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Temporal Variation (temporal + variation)
Kinds of Temporal Variation Selected AbstractsTEMPORAL VARIATION IN DIVERGENT SELECTION ON SPINE NUMBER IN THREESPINE STICKLEBACKEVOLUTION, Issue 12 2002T. E. Reimchen Abstract., Short-term temporal cycles in ecological pressures, such as shifts in predation regime, are widespread in nature yet estimates of temporal variation in the direction and intensity of natural selection are few. Previous work on threespine stickleback (Gasterosteus aculeatus) has revealed that dorsal and pelvic spines are a defense against gape-limited predators but may be detrimental against grappling insect predators. In this study, we examined a 15-year database from an endemic population of threespine stickleback to look for evidence of temporal shifts in exposure to these divergent predation regimes and correlated shifts in selection on spine number. For juveniles, we detected selection for increased spine number during winter when gape-limited avian piscivores were most common but selection for decreased spine number during summer when odonate predation was more common. For subadults and adults, which are taken primarily by avian piscivores, we predicted selection should generally be for increased spine number in all seasons. Among 59 comparisons, four selection differentials were significant (Bonferroni corrected) and in the predicted direction. However, there was also substantial variability in remaining differentials, including two examples with strong selection for spine reduction. These reversals were associated with increased tendency of the fish to shift to a benthic niche, as determined from examination of stomach contents. These dietary data suggest that increased encounter rates with odonate predation select for spine reduction. Strong selection on spine number was followed by changes in mean spine number during subsequent years and a standard quantitative genetic formula revealed that spine number has a heritable component. Our results provide evidence of rapid morphological responses to selection from predators and suggest that temporal variation in selection may help maintain variation within populations. Furthermore, our findings indicate that variable selection can be predicted if the agents of selection are known. [source] Geographic and Temporal Variation of the Male Zebra Finch Distance CallETHOLOGY, Issue 4 2005David Runciman Temporal and geographic variation of acoustic signals can provide insights into dispersal patterns, population history and speciation. Vocalizations that are transmitted from one generation to the next are of particular value in this respect because they can reveal patterns of gene flow, effectively behaving as population markers. The male zebra finch Taeniopygia guttata distance call is one such vocalization; sons learn their father's distance call in the first 40 d of life and it is individually stereotyped thereafter. We investigated geographic variation in the zebra finch by comparing the structure of distance calls recorded from 61 males from six populations across the continent-wide range of the Australian subspecies T. g. castanotis. Intra-population variation was high, in many cases greater than the variation among all males recorded, possibly because of population interchange. However, three of six call variables measured, including the newly discovered modulated element, varied geographically although the pattern of distance call variation did not agree with that of geographic proximity of populations. The proportion of calls with a modulated element increased dramatically over 7 yr in central Australia but there was no change over a similar period of time in south-eastern Australia where no calls contained the element. The findings suggest that interchange among widely separated populations may be commonplace in Australian zebra finches, with the possible exception of those from south-eastern Australia. [source] Temporal Variation in Cleanerfish and Client Behaviour: Does It Reflect Ectoparasite Availability?ETHOLOGY, Issue 6 2003Isabelle M. Côté We tested the importance of ectoparasites as the proximate cause of cleaning interactions by comparing the activity of Caribbean cleaning gobies (Elacatinus evelynae) and of their clients during three daily periods (early morning, midday, and late afternoon) in which ectoparasite availability varied naturally. Emergence from the benthos of gnathiid isopod larvae, the main target of cleaning goby predation, was higher at night, when cleaners were inactive, than during the day. As a result, overall ectoparasite loads on client fish tended to be higher in the morning. Inspection bouts by cleaning gobies were longest in the morning, but also at midday when ectoparasite availability on clients was lower. Client fish were observed at cleaning stations most often in the