bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of regular voluntary exercise on spontaneous and social stress‐affected sleep in mice
Authors: Lancel Marike , Droste Susanne K. , Sommer Susanne , Reul Johannes M. H. M.
Published: May 2003

To investigate the impact of regular physical exercise on sleep, we assessed sleep–wake behaviour in male C57BL/6N mice with and without long‐term access (i.e. 4 weeks) to a running wheel. We studied sleep–wake behaviour during undisturbed conditions as well as after social stress. The exercising mice ran approximately 4 km/day, which affected their physical constitution, their spontaneous sleep–wake pattern and their endocrine and sleep responses to stress. When compared with the control mice, exercising animals had more muscle substance, less body fat and heavier adrenal glands. At baseline, exercising mice showed fewer, but longer‐lasting, sleep episodes (indicating improved sleep consolidation) and less rapid‐eye‐movement sleep. In both control and exercising mice, mild social stress (elicited by a 15‐min social conflict) evoked elevated plasma levels of adrenocorticotrophic hormone and corticosterone, an increase in non‐rapid‐eye‐movement sleep, an enhancement of low‐frequency activity in the electroencephalogram within non‐rapid‐eye‐movement sleep (indicating increased sleep intensity) and a decrease in wakefulness. However, as compared with the control animals, exercising mice responded to social stress with higher corticosterone levels, but not adrenocorticotrophic hormone levels, suggesting an increased sensitivity of their adrenal glands to adrenocorticotrophic hormone. Moreover, in control mice, social stress increased rapid‐eye‐movement sleep in parallel to non‐rapid‐eye‐movement sleep, whereas this stressor selectively decreased rapid‐eye‐movement sleep in exercising animals. Corticosterone is known to decrease rapid‐eye‐movement sleep. Therefore, changes in the regulation of the hypothalamic‐pituitary‐adrenocortical axis as a result of the long‐term exercise may contribute to the observed differences in spontaneous and social stress‐affected sleep. In conclusion, regular exercise appears to increase sleep quality and reverses the effects of mild social stress on rapid‐eye‐movement sleep.
Stress‐mediated heart rate dynamics after deletion of the gene encoding corticotropin‐releasing factor receptor 2
Authors: Stiedl Oliver , Meyer Michael , Kishimoto Toshimitsu , Rosenfeld Michael G. , Spiess Joachim
Published: May 2003

The objective of the present study was to investigate the potential role of corticotropin‐releasing factor receptor subtype 2 (CRFR2) in autonomic regulation of heart rate and heart rate variability under physiological conditions in conscious mice. Heart rate dynamics during novelty exposure and auditory fear conditioning were assessed by radiotelemetry. Heart rate responses and heart rate variability values were not different in CRFR2+/+ and CRFR2−/− mice during novelty exposure, which was associated with similar locomotor activity exhibited by both genotypes. The heart rate responses during retention of conditioned auditory fear were similar and the exponential relationship between heart rate and heart rate variability was independent of genotype. Pharmacological stimulation of the peripheral CRFR2β by intraperitoneal injection of 200 ng human/rat corticotropin‐releasing factor yielded a sustained tachycardia in wildtype control (CRFR2+/+) mice which was absent in CRFR2‐deficient (CRFR2−/−) mice. Similarly, the tachycardia was effectively blocked by preinjection of the CRFR2 antagonist antisauvagine‐30. In conclusion, the results indicate the involvement of CRFR2 in heart rate dynamics upon pharmacological stimulation but demonstrate that CRFR2 is not involved in baseline heart rate regulation and stress‐mediated modulation of heart rate responses.
Removal of PSA from NCAM affects the survival of magnocellular vasopressin‐ and oxytocin‐producing neurons in organotypic cultures of the paraventricular nucleus
Authors: Vutskits L. , Gascon E. , Kiss J. Z.
Published: May 2003

The expression of the polysialic acid neural cell adhesion molecule (PSA‐NCAM) in the hypothalamo‐neurohypophyseal system has been correlated with morphofunctional plasticity. In this study, we investigated the role of PSA‐NCAM in the survival of oxytocin (OT)‐ and vasopressin (VP)‐producing magnocellular cells of this system. We used a recently developed organotypic slice culture model of the rat hypothalamic paraventricular nucleus (PVN) in which ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) are potent survival factors for magnocellular neurons. We demonstrate by means of confocal microscopy that cultured magnocellular VP and OT neurons express strong immunoreactivity for PSA‐NCAM. Removal of PSA from NCAM by the enzyme Endo N leads to a significant loss of both VP and OT neurons in the presence of low concentrations of CNTF. Endo N treatment did not change cell survival in the presence of LIF. These results suggest that, in addition to its role in neuro‐glial plasticity, PSA‐NCAM might also influence the trophic factor responsiveness of hypothalamic VP and OT neurosecretory cells.
Pleiotrophin exhibits a trophic effect on survival of dopaminergic neurons in vitro
Authors: Hida Hideki , Jung Cha‐Gyun , Wu Chen‐Zhen , Kim Hye‐Jung , Kodama Yuji , Masuda Tadashi , Nishino Hitoo
Published: May 2003

