bluuebunny/crossref_metadata_2025_split huggingface dataset:
Internal conductance does not scale with photosynthetic capacity: implications for carbon isotope discrimination and the economics of water and nitrogen use in photosynthesis
Authors: WARREN CHARLES R. , ADAMS MARK A. 
Published: September 2005

ABSTRACTCentral paradigms of ecophysiology are that there are recognizable and even explicit and predictable patterns among species, genera, and life forms in the economics of water and nitrogen use in photosynthesis and in carbon isotope discrimination (Δ). However most previous examinations have implicitly assumed an infinite internal conductance (gi) and/or that internal conductance scales with the biochemical capacity for photosynthesis. Examination of published data for 54 species and a detailed examination for three well‐characterized species –Eucalyptus globulus, Pseudotsuga menziesii and Phaseolus vulgaris– show these assumptions to be incorrect. The reduction in concentration of CO2 between the substomatal cavity (Ci) and the site of carbon fixation (Cc) varies greatly among species. Photosynthesis does not scale perfectly with gi and there is a general trend for plants with low gi to have a larger draw‐down from Ci to Cc, further confounding efforts to scale photosynthesis and other attributes with gi. Variation in the gi–photosynthesis relationship contributes to variation in photosynthetic ‘use’ efficiency of N (PNUE) and water (WUE). Δ is an information‐rich signal, but for many species only about two‐thirds of this information relates to A/gs with the remaining one‐third related to A/gi. Using data for three well‐studied species we demonstrate that at common WUE, Δ may vary by up to 3‰. This is as large or larger than is commonly reported in many interspecific comparisons of Δ, and adds to previous warnings about simplistic interpretations of WUE based on Δ. A priority for future research should be elucidation of relationships between gi and gs and how these vary in response to environmental conditions (e.g. soil water, leaf‐to‐air vapour pressure deficit, temperature) and among species.
Ecological physiology of Pereskia guamacho, a cactus with leaves
Authors: EDWARDS ERIKA J. , DIAZ MIRIAM 
Published: September 2005

ABSTRACTThe specialized physiology of leafless, stem‐succulent cacti is relatively well understood. This is not true, however, for Pereskia (Cactaceae), the 17 species of leafy trees and shrubs that represent the earliest diverging lineages of the cacti. Here we report on the water relations and photosynthesis of Pereskia guamacho, a small tree of the semiarid scrubland of Venezuela's Caribbean coast. Sapwood‐specific xylem conductivity (Ksp) is low when compared to other vessel‐bearing trees of tropical dry systems, but leaf‐specific xylem conductivity is relatively high due to the high Huber value afforded by P. guamacho's short shoot architecture. P. guamacho xylem is not particularly vulnerable to drought‐induced cavitation, especially considering the high leaf water potentials maintained year round. This is confirmed by the lack of significant variation exhibited in Ksp between wet and dry seasons. In the rainy season, P. guamacho exhibited C3‐like patterns of stomatal conductance, but during a prolonged drought we documented nocturnal stomatal opening with a concomitant accumulation of titratable acid in leaves. This suggests that P. guamacho can perform drought‐induced crassulacean acid metabolism (CAM photosynthesis), although δ13C values imply that most carbon is assimilated via the C3 pathway. P. guamacho leaves display very low stomatal densities, and maximum stomatal conductance is low whether stomata open during the day or night. We conclude that leaf performance is not limited by stem hydraulic capacity in this species, and that water use is conservative and tightly regulated at the leaf level.
Adaptive speciation when assortative mating is based on female preference for male marker traits
Authors: DOEBELI M. 
Published: September 2005