afternoon, when they harboured few ectoparasites, but they were more likely to adopt incitation poses, which increase the likelihood of being cleaned, in the morning than later in the day. Most cleaner and client behaviours therefore did not change predictably in response to natural diurnal variation in ectoparasite availability. Our study suggests that the ultimate and proximate causes of cleaning behaviour need not necessarily coincide. [source] Temporal Variations in Fine Sand Assemblages in the North Aegean Sea (Eastern Mediterranean)INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2004Evdokia Kourelea Abstract Two sites were selected in the North Aegean Sea for the study of shallow fine sand assemblages, which are poorly known in the Eastern Mediterranean. The biomonitoring of these sites can provide useful information on the impact of human activities on the macrofaunal and meiofaunal composition of these assemblages. In order to examine this impact, sampling took place in five different periods between 2000 and 2001. The qualitative and quantitative compositions of the communities at the two sites showed certain differences, mostly between the sites and the year of sampling rather than between sampling periods, which would be the expected outcome. The communities seem to be affected by a combination of the human activities with the particular hydrodynamics of the studied sites. [source] Temporal Variations of Nutrients, Chlorophyll a and Particulate Matter in Three Coastal Lagoons of Amvrakikos Gulf (Ionian Sea, Greece)MARINE ECOLOGY, Issue 3 2001Konstantinos A. Kormas Abstract. The temporal variations of nutrients, chlorophyll a (chl a), suspended particulate matter (SPM) and particulate organic carbon (POC) were measured over 12 months in three shallow coastal brackish water lagoons of the Amvrakikos Gulf, Ionian Sea. Two of the lagoons, Tsoukalio and Rodia, are interconnected but separated from Logarou by a narrow strip of land. Logarou has a better water exchange with the sea as indicated by the higher salinity and dissolved oxygen concentrations and the smaller variation of the above-mentioned parameters. Nitrate concentrations were largely the same in the three lagoons and higher than in the Amvrakikos Gulf. Phosphate concentrations in Logarou exceeded by far those of Tsoukalio/Rodia; the increased phosphate levels recorded in January caused an extended phytoplankton bloom with chl a concentrations higher than in the other two lagoons. Chl a in Tsoukalio was positively correlated with nitrate whereas in the most shallow lagoon, Logarou, it showed a positive correlation with light winds (force 4 and lower), probably caused by resuspension from the sediment. Increased phytoplankton biomass in Logarou coupled with the better water exchange may be related to the higher fish production in this lagoon. [source] Temporal Variations in Microvolt T-Wave Alternans Testing after Acute Myocardial InfarctionANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2007F.E.S.C., Mário Martins Oliveira M.D. Background: Microvolt T-wave alternans (TWA) have been accepted as a tool for assessing vulnerability to ventricular tachyarrhythmias. There is lack of data concerning prospective temporal variations in TWA measurements after acute myocardial infarction (AMI). We analysed the temporal patterns of TWA in post-AMI patients. Methods and Results: TWA tests were performed <1 month (TWA_early) and 6 months (TWA_late) after AMI in 51 consecutive patients treated with successful percutaneous coronary intervention (PCI). Twenty seven patients (53%) had anterior wall infarctions and 24 (47%) had inferior/lateral wall infarctions. TWA was measured during a treadmill manual exercise protocol and defined as positive, negative and indeterminate. Group A included patients with TWA negative in both tests and Group B included those with TWA abnormal (positive or indeterminate) at first or second determinations. TWA_early was negative, positive and indeterminate in 38 (74.6%), 8 (15.6%) and 5 (9.8%) patients, respectively, whereas TWA_late was negative, positive and indeterminate in 30 (58.9%), 14 (27.4%) and 7 (13.7%) patients, respectively. TWA_early was classified as normal in 74.6% and abnormal in 25.4% of the cases, and TWA_late was normal in 58.9% and abnormal in 41.1%. TWA tests were concordant in 36 patients (70.6%) and discordant 15 patients (29.4%). At TWA_late, 10 patients (19.6%) changed from TWA negative to TWA abnormal and 4 patients (7.8%) from TWA abnormal to TWA negative. After TWA_early+TWA_late, 45% of the patients had 1 test classified as abnormal. Left ventricular ejection fraction was <50% in 22% of Group A and 52% of Group B (P = 0.037). Conclusions: In the era of primary PCI, temporal changes in TWA measurements may occur frequently during the first 6 months post-AMI. These findings should be considered in risk stratification