Home About us Contact
|
Home About us Contact | ||
|
|
||
Group Composition (group + composition)
Kinds of Group Composition Selected AbstractsBenefits of communal breeding in burying beetles: a field experimentECOLOGICAL ENTOMOLOGY, Issue 3 2000Anne-Katrin Eggert Summary 1. The ultimate causes of communal breeding and joint parental care in various species of Nicrophorus burying beetles have not been resolved satisfactorily. One hypothesis suggests that females remain on the carcass for extended periods of time because joint defence affords them improved probabilities of retaining the carcass successfully in the face of intense competition from intra-generic competitors. 2. In a field experiment designed to test this hypothesis in N. defodiens (Mannerheim), breeding associations of two females and a male were no more successful at retaining their carcass than were monogamous pairs, lending no support to the hypothesis. 3. Intra-generic intruders that usurped already-buried carcasses were typically much larger than the original residents. 4. The body size of original residents affected both the burial depth and the probability of a takeover. Larger beetles buried the carcass deeper and were more likely to retain possession of the carcass. Group composition also did not affect the depth at which carcasses were buried. 5. Severe and even fatal injuries incurred by some residents indicated the occurrence of violent and damaging fights between competitors over carcasses in the field. [source] Coping strategies in farmed African catfish Clarias gariepinus.JOURNAL OF FISH BIOLOGY, Issue 10 2010Does it affect their welfare? The objective of this study was to assess whether and how coping strategies affect the welfare of African catfish Clarias gariepinus housed at low and high densities. Group composition influenced feed intake; re-active groups (comprised of 100% re-active fish) had a lower specific growth rate (G) and feed intake and a higher feed conversion ratio (RFC) than pro-active groups. Furthermore, re-active groups had a lower energy retention than pro-active groups. The latter was fully due to differences in feed intake, since energy partitioning (on % total gross energy intake basis) was similar among the group composition treatments. Fish held at high stocking density showed a higher RFC and feeding speed and a lower energy retention and agonistic behaviour. None of the measured variables was influenced by the interaction effect. In mixed groups, G and number of skin lesions seemed to be affected by different behavioural phenotypes at low stocking density, but not at high density. These results indicate that both stocking density and group composition affect physical and behavioural responses of C. gariepinus. Furthermore, physical and behavioural data of individual fish housed in mixed groups suggest that coping strategy affects the fitness of different behavioural phenotypes at low, but not at high, stocking density. [source] Spatial Association in a Highly Inbred Ungulate Population: Evidence of Fine-Scale Kin RecognitionETHOLOGY, Issue 2 2008Jorge Cassinello We present the first evidence of fine-scale kin recognition, based on a continuous measure of relatedness, in ungulates. The spatial association between herdmates of a captive population of aoudad (Ammotragus lervia), where all the individuals are related, is analysed during resting time. Our goal was to estimate which factors influence individuals' associations. The study population is highly inbred, although it does not show serious deleterious effects caused by consanguinity. It comprises a single captive herd, reproducing freely and in good conditions for more than 10 yr. It emerges that kin, measured as the coefficient of relationship between two given herdmates, is the main factor determining the spatial association (e.g. average distance) of male,male and female,female dyads, as more-related individuals tend to rest closer to each other than less-related ones. As for male,female dyads, individuals of a similar age tend to stay closer. To rule out any familiarity confounding effects, individuals' cohabitation time in the herd was added as a random factor in the analyses. Concerning the type of dyad, mother,calf dyads are characterized by higher proximity than others, particularly during the suckling period, whereas males tend to stay closer to each other than females or male,female dyads, being also more kin-related. Female social rank does not influence spatial association between herdmates. These results are related to group composition of the species in the wild, which are characterized by intense mother,calf bonds and all-male groups that are probably kin-related. It is seen that adult male,female associations are not related to kinship, but to age similarity, which is in accord with the assumption that main family groups in the wild are formed by matrilineal lines, whereas males are the dispersing sex. [source] Sex, Rank and Age Differences in the Japanese Macaque (Macaca fuscata yakui) Participation in Inter-Group EncountersETHOLOGY, Issue 5 2005Bonaventura Majolo In many species interactions among group are often characterized by agonistic behaviour. Although animals may participate in inter-group encounters in different ways, depending on their energetic requirements, reproductive tactics, and/or developmental stage, the proximate causes affecting an animal's participation in inter-group encounters are still poorly understood. Indeed, many studies have analysed the behaviour of males and females during inter-group encounters without considering the importance of additional factors (e.g. rank). This study focuses on wild non-provisioned Japanese macaques (Macaca fuscata yakui) living on Yakushima Island, Japan. It aims to determine how monkeys of different sex, age, and rank behave during inter-group encounters and it discusses the implications and consequences of their behaviour on group composition and male dispersal. Males participated significantly more than females in inter-group encounters, by displaying more aggressive or affiliative behaviour. High-ranking and/or adult males were more aggressive than low-ranking and/or subadult males during encounters occurring in the mating season and they also showed more herding behaviour. This trend was not found in inter-group encounters occurring during the non-mating season. Finally, males which then emigrated to new groups were low-ranking and/or subadult individuals. Those males displayed more affiliative behaviour towards foreign males than males which did emigrate. These data indicate that in non-territorial species with male dominance over female and high competition for mating partners males play an active, and often aggressive, role during inter-group encounter while female participation is scarce. Factors such as age, rank and period of the year (in seasonally breeding species) have to be taken into considerations when analysing interactions between groups and their effects on group composition and social behaviour. [source] The extent of dissent: The effect of group composition and size on Israeli decisions to confront low intensity conflictEUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 4 2002Ranan D. Kuperman This article tests a number of hypotheses about foreign policy decision making within parliamentary democracies. First it explores the origins of debates among