AbstractAdaptive speciation occurs when frequency‐dependent ecological interactions generate conditions of disruptive selection to which lineage splitting is an adaptive response. Under such selective conditions, evolution of assortative mating mechanisms enables the break‐up of the ancestral lineage into diverging and reproductively isolated descendent species. Extending previous studies, I investigate models of adaptive speciation due to the evolution of indirect assortative mating that is based on three different mating traits: the degree of assortativity, a female preference trait and a male marker trait. For speciation to occur, linkage disequilibria between different mating traits, e.g. between female preference and male marker traits, as well as between mating traits and the ecological trait, must evolve. This can lead to novel speciation scenarios, e.g. when reproductive isolation is generated by a splitting in the degree of assortativeness, with one of the emerging lineages mating assortatively, and the other one disassortatively. I investigate the effects of variation in various model parameters on the likelihood of speciation, as well as robustness of speciation to introducing costs of assortative mating. Even though in the models presented speciation requires the genetic potential for strong assortment as well as rather restrictive ecological conditions, the results show that adaptive speciation due to the evolution of assortative mating when mate choice is based on separate female preference and male marker traits is a theoretically plausible evolutionary scenario.
Are hybridogenetic complexes structured by habitat in water frogs?
Authors: PLENET S. , JOLY P. , HERVANT F. , FROMONT E. , GROLET O. 
Published: September 2005

AbstractThe success and the evolutionary fate of hybridogenetic lineages are explained by both a generalistic heterosis hypothesis and an alternative hypothesis, the habitat segregation hypothesis. Because such hypotheses have rarely been tested at the level of whole habitats, our aim was to compare performances of two taxa within a hybridogenetic complex across diverse natural habitats. We took advantage of the waterfrog hybridogenetic complex (Rana esculenta and R. lessonae) by rearing tadpoles in natural contrasted habitats by means of enclosure experiments. We also monitored the frequency of each taxon in the waterfrog assemblages that naturally breed in the studied ponds. The hybridogenenetic taxon showed no evidence of broader tolerance as growth, development and physiology strongly varied in response to environmental heterogeneity. Our study reveals a differential success of the hybridogenetic taxon and its sexual host among environments. Moreover, hybridogenetic taxa rarely dominated the sexual species in natural assemblages. Consequently, our results show that the generalistic model does not explain the success of hybridogenetic lineages, but rather support the habitat segregation, among other alternative concepts.
Disjunct distributions during glacial and interglacial periods in mountain butterflies: Erebia epiphron as an example
Authors: Schmitt T. , Hewitt G. M. , Müller P. 
Published: September 2005

Abstract
Over several decades, the distribution patterns and evolution of alpine disjunct species has become an increasingly discussed subject. Large scale genetic analysis has allowed the resolution of the past range changes and intraspecific evolution of many species, in Europe especially of Mediterranean origin. However, the phylogeographic structures of species with arctic–alpine disjunct distribution patterns are relatively poorly studied. The existing phylogeographic analysis (mostly of alpine plant species) supports disjunct distributions during glacial as well as post-glacial periods for a number of species. However, several questions still remain unresolved and we therefore analysed the Mountain Ringlet Erebia epiphron as a model for such alpine disjunct species. We found strong differentiation into five different lineages supporting five differentiation centres: (i) the eastern Pyrenees, (ii) the mountain ranges between the central Pyrenees and south-western Alps, (iii, iv) two areas along the southern Alps margin and (v) the northern Alps margin. We propose that these patterns evolved due to the humidity requirements of this species, which did not allow survival in the dry glacial steppes, but along the margins of the wetter glaciated high mountain ranges.
Timing and tempo of primate speciation
Authors: Curnoe D. , Thorne A. , Coate J. A. 
Published: September 2005