To understand what kind of trophic factors are up‐regulated in dopamine (DA)‐depleted striatum, we first analysed the up‐regulation of mRNAs using a DNA microarray in DA‐depleted striatum where DAergic inputs were denervated by 6‐OHDA. We then investigated whether or not such trophic factors had an effect on cultured dopaminergic neurons. The microarray analysis revealed that pleiotrophin (PTN), glial‐derived neurotopic factor (GDNF) and others were up‐regulated in DA‐depleted striatum. As PTN has been reported to have a wide range of trophic effects on neurons, we focused on the functional role of PTN in the present study. The increase in PTN mRNA was confirmed by Northern blotting at 1–3 weeks after the lesion, reaching a peak at 1 week. In embryonic day 15 mesencephalic neuron culture, PTN increased the number of tyrosine hydroxylase (TH) ‐positive neurons in a dose‐dependent manner (125.2 ± 2.0% of the control at 50 ng/mL), while a family protein, midkine (10 ng/mL) did not show any trophic effect (99.3 ± 0.7%). In addition, the PTN effect on DAergic neurons was additive to the GDNF effect. As PTN did not increase the number of microtubule‐associated protein‐2 (MAP 2)‐positive neurons or promote the proliferation of dopaminergic progenitors in a bromodeoxyuridine (BrdU) labelling study, the effect appeared to enhance the specific survival of dopaminergic neurons. Expression of PTN receptors (syndecan‐3, PTP‐ζ) was detected on the cultured mesencephalic neurons, and also up‐regulated in DA‐depleted striatum. The data indicate that PTN is up‐regulated in DA‐depleted striatum and exhibits a trophic effect specifically on the survival of cultured dopaminergic neurons.
Synaptic changes characterize early behavioural signs in the ME7 model of murine prion disease
Authors: Cunningham C. , Deacon R. , Wells H. , Boche D. , Waters S. , Diniz C. Picanco , Scott H. , Rawlins J. N. P. , Perry V. H.
Published: May 2003

Prion diseases are fatal, chronic neurodegenerative diseases of mammals, characterized by amyloid deposition, astrogliosis, microglial activation, tissue vacuolation and neuronal loss. In the ME7 model of prion disease in the C57BL/6 J mouse, we have shown previously that these animals display behavioural changes that indicate the onset of neuronal dysfunction. The current study examines the neuropathological correlates of these early behavioural changes. After injection of ME7‐infected homogenate into the dorsal hippocampus, we found statistically significant impairment of burrowing, nesting and glucose consumption, and increased open field activity at 13 weeks. At this time, microglia activation and PrPSc deposition was visible selectively throughout the limbic system, including the hippocampus, entorhinal cortex, medial and lateral septum, mamillary bodies, dorsal thalamus and, to a lesser degree, in regions of the brainstem. No increase in apoptosis or neuronal cell loss was detectable at this time, while in animals at 19 weeks postinjection there was 40% neuronal loss from CA1. There was a statistically significant reduction in synaptophysin staining in the stratum radiatum of the CA1 at 13 weeks indicating loss of presynaptic terminals. Damage to the dorsal hippocampus is known to disrupt burrowing and nesting behaviour. We have demonstrated a neuropathological correlate of an early behavioural deficit in prion disease and suggest that this should allow insights into the first steps of the neuropathogenesis of prion diseases.
Effect of lidocaine and NMDA injections into the medial pontobulbar reticular formation on mastication evoked by cortical stimulation in anaesthetized rabbits
Authors: Scott G. , Westberg K. G. , Vrentzos N. , Kolta A. , Lund J. P.
Published: May 2003

Neurons of the dorsal nucleus reticularis pontis caudalis (nPontc) fire rhythmically during fictive mastication, while neurons of the ventral half tend to fire tonically (Westberg et al., 2001). This paper describes the changes in the pattern of rhythmical mastication elicited by stimulation of the sensorimotor cortex during inhibition or excitation of neurons in this nucleus and adjacent parts of nucleus reticularis gigantocellularis (Rgc) in the anaesthetized rabbit. Masticatory movements and electromyographic (EMG) activity of the masseter and digastric muscles produced by cortical stimulation were recorded before, during and after injections of a local anaesthetic (lidocaine) or excitatory amino acid N‐methyl‐d‐aspartate (NMDA) into nPontc and Rgc through a microsyringe with attached microelectrode to record neuronal activity. Lidocaine inhibited local neurons and modified the motor program, and the effects varied with the site of injection. Most injections into the ventral half of nPontc increased cycle duration, digastric burst duration and burst area. The action of lidocaine in dorsal nPontc was more variable, although burst duration and area were often decreased. The effects on the muscle activity were always bilateral. Lidocaine block of the rostromedial part of Rgc had no effect on movements or on EMGs. Injections of NMDA excited local neurons and when injected into ventral nPontc, it completely blocked mastication. Dorsal injections either had no effect or increased cycle frequency, while decreasing burst duration and area. No increases in EMG burst duration or area were observed with NMDA. Our findings suggest that neurons of ventral nPontc tonically inhibit other parts of the central pattern generator during mastication, while dorsal neurons have mixed effects. We incorporated these findings into a new model of the masticatory central pattern generator.
Gene expression of neuropeptide Y in the nucleus of the solitary tract is activated in rats under restricted daily feeding but not under 48‐h food deprivation
Authors: Ishizaki Kouji , Honma Sato , Katsuno Yumiko , Abe Hiroshi , Masubuchi Satoru , Namihira Masakazu , Honma Ken‐ichi
Published: May 2003

