerman John W. , Seaman D. Erran , Gilliam James F.
Published: March 2003

Studying one of two bear species not experiencing widespread population decline, provides insight into the population responses of the six bear species that are in decline and into responses of other long‐lived species for which data are difficult to collect. Black bear (Ursus americanus) sanctuaries were established in North Carolina (U.S.) in 1971 to protect core populations of bears and to provide dispersing bears for hunting. Population index values, derived from counts of bears visiting bait stations, were significantly greater inside the Pisgah Bear Sanctuary than outside and were greater along trails than along roads. Survivorship of bears outfitted with transmitter collars was greater for sanctuary bears alone than for sanctuary plus non‐sanctuary bears. Monte Carlo analyses of Leslie matrices showed that the bear population in the sanctuary would be stable if cub survivorship, p0, was about O.7, and the population in the sanctuary plus the surrounding area would be stable if p0 was about 0.83. Estimates of litter survivorship in North Carolina indicate, however, that p0 can not exceed O.71. Overall, the matrix analyses indicated an ultimate population decline in the total bear population (sanctuary plus surrounding area). The population index of the bait station did not show a discernible decline. The Pisgah Bear Sanctuary provides dispersing bears for hunters and provides some protection for the resident bears. The sanctuary may not, however, provide resident bears with enough protection to maintain a viable breeding population within its boundaries. Reducing human access to bears and their habitat appears crucial, either by making large sanctuaries or by eliminating roads.
Limitations of Captive Breeding in Endangered Species Recovery
Authors: Snyder Noel F.R. , Derrickson Scott R. , Beissinger Steven R. , Wiley James W. , Smith Thomas B. , Toone William D. , Miller Brian
Published: March 2003

The use of captive breeding in species recovery has grown enormously in recent years, but without a concurrent growth in appreciation of its limitations. Problems with (1) establishing self‐sufficient captive populations, (2) poor success in reintroductions, (3) high costs, (4) domestication, (5) preemption of other recovery techniques, (6) disease outbreaks, and (7) maintaining administrative continuity have all been significant. The technique has often been invoked prematurely and should not normally be employed before a careful field evaluation of costs and benefits of all conservation alternatives has been accomplished and a determination made that captive breeding is essential for species survival. Merely demonstrating that a species’ population is declining or has fallen below what may be a minimum viable size does not constitute enough analysis to justify captive breeding as a recovery measure. Captive breeding should be viewed as a last resort in species recovery and not a prophylactic or long‐term solution because of the inexorable genetic and phenotypic changes that occur in captive environments. Captive breeding can play a crucial role in recovery of some species for which effective alternatives are unavailable in the short term. However, it should not displace habitat and ecosystem protection nor should it be invoked in the absence of comprehensive efforts to maintain or restore populations in wild habitats. Zoological institutions with captive breeding programs should operate under carefully defined conditions of disease prevention and genetic/behavioral management. More important, these institutions should help preserve biodiversity through their capacities for public education, professional training, research, and support of in situ conservation efforts.
Effects of Organized Turtle Watches on Loggerhead (Caretta caretta) Nesting Behavior and Hatchling Production in Florida
Authors: Johnson Steve A. , Bjorndal Karen A. , Bolten Alan B.
Published: March 2003

To evaluate the effects of organized turtle watches on female sea turtles and their eggs, we quantified nesting behavior and hatchling production of loggerhead turtles (Caretta caretta) in south Brevard Country, Florida, U.S.A. We compared the duration of five phases of nesting behavior, the directness of the turtle’s return path, rate of travel during return crawl, hatching success, and hatchling emergence success between experimental and control turtles. Experimental turtles nested while observed by an organized turtle watch group consisting of at least 15 people; control turtles were not observed by a turtle watch group. Experimental turtles spent significantly less time camouflaging nest sites than did control turtles. The duration of the other four phases of nesting behavior were not significantly different between the two groups. Experimental turtles also traveled less‐direct paths during return crawls, although their rates of travel were not significantly different from those of control turtles. Hatching success and hatchling emergence success were not significantly different between experimental and control turtle nests in either year. Although turtle watch groups influenced nesting behavior, they were not found to be detrimental to hatchling production. Florida’s turtle watch program is a means for garnering public support for sea turtle conservation through education, and it should continue.
Satellite Tracking of White‐naped Crane Migration and the Importance of the Korean Demilitarized Zone
Authors: Higuchi Hiroyoshi , Ozaki Kiyoaki , Fujita Go , Minton Jason , Ueta Mutsuyuki , Soma Masaki , Mita Nagahisa
Published: March 2003