Abstract
Published molecular clocks for primates are used to estimate typical divergence times for phylogroups (1.6 Ma), species (3.3 Ma), sister species (2.7 Ma), genera (8.9 Ma) and sister genera (8.6 Ma). Significant median differences exist between major groups (infraorders and superfamilies) for various divergence times. These data are employed to estimate typical maximum duration of speciation. Typical primate values (1.1 Ma) suggest this process to be faster than is characteristic of many vertebrates. However, after considering divergence times for hybridizing congeneric and confamilial primates, this value is likely only to estimate the commencement of prezygotic isolating mechanisms, rather than the completion of reproductive isolation. Thus, speciation typically takes around 1.0 Ma to more than 4.0 Ma to occur, depending on whether prezygotic or post-zygotic isolating mechanisms are emphasized. Typical primate genus age is around 5.3 Ma, but we note differences among major groups. In light of these estimates, the classification of humans and chimpanzees is reconsidered using a molecular yardstick approach. Three taxonomic frameworks may flow from molecular analyses, all of them having major implications for understanding the evolution of humans and chimpanzees.
Size asymmetry in intraspecific competition and the density-dependence of inbreeding depression in a natural plant population: a case study in cassava (Manihot esculenta Crantz, Euphorbiaceae)
Authors: Pujol B. , Mckey D. 
Published: September 2005

Abstract
The effects of competition on the genetic composition of natural populations are not well understood. We combined demography and molecular genetics to study how intraspecific competition affects microevolution in cohorts of volunteer plants of cassava (Manihot esculenta) originating from seeds in slash-and-burn fields of Palikur Amerindians in French Guiana. In this clonally propagated crop, genotypic diversity is enhanced by the incorporation of volunteer plants into farmers’ stocks of clonal propagules. Mortality of volunteer plants was density-dependent. Furthermore, the size asymmetry of intraspecific competition increased with local clustering of plants. Size of plants was correlated with their multilocus heterozygosity, and stronger size-dependence of survival in clusters of plants, compared with solitary plants, increased the magnitude of inbreeding depression when competition was severe. The density-dependence of inbreeding depression of volunteer plants helps explain the high heterozygosity of volunteers that survive to harvest time and thus become candidates for clonal propagation. This effect could help favour the maintenance of sex in this ‘vegetatively’ propagated crop plant.
A quantitative trait locus for recognition of foreign eggs in the host of a brood parasite
Authors: Martín-Gálvez D. , Soler J. J. , Martínez J. G. , Krupa A. P. , Richard M. , Soler M. , Møller A. P. , Burke T. 
Published: September 2005

Abstract
Avian brood parasites reduce the reproductive output of their hosts and thereby select for defence mechanisms such as ejection of parasitic eggs. Such defence mechanisms simultaneously select for counter-defences in brood parasites, causing a coevolutionary arms race. Although coevolutionary models assume that defences and counter-defences are genetically influenced, this has never been demonstrated for brood parasites. Here, we give strong evidence for genetic differences between ejector and nonejectors, which could allow the study of such host defence at the genetic level, as well as studies of maintenance of genetic variation in defences. Briefly, we found that magpies, that are the main host of the great spotted cuckoo in Europe, have alleles of one microsatellite locus (Ase64) that segregate between accepters and rejecters of experimental parasitic eggs. Furthermore, differences in ejection rate among host populations exploited by the brood parasite covaried significantly with the genetic distance for this locus.
Genotype × environment interaction for male attractiveness in an acoustic moth: evidence for plasticity and canalization
Authors: Danielson-François A. M. , Kelly J. K. , Greenfield M. D. 
Published: September 2005

Abstract
The lek paradox arises when choosy females deplete the genetic variance for male display traits from a population, yet substantial additive genetic variation (VA) in male traits persists. Thus, the lek paradox can be more generally stated as one of the most fundamental evolutionary questions: What maintains genetic variation in natural populations? One solution to this problem may be found in the condition-dependent nature of many sexually selected traits. Genotype × environment (G × E) interactions can maintain VA under conditions of environmental heterogeneity provided certain restrictions are met, although antagonistic pleiotropy has also been proposed as a mechanism. Here, we provide evidence for G × E interactions and against the role of antagonistic pleiotropy in the maintenance of VA for sexually selected traits. Using inbred lines of the lesser waxmoth Achroia grisella, we measured VA for song attractiveness, condition and development rate under different competitive environments and found that genotypes differed in their plasticity. We argue that variation persists in natural populations because G × E interactions prevent any one variant from producing the optimal phenotype across all environments.
Neural correlates of the proximity and quantity of anticipated food rewards in the ventral striatum of domestic chicks
Authors: Izawa Ei‐Ichi , Aoki Naoya , Matsushima Toshiya 
Published: September 2005

