4451
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Winnard AL, Di Stefano J, Coulson G. Habitat use of a critically-endangered species in a predator-free but degraded reserve in Australia. WILDLIFE BIOLOGY 2013. [DOI: 10.2981/12-116] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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4452
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Pellock S, Thompson A, He K, Mecklin C, Yang J. Validity of Darwin’s naturalization hypothesis relates to the stages of invasion. COMMUNITY ECOL 2013. [DOI: 10.1556/comec.14.2013.2.7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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4453
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Berrios R, Totterdell P, Niven K. Why Do You Make Us Feel Good? Correlates and Interpersonal Consequences of Affective Presence in Speed-dating. EUROPEAN JOURNAL OF PERSONALITY 2013; 29:72-82. [PMID: 25750481 PMCID: PMC4342761 DOI: 10.1002/per.1944] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 10/17/2013] [Accepted: 10/17/2013] [Indexed: 11/11/2022]
Abstract
Recent research indicates that people consistently make others feel a certain way (e.g. happy or stressed). This individual difference has been termed affective presence, but little is known about its correlates or consequences. The present study investigated the following: (i) whether affective presence influences others' romantic interest in a person and (ii) what types of people have positive and negative affective presence. Forty volunteers took part in a speed-dating event, during which they dated six or seven opposite-sex partners. A Social Relations Model analysis confirmed that individuals prompted consistent positive emotional reactions in others. Participants were more likely to want to see dates with greater positive affective presence again in the future, and positive affective presence explained the effects of perceived responsiveness on romantic interest. Associations between positive affective presence and trait predictors, including emotion regulation, emotional expressiveness, attachment style, agreeableness and extraversion, were also observed. The findings indicate that what emotionally distinguishes one individual from another lies in part in the emotional consequences of their behaviours on others. © 2013 The Authors. European Journal of Personality published by John Wiley & Sons Ltd on behalf of European Association of Personality Psychology.
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4454
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Martin PA, Newton AC, Bullock JM. Carbon pools recover more quickly than plant biodiversity in tropical secondary forests. Proc Biol Sci 2013; 280:20132236. [PMID: 24197410 DOI: 10.1098/rspb.2013.2236] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Although increasing efforts are being made to restore tropical forests, little information is available regarding the time scales required for carbon and plant biodiversity to recover to the values associated with undisturbed forests. To address this knowledge gap, we carried out a meta-analysis comparing data from more than 600 secondary tropical forest sites with nearby undisturbed reference forests. Above-ground biomass approached equivalence to reference values within 80 years since last disturbance, whereas below-ground biomass took longer to recover. Soil carbon content showed little relationship with time since disturbance. Tree species richness recovered after about 50 years. By contrast, epiphyte richness did not reach equivalence to undisturbed forests. The proportion of undisturbed forest trees and epiphyte species found in secondary forests was low and changed little over time. Our results indicate that carbon pools and biodiversity show different recovery rates under passive, secondary succession and that colonization by undisturbed forest plant species is slow. Initiatives such as the Convention on Biological Diversity and REDD+ should therefore encourage active management to help to achieve their aims of restoring both carbon and biodiversity in tropical forests.