The two neuropeptide Y (NPY) systems innervating the hypothalamic paraventrivular nucleus were examined regarding their roles in the prefeeding corticosterone peak developed under restricted daily feeding (RF). Protein and mRNA levels of NPY were measured in the arcuate nucleus (ARC) and the nucleus of the solitary tract (NST) in rats under 48‐h food deprivation (48‐hFD), RF, and 72‐h food deprivation imposed after RF (post‐RF 72‐hFD) with 7 days of ad libitum feeding in between. NPY protein and mRNA levels in the ARC significantly increased with 48‐hFD and decreased with re‐feeding, whereas those in the NST were not changed by 48‐hFD. When rats had RF imposed with free access to food from 10.00 to 12.00 h (lights on from 06.00 to 18.00 h) for 3 weeks, NPY concentrations in the ARC increased at 10.00 h, just prior to the daily meal, but those in the NST did not change significantly throughout the period examined. On the other hand, NPY mRNA levels in both the ARC and NST increased before the meal supply and remained high for 4 h after feeding. Under post‐RF 72‐hFD, the prefeeding peak of NPY mRNA was detected in the NST, but NPY mRNA levels in the ARC were continuously high throughout the 24‐h period. These findings indicate that the NPY neurons from the NST are specifically activated by RF, whereas those from the ARC are generally stimulated by an increased food demand.
Characteristics of Rapid Rhythms Recorded Within Pulmonary Veins During Atrial Fibrillation
Authors: TADA HIROSHI , ÖZAYDIN MEHMET , ORAL HAKAN , KNIGHT BRADLEY P. , CHUGH AMAN , SCHARF CHRISTOPH , PELOSI FRANK , STRICKBERGER S. ADAM , MORADY FRED
Published: May 2003

Rapid rhythms often arise in the pulmonary veins during atrial fibrillation (AF). The activation patterns within pulmonary veins during these rapid rhythms are not well described. In 39 patients with paroxysmal AF, ostial recordings were obtained during AF in 110 pulmonary veins with a decapolar distal ring catheter. Pulmonary vein tachycardia (PVT) was defined as a pulmonary vein (PV) rhythm that had a cycle length shorter than at the adjacent left atrium. During AF, PVT was recorded in 93% of PV's, usually in the form of intermittent bursts that had a mean duration of 1,325 ± 647 ms and mean cycle length of 125 ± 20 ms. The mean cycle length of continuous PVT's (141 ± 25) was longer than the mean cycle length of intermittent bursts of PVT (P < 0.05). The intermittent PVT's were associated with a shorter left atrial cycle length than were the continuous PVT's. In 90% of PVTs, complex activation patterns attributable to simultaneous recordings from two or more overlapping fascicles were present at a segment of the pulmonary vein ostium, and the mean cycle length of these recordings was 80 ± 32 ms. PVT during AF is much more often intermittent than continuous. The relationship between PVT cycle length and left atrial cycle length suggests that PVT's influence the left atrium during AF. PVT must be distinguished from recordings within PV's that have a short cycle length as a result of simultaneous recordings from two or more overlapping fascicles. (PACE 2003; 26:1342–1347)
Anatomic Characteristics of Extensions of Atrial Myocardium into the Pulmonary Veins in Subjects With and Without Atrial Fibrillation
Authors: KHOLOVÁ IVANA , KAUTZNER JOSEF
Published: May 2003

Myocardial extensions around pulmonary veins (PVs) have been recognized as the most important sites of origin for arrhythmogenic foci that trigger atrial fibrillation. The aim of this study was to evaluate the characteristics of atrial myocardium in pulmonary veins from subjects with and without a history of atrial fibrillation. A total number of 43 human hearts obtained at autopsy were studied (27 men, 16 women, mean age 67 ± 8 years). Sixteen subjects (group 1) had a history of atrial fibrillation (11 men, mean age 66 ± 10 years). The remaining 27 subjects (group 2) were without arrhythmia (16 men, mean age 68 ± 8 years). The presence and morphology of the myocardial extensions were studied microscopically. Of the total number of 172 PVs evaluated, myocardial extensions were revealed in 117 (68%) cases. Myocardial fibers were arranged in a variable manner with the most prevailing circular pattern. Continuous extensions were present in 74, while a discontinuous pattern was revealed in 29 PVs. Maximum extension of the sleeves reached 48 mm (mean 7.7–10 mm) and their maximum thickness was 5 mm. Myocardial extensions were longer and thicker in the upper PVs from subjects with previous atrial fibrillation. In conclusion, a significant interindividual variability in the presence, arrangement, and thickness of atrial myocardial sleeves into PVs was revealed. Patients with a history of atrial fibrillation were found to have longer and thicker myocardial extensions into the upper PVs, and this finding may have implications for the catheter ablation technique. (PACE 2003; 26:1348–1355)
Left Atrial Flutter After Segmental Ostial Radiofrequency Catheter Ablation for Pulmonary Vein Isolation
Authors: ORAL HAKAN , KNIGHT BRADLEY P. , MORADY FRED
Published: May 2003