strategies following AMI. [source] THE PHENOTYPIC VARIANCE WITHIN PLASTIC TRAITS UNDER MIGRATION-MUTATION-SELECTION BALANCEEVOLUTION, Issue 6 2006Xu-Sheng Zhang Abstract How phenotypic variances of quantitative traits are influenced by the heterogeneity in environment is an important problem in evolutionary biology. In this study, both genetic and environmental variances in a plastic trait under migration-mutation-stabilizing selection are investigated. For this, a linear reaction norm is used to approximate the mapping from genotype to phenotype, and a population of clonal inheritance is assumed to live in a habitat consisting of many patches in which environmental conditions vary among patches and generations. The life cycle is assumed to be selection-reproduction-mutation-migration. Analysis shows that phenotypic plasticity is adaptive if correlations between the optimal phenotype and environment have become established in both space and/or time, and it is thus possible to maintain environmental variance (VE) in the plastic trait. Under the special situation of no mutation but maximum migration such that separate patches form an effective single-site habitat, the genotype that maximizes the geometric mean fitness will come to fixation and thus genetic variance (VG) cannot be maintained. With mutation and/or restricted migration, VG can be maintained and it increases with mutation rate but decreases with migration rate; whereas VE is little affected by them. Temporal variation in environmental quality increases VG while its spatial variance decreases VG. Variation in environmental conditions may decrease the environmental variance in the plastic trait. [source] Annual cycle and inter-annual variability of gross primary production and ecosystem respiration in a floodprone river during a 15-year periodFRESHWATER BIOLOGY, Issue 5 2006URS UEHLINGER Summary 1. Temporal variation in ecosystem metabolism over a 15-year period (1986,2000) was evaluated in a seventh order channelised gravel bed river (mean annual discharge 48.7 m3 s,1) of the Swiss Plateau. The river is subject to frequent disturbance by bed-moving spates. Daily integrals of gross primary production (GPP) and ecosystem respiration (ER) were calculated based on single-station diel oxygen curves. 2. Seasonal decomposition of the time series of monthly metabolism rates showed that approximately 50% of the variation of GPP and ER can be attributed to season. Annual GPP averaged 5.0 ± 0.6 g O2 m,2 day,1 and showed no long-term trend. 3. Ecosystem respiration, averaging 6.2 ± 1.4 g O2 m,2 day,1, declined from 8.8 to 4.1 g O2 m,2 day,1 during the 15-year period. This significant trend paralleled a decline in nitrate and soluble reactive phosphorus concentrations, and the biochemical oxygen demand discharged by sewage treatment facilities upstream of the study reach. The ratio of GPP to ER (P/R) increased from 0.53 to about 1 as consequence of ER reduction. 4. Bed moving spates reduced GPP by 49% and ER by 19%. Postspate recovery of GPP was rapid between spring and autumn and slow during winter. Recovery of ER lacked any seasonal pattern. Annual patterns of daily GPP and to a minor extent of daily ER can be described as a sequence of recovery periods frequently truncated by spates. 5. The study showed that disturbance by frequent bed-moving spates resulted in major stochastic variation in GPP and ER but annual patterns were still characterised by a distinct seasonal cycle. It also became evident that stream metabolism is a suitable method to assess effects of gradual changes in water quality. [source] The use of periphytic diatoms as a means of assessing impacts of point source inorganic nutrient pollution in south-eastern AustraliaFRESHWATER BIOLOGY, Issue 5 2006JOCELYN DELA-CRUZ Summary 1. Periphytic diatoms are used as indicators of water quality because their ecological tolerances or preferences to environmental variables are thought to be predictable. However, much of the present autecological information for periphytic diatoms has been derived from studies conducted in the northern hemisphere. In this present study we used periphytic diatoms to determine the impacts of inorganic nutrient pollution in a tidal river system in the temperate latitudes of south-east Australia. In so doing, we assess the suitability of the use of the ,northern hemisphere' ecological tolerance/preference data for periphytic diatoms. 2. Artificial substrates were used to collect periphytic diatoms at 35 sites, which were positioned along the riverbanks and the middle of the river at various distances upstream and downstream of the sewage outfall. The sampling design took into account tidal excursions and the observed sewage plume dynamics. Periphytic diatoms were collected during the austral winter month of August and the austral spring months of September and October. We deployed the artificial substrates for 4 weeks to allow the periphytic diatoms to recruit and colonise, before identifying and enumerating the assemblages. 