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Affiliation(s)
- Philip A Martin
- Centre for Ecology and Hydrology, , Benson Lane, Wallingford, Oxfordshire OX10 8BB, UK, Centre for Conservation Ecology and Environmental Science, School of Applied Sciences, Bournemouth University, , Poole BH12 5BB, UK
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4455
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Potential corridors and barriers for plague spread in Central Asia. Int J Health Geogr 2013; 12:49. [PMID: 24171709 PMCID: PMC4228490 DOI: 10.1186/1476-072x-12-49] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 10/23/2013] [Indexed: 12/02/2022] Open
Abstract
Background Plague (Yersinia pestis infection) is a vector-borne disease which caused millions of human deaths in the Middle Ages. The hosts of plague are mostly rodents, and the disease is spread by the fleas that feed on them. Currently, the disease still circulates amongst sylvatic rodent populations all over the world, including great gerbil (Rhombomys opimus) populations in Central Asia. Great gerbils are social desert rodents that live in family groups in burrows, which are visible on satellite images. In great gerbil populations an abundance threshold exists, above which plague can spread causing epizootics. The spatial distribution of the host species is thought to influence the plague dynamics, such as the direction of plague spread, however no detailed analysis exists on the possible functional or structural corridors and barriers that are present in this population and landscape. This study aims to fill that gap. Methods Three 20 by 20 km areas with known great gerbil burrow distributions were used to analyse the spatial distribution of the burrows. Object-based image analysis was used to map the landscape at several scales, and was linked to the burrow maps. A novel object-based method was developed – the mean neighbour absolute burrow density difference (MNABDD) – to identify the optimal scale and evaluate the efficacy of using landscape objects as opposed to square cells. Multiple regression using raster maps was used to identify the landscape-ecological variables that explain burrow density best. Functional corridors and barriers were mapped using burrow density thresholds. Cumulative resistance of the burrow distribution to potential disease spread was evaluated using cost distance analysis. A 46-year plague surveillance dataset was used to evaluate whether plague spread was radially symmetric. Results The burrow distribution was found to be non-random and negatively correlated with Greenness, especially in the floodplain areas. Corridors and barriers showed a mostly NWSE alignment, suggesting easier spreading along this axis. This was confirmed by the analysis of the plague data. Conclusions Plague spread had a predominantly NWSE direction, which is likely due to the NWSE alignment of corridors and barriers in the burrow distribution and the landscape. This finding may improve predictions of plague in the future and emphasizes the importance of including landscape analysis in wildlife disease studies.
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4456
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Lykes VA, Kemmelmeier M. What Predicts Loneliness? Cultural Difference Between Individualistic and Collectivistic Societies in Europe. JOURNAL OF CROSS-CULTURAL PSYCHOLOGY 2013. [DOI: 10.1177/0022022113509881] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Using two multilevel analyses of residents in 12 (1992 Eurobarometer; N = 3,902) and 22 (2006 European Social Survey, N = 38,867) European societies, respectively, we examined loneliness as a function of dominant cultural values. Levels of loneliness were higher in collectivistic compared with individualistic societies, but societies differed in terms of their predictors of loneliness. In collectivistic societies, the absence of interactions with family was more closely linked to loneliness than was the case in individualistic societies. Conversely, in individualistic societies, the absence of interactions with friends and having a confidant was more closely linked to loneliness than in collectivistic societies. Findings are consistent with the notion that autonomy and choice with regard to interaction partners have greater implications for well-being in individualistic societies whereas traditional social bonds are more potent in collectivistic societies.
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4457
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Environmental conditions during breeding modify the strength of mass-dependent carry-over effects in a migratory bird. PLoS One 2013; 8:e77783. [PMID: 24143258 PMCID: PMC3797109 DOI: 10.1371/journal.pone.0077783] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/12/2013] [Indexed: 11/19/2022] Open
Abstract
In many animals, processes occurring in one season carry over to influence reproductive success and survival in future seasons. The strength of such carry-over effects is unlikely to be uniform across years, yet our understanding of the processes that are capable of modifying their strength remains limited. Here we show that female light-bellied Brent geese with higher body mass prior to spring migration successfully reared more offspring during breeding, but only in years where environmental conditions during breeding were favourable. In years of bad weather during breeding, all birds suffered reduced reproductive output irrespective of pre-migration mass. Our results suggest that the magnitude of reproductive benefits gained by maximising body stores to fuel breeding fluctuates markedly among years in concert with conditions during the breeding season, as does the degree to which carry-over effects are capable of driving variance in reproductive success among individuals. Therefore while carry-over effects have considerable power to drive fitness asymmetries among individuals, our ability to interpret these effects in terms of their implications for population dynamics is dependent on knowledge of fitness determinants occurring in subsequent seasons.