Segmental ostial ablation to electrically isolate pulmonary veins has been performed for atrial fibrillation. Left atrial flutter that utilized a critical isthmus adjacent to the ostium of the left superior pulmonary vein was diagnosed and successfully ablated in a patient 3 months after a successful pulmonary vein isolation procedure. Documenting the cause of symptoms after pulmonary vein isolation in patients with atrial fibrillation is critical in guiding therapy. (PACE 2003; 26:1417–1419)
The impact of diabetes‐related complications on healthcare costs: results from the United Kingdom Prospective Diabetes Study (UKPDS Study No. 65)
Authors: Clarke P. , Gray A. , Legood R. , Briggs A. , Holman R.
Published: May 2003

Aims To develop a model for estimating the immediate and long‐term healthcare costs associated with seven diabetes‐related complications in patients with Type 2 diabetes participating in the UK Prospective Diabetes Study (UKPDS).

Methods The costs associated with some major complications were estimated using data on 5102 UKPDS patients (mean age 52.4 years at diagnosis). In‐patient and out‐patient costs were estimated using multiple regression analysis based on costs calculated from the length of admission multiplied by the average specialty cost and a survey of 3488 UKPDS patients’ healthcare usage conducted in 1996–1997.

Results Using the model, the estimate of the cost of first complications were as follows: amputation £8459 (95% confidence interval £5295, £13 200); non‐fatal myocardial infarction £4070 (£3580, £4722); fatal myocardial infarction £1152 (£941, £1396); fatal stroke £3383 (£1935, £5431); non‐fatal stroke £2367 (£1599, £3274); ischaemic heart disease £1959 (£1467, £2541); heart failure £2221 (£1690, £2896); cataract extraction £1553 (£1320, £1855); and blindness in one eye £872 (£526, £1299). The annual average in‐patient cost of events in subsequent years ranged from £631 (£403, £896) for heart failure to £105 (£80, £142) for cataract extraction. Non‐in‐patient costs for macrovascular complications were £315 (£247, £394) and for microvascular complications were £273 (£215, £343) in the year of the event. In each subsequent year the costs were, respectively, £258 (£228, £297) and £204 (£181, £255).

Conclusions These results provide estimates of the immediate and long‐term healthcare costs associated with seven diabetes‐related complications.

Diabet. Med. 20, 442–450 (2003)
Evaluating the Importance of Human‐Modified Lands for Neotropical Bird Conservation
Authors: Petit Lisa J. , Petit Daniel R.
Published: May 2003

Abstract:Development of effective conservation plans for terrestrial animals will require some assessment of which human‐modified and natural habitats can support populations of priority species. We examined bird communities associated with 11 natural and human‐modified habitats in Panama and assessed the importance of those habitats for species of different vulnerability to disturbance. We calculated habitat importance scores using both relative habitat preferences and vulnerability scores for all species present. Species of moderate and high vulnerability were primarily those categorized as forest specialists or forest generalists. As expected, even species‐rich nonforest habitats provided little conservation value for the most vulnerable species. However, shaded coffee plantations and gallery forest corridors were modified habitats with relatively high conservation value. Sugar cane fields and Caribbean pine plantations offered virtually no conservation value for birds. Our method of assessing the conservation importance of different habitats is useful because it considers the types of species present and the potential role of the habitat in the conservation of those species ( i.e., habitat preference ). This method of habitat evaluation could be tailored to other conservation contexts with any measure of species vulnerability desired.
Isolation Management with Artificial Barriers as a Conservation Strategy for Cutthroat Trout in Headwater Streams
Authors: Novinger Douglas C. , Rahel Frank J.
Published: May 2003

Abstract: We evaluated the effectiveness of isolation management and stocking to meet protection and enhancement goals for native Colorado River cutthroat trout ( Oncorhynchus clarki pleuriticus ) in Wyoming (  U.S.A. ). As a management strategy of the Wyoming Game and Fish Department, cutthroat trout were isolated upstream of artificial barriers in small headwater streams. Non‐native trout that might have hybridized, competed with, or preyed upon cutthroat trout were removed from the isolated reaches, and then cutthroat trout of hatchery origin were stocked to augment populations. We monitored the abundance and body condition of cutthroat trout for 4–7 years following isolation in four streams with barriers and in two reference streams without barriers. Barriers limited new invasions by non‐native trout, and removals of non‐native trout greatly reduced their abundance but did not eliminate them ( mainly brook trout [ Salvelinus fontinalis] ). Wild cutthroat trout persisted in low numbers upstream of barriers, but there was no evidence of enhancement of populations. Stocked cutthroat trout did not persist upstream of barriers, and many moved downstream over barriers. The body condition of wild cutthroat trout was comparable among populations upstream and downstream of barriers and in reference streams. Isolation management provided only short‐term benefits by minimizing the risks of hybridization and allowed populations to persist during the study. Removal of non‐native trout and stocking did not enhance wild cutthroat trout populations, however, likely because the isolated reaches lacked critical habitat such as the deep pools necessary to sustain large fish. Also, barriers disrupt migratory patterns and prevent seasonal use of headwater reaches by adult cutthroat trout. Longer‐term consequences of isolation include vulnerability to stochastic processes and loss of genetic diversity. Where non‐native species pose an immediate threat to the survival of native fishes, isolation in headwater streams may be the only conservation alternative. In such situations, isolated reaches should be as large and diverse as possible, and improvements should be implemented to ensure that habitat requirements are met.
Effects of Habitat Fragmentation on Birds in Deciduous Forests in Japan
Authors: Kurosawa Reiko , Askins Robert A.
Published: May 2003