decision-makers. Are deliberations provoked by alternative organizational perspectives or by conflicting ideological orientations? Second, it asks how debates are resolved. On the one hand, it has been suggested that, because each minister has an equal vote, a compromise between decision-makers must be reached. On the other hand, it has been argued that the Prime Minister exerts considerable control and power in foreign policy matters in relation to other decision-makers. These questions were studied with the aid of data collected from a sample of 97 decision episodes between 1949 and 1982, where the Israeli government discussed how to respond to low-intensity aggression against Israeli citizens and soldiers. The results of this research demonstrate that internal debates are poorly associated with organizational or political diversity. Instead group size seems to be more important, although the relationship is not linear. In any case, the discussions usually concluded in a consensus around the Prime Minister's policy of choice, thus indicating that he or she is the paramount decision-maker. [source] The biology of lantibiotics from the lacticin 481 group is coming of ageFEMS MICROBIOLOGY REVIEWS, Issue 2 2007Alain Dufour Abstract Lantibiotics are antimicrobial peptides from the bacteriocin family, secreted by Gram-positive bacteria. These peptides differ from other bacteriocins by the presence of (methyl)lanthionine residues, which result from enzymatic modification of precursor peptides encoded by structural genes. Several groups of lantibiotics have been distinguished, the largest of which is the lacticin 481 group. This group consists of at least 16 members, including lacticin 481, streptococcin A-FF22, mutacin II, nukacin ISK-1, and salivaricins. We present the first review devoted to this lantibiotic group, knowledge of which has increased significantly within the last few years. After updating the group composition and defining the common properties of these lantibiotics, we highlight the most recent developments. The latter concern: transcriptional regulation of the lantibiotic genes; understanding the biosynthetic machinery, in particular the ability to perform in vitro prepeptide maturation; characterization of a novel type of immunity protein; and broad application possibilities. This group differs in many aspects from the best known lantibiotic group (nisin group), but shares properties with less-studied groups such as the mersacidin, cytolysin and lactocin S groups. [source] Tradeoffs and thresholds in the effects of nitrogen addition on biodiversity and ecosystem functioning: evidence from inner Mongolia GrasslandsGLOBAL CHANGE BIOLOGY, Issue 1 2010YONGFEI BAI Abstract Nitrogen (N) deposition is widely considered an environmental problem that leads to biodiversity loss and reduced ecosystem resilience; but, N fertilization has also been used as a management tool for enhancing primary production and ground cover, thereby promoting the restoration of degraded lands. However, empirical evaluation of these contrasting impacts is lacking. We tested the dual effects of N enrichment on biodiversity and ecosystem functioning at different organizational levels (i.e., plant species, functional groups, and community) by adding N at 0, 1.75, 5.25, 10.5, 17.5, and 28.0 g N m,2 yr,1 for four years in two contrasting field sites in Inner Mongolia: an undisturbed mature grassland and a nearby degraded grassland of the same type. N addition had both quantitatively and qualitatively different effects on the two communities. In the mature community, N addition led to a large reduction in species richness, accompanied by increased dominance of early successional annuals and loss of perennial grasses and forbs at all N input rates. In the degraded community, however, N addition increased the productivity and dominance of perennial rhizomatous grasses, with only a slight reduction in species richness and no significant change in annual abundance. The mature grassland was much more sensitive to N-induced changes in community structure, likely as a result of higher soil moisture accentuating limitation by N alone. Our findings suggest that the critical threshold for N-induced species loss to mature Eurasian grasslands is below 1.75 g N m,2 yr,1, and that changes in aboveground biomass, species richness, and plant functional group composition to both mature and degraded ecosystems saturate at N addition rates of approximately 10.5 g N m,2 yr,1. This work highlights the tradeoffs that exist in assessing the total impact of N deposition on ecosystem function. [source] Critical success factors for cross-functional teamwork in new product developmentINTERNATIONAL JOURNAL OF MANAGEMENT REVIEWS, Issue 3 2000Sarah Holland There is consensus that the effective implementation of cross-functional teams is critical to new product success. However, such teams face particular challenges because of well-documented barriers between functions. Furthermore, there is little evidence-based guidance for practitioners on how to achieve effective cross-functional teamwork. In order to address this gap, the literature on cross-functional teamwork was analysed to identify critical success factors. Using a heuristic team effectiveness model, these were categorized into six groups: task design, group composition, organizational context, internal processes, external processes and group psychosocial traits. Recent theory on group effectiveness has increasingly recognized the significance of a supportive organizational context, and this is particularly pertinent for cross-functional teams. Key success factors include strategic alignment between functions, a climate supportive of teamwork and team-based accountability. The findings are integrated into a diagnostic model which is intended to be of practical benefit to people designing, leading and facilitating cross-functional new product development teams. [source] Elephant calling patterns as indicators of group size and composition: the basis for an acoustic monitoring systemAFRICAN JOURNAL OF ECOLOGY, Issue 1 2003Katharine B. Payne The paper gives evidence that the vocal activity of elephants varies with group size, composition and reproductive status, and that elephants' calling patterns could therefore provide the basis for a remote monitoring system. We examined a 3-week set of array-based audio recordings of savanna elephants (Loxodonta africana), searching for diagnostic acoustic parameters. An acoustic array made it possible to locate recorded sounds and attribute the calls to particular elephants or elephant groups. Simultaneous video recordings made it possible to document visible behaviour and roughly correlate it with vocalizations. We compared several measures of call density in elephant groups containing up to 59 individuals, and found that rates of calling increased with increasing numbers of elephants. We divided all call events into three structural types (single-voice low-frequency calls, multiple-voice clustered low-frequency calls, and single-voice high frequency calls), and found that the incidence of these varies predictably with group composition. These results suggest the value of a network of listening systems in remote areas for the collection of information on elephant abundance and population structure. Résumé Cet article donne des preuves du fait que l'activité vocale des éléphants varie avec