3. Data analysis included two approaches: multivariate visualisations of combinations of environmental and biological data to investigate shifts in species structure of the periphytic diatom assemblage and multimetric indices based on ecological tolerance/preference data. 4. We found that the spatial patterns inferred from multivariate and multimetric analyses were consistent. Temporal variation in the composition of the periphytic diatom assemblage was greater than the spatial variation along horizontal sections of the river (in any one deployment) due mainly to shifts between winter and spring species. 5. Outfall effects were most apparent in winter, possibly because subsequent deployments were swamped by growth of spring periphytic diatoms. The outfall effects included a shift towards pollutant tolerant species and a reduction in the variability of the periphytic diatom assemblage across the river. 6. We conclude that the use of periphytic diatoms and associated ecological tolerance/preference data as a means of assessing impacts of point source inorganic nutrient pollution is effective. An understanding of river and sewage flow patterns is essential to the design of appropriate monitoring programmes and to the interpretation of results, especially as periphytic diatoms are sensitive to many environmental variables. [source] Temporal variation of energy reserves in mayfly nymphs (Hexagenia spp.) from Lake St Clair and western Lake ErieFRESHWATER BIOLOGY, Issue 10 2003J.F. Cavaletto Summary 1. We analysed changes in energy reserves (lipid and glycogen) and length,weight relationships of burrowing mayflies (Hexagenia spp.) in 1997,99 to compare an established population in Lake St Clair with a recovering population in western Lake Erie of the Laurentian Great Lakes. In addition, we measured changes in water temperature and potential food in both water columns and sediments. 2. Although overall mean values of lipid and glycogen levels of Hexagenia nymphs from Lake St Clair and western Lake Erie were not significantly different, there were differences in seasonal patterns between the two lakes. In Lake St Clair, levels were highest in early spring, declined throughout the year, and reached their lowest levels in fall during all 3 years of study. In contrast, levels in western Lake Erie were lower in spring, increased to a maximum in summer, then declined in fall. Seasonal patterns in length,weight relationships were similar to those for lipid and glycogen. 3. Total lipid as a percentage of dry weight did not increase with developmental stage of nymphs until just prior to metamorphosis and emergence from water. However, the major reserve lipid, triacylglycerols, increased systematically with development stage. In the final stage of development, triacylglycerols declined, probably as a result of energy consumption and its conversion to other biochemical components for metamorphosis and reproduction. 4. Indicators of potential food (algal fluorescence in the water column and chlorophyll a and chlorophyll a/phaeophytin ratio in sediments) suggest that Hexagenia in Lake St Clair have a food source that is benthic based, especially in early spring, whereas in western Lake Erie nymphs have a food source that is water column based and settles to the lake bottom during late spring and summer. [source] Temporal variation in breeding and cone size selection by three species of crossbills Loxia spp. in a native Scots pinewoodJOURNAL OF AVIAN BIOLOGY, Issue 3 2010Ron W. Summers The breeding biology and cone size selection of crossbills was studied mainly during 1995 to 2002 at Abernethy Forest, Scotland, an ancient native Scots pine Pinus sylvestris wood, where only a single crossbill species, the Scottish crossbill Loxia scotica, was assumed to occur and to be adapted to feed on seeds in Scots pine cones. However, three crossbill species (common Loxia curvirostra, Scottish and parrot crossbills Loxia pytyopsittacus) nested in some years, with the parrot crossbill being the most abundant. Most nests were in old large pines, with the three crossbill species not differing in their use of tree size or stand density for nesting. The mean clutch and brood sizes were 3.8 and 2.9, and their mean survivals were 86 and 74%, respectively, with no significant differences among species. The timing of breeding differed between species, with parrot crossbills breeding earliest (median date 21 March, including second attempts) and common crossbills breeding last (median date 21 April), probably in response to the differing accessibility of Scots pine seeds to these species. The difference in the time of breeding may reduce mixed mating. Crossbills foraged preferentially on trees with small cones when the cones were closed. Small cones had