Abstract:Although migratory forest birds have declined at many sites in Japan, the negative effect of forest fragmentation on bird populations has not been intensively studied. We sought to ( 1 ) determine whether there are particular bird species or groups of species that are sensitive to the area and isolation of forests in Japan and ( 2 ) compare the types of species that are area‐sensitive in Japan, Western Europe, and eastern North America. We estimated the abundance of breeding birds by using the fixed‐radius, point‐count method in 53 deciduous forests ( 1–5045 ha ) in southern Hokkaido. Forest area was positively related to the abundance ( average number of individuals per survey plot ) and species richness ( average number of species per survey plot ) of forest‐interior birds and was negatively related to the abundance and species richness of forest‐edge birds. As in eastern North America, forest area was the best predictor of the abundance of several species of forest birds. Also, some species were restricted to large forests, with minimum areas larger than expected by chance. Forest area was not significantly related to the total abundance of tropical migrants, but five of the nine potentially area‐sensitive species were tropical migrants. Jungle Crows ( Corvus macrorhynchos ), which are nest predators, were more abundant in small forests than in large forests, but Oriental Cuckoos ( Cuculus saturatus ), which were the most common brood parasites, were more abundant in large forests. To conserve area‐sensitive species in deciduous forests in northern Japan, it will be necessary to preserve large areas of contiguous forest and monitor the effect of predators on nest success.
Risks from Competitively Inferior Immigrant Populations: Implications of Mass Effects for Species Conservation
Authors: Thompson Colin J. , Thompson Ben J. P. , Burgman Mark A.
Published: May 2003

Abstract: Many species are maintained by a rain of propagules from a source population and thereby persist in a location from which they would ordinarily be excluded by competition. This is one explanation for the persistence of competitively inferior domestic species in natural environments. The purpose of our study was to estimate the effect of immigrant populations on competitively superior wild species in terms of the risks of decline—the quasiextinction risk—of the wild population and the quasiexplosion risk of the immigrant population. A simple mathematical model of escape and competition demonstrates that the risks to a wild population may be appreciable. We found that even when the species maintained by mass effects is not viable in the absence of competition and immigration, low escape rates ( e.g., enough to give the invasive population a net positive growth rate ) can make a wild‐competing species vulnerable within 10 years. The probability that the immigrant population will exceed lower bounds increases rapidly with rates of escape and growth.
Post‐Agricultural Succession in El Petén, Guatemala
Authors: Ferguson Bruce G. , Vandermeer John , Morales Helda , Griffith Daniel M.
Published: May 2003

Abstract:We compared post‐agricultural succession across the range of farming activities practiced in Guatemala's northern lowlands: agroforestry, swidden, ranching, and input‐intensive monocultures. At 10 sites over 13 to 40 months we assessed the following characteristics of trees and shrubs that were>1 cm diameter at breast height: height, basal‐area accumulation, recruitment of all individuals and fleshy‐fruited individuals, and accumulation of all species and fleshy‐fruited species. Succession, as measured by all these response variables except height, was dramatically faster on agroforestry and swidden sites than on pastures or input‐intensive monocultures. Overall recruitment was faster for swiddens than for agroforests, but other response variables did not differ significantly between the two treatments. Regression results suggest that initial ground cover by herbs inhibited recruitment of woody colonists. The significant positive coefficient for initial basal area and the significant negative coefficient for distance from forest for accumulation of both fleshy‐fruited individuals and species are probably explained by the behavioral responses of seed‐dispersing animals. Our results suggest that the conservation strategy of discouraging swidden agriculture in favor of sedentary, input‐intensive agriculture to relieve pressure on old‐growth forest may be counterproductive over the long term.
A Species‐Specific Approach to Modeling Biological Communities and Its Potential for Conservation
Authors: Olden Julian D.
Published: May 2003