la taille du groupe, sa composition et le statut reproducteur, et que le schéma des appels des éléphants pourrait donc constituer la base d'un système de contrôle continu à distance. Nous avons examiné trois semaines d'enregistrements audio d'éléphants de savane (Loxodonta africana) pour chercher des paramètres de diagnostic acoustique. Un arrangement acoustique permit de localiser les sons enregistrés et d'attribuer les appels à des éléphants identifiés ou à des groupes. Des enregistrements vidéo simultanés ont permis de documenter un comportement visible et de le mettre grossièrement en rapport avec les vocalisations. Nous avons comparé plusieurs mesures d'intensité d'appel dans des groupes qui comptaient jusqu'à 59 individus et nous avons constaté que le taux des appels augmentait avec le nombre d'éléphants. Nous avons classé tous les appels en trois types structuraux (appels à basse fréquence d'une voix unique, appels à basse fréquence de voix multiples, appels à haute fréquence d'une voix unique) et nous avons constaté que l'incidence de ceux-ci varie de façon prévisible selon la composition du groupe. Ces résultats incitent à croire qu'un réseau de systèmes d'écoute dans des endroits éloignés serait très utile pour la récolte d'informations sur l'abondance des éléphants et la structure de leurs populations. Introduction [source] Characterization of Azerbaijani and Croatian brown naphthalaneJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2005Andja Alajbeg Abstract In spite of the fact that noncolored (nonaromatic) naphthalane containing high sterane content has been proved as bioactive and efficient in the treatment of psoriasis vulgaris, brown naphthalanes, which contain aromatics, are still in use. Thousands of patients, who have been passing through the therapy, deserve thorough and permanent study of brown naphthalanes. For that reason, two frequently used brown naphthalane preparations, one of the Azerbaijani (N1) and the other of the Croatian (N2) origin, were studied. The samples underwent the study by means of GC, OT LC, and normal-phase HPLC, as separation techniques. In addition, some bulk properties, elemental composition, and group composition by 1H NMR were determined. GC-MS served in compound types, especially in sterane detection. Both of the samples were found to be unresolved complex mixtures, relatively poor in n -alkanes. Isoalkanes, cycloalkanes, and aromatic compounds, in a great variety of isomers and homologs, made the majority of both of the samples. N1 was a dark, viscous, nontransparent fluid with a strong petroleum smell. Aromatics, which made 53% mass by OT LC and 54% mass by 1H NMR were found to be composed of mono-, di-, and tri+-aromatic compounds. Tri+-aromatic compounds were three to four times more abundant in N1 than in N2. Beside hydrocarbons, N1 comprised some organic compounds with polar functional groups. Also, some asphaltenes were found in it. N1 contained well-presented steranes, which are thought to be bioactive naphthalane ingredients. N2 was a pale brown liquid, with smell similar to gasoline. It contained somewhat lower percentage of aromatics (46% mass) and comparatively lower percentage of tri+ fused aromatics among which carcinogens might be expected. N2 was almost purely composed of hydrocarbons. It seemed to contain low content of steranes due to relatively low upper temperature of the distillation range applied in N2 preparation. [source] Responses of a California annual grassland to litter manipulationJOURNAL OF VEGETATION SCIENCE, Issue 5 2008Kathryn L. Amatangelo Abstract Question: What are the physical and chemical effects of plant litter on annual grassland community composition, above-ground net primary production (ANPP), and density? Location: California annual grassland. Methods: We manipulated litter and light levels independently and in concert. Litter removal and litter addition treatments tested both the physical and chemical impacts of litter's presence. We additionally simulated the effect of litter physical shading by using shade cloth, and added powdered litter to test for the chemical impacts of decomposing litter. Results: Increased whole litter and shading decreased grass germination and establishment, but not that of forbs or legumes. Species shifts occurred within all groups across treatments, including a transition from small-seeded to large-seeded grass and legume species with increased shading. ANPP was highest in control plots (473 ± 59 g/m2), and species richness was highest in litter removal plots. While the physical effects of litter via shading were significant, the chemical effects of adding powdered litter were negligible. Conclusions: This work suggests that over one growing season, the physical impacts of litter are more important than chemical impacts in shaping community structure and ANPP in annual grasslands. Changes in light availability with altered litter inputs drive shifts in species and functional group composition. Litter feedbacks to ANPP and species composition of local patches may help maintain diversity and stabilize ANPP in this grassland. [source] Plant functional group composition and large-scale species richness in European agricultural landscapesJOURNAL OF VEGETATION SCIENCE, Issue 1 2008Jaan Liira Abstract Question: Which are the plant functional groups responding most clearly to agricultural disturbances? Which are the relative roles of habitat availability, landscape configuration and agricultural land use intensity in affecting the functional composition and diversity of vascular plants in agricultural landscapes? Location: 25 agricultural landscape areas in seven European countries. Methods: We examined the plant species richness and abundance in 4 km × 4 km landscape study sites. The plant functional group classification was derived from the BIOLFLOR database. Factorial decomposition of functional groups was applied. Results: Natural habitat availability and low land use intensity supported the abundance and richness of perennials, sedges, pteridophytes and high nature quality indicator species. The abundance of clonal species, C and S strategists was also correlated with habitat area. An increasing density of field edges explained a decrease in richness of high nature quality species and an increase in richness of annual graminoids. Intensive agriculture enhanced the richness of annuals and low nature quality species. Conclusions: Habitat patch availability and habitat quality are the main drivers of functional group composition and plant species richness in European agricultural landscapes. Linear elements do not compensate for the loss of habitats, as they mostly support disturbance tolerant generalist species. In order to conserve vascular plant species diversity in agricultural landscapes, the protection and enlargement of existing patches of (semi-) natural habitats appears to be more effective than relying on the rescue effect of linear elements. This should be done in combination with appropriate agricultural management techniques to limit the effect of agrochemicals to the fields. [source] A comparison of techniques for assessing dispersal behaviour in gundis: revealing dispersal patterns in the absence of observed dispersal behaviourMOLECULAR ECOLOGY, Issue 15 2008KAREN J NUTT Abstract Knowledge of the dispersal status of group members is important to understanding how sociality may have