thinner scales than large cones, suggesting that the preference for small cones was related to higher feeding rates on these cones when cones are closed. Such a preference was also found for captive crossbills with the Scottish crossbill showing a more pronounced preference for smaller cones than the larger-billed parrot crossbill. However, crossbills selected larger cones within trees and trees with larger cones once the cones opened in April. Such a shift occurred presumably because variation in scale thickness has little impact on seed accessibility once cones open, and larger cones have larger and more seeds. The greater ability of parrot crossbills to exploit seeds in closed Scots pine cones allowed parrot crossbills to start breeding earlier and to have young when seeds were most accessible. Only after the cones opened were the smaller-billed common crossbills able to easily access seeds and to start breeding. The time of breeding of Scottish crossbills was intermediate between common and parrot crossbills, and they probably had an intermediate ability to exploit Scots pine cones. The reason why there were few Scottish crossbills nesting in Abernethy Forest remains a puzzle, considering that native pine wood is assumed to be the ancestral habitat to which the Scottish crossbill is adapted. The breeding season for all crossbills ended in June, when most of the seed from a given cone cohort was shed. This is when starved broods were found, not associated with bad weather. [source] Size matters sometimes: wall height and the structure of subtidal benthic invertebrate assemblages in south-eastern Australia and Mediterranean SpainJOURNAL OF BIOGEOGRAPHY, Issue 12 2003A. R. Davis Abstract Aim, Variation in the structure of shallow subtidal invertebrate assemblages was examined over three spatial scales; within reef, between reef and between continents. We sought to provide a context from which to examine and interpret ecological processes between continents. In addition, we predicted that variation in pattern would increase as the scale of examination increased. Location, Reefs near Wollongong and within Jervis Bay in south-eastern Australia and Mediterranean reefs on the Costa Brava (Catalonia), north-eastern Spain. Methods, We compared assemblages on vertical rock walls of two heights , short (< 2 m) and tall (> 3 m) in two temperate regions over the same depth range. Specifically we examined the diversity and cover of invertebrates, the cover and biomass of foliose and crustose algae, the size of invertebrate colonies and the biomass of urchins on short and tall walls (n = 3) at each of two locations in each country. Results, Foliose algae dominated rock walls in Spain and although invertebrate cover was high, colonies were generally very small. Two urchin species were commonly encountered on rock walls in Spain, Arbacia lixula and Paracentrotus lividus; their biomass was relatively low and did not differ significantly between short and tall walls. These findings contrasted strongly with south-eastern Australia, where foliose algae were almost completely absent. A single urchin species, Centrostephanus rodgersii occurred with extremely high biomass on short walls, which were dominated by grazer-resistant crustose calcareous algae. In contrast, the biomass of this urchin was low on tall walls, which were dominated by invertebrates, usually exceeding 95% in cover. Invertebrate colonies were significantly larger on both short and tall walls in south-eastern Australia relative to the Mediterranean. Findings within a country were consistent between the replicate rock walls and between locations. In contrast to our prediction, however, there was significant variation among walls within a location, but not among locations within a continent. Temporal variation in the structure of these assemblages was not examined, but appears limited. Main conclusions, We conclude that submarine topography, i.e. the presence of short or tall rock walls, as a function of rock type and structure, has a marked impact on community structure in south-eastern Australia, but made little difference to the structure of the assemblage in Mediterranean Spain. The differences in structure we observed between walls of different heights in Australia were correlated with differences in the biomass of urchins and they appear to be major determinants of assemblage structure. Interactions among species are often reported from disparate parts of the globe with little or no reference to the structure of the assemblage of which they are a part; we contend that this will hinder interpretation. Our data are consistent with the organisms in these two regions experiencing distinct selection pressures; for example high levels of urchin grazing activity in south-eastern Australia, and shading and whiplash associated with an algal canopy in the Mediterranean. It may not be