Abstract:Community‐level approaches to biological conservation are now recognized as a major advance in most current single‐species conservation and management practices. Existing approaches for modeling bio‐ logical communities, have limited utility, however, because they commonly examine community metrics ( e.g., species richness, assemblage “types” ) and consequently do not consider the identity of the species that compose the community. This is a critical shortcoming because the functional differences among species ultimately translate into the differential vulnerability of biological communities to natural and human‐related environmental change. To address this concern I present a novel, species‐specific approach to modeling communities using a multiresponse, artificial neural network. This provides an analytical approach that facilitates the development of a single, integrative model that predicts the entire species membership of a community while still respecting differences in the functional relationship between each species and its environment. I used temperate‐lake fish communities to illustrate the utility of this modeling approach and found that predictions of community composition by the neural network were highly concordant with observed compositions of the 286 study lakes. Average similarity between observed and predicted community composition was 80% ( 22 out of the 27 species correctly classified ), and the model predicted a significant portion of the community composition in 91% of the lakes. I discuss the importance of the lake habitat variables for predicting community composition and explore the spatial distribution of model predictions in light of recent species invasions. The proposed modeling approach provides a powerful, quantitative tool for developing community predictive models that explicitly consider species membership, and thus each species' functional role in the community. Such models will contribute significantly to the study and conservation of biological communities.
Estimating Diversity in Unsampled Habitats of a Biogeographical Province
Authors: Rosenzweig Michael L. , Turner Will R. , Cox Jonathan G. , Ricketts Taylor H.
Published: May 2003

Abstract: Estimating the number of species in a biogeographical province can be problematic. A number of methods have been developed to overcome sample‐size limits within a single habitat. We evaluated six of these methods to see whether they could also compensate for incomplete habitat samples. We applied them to the butterfly species of the 110 ecoregions of Canada and the United States. Two of the methods use the frequency of species that occur in a few of the sampled ecoregions. These two methods did not work. The other four methods estimate the asymptote of the species‐accumulation curve ( the graph of “number of species in a set of samples” versus “number of species occurrences in those samples” ). The asymptote of this curve is the actual number of species in the system. Three of these extrapolation estimators produced good estimates of total diversity even when limited to 10% of the ecoregions. Good estimates depend on sampling ecoregions that are hyperdispersed in space. Clustered sampling designs ruin the usefulness of the three successful methods. To ascertain their generality, our results must be duplicated at other scales and for other taxa and in other provinces.
Sex‐Specific Consequences of Recent Inbreeding in an Ancestrally Inbred Population of New Zealand Takahe
Authors: Jamieson Ian G. , Roy Michael S. , Lettink Marieke
Published: May 2003

Abstract: Although the negative effects of close inbreeding in captive populations are well known, inbreeding in small, free‐ranging populations is less well understood. During the mid‐1980s, small numbers of the flightless Takahe (  Porphyrio hochstetteri  ) were successfully translocated from the last remaining population in mountainous Fiordland to four island refuges. Previous research has shown that introduced island Takahe and their descendents lay significantly more infertile eggs and raise fewer juveniles per egg than Takahe in their native habitat in Fiordland. Here we first show that the remnant population of Takahe in Fiordland was likely to have been severely inbred. From this we hypothesize that further, recent inbreeding ( based on four generations of pedigree data ) by Takahe on islands should have negligible fitness consequences. This hypothesis is only partially supported. Mean hatching and fledging success has remained consistently low ( <40% and 77%, respectively ) and was not correlated with the rapid increase in the average inbreeding coefficient of island Takahe since 1991. Neither the inbreeding coefficient of a pair's offspring nor the inbreeding status of the breeding male had a significant effect on hatching or fledging success. Similarly, the inbreeding status of the breeding female had no significant effect on hatching success. However, the inbreeding status of the female did negatively affect fledging success. Why poor reproductive success was further exacerbated by inbreeding in females but not in males or pairs is unknown, although a similar pattern has been reported in an island population of Song Sparrows (   Melospiza melodia  ). We speculate that the generally lower reproductive success that most island Takahe exhibit is a result of environment‐dependent inbreeding depression. We conclude from our pedigree analysis that island Takahe are undergoing further inbreeding depression, but the reduction in fitness appears to be expressed in inbred females only.
Benzoin Gardens in North Sumatra, Indonesia: Effects of Management on Tree Diversity
Authors: García‐Fernández Carmen , Casado Miguel A. , Pérez Manuel Ruiz
Published: May 2003

Abstract:In recent years, research on tropical forest conservation has increasingly focused on traditional management systems as a means of achieving a balance between conservation and development.Styrax paralleloneurum, a forest‐canopy tree species that produces benzoin, an aromatic resin, is cultivated in such a system. This study is an attempt to determine the impact of benzoin garden management on forest structure, species composition, and diversity. Forty‐five gardens were chosen for study in two Northern Sumatra villages, where data on management practices and ecological structure were gathered. Ecological information was also collected from abandoned benzoin gardens and primary forest areas for purposes of comparison. Although benzoin management requires that competing vegetation be thinned, these activities are not intensive, allowing species that coppice to remain in the garden and thereby reducing the effects of competitive exclusion mechanisms on species composition. Tree species diversity in abandoned gardens was similar to that in primary forest, but endemic species and species characteristic of mature habitats were less common. Traditional benzoin garden management represents only a low‐intensity disturbance and maintains an ecological structure that allows effective accumulation of forest species over the long term.
Wild Populations of a Reef Fish Suffer from the “Nondestructive” Aquarium Trade Fishery
Authors: Kolm Niclas , Berglund Anders
Published: May 2003