evolved within a species. I assessed the effectiveness of four techniques for elucidating dispersal behaviour in a rock-dwelling rodent (Ctenodactylus gundi) with small group sizes (2,10 animals): genetic parentage assignment, haplotype data and kinship analyses, assignment testing, and F -statistics. The first two methods provided the greatest insight into gundi dispersal behaviour. Assignment testing and F -statistics proved of limited use for elucidating fine-scale dispersal, but could detect large-scale patterns despite low sex-biased dispersal intensity (1.9 : 1) because of moderate genetic differentiation among groups (FST = 0.10). Findings are discussed in light of current dispersal theory. In general, gundi dispersal is plastic, and seems to be dependent on body weight (for males), group composition, and scale of analysis (total dispersal events recorded within the population were almost twice the immigration rate into the population). Most groups were comprised of a single matriline and one immigrant male. Immigrant rather than philopatric males bred with group females. Dispersal among groups was male-biased, but dispersal or philopatry could occur by either sex. During a drought, both sexes delayed dispersal and cooperative social units formed. Whether such behaviour resulted directly from the drought or not remains unclear, however, since comparative information was not available from nondrought years. Combining fine-scale analyses with information on large-scale patterns provided substantial insight into gundi dispersal behaviour despite the limited movement of animals during a drought, and may prove useful for elucidating dispersal behaviour in other social animals. [source] Fine-scale population genetic structure in a fission,fusion societyMOLECULAR ECOLOGY, Issue 11 2008ELIZABETH A. ARCHIE Abstract Nonrandom patterns of mating and dispersal create fine-scale genetic structure in natural populations , especially of social mammals , with important evolutionary and conservation genetic consequences. Such structure is well-characterized for typical mammalian societies; that is, societies where social group composition is stable, dispersal is male-biased, and males form permanent breeding associations in just one or a few social groups over the course of their lives. However, genetic structure is not well understood for social mammals that differ from this pattern, including elephants. In elephant societies, social groups fission and fuse, and males never form permanent breeding associations with female groups. Here, we combine 33 years of behavioural observations with genetic information for 545 African elephants (Loxodonta africana), to investigate how mating and dispersal behaviours structure genetic variation between social groups and across age classes. We found that, like most social mammals, female matrilocality in elephants creates co-ancestry within core social groups and significant genetic differentiation between groups (,ST = 0.058). However, unlike typical social mammals, male elephants do not bias reproduction towards a limited subset of social groups, and instead breed randomly across the population. As a result, reproductively dominant males mediate gene flow between core groups, which creates cohorts of similar-aged paternal relatives across the population. Because poaching tends to eliminate the oldest elephants from populations, illegal hunting and poaching are likely to erode fine-scale genetic structure. We discuss our results and their evolutionary and conservation genetic implications in the context of other social mammals. [source] Molecular ecology of social behaviour: analyses of breeding systems and genetic structureMOLECULAR ECOLOGY, Issue 2 2001Kenneth G. Ross Abstract Molecular genetic studies of group kin composition and local genetic structure in social organisms are becoming increasingly common. A conceptual and mathematical framework that links attributes of the breeding system to group composition and genetic structure is presented here, and recent empirical studies are reviewed in the context of this framework. Breeding system properties, including the number of breeders in a social group, their genetic relatedness, and skew in their parentage, determine group composition and the distribution of genetic variation within and between social units. This group genetic structure in turn influences the opportunities for conflict and cooperation to evolve within groups and for selection to occur among groups or clusters of groups. Thus, molecular studies of social groups provide the starting point for analyses of the selective forces involved in social evolution, as well as for analyses of other fundamental evolutionary problems related to sex allocation, reproductive skew, life history evolution, and the nature of selection in hierarchically structured populations. The framework presented here provides a standard system for interpreting and integrating genetic and natural history data from social organisms for application to a broad range of evolutionary questions. [source] Temporal and spatial variability in soil food web structureOIKOS, Issue 11 2007Matty P. Berg Heterogeneity is a prominent feature of most ecosystems. As a result of environmental heterogeneity the distribution of many soil organisms shows a temporal as well as horizontal and vertical spatial patterning. In spite of this, food webs are usually portrayed as static networks with highly aggregated trophic groups over broader scales of time and space. The variability in food web structure and its consequences have seldom been examined. Using data from a Scots pine forest soil in the Netherlands, we explored (1) the temporal and spatial variability of a detrital food web and its components, (2) the effect of taxonomic resolution on the perception of variability over time and across space, and (3) the importance of organic matter quality as an explanatory factor for variability in food web composition. Compositional variability, expressed using the Bray-Curtis similarity index, was measured over 2.5 years using a stratified litterbag design with three organic horizons per litterbag set. Variability in community composition and organic matter degradation increased over time in the litter horizon only. Seasonal variation in community composition was larger than variation between samples from the same season in different years. Horizontal spatial variability in community composition and organic matter degradation was relatively low, with no increase in variability with increasing distance between samples. Vertically, communities and organic matter degradation was more different between the non-adjacent litter and humus horizons than between adjacent layers. These findings imply that soil food webs, at least in temperate forest plantations, are more variable than is currently appreciated in experiments and model studies, and that organic matter turnover might be an important factor explaining variability in community composition. Species composition was more variable than functional group composition, which implies that aggregated food webs will seem less sensitive to local temporal and spatial changes than they in fact are. [source] An experimental test of the effect of plant functional group diversity on arthropod diversityOIKOS, Issue 2 2000Amy J. Symstad Characteristics used to categorize plant species into functional