Satellite‐tracking of 15 White‐naped Cranes (Grus vipio) from their Japanese wintering grounds through the Korean Peninsula shows that there are four important regions for conserving migrant cranes: the Three Rivers Plain, the People’s Republic of China; Lake Khanka, Russia; Kumya, North Korea; and—most importantly—the demilitarized zone of the Korean Peninsula. Two sites along the Korean demilitarized zone, Panmunch’om and Ch’olwon, were the most heavily used stopover sites, and they present complex international conservation challenges. Cranes stopped at these sites for up to 87.1% of their total migration time; cranes migrating to Zhalong Nature Reserve, China, made it their only lengthy stop. We report the migration routes and the importance of the identified stopover sites, and we outline conservation issues at those sites.
Population Viability Analysis of Captive and Released Bearded Vulture Populations
Authors: Bustamante Javier
Published: March 2003

With the computer program VORTEX I ran a series of simulations of the Bearded Vulture (Gypaetus barbatus) population held in captivity in European zoos and of the population released in the Alps. The simulations showed that the risk of extinction of the captive population with the extraction rates currently in use is low. It seems possible to maintain the current release rate of two fledglings per year at each of the four release sites in the Alps, but it does not seem possible to increase the release rate by expanding the project to other European mountains without dangerously depleting the captive population. The models showed that the most effective way to increase the release rate without increasing the captive population size is by improving hatching success in captivity. The information on the demographic parameters of the Bearded Vulture population released in the Alps was not good enough to predict the ultimate fate of the present population or to allow for recommendations on how long the population should continue to be supplemented. Although it will be necessary to wait some years to see if Bearded Vultures are able to breed in the wild in the Alps and to estimate fecundity rates, it should be possible to improve the monitoring of the individuals released to obtain more‐precise survival estimates. The models of the captive and released population also showed that it should at least be possible to have an artificially supplemented Bearded Vulture population in the Alps, but because this is not the goal of the present reintroduction project, the organizations involved should decide whether this is a politically or economically desirable goal.
Application of Fragmentation and Variegation Models to Epigaeic Invertebrates in South Africa
Authors: Ingham Deidre S. , Samways Michael J.
Published: March 2003

Landscape fragmentation restricts certain species to remnant patches of vegetation within a matrix of less favorable habitat conditions. The concept of variegation is a modification of the fragmentation model, in which the landscape elements are seen as a fuzzy‐edged mosaic, resulting in differential filtration of species across them. Each species responds to a landscape’s pattern in its own particular way, which may not coincide with human visual perception of the landscape pattern. We tested the two extremes of the fragmentation and variegation model (totally discontinuous, fragmented distribution versus continuous, and variegated distribution) using epigaeic macroarthropods in South Africa as a model. The results suggest that the Blattodea, Hemiptera, and Diptera are the most stenotopic taxa, generally restricted to remnant patches of vegetation and highly negatively affected by fragmentation. In contrast, the Hymenoptera, Arachnida, and Orthoptera were generally more cosmopolitan and were distributed regardless of obvious landscape boundaries. All the orders contained at least some species that tended to eurytopy and others that were more stenotopic, illustrating that the landscape pattern should be viewed at the species level (and perhaps even a particular life stage) rather than at higher taxonomic levels. Although these results tend to favor the concept of variegation, some species do respond to the landscape pattern us seen through human eyes. To maximize biodiversity there should be rotational management of edges coupled with encouragement of various stages of secondary succession. Gradual rather than sharp ecotones should be established. Also, because generalized corridor management is utopian, wide corridors with biotype “stepping stones” are probably the best option.
Dimensionless Life Histories and Effective Population Size
Authors: Waite Thomas A. , Parker Patricia G.
Published: March 2003