Abstract: The commercial fishery for coral reef fish for the aquarium trade has begun to change, at least in some parts of the world, from destructive methods such as cyanide and dynamite fishing to less‐destructive methods such as hand‐net fishing. However, data on the effects on wild populations of such relatively nondestructive methods is nonexistent. The Banggai cardinalfish (   Pterapogon kauderni ) is a paternal mouthbrooder living in groups of 2–200 individuals in the proximity of sea urchins (   Diadema setosum ). This fish has limited dispersal abilities because it lacks a pelagic larval phase, and it is believed to be endemic to the Banggai archipelago off the east coast of Sulawesi, Indonesia. Since its rediscovery in 1995, the Banggai cardinalfish has become a popular aquarium fish, and thousands have been exported—mainly to North America, Japan, and Europe. To study the effects of the aquarium trade fishery on wild populations of the Banggai cardinalfish, we performed a field study in which we quantified density, age distribution ( quantified as the ratio of numbers of juveniles to adults ) and habitat quality ( i.e., sea urchin density ) at eight sites in the Banggai archipelago. Through interviews with local fishers, we estimated the fishing pressure at each site and related this to data on fish density. We found a marginally significant negative effect of fishing pressure on density of fish and significant negative effects on group size in both sea urchins and fish. We did not find any effect of fishing on fish size structure. To our knowledge this is the first study to compare sites under different amounts of fishing pressure that has demonstrated the negative effects of the aquarium trade on wild populations of reef fish, despite the widespread use of relatively nondestructive fishing methods.
Using Population Projection Matrices to Evaluate Recovery Strategies for Snake River Spring and Summer Chinook Salmon
Authors: Wilson Paul H.
Published: May 2003

Abstract: I explored the efficacy of alternative actions to recover threatened Snake River chinook salmon ( Onchorhyncus tshawytscha ). I compared the potential to increase population growth rates from two different actions: ( 1 ) habitat restoration efforts, aimed at increasing egg‐to‐smolt survival rate, and ( 2 ) dam breaching, intended to improve smolt‐to‐spawner survival. Eight dams obstruct the migration corridor these populations traverse as juveniles ( downstream ) and as adults ( upstream ), and a large portion of the juvenile migrants are collected and transported past most of the dams on barges or trucks. I applied sensitivity, elasticity, and direct perturbation analyses to an age‐structured projection matrix to predict potential effects from simultaneous, nonproportional changes in multiple survival rates. Throughout the analyses, I explicitly incorporated alternative assumptions about the effectiveness of transportation, which is known to be influential. Results of the numerical experiments suggest that dam breaching has more potential to increase population growth rates than habitat restoration, except for the most optimistic assumption about the efficacy of transportation. I then fit the matrix to historical data to identify life stages in which actual decreases in survival rates have caused the observed declines in abundance. There was no reduction in egg‐to‐smolt survival, indicating that neither habitat deterioration nor hatchery impacts ( in that life stage ) caused the stocks to decline. The large decrease in smolt‐to‐adult survival rate from the historical period, when there were fewer dams, is consistent with the hypothesis that increased stress from transportation and passage through additional dams on the Snake River has elevated delayed mortality levels.
Primate Hotspots on Borneo: Predictive Value for General Biodiversity and the Effects of Taxonomy
Authors: Meijaard E. , Nijman V.
Published: May 2003

Abstract:The identification of hotspots, or geographic areas that are particularly rich in biodiversity, is increasingly used to set conservation priorities. We investigated the spatial patterns of primate species richness and endemism in Borneo to assess whether primates are good indicators of biodiversity hotspots for other taxa. Based on locality records for the 13 primate species present on the island ( n= 1414, range 26–273 records/species ), we prepared primate distribution maps. By overlaying these distribution maps in a geographic information system, we created maps that revealed the most species‐rich area to be a tropical wet evergreen forest in central‐eastern East Kalimantan, Indonesia, in which 11 species coexisted. No other studies had so far identified this region as a biodiversity hotspot. Generally, the Malaysian states of Sabah and Sarawak are considered richest in general species diversity. We suggest that the main reason for this is the low number of biodiversity studies that have been conducted in Indonesian Borneo compared with Malaysian Borneo and a focus in biodiversity studies on mountain habitats rather than lowlands. We used two alternative taxonomic classifications of Bornean primates, one based on a biological and the other on a phylogenetic species concept, to determine whether the outcome of hotspot identification depended on taxonomic classification. The location of endemic primate species hotspots depended on the choice of species concept, whereas identification of the hotspots of primate species richness was not affected by choice of species concept. Our results suggest that a hotspot identification based on a relatively small group of taxa can vary with the group of species under investigation and their taxonomic classifications. Because of the lack of congruence between fine‐scale hotspots of Bornean primate diversity and other hotspots reported in the literature, Bornean primates appear unsuitable for identifying areas of general species richness. Bornean primates may, however, be useful indicators of lowland diversity on the island.
Loss of Genetic Variation in Greater Prairie Chickens Following a Population Bottleneck in Wisconsin, U.S.A.
Authors: Bellinger M. Renee , Johnson Jeff A. , Toepfer John , Dunn Peter
Published: May 2003