groups for their effects on ecosystem functioning may also be relevant to higher trophic levels. In addition, plant and consumer diversity should be positively related because more diverse plant communities offer a greater variety of resources for the consumers. Thus, the functional group composition and richness of a plant community may affect the composition and diversity of the herbivores and even higher trophic levels associated with that community. We tested this hypothesis by sampling arthropods with a vacuum sampler (34,531 individuals of 494 species) from an experiment in which we manipulated plant functional group richness and composition. Plant manipulations included all combinations of three functional groups (forbs, C3 graminoids, and C4 graminoids) removed zero, one, or two at a time from grassland plots at Cedar Creek Natural History Area, MN. Although total arthropod species richness was unrelated to plant functional group richness or composition, the species richness of some arthropod orders was affected by plant functional group composition. Two plant characteristics explained most of the effects of plant functional groups on arthropod species richness. Nutritional quality, a characteristic related to ecosystem functioning, and taxonomic diversity, a characteristic not used to designate plant functional groups, seemed to affect arthropod species richness both directly and indirectly. Thus, plant functional groups designated for their effects on ecosystem processes will only be partially relevant to consumer diversity and abundance. [source] Short-term effects of coping skills training in school-age children with type 1 diabetesPEDIATRIC DIABETES, Issue 3pt2 2008Jodie M Ambrosino Objective:, Little is known about the use of psychosocial interventions in children younger than adolescence with type 1 diabetes (T1D) and their parents. We report preliminary short-term outcomes of a randomized controlled trial of coping skills training (CST) compared with group education (GE) in school-aged children with T1D and their parents. Methods:, One hundred and eleven children (range = 8,12 yr) with T1D for at least 6 months (3.71 ± 2.91 yr) were randomized to CST (55.6% female (F); 81.5% white (W)) or GE (69.7% F; 90.9% W). Children and parents (n = 87) who completed the intervention, baseline, 1- and 3-month data are included. Children completed measures of self-efficacy, coping, and quality of life; parents completed measures of family functioning (adaptability and cohesion), diabetes-related conflict, parent depression, and parent coping. Metabolic control was assessed with glycosylated hemoglobin A1c. Mixed-model repeated measures anova was used to analyze the data. Results:, CST and GE group composition was generally comparable. Children had good psychosocial adaptation and metabolic status. CST parents reported significantly more improvement in family adaptability compared with GE parents, and a trend was seen indicating that CST children showed greater improvement in life satisfaction than GE children. Effect sizes for this short-term follow-up period were small, but group participants were receptive to the intervention and reported positive gains. Conclusions:, In these preliminary results, CST and GE were more similar than different across multiple measure of psychosocial adaptation, although CST showed promising statistical trends for more adaptive family functioning and greater life satisfaction. Longer term follow-up is underway. [source] Absence of Iatrogenic or Contagion Effects in Adolescent Group Therapy: Findings from the Cannabis Youth Treatment (CYT) StudyTHE AMERICAN JOURNAL ON ADDICTIONS, Issue 2006Joseph A. Burleson PhD Though widely used and presumed effective in practice, some scholars (Dishion et al., 1999) have raised the concern that group therapy for adolescents with substance use disorder and a range of deviancy has the potential for causing iatrogenic effects (e.g., increased substance use, behavior and legal problems) for those with low deviancy. Using data from 400 youth in the largest adolescent treatment experiment conducted to date (Dennis et al., 2004), this study shows that group composition in terms of conduct disorder symptoms is not associated with worse substance use, psychological, environmental or legal treatment outcomes. The results actually indicated that there was a slight advantage for youth with high conduct disorder to be included in the groups with less symptoms. The results appear consistent with recent meta-analyses of delinquency studies (Lipsey, 2006) which have found no evidence of iatrogenic effects. These results support the common clinical belief that group therapy for youths with substance use disorders is a safe and effective treatment modality. [source] Geographic distribution and demography of Pithecia aequatorialis (pitheciidae) in Peruvian AmazoniaAMERICAN JOURNAL OF PRIMATOLOGY, Issue 12 2009Rolando Aquino Abstract To study the geographic distribution and demographic characteristics of Pithecia aequatorialis in Peruvian Amazonia, we undertook surveys and transect census in three river basins (Río Itaya, Río Tigre and Río Curaray) between 2004 and 2008. A total of 123 groups of P. aequatorialis was encountered during 1623,km of transect walks. Group size was uniform among the three areas (3.4,3.6 individuals), but surprisingly, population densities were higher in the area with strong hunting pressure (Río Itaya: 7.8,ind./km2, vs. 5.6 and 5.9,km2 in the Río Tigre and Río Curaray basins, respectively). The most common group composition included an adult pair with one offspring. Groups with more than one adult male and/or female accounted for 35% of sightings. Our observations extend P. aequatorialis range in Peru further south to the area between the Río Tigre and Río Corrientes, but exclude the area to the north between the Río Curaray and Río Napo. These findings are in contrast to previous distribution maps. P. aequatorialis was rarely seen in interspecific association during our censuses. Am. J. Primatol. 71:964,968, 2009. © 2009 Wiley-Liss, Inc. [source] Habitat fragmentation and population size of the black and gold howler monkey (Alouatta caraya) in a semideciduous forest in Northern ArgentinaAMERICAN JOURNAL OF PRIMATOLOGY, Issue 9 2007Gabriel E. Zunino Abstract A population of black and gold howler monkeys (Alouatta caraya) living near the southern limit of its distribution in a semideciduous forest located in northern Argentina was studied in 2003 to evaluate the possible effects of habitat fragmentation , owing to logging , on its density and social organization within it. Aerial photographs taken in 1982, 1992, and 2001 were used to compare maps of vegetation. These maps were used to evaluate changes in the area covered by forest fragments. From March to June 2003, 10-day monthly surveys of howlers were made in each fragment. A total of 232 individual howlers were counted, belonging to 34 groups plus a solitary adult female. Groups ranged from 2 to 19 individuals (mean = 6.82, SD = 4.23), and 21% of the groups contained more than one adult male. Adults accounted for 55% of the individuals, immatures for 45%, and infants represented 13% of the total. Data obtained were compared with information available for the same population for 1982 and 1995. Results revealed no significant changes in the area of fragments, the crude and ecological density of howlers, and group composition. Group sizes and group composition of howlers suggest that the population remained stable over the past 22 years. The density, number of groups, and individuals appears not to be affected by fragmentation and logging, but crude density was low compared with other less-disturbed habitats. The status of the population remains uncertain owing to isolation, and because there are no protected areas to ensure its stability for the future. Am. J. Primatol. 