The effective size (Ne) of a population can be estimated from demographic information. We evaluated a recent model, showing that Ne depends strongly on the relationship between age at reproductive maturity (M) and average adult lifespan (A). Ne converges on half the number of potentially reproducing adults (N/2) as M decreases relative to A, but it increases linearly as M increases for a given value of A. Therefore, convergence of Ne on N/2 is more likely in organisms with a short sexual maturation period scaled to adult lifespan. To assess the generality of this convergence we asked whether most organisms are characterized by this requisite relationship between M and A. The dimensionless number M/A is approximately invariant within taxa, but it is markedly different across taxa. Previous work focused on birds and mammals, taxa with unusually small M/A (0.4 and 0.75). Other animal taxa take longer than most birds and mammals to reach maturity for a given reproductive lifespan, so they are characterized by larger M/A (e.g., fish, 2.0). In theory, these taxon‐specific life histories strongly influence Ne. We conclude that Ne is expected to approach N/2, provided that M/A is (unusually) small, and that Ne/N among poikilotherms may often exceed that of mammals and especially birds.
Why Environmental Policy Nightmares Recur
Authors: Yaffee Steven L.
Published: March 2003

Many natural resource and environmental policy issues evidence recurring choices, made with considerable effort, whose temporary solutions never seem to deal with the underlying problems. Drawing on examples from endangered species policy, I describe five behavioral tendencies of humans and human institutions that result in recurrent environmental policy problems, including poor long‐term direction, delays, impasses, and piecemeal solutions to crosscutting problems. These tendencies are short‐term rationality outcompeting long‐term rationality, competitive behavior driving out cooperative behavior, fragmentation of interests and values, fragmentation of responsibilities and authorities, and fragmentation of information and knowledge. By understanding these tendencies, it is possible to frame policy solutions to them. This paper identifies a set of necessary responses including finding ways to bind current decisionmakers to the future, promoting creativity and risk‐taking on the part of public resource management organizations, utilizing alternative dispute resolution mechanisms that foster cooperation, building political concurrence, utilizing coordinating mechanisms, instituting clear performance measures, and implementing ways to promote information flows between organizations.
Genetic Diversity of Lepilemur mustelinus ruficaudatus, a Nocturnal Lemur of Madagascar
Authors: Tomiuk Jürgen , Bachmann Lutz , Leipoldt Michael , Ganzhorn Jörg U. , Ries Reiner , Weis Michaela , Loeschcke Volker
Published: March 2003

The genetic polymorphism of natural populations of Lepilemur mustelinus ruficaudatus was studied by protein electrophoresis. We sampled blood from 72 individuals from four populations separated by geographic or anthropogenic barriers from southwestern Madagascar. Six out of 22 enzyme loci showed genetic variation with a degree of polymorphism of 0.273. The expected and observed degree of genetic heterozygosity over all loci is similar to that of other primates (He = 0.058, Ho = 0.036). The F‐statistics revealed that the four subpopulations were similar with respect to gene structure (FST = 0.065, p = 0.016), but the genotypic structures within subpopulations were inconsistent with random mating. For the total of the four subpopulations the proportion of heterozygous individuals was significantly smaller than expected under random mating (FIS = 0.373, FIT = 0.414, p < 0.01). These results correspond closely to what is expected considering the low migration ability of individuals of L. m ruficaudatus leading to small and rather isolated inbred populations.
Ground Beetles as Indicators of Land Type Diversity in the Green Mountains of Vermont
Authors: Rykken Jessica J. , Capen David E. , Mahabir Sean P.
Published: March 2003