Abstract: Over the last century, populations of the Greater Prairie Chicken (   Tympanuchus cupido ) have declined or gone extinct throughout midwestern North America. In Wisconsin the population declined by 50% from 1951 to 1961 and has remained at low ( 1500 individuals ) but fluctuating levels for the past 40 years. We examined historic ( 1951 ) and contemporary ( 1996–1999 ) populations of prairie chickens in Wisconsin to determine whether there was a loss of genetic variation following the population bottleneck. We compared microsatellite DNA variation at six loci in historic ( 1951, n = 47 ) and contemporary ( 1996–1999, n = 87 ) populations. Population mean heterozygosity and number of alleles per locus were significantly lower in the late 1990s than in 1951. This loss of genetic variation following a population bottleneck is consistent with the results of a similar study in Illinois, but we found no evidence of a reduction in hatching success.
Ecological, Behavioral, and Life‐History Correlates of Mammal Extinctions in West Africa
Authors: Brashares Justin S.
Published: May 2003

Abstract:Identifying the biological traits of species that predispose them to extinction is a focus of research in evolutionary ecology and conservation biology. This research has traditionally been divided between studies of extinction or decline in undisturbed habitat islands and studies of the persistence of species affected adversely by human influence. I combined these approaches to test for correlations between nine ecological, behavioral, and life‐history traits and vulnerability to local extinction for 41 species of carnivores, primates, and ungulates in fragmented and exploited habitats in Ghana, West Africa, while accounting statistically for phylogeny. Species distributed in isolated populations were most prone to local extinction, and monogamous species and those wherein males defended small harems were also prone to extinction. Body size, fecundity, abundance, habitat specialization, trophic group, and the degree to which hunters and consumers preferred a species generally were unrelated to species persistence. Although population isolation and mating system were the only traits that explained a significant amount of the observed variation in persistence of all species, analyses of carnivores, primates, and ungulates as groups yielded varied results. Mammals most prone to local extinction in my study reserves were also those listed by the World Conservation Union as being at greatest risk of global extinction. Thus, my results suggest that the relative isolation of populations and the mating system displayed by mammals may be good general predictors of their persistence.
Protected Areas and Climate Change: a Case Study of the Cacti in the Tehuacán‐Cuicatlán Biosphere Reserve, México
Authors: Téllez‐Valdés Oswaldo , D¡Vila‐Aranda Patricia
Published: May 2003

Abstract: We examined the effects of climate change on the future distribution patterns of 20 species of Cactaceae in a protected area of México. Our study area was the biosphere reserve of Tehuacán‐Cuicatlán in central México. Cactaceae species in the reserve were selected because they are often the dominant elements of the communities and play an important social role as a source of food, construction, and fuel. We used a floristic database and a bioclimatic modeling approach to examine 19 climatic parameters and to obtain the current potential distribution pattern of each species. Three different future climate scenarios were selected, on the basis of the predictions of several authors about future climate change. We considered the following three future scenarios: ( 1 ) +1° C and –10% rainfall; ( 2 ) +2° C and –10% rainfall; ( 3 ) +2° C and –15% rainfall. Each scenario implies different potential distribution patterns for the species involved; these patterns were analyzed in relationship to the reserve boundaries. In particular, the third scenario indicated three distinct possibilities: ( 1 ) a drastic distribution contraction in which most of the remaining populations will inhabit restricted areas out of reserve boundaries or will became extinct; ( 2 ) restriction of remaining populations mainly within reserve boundaries; and ( 3 ) contraction of species distribution pattern but populations remaining within and outside the reserve boundaries. Our results highlight the importance of considering the effects of possible future climate changes on the selection of conservation areas. Accordingly, we believe that our bioclimatic modeling approach represents a useful tool with which to make decisions about the definition of protected areas, once the current potential distribution pattern of some selected species is known.
Ecological Heterogeneity in the Effects of Grazing and Fire on Grassland Diversity
Authors: Harrison S. , Inouye B. D. , Safford H. D.
Published: May 2003

Abstract: Grazing and fire and are major forces shaping patterns of native and exotic species diversity in many grasslands, yet both of these disturbances have notoriously variable effects. Few studies have examined how landscape‐level heterogeneity in grassland characteristics, such as soil‐based variation in biomass and species composition, may contribute to variation in the effects of fire or grazing. We studied the effects of livestock grazing and fire in a mosaic of serpentine and nonserpentine soils in California, where most grasslands are dominated by exotic annuals and serpentine soil is the major refuge for native grassland species. We predicted that the effects of disturbance would be proportional to productivity and therefore would be greater on nonserpentine than serpentine soils. We measured species composition at 80–100 grazed or ungrazed sites for 2 years before ( 1998–1999 ) and 2 years after ( 2000–2001 ) an autumn wildfire. Both disturbances increased total species richness on both soils. However, fire enhanced total and exotic species richness more on nonserpentine soils and enhanced native species richness more on serpentine soils. Grazing increased native species richness on serpentine soils but not on nonserpentine soils. These soil‐disturbance interactions suggest that the use of fire and grazing to manage native species diversity in wildlands must be done with careful attention to background ecological heterogeneity.