69:966,975, 2007. © 2007 Wiley-Liss, Inc. [source] Patterns of male residency and intergroup transfer in gray-cheeked mangabeys (Lophocebus albigena)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2005William Olupot Abstract We describe the movements and fates of 36 collared gray-cheeked male mangabeys (Lophocebus albigena) that resided in seven social groups in Kibale National Park, Uganda. The male mangabeys were captured, radiotagged, and then contacted regularly over a period of up to 8 years. Individuals varied considerably in how tightly they were associated with their groups. "Central" males were usually found in close spatial association with their own groups, but they sometimes visited others. "Peripheral" males were often found several hundred meters away from their own groups. Most adult males were characterized by repeated intergroup transfers, manifested as "visits" and "dispersals." Visits were transfers that did not result in mating. The visits were brief, and ranged from a few minutes to a few days before the male returned to his previous group, moved on to another group, or returned to solitary life. The term "dispersal" refers to a transfer that results in mating, after which the male remains in the new group. Young males began to drift away from their natal groups in early subadulthood, but the timing of first associations with estrous females in other groups was highly variable. Natal dispersers were generally solitary for a month or more, and at least half moved into nonadjacent groups. Secondary dispersal was common. After they immigrated, adult males remained in a group for a median of 19 months before they emigrated again, with the probability of departure being approximately constant in time. Secondary dispersal was usually made into an adjacent group and lasted less than 7 days. Emigration and immigration were not seasonal, and males emigrated singly and apparently independently; however, immigrations were clumped in time, and male dispersal contributed to considerable heterogeneity of group composition. L. albigena dispersal patterns are intermediate between those described for Papio baboons and forest Cercopithecus, and models that predict demographic consequences of dispersal for baboons can be refined to apply to mangabeys. Am. J. Primatol. 66:331,349, 2005. © 2005 Wiley-Liss, Inc. [source] Simulation of the population dynamics and social structure of the Virunga mountain gorillasAMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2004Martha M. Robbins Abstract An agent-based model was developed to simulate the growth rate, age structure, and social system of the endangered mountain gorillas (Gorilla beringei beringei) in the Virunga Volcanoes region. The model was used to compare two types of data: 1) estimates of the overall population size, age structure, and social structure, as measured by six censuses of the entire region that were conducted in 1971,2000; and 2) information about birth rates, mortality rates, dispersal patterns, and other life history events, as measured from three to five habituated research groups since 1967. On the basis of the research-group data, the "base simulation" predicted a higher growth rate than that observed from the census data (3% vs. 1%). This was as expected, because the research groups have indeed grown faster than the overall population. Additional simulations suggested that the research groups primarily have a lower mortality rate, rather than higher birth rates, compared to the overall population. Predictions from the base simulation generally fell within the range of census values for the average group size, the percentage of multimale groups, and the distribution of females among groups. However, other discrepancies predicted from the research-group data were a higher percentage of adult males than observed, an overestimation of the number of multimale groups with more than two silverbacks, and an overestimated number of groups with only two or three members. Possible causes for such discrepancies include inaccuracies in the census techniques used, and/or limitations with the long-term demographic data set obtained from only a few research groups of a long-lived species. In particular, estimates of mortality and male dispersal obtained from the research groups may not be representative of the entire population. Our final simulation addressed these discrepancies, and provided a better basis for further studies on the complex relationships among individual life history events, group composition, population age structure, and growth rate patterns. Am. J. Primatol. 63:201,223, 2004. © 2004 Wiley-Liss, Inc. [source] Rate of succession in restored wetlands and the role of site contextAPPLIED VEGETATION SCIENCE, Issue 3 2010Jeffrey W. Matthews Abstract Question: Are changes in plant species composition, functional group composition and rates of species turnover consistent among early successional wetlands, and what is the role of landscape context in determining the rate of succession? Location: Twenty-four restored wetlands in Illinois, USA. Methods: We use 4 years of vegetation sampling data from each site to describe successional trends and rates of species turnover in wetlands. We quantify: (1) the rate at which composition changes from early-successional to late-successional species and functional groups, as indicated by site movement in ordination space over time, and (2) the rate of change in the colonization and local extinction of individual species. We correlate the pace of succession to site area, isolation and surrounding land cover. Results: Some commonalities in successional trends were evident among sites. Annual species were replaced by clonal perennials, and colonization rates declined over time. However, differences among sites outweighed site age in determining species composition, and the pace of succession was influenced by a site's landscape setting. Rates of species turnover were higher in smaller wetlands. In addition, wetlands in agricultural landscapes underwent succession more rapidly, as indicated by a rapid increase in dominance by late-successional plants. Conclusions: Although the outcome of plant community succession in restored wetlands was somewhat predictable, species composition and the pace of succession varied among sites. The ability of restoration practitioners to accelerate succession through active manipulation may be contingent upon landscape context. [source] Herbaceous vegetation change in variable rangeland environments: The relative contribution of grazing and climatic variabilityAPPLIED VEGETATION SCIENCE, Issue 2 2001Samuel D. Fuhlendorf Hatch et al. (1990) Abstract. A 44-yr record of herbaceous vegetation change was analysed for three contrasting grazing regimes within a semi-arid savanna to evaluate the relative contribution of confined livestock grazing and climatic variability as agents of vegetation change. Grazing