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4458
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Harrison XA, York JE, Cram DL, Young AJ. Extra-group mating increases inbreeding risk in a cooperatively breeding bird. Mol Ecol 2013; 22:5700-15. [DOI: 10.1111/mec.12505] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 08/15/2013] [Accepted: 08/24/2013] [Indexed: 01/11/2023]
Affiliation(s)
- X. A. Harrison
- Institute of Zoology; Zoological Society of London; Regent's Park London NW1 4RY UK
- Centre for Ecology & Conservation; University of Exeter; Tremough Campus; Penryn Cornwall TR10 9EZ UK
| | - J. E. York
- Centre for Ecology & Conservation; University of Exeter; Tremough Campus; Penryn Cornwall TR10 9EZ UK
| | - D. L. Cram
- Centre for Ecology & Conservation; University of Exeter; Tremough Campus; Penryn Cornwall TR10 9EZ UK
| | - A. J. Young
- Centre for Ecology & Conservation; University of Exeter; Tremough Campus; Penryn Cornwall TR10 9EZ UK
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4459
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Boothroyd-Roberts K, Gagnon D, Truax B. Hybrid poplar plantations are suitable habitat for reintroduced forest herbs with conservation status. SPRINGERPLUS 2013; 2:507. [PMID: 24156089 PMCID: PMC3797915 DOI: 10.1186/2193-1801-2-507] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 09/25/2013] [Indexed: 11/10/2022]
Abstract
Plantations of fast-growing tree species may be of use in conservation by accelerating the restoration of forest habitat on abandoned farmland and increasing connectivity in fragmented landscapes. The objective of this study was to determine if hybrid poplar plantations can be suitable habitats for the reintroduction of native forest plant species and, if so, which abiotic factors predict successful reintroduction. Four species of forest herb species (Trillium grandiflorum, Sanguinaria canadensis, Maianthemum racemosum, Asarum canadense), of which three have legal conservation status, were transplanted into experimental plantations of two hybrid poplar clones and nearby second-growth woodlots at six sites in southern Quebec, Canada. The transplanted individuals were protected from deer browsing with exclusion cages. After two years, the plant responses of all four species were stable or increased over two years in both types of hybrid poplar plantations. Sanguinaria showed a better response in the plantations than in the woodlots, preferring the rich post-agricultural soils of the plantations with low C:N ratios. Asarum and Maianthemum showed no significant difference between stand types, while Trillium grew better in the woodlots than in the plantations. Much of the variability in the response of the latter three species was unexplained by the measured environmental variables. These results suggest that certain forest herb species can be reintroduced as juvenile plants into plantations, knowing that their spontaneous recolonization is often limited by dispersal and/or seedling establishment. Plantations could also contribute to the conservation of biodiversity by providing an environment for the cultivation of forest herb species as an alternative to their destructive harvest from natural populations.
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Affiliation(s)
- Kathleen Boothroyd-Roberts
- Centre d'étude de la forêt, Université du Québec à Montréal, CP 8888 succ. Centre-ville, Montreal, Quebec H3C 3P8 Canada
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4460
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Physicians' Radiation Exposure in the Catheterization Lab. JACC Cardiovasc Interv 2013; 6:1095-102. [DOI: 10.1016/j.jcin.2013.05.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 04/26/2013] [Accepted: 05/09/2013] [Indexed: 11/17/2022]
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4461
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Norghauer JM, Newbery DM. Herbivores differentially limit the seedling growth and sapling recruitment of two dominant rain forest trees. Oecologia 2013; 174:459-69. [PMID: 24072438 DOI: 10.1007/s00442-013-2769-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 08/30/2013] [Indexed: 11/26/2022]
Abstract
Resource heterogeneity may influence how plants are attacked and respond to consumers in multiple ways. Perhaps a better understanding of how this interaction might limit sapling recruitment in tree populations may be achieved by examining species' functional responses to herbivores on a continuum of resource availability. Here, we experimentally reduced herbivore pressure on newly established seedlings of two dominant masting trees in 40 canopy gaps, across c. 80 ha of tropical rain forest in central Africa (Korup, Cameroon). Mesh cages were built to protect individual seedlings, and their leaf production and changes in height were followed for 22 months. With more light, herbivores increasingly prevented the less shade-tolerant Microberlinia bisulcata from growing as tall as it could and producing more leaves, indicating an undercompensation. The more shade-tolerant Tetraberlinia bifoliolata was much less affected by herbivores, showing instead near to full compensation for leaf numbers, and a negligible to weak impact of herbivores on its height growth. A stage-matrix model that compared control and caged populations lent evidence for a stronger impact of herbivores on the long-term population dynamics of M. bisulcata than T. bifoliolata. Our results suggest that insect herbivores can contribute to the local coexistence of two abundant tree species at Korup by disproportionately suppressing sapling recruitment of the faster-growing dominant via undercompensation across the light gradient created by canopy disturbances. The functional patterns we have documented here are consistent with current theory, and, because gap formations are integral to forest regeneration, they may be more widely applicable in other tropical forest communities. If so, the interaction between life-history and herbivore impact across light gradients may play a substantial role in tree species coexistence.