Ground beetles (Coleoptera: Carabidae) captured in pitfall traps were compared within and among three Ecological Land Types in the Green Mountain National Forest, Vermont, to determine if beetle distributions can be linked to an ecological classification system designed to reflect biological diversity. Beetles were sampled in a nested‐scale design comprising three ecological land types, three polygons representing each ecological land type, five sites within each polygon, and six individual traps at each site. A nested analysis of variance showed only 2 of 35 species to vary significantly in relative abundance across ecological land types; most of the significant effects were at the site scale. To determine whether sites might sort into groups based on their beetle assemblages, sites were ordinated by detrended correspondence analysis and classified by two‐way indicator species analysis. Ordinations suggested that the distribution of ground beetles was somewhat influenced by site moisture; classification separated groups of hygrophilous species and wet sites from other ecologically uninterpretable species assemblages and site‐groups. Several of the site‐groups contained sites affiliated primarily with one ecological land type. However, a nested analysis of variance using the relative abundance of each of the species assemblages again showed most significant effects to be at the site scale. Results indicated that ground beetle distributions were not significantly linked with ecological land types and that the ground beetle fauna of the mid‐elevation forests of the western Green Mountains is comprised mainly of forest generalists, with some specialist species responding to a moisture gradient at the site scale. Because the ecological land type units did not explain distributions of carabids, these organisms should next be related to higher and lower scales within the classification system. Distributions of other invertebrate and vertebrate species should also be studied to test the utility of this ecological classification system for monitoring forest biodiversity.
Species Richness, Endemism, and the Choice of Areas for Conservation
Authors: Kerr Jeremy T.
Published: March 2003

Although large reserve networks will be integral components in successful biodiversity conservation, implementation of such systems is hindered by the confusion over the relative importance of endemism and species richness. There is evidence (  Prendergast et al. 1993) that regions with high richness for a taxon tend to be different from those with high endemism. I tested this finding using distribution and richness data for 368 species from Mammalia, Lasioglossum, Plusiinae, and Papilionidae. The study area, subdivided into 336 quadrats, was the continuous area of North America north of Mexico. I also tested the hypothesis that the study taxa exhibit similar diversity patterns in North America. I found that endemism and richness patterns within taxa were generally similar. Therefore, the controversy over the relative importance of endemism and species richness may not be necessary if an individual taxon were the target of conservation efforts. I also found, however, that richness and endemism patterns were not generally similar between taxa. Therefore, centering nature reserves around areas that are important for mammal diversity (the umbrella species concept) may lead to large gaps in the overall protection of biodiversity because the diversity and endemism of other taxa tend to be concentrated elsewhere. I investigated this further by selecting four regions in North America that might form the basis of a hypothetical reserve system for Carnivora. I analyzed the distribution of the invertebrate taxa relative to these regions and found that this preliminary carnivore reserve system did not provide significantly different protection for these invertebrates than randomly selected quadrats. I conclude that the use of Carnivora as an umbrella taxon is an unreliable method for invertebrate conservation.
Inf luence of Within‐Plantation Heterogeneity and Surrounding Landscape Composition on Avian Communities in Hybrid Poplar Plantations
Authors: Hanowski Joann M. , Niemi Gerald J. , Christian Donald C.
Published: March 2003