intensity had a significant, directional effect on the relative composition of short- and mid-grass response groups; their composition was significantly correlated with time since the grazing regimes were established. Interannual precipitation was not significantly correlated with response group composition. However, interannual precipitation was significantly correlated with total plant basal area while time since imposition of grazing regimes was not, but both interannual precipitation and time since the grazing regimes were established were significantly correlated with total plant density. Vegetation change was reversible even though the herbaceous community had been maintained in an altered state for ca. 60 yr by intensive livestock grazing. However, ca. 25 yr were required for the mid-grass response group to recover following the elimination of grazing and recovery occurred intermittently. The increase in mid-grass composition was associated with a significant decrease in total plant density and an increase in mean individual plant basal area. Therefore, we failed to reject the hypotheses based on the proportional change in relative response group composition with grazing intensity and the distinct effects of grazing and climatic variability on response group composition, total basal area and plant density. Long-term vegetation change indicates that grazing intensity established the long-term directional change in response group composition, but that episodic climate events defined the short-term rate and trajectory of this change and determines the upper limit on total basal area. The occurrence of both directional and non-directional vegetation responses were largely a function of (1) the unique responses of the various community attributes monitored and (2) the distinct temporal responses of these community attributes to grazing and climatic variation. This interpretation supports previous conclusions that individual ecosystems may exist in equilibrial and non-equilibrial states at various temporal and spatial scales. [source] Within-population variation in social strategies characterize the social and mating system of an Australian lizard, Egernia whitiiAUSTRAL ECOLOGY, Issue 8 2009GEOFFREY M. WHILE Abstract The lizard genus Egernia has been suggested as an excellent model system for examining the evolution of sociality as it exhibits considerable diversity in social organization both between and within species. To date the majority of work examining the factors responsible for the evolution of sociality within Egernia has advocated a broad scale approach; identifying the social structure of specific species or populations and comparing the degree of sociality between them. However, we argue that significant advancements could also be gained by examining variation in social strategies within populations. Here we integrate a detailed, 3-year, field-based examination of social spacing and juvenile dispersal with molecular analyses of paternity to determine the social and mating system of a Tasmanian population of White's skink (Egernia whitii). We show that E. whitii live in small stable family groups consisting of an adult male, his female partner(s), as well as juvenile or sub-adults individuals. In addition, while the mating system is characterized by considerable genetic monogamy, extra-pair fertilizations are relatively common, with 34% of litters containing offspring sired by males from outside the social group. We also show that traits related to social organization (social group composition, group size, stability and the level of extra-pair paternity) vary both between and within individuals. We suggest that ecological factors, such as habitat saturation, quality and availability, play a key role in maintaining between individual variation in social strategies, and that examining these individual level processes will allow us to more clearly understand variation in sociality among species. [source] Impacts of the invasive Argentine ant on native ants and other invertebrates in coastal scrub in south-eastern AustraliaAUSTRAL ECOLOGY, Issue 3 2009ALEXEI D. ROWLES Abstract Invasive ants threaten native biodiversity and ecosystem function worldwide. Although their principal direct impact is usually the displacement of native ants, they may also affect other invertebrates. The Argentine ant, Linepithema humile (Dolichoderinae), one of the most widespread invasive ant species, has invaded native habitat where it abuts peri-urban development in coastal Victoria in south-eastern Australia. Here we infer impacts of the Argentine ant on native ants and other litter and ground-dwelling invertebrates by comparing their abundance and taxonomic composition in coastal scrub forest either invaded or uninvaded by the Argentine ant. Species composition of native ants at bait stations and extracted from litter differed significantly between Argentine ant-invaded and uninvaded sites and this was consistent across years. Argentine ants had a strong effect on epigeic ants, which were either displaced or reduced in abundance. The native ant Rhytidoponera victoriae (Ponerinae), numerically dominant at uninvaded sites, was completely absent from sites invaded by the Argentine ant. However, small hypogeic ants, including Solenopsis sp. (Myrmicinae) and Heteroponera imbellis (Heteroponerinae), were little affected. Linepithema humile had no detectable effect upon the abundance and richness of other litter invertebrates. However, invertebrate group composition differed significantly between invaded and uninvaded sites, owing to the varied response of several influential groups (e.g. Collembola and Acarina). Floristics, habitat structure and measured environmental factors did not differ significantly between sites either invaded or uninvaded by Argentine ants, supporting the contention that differences in native ant abundance and species composition are related to invasion. Changes in the native ant community wrought by Argentine ant invasion have important implications for invertebrate communities in southern Australia and may affect key processes, including seed dispersal. [source] Focus group composition: a comparison between natural and constructed groupsAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 2 2001Julie Leask Objective: To provide insight into the effects of focus group composition. Method: In an early phase of an ongoing study of parental reception to messages about childhood immunisation, we conducted four focus groups; two with participants who had never met before (constructed groups) and two with participants who were part of a preestablished first-time mothers' group (natural groups). Results: Marked differences were noted in the group dynamics, depth of interaction and diversity between groups. Discussions with constructed groups were animated, enthusiastic, expressed more divergent views and articulated greater complexities of the topic. Discussions with natural groups were generally flatter and less enthusiastic, displaying a higher level of apparent conformity to conventional wisdom. The need to protect other participants from potentially disturbing information about vaccination was expressed across groups but acted to censor natural groups, where participants knew more of each others' sensitivities. Implications: Insight into the factors contributing to such differences may enhance understanding of