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Affiliation(s)
- Julian M Norghauer
- Institute of Plant Sciences, University of Bern, 21 Altenbergrain, 3013, Bern, Switzerland,
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4462
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Hall SJ, Silver WL. Iron oxidation stimulates organic matter decomposition in humid tropical forest soils. GLOBAL CHANGE BIOLOGY 2013; 19:2804-13. [PMID: 23606589 DOI: 10.1111/gcb.12229] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 03/18/2013] [Indexed: 05/14/2023]
Abstract
Humid tropical forests have the fastest rates of organic matter decomposition globally, which often coincide with fluctuating oxygen (O2 ) availability in surface soils. Microbial iron (Fe) reduction generates reduced iron [Fe(II)] under anaerobic conditions, which oxidizes to Fe(III) under subsequent aerobic conditions. We demonstrate that Fe (II) oxidation stimulates organic matter decomposition via two mechanisms: (i) organic matter oxidation, likely driven by reactive oxygen species; and (ii) increased dissolved organic carbon (DOC) availability, likely driven by acidification. Phenol oxidative activity increased linearly with Fe(II) concentrations (P < 0.0001, pseudo R(2) = 0.79) in soils sampled within and among five tropical forest sites. A similar pattern occurred in the absence of soil, suggesting an abiotic driver of this reaction. No phenol oxidative activity occurred in soils under anaerobic conditions, implying the importance of oxidants such as O2 or hydrogen peroxide (H2 O2 ) in addition to Fe(II). Reactions between Fe(II) and H2 O2 generate hydroxyl radical, a strong nonselective oxidant of organic compounds. We found increasing consumption of H2 O2 as soil Fe(II) concentrations increased, suggesting that reactive oxygen species produced by Fe(II) oxidation explained variation in phenol oxidative activity among samples. Amending soils with Fe(II) at field concentrations stimulated short-term C mineralization by up to 270%, likely via a second mechanism. Oxidation of Fe(II) drove a decrease in pH and a monotonic increase in DOC; a decline of two pH units doubled DOC, likely stimulating microbial respiration. We obtained similar results by manipulating soil acidity independently of Fe(II), implying that Fe(II) oxidation affected C substrate availability via pH fluctuations, in addition to producing reactive oxygen species. Iron oxidation coupled to organic matter decomposition contributes to rapid rates of C cycling across humid tropical forests in spite of periodic O2 limitation, and may help explain the rapid turnover of complex C molecules in these soils.
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Affiliation(s)
- Steven J Hall
- Department of Environmental Science, Policy, and Management, University of California-Berkeley, Berkeley, CA 94720, USA.
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4463
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Hydrographic influences on the summer dive behaviour of Weddell seals (Leptonychotes weddellii) in Atka Bay, Antarctica. Polar Biol 2013. [DOI: 10.1007/s00300-013-1384-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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4464
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Dostál P, Müllerová J, Pyšek P, Pergl J, Klinerová T. The impact of an invasive plant changes over time. Ecol Lett 2013; 16:1277-84. [PMID: 23953187 DOI: 10.1111/ele.12166] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/08/2013] [Accepted: 07/17/2013] [Indexed: 11/28/2022]
Abstract
Many exotic plant invaders pose a serious threat to native communities, but little is known about the dynamics of their impacts over time. In this study, we explored the impact of an invasive plant Heracleum mantegazzianum (giant hogweed) at 24 grassland sites invaded for different periods of time (from 11 to 48 years). Native species' richness and productivity were initially reduced by hogweed invasion but tended to recover after ~30 years of hogweed residence at the sites. Hogweed cover declined over the whole period assessed. A complementary common garden experiment suggested that the dynamics observed in the field were due to a negative plant-soil feedback; hogweed survival and biomass, and its competitive ability were lower when growing in soil inocula collected from earlier-invaded grasslands. Our results provide evidence that the initial dominance of an invasive plant species and its negative impact can later be reversed by stabilising processes.