AbstractTo identify the neuro‐cognitive substrates of valuation and choice, we analysed the neural correlates of anticipated food rewards in the ventral striatum of freely behaving chicks. One‐week‐old chicks were trained in a color‐discrimination task using four color cues (red, yellow, green and blue), each of which was associated with a different food reward. Choosing a red bead was immediately rewarded with a large amount of food, choosing a yellow bead resulted in an immediate‐small food reward, and choosing a green bead resulted in a late‐large food reward. We selected chicks that consistently chose a large and immediate food reward (red over yellow, and red over green), with the proximity of the food valued higher than the size of the food reward (yellow over green). Of the 47 neurons recorded from the ventral striatum of these chicks, 20 neurons selectively showed cue‐period responses to cues associated with food rewards. Five of these 20 neurons responded differentially during the cue period according to the expected delay to reward, and were thus assumed to code for the proximity of the reward. Additionally, three other neurons responded to the quantity of the reward. Furthermore, in the post‐operant delay period, many of these 20 neurons showed reward‐related activities that were linked to the proximity or presence of the food reward. We therefore propose that impulsive choice and behavioral perseveration observed after lesions of the ventral striatum could be due to impaired anticipation of rewards in the cue and delay periods, respectively.
Oil pollution and climate have wide‐scale impacts on seabird demographics
Authors: Votier Stephen C. , Hatchwell Ben J. , Beckerman Andrew , McCleery Robin H. , Hunter Fiona M. , Pellatt Jayne , Trinder Mark , Birkhead Tim R. 
Published: September 2005

AbstractOil spills often spell disaster for marine birds caught in slicks. However, the impact of oil pollution on seabird population parameters is poorly known because oil spills usually occur in wintering areas remote from breeding colonies where birds may be distributed over a wide area, and because it is difficult to separate the effects of oil pollution from the effect of natural environmental variation on seabird populations. Using a long‐term data set we show that over‐winter survival of adult common guillemots (Uria aalge) is negatively affected by both the incidence of four major oil‐spills in their wintering grounds and high values of the North Atlantic Oscillation (NAO) index. After controlling for the effect of the NAO index, we show that winter mortality of adult guillemots is doubled by major oil pollution incidents. Our results demonstrate that oil pollution can have wide‐scale impacts on marine ecosystems that can be quantified using populations of marked individuals to estimate survival.
Tracking Post‐school Destinations of Young People with Mild Intellectual Disabilities: The Problem of Attrition
Authors: Caton Sue , Kagan Carolyn 
Published: September 2005

Background  This research was carried out as an assessment of the transition towards adult life for school leavers with mild intellectual disabilities. Ninety young people who were enrolled at three schools for people with mild intellectual disabilities were followed up for the first 12–18 months after they left school to assess how they experienced this transition.Methods  Young people were interviewed using semi‐structured interviews before they left school regarding their aspirations for school leaving. They were then followed up and those who were traced were interviewed a second time regarding how they had experienced the previous year.Results  There were a number of difficulties encountered in following up the school leavers. Most importantly, there were a high number of participants who were unable to be traced for the study, by the schools, the careers office, or other service providers. The attrition started early in the transition process and was largely overlooked by the schools and careers service, presenting a challenge for successful transition experiences.Discussion  The implications of the high level of attrition are discussed. In addition, the impact of a number of new initiatives are discussed.
Barriers to Caregiver Compliance with Eating and Drinking Recommendations for Adults with Intellectual Disabilities and Dysphagia
Authors: Chadwick Darren D. , Jolliffe Jane , Goldbart Juliet , Burton Mark H. 
Published: September 2005