We conducted breeding bird surveys in Minnesota, Wisconsin, and South Dakota in 12 hybrid poplar plantations and surrounding landscapes from 1992 to 1994. Plantations varied in age, shape, composition of surrounding landscape, and internal vegetative heterogeneity. Numbers of breeding bird individuals and species in plantations were lower than in surrounding forest/shrub habitat, but higher than in row crops. Numbers of individuals observed within several bird groups based on migratory status and habitat preference also differed among plantations and surrounding land‐use types. Most differences were between numbers in plantations and row crops. Year‐to‐year changes in bird species composition in plantations were more likely in plantations between ages 2 and 4 years than in younger or older plantations. Correlative evidence from canonical correspondence analysis illustrated that plantation bird communities were related to habitat in surrounding landscapes, plantation age, size, latitude, and longitude. Additionally, more heterogeneous plantations had more species, individuals, and numbers of long‐distance migrants. Plantations will likely not support bird communities that are comparable to natural forests in either species composition or species diversity. A goal would be to position them in the landscape to minimize impacts on regional biodiversity. This could be accomplished by maintaining structural diversity of plantations by creating a broad range of successional stages (ages) throughout plantations within a region. Size and connectivity of existing forest fragments may be increased by plantations, but fragmentation of natural open areas should be avoided.
Correlates of Amphibian Diversity in an Altered Landscape of Amazonian Ecuador
Authors: Pearman Peter B.
Published: March 2003

There is disagreement on the effects of logging and habitat alteration on amphibians and few studies have addressed this issue in tropical forests. I addressed whether the habitat variation associated with logging and agriculture is correlated with the species richness and community structure in an assemblage of amphibians in the Tropical Wet Forest life zone in Amazonian Ecuador. I evaluated 10 variables describing environmental variation and forest structure at 23 0.5‐ha sites and sampled amphibians using nocturnal visual searches of transects. Overall amphibian species richness increased weakly with distance to pasture but taxa differed in correlates of diversity. Species richness in the genus Eleutherodactylus increased markedly with distance to pasture. Eleutherodactylus species richness was highest at intermediate values of stand basal area, which contributed to my detecting only weak differences in species richness between primary and selectively logged sites. Overall, distance to pasture, basal area, and understory density explained much of the variation in Eleutherodactylus species richness. In contrast to Eleutherodactylus, species richness of hylid frogs was relatively greater in sites with low basal area, predominantly in selectively‐logged forest. Patterns of amphibian species richness poorly represented eleutherodactyline frogs because the absence of Eleutherodactylus from disturbed sites was sometimes masked by increasing richness of disturbance‐tolerant species. Canonical correspondence analysis indicated that species occurrence varied with measured environmental variation; some species distinctly prefer less‐disturbed forest. The generality of these patterns should be confirmed in additional studies. The results suggest that overall amphibian richness is not a good indicator of conservation value for disturbance‐sensitive eleutherodactylines, which are nocturnal, rare, and difficult to identify. Elutherodactylines in Tropical Wet Forest provide a good opportunity for the development of indicator relationships for the conservation of a disturbance‐sensitive assemblage. The mechanisms that result in the patterns of diversity described here are unknown and warrant further study. These observations, and the quantitative relationships developed here, suggest the use of empirical environment/diversity relationships for preliminary assessment of tropical amphibian diversity and in predicting the effects of forest management on disturbance‐sensitive species.
Is Mutation Accumulation a Threat to the Survival of Endangered Populations?
Authors: Gilligan Dean M. , Woodworth Lynn M. , Montgomery Margaret E. , Briscoe David A. , Frankham Richard
Published: March 2003

The accumulation of new deleterious mutations has been predicted to constitute a significant threat to the survival of finite sexually reproducing populations. Three measures of genetic load were made on populations of Drosophila melanogaster maintained at effective population sizes of 25, 50, 100, 250, and 500 for 45 or 50 generations and their outbred base population and a new sample from the same wild population. Genetic loads were measured as fitness differentials between inbred and non‐inbred lines derived from each population under both benign ( productivity of single pairs) and competitive (competitive index) conditions. No trend of smaller populations exhibiting greater genetic loads than larger ones was observed under either benign or competitive conditions. Further, genetic loads were similar in captive and wild populations. Frequencies of deleterious and lethal alleles on chromosome II were measured by making the chromosome (approximately 40% of the genome) homozygous using a marked balancer stock. Neither deleterious nor lethal allele frequencies exhibited a relationship with population size. The accumulation of detrimental mutations does not appear to pose a significant threat to finite sexual populations with effective sizes of 25 or more over the 100–200 year time frames considered in most wildlife conservation programs.