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Affiliation(s)
- Petr Dostál
- Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43, Průhonice, Czech Republic
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4465
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Prevalence of pink-footed goose grubbing in the arctic tundra increases with population expansion. Polar Biol 2013. [DOI: 10.1007/s00300-013-1374-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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4466
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Sayan S, Krymkowski DH, Manning RE, Valliere WA, Rovelstad EL. Cultural influence on crowding norms in outdoor recreation: a comparative analysis of visitors to national parks in Turkey and the United States. ENVIRONMENTAL MANAGEMENT 2013; 52:493-502. [PMID: 23685980 DOI: 10.1007/s00267-013-0076-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 05/06/2013] [Indexed: 06/02/2023]
Abstract
Formulation of standards of quality in parks and outdoor recreation can be guided by normative theory and related empirical methods. We apply this approach to measure the acceptability of a range of use levels in national parks in Turkey and the United States. Using statistical methods for comparing norm curves across contexts, we find significant differences among Americans, British, and Turkish respondents. In particular, American and British respondents were substantially less tolerant of seeing other visitors and demonstrated higher norm intensity than Turkish respondents. We discuss the role of culture in explaining these findings, paying particular attention to Turkey as a traditional "contact culture" and the conventional emphasis on solitude and escape in American environmental history and policy. We conclude with a number of recommendations to stimulate more research on the relationship between culture and outdoor recreation.
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4467
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Audusseau H, Nylin S, Janz N. Implications of a temperature increase for host plant range: predictions for a butterfly. Ecol Evol 2013; 3:3021-9. [PMID: 24101991 PMCID: PMC3790548 DOI: 10.1002/ece3.696] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 06/25/2013] [Accepted: 06/26/2013] [Indexed: 11/09/2022] Open
Abstract
Although changes in phenology and species associations are relatively well-documented responses to global warming, the potential interactions between these phenomena are less well understood. In this study, we investigate the interactions between temperature, phenology (in terms of seasonal timing of larval growth) and host plant use in the polyphagous butterfly Polygonia c-album. We found that the hierarchy of larval performance on three natural host plants was not modified by a temperature increase as such. However, larval performance on each host plant and temperature treatment was affected by rearing season. Even though larvae performed better at the higher temperature regardless of the time of the rearing, relative differences between host plants changed with the season. For larvae reared late in the season, performance was always better on the herbaceous plant than on the woody plants. In this species, it is likely that a prolonged warming will lead to a shift from univoltinism to bivoltinism. The demonstrated interaction between host plant suitability and season means that such a shift is likely to lead to a shift in selective regime, favoring specialization on the herbaceous host. Based on our result, we suggest that host range evolution in response to temperature increase would in this species be highly contingent on whether the population undergoes a predicted shift from one to two generations. We discuss the effect of global warming on species associations and the outcome of asynchrony in rates of phenological change.
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Affiliation(s)
- Hélène Audusseau
- Department of Zoology, Stockholm University Svante Arrhenius väg 18 B, 106 91, Stockholm, Sweden
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4468
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Gibson BS, Colberg SR, Poirier P, Vancea DMM, Jones J, Marcus R. Development and validation of a predictive model of acute glucose response to exercise in individuals with type 2 diabetes. Diabetol Metab Syndr 2013; 5:33. [PMID: 23816355 PMCID: PMC3701573 DOI: 10.1186/1758-5996-5-33] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 06/21/2013] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Our purpose was to develop and test a predictive model of the acute glucose response to exercise in individuals with type 2 diabetes. DESIGN AND METHODS Data from three previous exercise studies (56 subjects, 488 exercise sessions) were combined and used as a development dataset. A mixed-effects Least Absolute Shrinkage Selection Operator (LASSO) was used to select predictors among 12 potential predictors. Tests of the relative importance of each predictor were conducted using the Lindemann Merenda and Gold (LMG) algorithm. Model structure was tested using likelihood ratio tests. Model accuracy in the development dataset was assessed by leave-one-out cross-validation.Prospectively captured data (47 individuals, 436 sessions) was used as a test dataset. Model accuracy was calculated as the percentage of predictions within measurement error. Overall model utility was assessed as the number of subjects with ≤1 model error after the third exercise session. Model accuracy across individuals was assessed graphically. In a post-hoc analysis, a mixed-effects logistic regression tested the association of individuals' attributes with model error. RESULTS Minutes since eating, a non-linear transformation of minutes since eating, post-prandial state, hemoglobin A1c, sulfonylurea status, age, and exercise session number were identified as novel predictors. Minutes since eating, its transformations, and hemoglobin A1c combined to account for 19.6% of the variance in glucose response. Sulfonylurea status, age, and exercise session each accounted for <1.0% of the variance. In the development dataset, a model with random slopes for pre-exercise glucose improved fit over a model with random intercepts only (likelihood ratio 34.5, p < 0.001). Cross-validated model accuracy was 83.3%.In the test dataset, overall accuracy was 80.2%. The model was more accurate in pre-prandial than postprandial exercise (83.6% vs. 74.5% accuracy respectively). 31/47 subjects had ≤1 model error after the third exercise session. Model error varied across individuals and was weakly associated with within-subject variability in pre-exercise glucose (Odds ratio 1.49, 95% Confidence interval 1.23-1.75). CONCLUSIONS The preliminary development and test of a predictive model of acute glucose response to exercise is presented. Further work to improve this model is discussed.