the contexts in which constructed groups are more appropriate. The processes of social censorship may be of primary interest to the researcher. However, where it is paramount to elicit a range of opinions about a potentially controversial topic, we suggest that natural groups in the delicate stage of norming be avoided. The peculiarities of each individual research circumstance are best explored in pilot studies. [source] Nutrient Limitation to Primary Productivity in a Secondary Savanna in Venezuela1BIOTROPICA, Issue 4 2002Nichole N. Barger ABSTRACT We examined nutrient limitation to primary productivity in a secondary savanna in the interior branch of the Coastal Range of Venezuela, which was converted from forest to savanna more than 100 years ago. We manipulated soil nutrients by adding nitrogen (+N), phosphorus and potassium (+PK), and nitrogen, phosphorus, and potassium (+NPK) to intact savanna. Eleven months after fertilization, we measured aboveground biomass and belowground biomass as live fine roots in the top 20 cm of soil, and species and functional group composition in response to nutrient additions. Aboveground biomass was highest in the NPK treatment ([mean g/m2]; control = 402, +N = 718, +PK = 490, +NPK = 949). Aboveground production, however, appeared to be limited primarily by N. Aboveground biomass increased 78 percent when N was added alone but did not significantly respond to PK additions when compared to controls. In contrast to aboveground biomass, belowground biomass increased with PK additions but showed no significant increase with N (depth 0,20 cm; [mean g/m2]; control = 685, +N = 443, +PK = 827, +NPK = 832). There was also a 36 percent increase in root length with PK additions when compared to controls. Whole savanna shoot:root ratios were similar for control and +PK (0.6), while those for +N or +NPK fertilization were significantly higher (1.7 and 1.2, respectively). Total biomass response (above + belowground) to nutrient additions showed a strong N and PK co-limitation ([mean g/m2]; control = 1073, +N = 1111, +PK = 1258, +NPK = 1713). Aboveground biomass of all monocots increased with N additions, whereas dicots showed no response to nutrient additions. Trachypogon spp. (T. plumosus+T. vestitus) and Axonopus canescens, the two dominant grasses, made up more than 89 percent of the total aboveground biomass in these sites. Trachypogon spp. responded to NPK, whereas A. canescens, sedges, and the remaining monocots only responded to N. Even though nutrient additions resulted in higher aboveground biomass in N and NPK fertilized plots, this had little effect on plant community composition. With the exception of sedges, which responded positively to N additions and increased from 4 to 8 percent of die plant community, no changes were observed in plant community composition after 11 months. RESUMEN En este estudio se examinaron las limitaciones nutricionales en la productividad primatia de una sabana secundaria de más de 100 años localizada en el brazo interior de la Cordillera de la Costa de Venezuela. Se manipularon los nutrientes del suelo mediante la adición de nitrógeno (+N), fósforo y potasio (+PK), y nitrógeno, fósforo, y potasio (+NPK) al suelo de la sabana. Después de once meses de iniciarse los experimentos se midió la respuesta a la adición de nutrientes en términos de producción de biomasa aérea, biomasa de raíces finas vivas en los primeros 20 cm de suelo, y cambios en la composición de especies y grupos funcionales. La biomasa aérea fue mayor en las parcelas fertilizadas con N o en combinación de NPK ([promedio g/m2]; control = 402, +N = 718, +PK = 490, +NPK = 949) indicando que la producción aéiea está limitada principalmente por N. No hubo respuesta estadísticamente significativa a la adición de PK con respecto a los controles. La biomasa de raíces finas aumentó con la adición de PK y NPK mientras que no hubo aumento significativo con N (Profundidad 0,20 cm; [promedio g/m2]; control=685, +N=443, +PK=827, +NPK=832). La adición de PK modificó la arquitectura radical con un anmento de 36 por ciento en la longitud de las raíces con respecto al control. La relación vástago/raíz fue similar en los tratmientos controly + PK (0.6), pero significativamente mayor en +N (1.7)y +NPK(1.2) indicando nuevamente una limitación principal por N. La respuesta de la biomasa total (vástago +raíces vivas) a la adición de nutrientes refleja una colimitación de N y PK ([promedio g/m2]; control=1073, +N=1111, +PK+1258,+NPK=1713). La biomasa aérea de las monocotiledóneas aumentó de N, mientras que no hubo respuesta significativa a la adición de nutrientes en las dicotiledóneas. Trachypogon spp (T. Plumosus+T. vestitus) and Axonopus canescens, las dos gramíneas dominantes, representaron más del 89 por ciento de la biomasa total en las parcelas. Trachypogon spp respondieron a NPK, mientras que A. canescens, cuoeráceas, y las otras monocotiledóneas sólo respondieron a N. No hubo cambios significativos en la composición de especies como respuesta a la adición de nutrientes, con la excepción de las ciperáceas que respondieron significativamente a la adición de N con un aumento de 4 a 8 por ciento. [source] Mechanisms linking plant species richness to foraging of a large herbivoreJOURNAL OF APPLIED ECOLOGY, Issue 4 2010Ling Wang Summary 1.,There is general concern that local loss of plant diversity will adversely impact net primary productivity and other ecosystem properties. However, mechanisms linking plant diversity with other trophic levels, especially for large herbivores, are poorly understood. 2.,We examine the responses of foraging sheep to changes in plant species richness in an indoor cafeteria experiment involving six plant species richness levels (1, 2, 4, 6, 8 and 11 species) and three plant functional group compositions within each level, and in a field experiment involving three plant species richness levels (1, 4,6 or >8 species). 3.,Sheep preferred a diverse diet over a single diet even when palatable species were in the diet. Voluntary daily intake steadily rose with increases in plant species richness in both cafeteria and field experiments. The overall nutrient intake (i.e. daily energy and protein intakes) of sheep in the cafeteria also rose significantly with increased plant species richness until it reached a plateau at eight species. The quality of the diet selected by sheep was also significantly affected by plant species richness, but the variation of dietary quality was small and variable. 4.,High nutrient acquisition by the sheep depended on selecting those palatable species with high nutrient content from the plant forage on offer together with the complementary effects of plant species richness, especially for plant functional group richness. 5.,Synthesis and applications. Our experiments demonstrate an asymptotic relationship between plant species richness and voluntary intake by sheep. Increases in plant species richness from a low level led to increased daily nutrient intake, and presumably performance of the sheep. Natural grasslands are generally low in nutritional quality and so plant species richness will critically influence herbivore food intake and nutrition. The asymptotic relationship indicates that the maintenance of plant species richness in rangelands will benefit both domestic herbivore production and the conservation of biodiversity. [source] | ||||||||||||||||||||||