Background  There is scant research on the subject of dysphagia and people with intellectual disabilities. This study explores the barriers which caregivers believe make following Speech and Language Therapists’ (SLTs) dysphagia management strategies more difficult.Method  Semi‐structured open‐ended interviews were conducted with 46 caregivers who supported 40 intellectually disabled adults with dysphagia.Results  Caregivers perceived particular difficulties in modifying food and drinks to safe consistencies, achieving the agreed positioning during mealtimes, and in using support and prompting strategies. Problematic support and prompting strategies included difficulties with pacing correctly; facilitating people to adequately relax and concentrate; observing and prompting people to pace suitably and take safe amounts of food and drink in each mouthful. Additional barriers identified included time pressures, staff turnover and insufficient reviewing of SLT management strategies by caregivers.Conclusions  Findings suggest that additional training and monitoring is required to ensure caregivers are aware of their role and responsibility in promoting safe oral intake for adults with dysphagia and intellectual disabilities. Ongoing support is suggested for people with intellectual disabilities and dysphagia to help them understand the reasoning behind management strategies.
Emerging Trends in the Use of Drugs to Manage the Challenging Behaviour of People with Intellectual Disability
Authors: McGillivray Jane A. , McCabe Marita P. 
Published: September 2005

Background  Concerns about the pharmacological management of the behaviour of individuals with intellectual disability have resulted in the development of legislative and procedural controls.Method  This Australian study provided a comparison of 873 reported cases where drugs were administered to manage behaviour in March 2000, with 762 cases reported in March 1993. Drug use in individuals who remained medicated across time (n = 316: recurrent sample) was also compared with those who were reported only in 1993 (n = 329: limited sample).Results  A small decrease in the proportion of individuals who were reported to have received medication was evident over time (from 5% to 4.5% of total population). However, this was accompanied by an increase in drug diversity and interclass polypharmacy. An increase in antidepressant use was evident (from 7.4% to 13.8% of reported drugs), and there was a trend towards greater reporting of medication for acute behavioural problems and medication use with children. Greater use of antipsychotic drugs was evident in individuals who remained medicated across time compared with those who did not.Conclusions  The findings suggest the need for continuous research into practice. The fact that many individuals receive medication over long periods makes it incumbent on service providers to engage in regular, comprehensive and individualized review and evaluation of medication regimes.
Is Physical Activity Counseling Effective for Older People? A Cluster Randomized, Controlled Trial in Primary Care
Authors: Kerse Ngaire , Elley C. Raina , Robinson Elizabeth , Arroll Bruce 
Published: September 2005

Objectives: To establish the effectiveness of the Green Prescription physical activity counseling program in increasing activity and quality of life in older community‐dwelling people.Design: Post hoc subgroup analysis of a large cluster randomized, controlled trial.Setting: One hundred seventeen doctors in 42 primary care practices (74% participation rate) in the Waikato region of New Zealand.Participants: Two hundred seventy sedentary primary healthcare patients aged 65 and older (67% participation rate).Intervention: Patients in intervention practices prompted their primary care doctors or practice nurse to deliver brief activity counseling. A “Green Prescription” was written involving the negotiation of activity goals. Trained exercise specialists from a regional sports foundation gave follow‐up telephone support over 3 months.Measurements: Leisure moderate and vigorous physical activity, total energy expenditure, systolic and diastolic blood pressure, health‐related quality of life, musculoskeletal injuries, falls, and hospitalizations.Results: After 12 months of follow‐up, leisure time moderate activity increased by 0.67 h/wk more in the intervention group than the control group (95% confidence interval (CI)=0.17–1.17) and energy expenditure increased by 2.67 kcal/kg per week (95% CI=0.87–4.47) more. For intervention group participants, vitality and general health scales of the 36‐item Short Form showed statistically and clinically relevant improvements, and there was a decrease in hospitalizations (P<.03). There were no observable changes in blood pressure, injuries, or falls as a result of the Green Prescription program.Conclusion: This physical activity intervention improved activity, energy expenditure, health‐related quality of life, and hospitalizations for older primary care patients. Systematic inclusion of the Green Prescription in routine primary health care will probably lead to health gain for older people.