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Affiliation(s)
- Bryan S Gibson
- Veterans Affairs Medical Center, Salt Lake City, UT, USA.
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4469
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Poulin R, Krasnov BR, Pilosof S, Thieltges DW. Phylogeny determines the role of helminth parasites in intertidal food webs. J Anim Ecol 2013; 82:1265-75. [PMID: 23800281 DOI: 10.1111/1365-2656.12101] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/14/2013] [Indexed: 01/23/2023]
Abstract
1. Parasites affect interactions among species in food webs and should be considered in any analysis of the structure, dynamics or resilience of trophic networks. 2. However, the roles of individual parasite species, such as their importance as connectors within the network, and what factors determine these roles, are yet to be investigated. Here, we test the hypotheses that the species roles of trematode, cestode and nematode parasites in aquatic food webs are influenced by the type of definitive host they use, and also determined by their phylogenetic affiliations. 3. We quantified the network role of 189 helminth species from six highly resolved intertidal food webs. We focused on four measures of centrality (node degree, closeness centrality, betweenness centrality and eigenvalue centrality), which characterize each parasite's position within the web, and on relative connectedness of a parasite species to taxa in its own module vs. other modules of the web (within-module degree and participation coefficient). 4. All six food webs displayed a significant modular structure, that is, they consisted of subsets of species interacting mostly with each other and less with species from other subsets. We demonstrated that the parasites themselves are not generating this modularity, though they contribute to intermodule connectivity. 5. Mixed-effects models revealed only a modest influence of the type of definitive host used (bird or fish) and of the web of origin on the different measures of parasite species roles. In contrast, the taxonomic affiliations of the parasites, included in the models as nested random factors, accounted for 37-93% of the total variance, depending on the measure of species role. 6. Our findings indicate that parasites are important intermodule connectors and thus contribute to web cohesion. We also uncover a very strong phylogenetic signal in parasite species roles, suggesting that the role of any parasite species in a food web, including new invasive species, is to some extent predictable based solely on its taxonomic affiliations.
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Affiliation(s)
- Robert Poulin
- Department of Zoology, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
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4470
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Smith AL, Michael Bull C, Driscoll DA. Successional specialization in a reptile community cautions against widespread planned burning and complete fire suppression. J Appl Ecol 2013. [DOI: 10.1111/1365-2664.12119] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Annabel L. Smith
- Australian Research Council Centre of Excellence for Environmental Decisions and the National Environmental Research Program Environmental Decisions Hub Fenner School of Environment and Society The Australian National University Fenner Building 141 Canberra ACT 0200 Australia
| | - C. Michael Bull
- School of Biological Sciences Flinders University GPO Box 2100 Adelaide SA 5001 Australia
| | - Don A. Driscoll
- Australian Research Council Centre of Excellence for Environmental Decisions and the National Environmental Research Program Environmental Decisions Hub Fenner School of Environment and Society The Australian National University Fenner Building 141 Canberra ACT 0200 Australia
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4471
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Female mediation of competitive fertilization success in Drosophila melanogaster. Proc Natl Acad Sci U S A 2013; 110:10693-8. [PMID: 23757499 DOI: 10.1073/pnas.1300954110] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
How females store and use sperm after remating can generate postcopulatory sexual selection on male ejaculate traits. Variation in ejaculate performance traits generally is thought to be intrinsic to males but is likely to interact with the environment in which sperm compete (e.g., the female reproductive tract). Our understanding of female contributions to competitive fertilization success is limited, however, in part because of the challenges involved in observing events within the reproductive tract of internally fertilizing species while discriminating among sperm from competing males. Here, we used females from crosses among isogenic lines of Drosophila melanogaster, each mated to two genetically standardized males (the first with green- and the second with red-tagged sperm heads) to demonstrate heritable variation in female remating interval, progeny production rate, sperm-storage organ morphology, and a number of sperm performance, storage, and handling traits. We then used multivariate analyses to examine relationships between this female-mediated variation and competitive paternity. In particular, the timing of female ejection of excess second-male and displaced first-male sperm was genetically variable and, by terminating the process of sperm displacement, significantly influenced the relative numbers of sperm from each male competing for fertilization, and consequently biased paternity. Our results demonstrate that females do not simply provide a static arena for sperm competition but rather play an active and pivotal role in postcopulatory processes. Resolving the adaptive significance of genetic variation in female-mediated mechanisms of sperm handling is critical for understanding sexual selection, sexual conflict, and the coevolution of male and female reproductive traits.
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4472
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Sakamaki T, Richardson JS. Nonlinear variation of stream-forest linkage along a stream-size gradient: an assessment using biogeochemical proxies of in-stream fine particulate organic matter. J Appl Ecol 2013. [DOI: 10.1111/1365-2664.12099] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - John S. Richardson
- Department of Forest and Conservation Sciences; University of British Columbia; Vancouver; BC; V6T 1Z4; Canada
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4473
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Occurrence patterns of lichens on stumps in young managed forests. PLoS One 2013; 8:e62825. [PMID: 23638150 PMCID: PMC3634766 DOI: 10.1371/journal.pone.0062825] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Accepted: 03/26/2013] [Indexed: 11/28/2022] Open
Abstract
The increasing demand for forest-derived bio-fuel may decrease the amount of dead wood and hence also the amount of available substrate for saproxylic ( = dead-wood dependent) organisms. Cut stumps constitute a large portion of dead wood in managed boreal forests. The lichen flora of such stumps has received little interest. Therefore, we investigated which lichens that occur on stumps in young (4–19 years), managed forests and analyzed how species richness and occurrence of individual species were related to stump and stand characteristics. We performed lichen inventories of 576 Norway spruce stumps in 48 forest stands in two study areas in Central Sweden, recording in total 77 lichen species. Of these, 14 were obligately lignicolous, while the remaining were generalists that also grow on bark, soil or rocks. We tested the effect of characteristics reflecting successional stage, microclimate, substrate patch size, and the species pool in the surrounding area on (1) total lichen species richness, (2) species richness of obligately lignicolous lichens and (3) the occurrence of four obligately lignicolous lichen species. The most important variables were stump age, with more species on old stumps, and study area, with similar total species richness but differences in occupancy for individual species. Responses for total lichen species richness and species richness of obligately lignicolous lichens were overall similar, indicating similar ecological requirements of these two groups. Our results indicate that species richness measurements serve as poor proxies for the responses of individual, obligately lignicolous lichen species.
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4474
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Xiao Z, Gao X, Zhang Z. The combined effects of seed perishability and seed size on hoarding decisions by Pére David’s rock squirrels. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1531-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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4475
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Roche DG, Taylor MK, Binning SA, Johansen JL, Domenici P, Steffensen JF. Unsteady flow affects swimming energetics in a labriform fish (Cymatogaster aggregata). J Exp Biol 2013; 217:414-22. [DOI: 10.1242/jeb.085811] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
Unsteady water flows are common in nature, yet the swimming performance of fishes is typically evaluated at constant, steady speeds in the laboratory. We examined how cyclic changes in water flow velocity affect the swimming performance and energetics of a labriform swimmer, the shiner surfperch, Cymatogaster aggregata. Using intermittent-flow respirometry, we measured critical swimming speed (Ucrit), oxygen consumption rate (ṀO2) and pectoral fin use in steady flow versus unsteady flows with either low (0.5 body lengths per second; BLs-1) or high amplitude (1.0 BLs-1) velocity fluctuations, with a 5 s period. Individuals in low amplitude unsteady flow performed as well as fish in steady flow. However, swimming costs in high amplitude unsteady flow were on average 25.3 % higher than in steady flow and 14.2% higher than estimated values obtained from simulations based on the non-linear relationship between swimming speed and oxygen consumption rate in steady flow. Time-averaged pectoral fin use (fin beat frequency measured over 300 s) was similar among treatments. However, measures of instantaneous fin use (fin beat period) and body movement in high amplitude unsteady flow indicate that individuals with greater variation in the duration of their fin beats were better at holding station and consumed less oxygen than fish with low variation in fin beat period. These results suggest that the costs of swimming in unsteady flows are context dependent in labriform swimmers, and may be influenced by individual differences in the ability of fishes to adjust their fin beats to the flow environment.
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