appropriate to contrast processes operating at very large (intercontinental) scales unless context can be established with a clear understanding of ecological pattern. Objectivos, En el presente trabajo hemos examinado la variación en estructura de comunidades de invertebrados de aguas someras a tres escalas espaciales: dentro de arrecifes rocosos, entre arrecifes y entre continentes. Nuestro objetivo era proveer un contexto para examinar y interpretar procesos ecológicos entre continentes. Además, realizamos la predicción de que el modelo de variación aumentaría conforme aumentaba la escala de observación. Localidad, Arrecifes rocosos cerca de Wollongong y en Jarvis Bay en la zona sudeste de Australia y arrecifes rocosos mediterráneos en la Costa Brava (Cataluña), en el nordeste de España. Metodos, Comparamos comunidades en paredes rocosas verticales de dos alturas , bajas (< 2 m) y altas (> 3 m) en dos regiones templadas y dentro del mismo rango de profundidades. Específicamente, examinamos la diversidad y el recubrimiento de invertebrados, el recubrimiento y la biomasa de algas foliosas e incrustantes, la medida de las colonias de invertebrados y la biomasa de erizos en paredes bajas y altas (n = 3) en dos localidades de cada país. Resultados, Las algas foliosas dominaban las paredes rocosas en España y, aunque el recubrimiento de invertebrados era alto, las colonias eran generalmente muy pequeñas. Dos especies de erizos eran comunes en las paredes rocosas en España: Arbacia lixula y Paracentrotus lividus. Su biomasa total era relativamente pequeña y no mostraba diferencias significativas entre paredes bajas y altas. Estos resultados contrastan con los hallados en el sudeste de Australia, donde las algas foliosas eran prácticamente ausentes. Una única especie de erizo, Centrostephanus rodgersii, se encontraba en las paredes bajas, donde presentaba elevadas biomasas. Estas paredes estaban dominadas por algas incrustantes y carbonatadas resistentes al ramoneo por erizos. En cambio, la biomasa de este erizo era baja en paredes altas, que estaban dominadas por invertebrados, con recubrimientos normalmente por encima del 95%. Las colonias de invertebrados eran significativamente más grandes tanto en las paredes altas como bajas en el sudeste de Australia en comparación con el Mediterráneo. Los resultados dentro de cada país eran consistentes entre las réplicas de paredes estudiadas y entre localidades. Contrariamente a nuestra predicción, sin embargo, había una variación significativa entre paredes dentro de una localidad pero no entre localidades dentro de un continente. La variación temporal en estructura en estas comunidades no fue estudiada, pero parece ser limitada. Conclusiones Principales, Concluimos que la topografía submarina, esto es, la presencia de paredes bajas o altas en función del tipo de roca y estructura, tiene un efecto importante en la estructura de las comunidades en el sudeste de Australia. Este factor, sin embargo, tiene un efecto muy limitado en el Mediterráneo español. Las diferencias en estructura observadas entre paredes de diferentes alturas en Australia se correlacionan con diferencias en la biomasa de erizos, los cuales parecen ser determinantes en la estructura de las comunidades. Frecuentemente se estudian interacciones entre especies en zonas alejadas del globo con escasa o nula referencia a la estructura de la comunidad de la que forman parte. En nuestra opinión este hecho impide una correcta interpretación. Nuestros datos son consistentes con la idea de que los organismos en las dos regiones estudiadas experimentan diversas presiones selectivas, por ejemplo, niveles altos de ramoneo por erizos en el sudeste de Australia, y oscurecimiento y disturbancia mecánica asociadas a la cobertura de algas en el Mediterráneo. No parece apropiado comparar procesos que operan a escalas muy amplias (intercontinentales) sin establecer antes un contexto con una comprensión clara de los parámetros ecológicos. [source] Effects of natural disturbance and selective logging on Nothofagus forests in south-central ChileJOURNAL OF BIOGEOGRAPHY, Issue 7 2002William Pollmann Aim Changes in stand structure, floristic composition and tree population dynamics during the last four centuries were described in southern temperate rain forests. The impacts of natural and anthropogenic disturbance since the late 1560s were examined for old-growth and logged forests. Location The study was conducted in montane Nothofagus alpina forests in the Andean Range of south-central Chile. Study sites were located at a range of altitudes between 1000 and 1250 m a.s.l. Methods Temporal variation in species recruitment and annual dendroecological data were used to determine the historical development and disturbance history of three old-growth forests, and three stands after selective logging in the late 1880s to early 1900s. Considering the spatial structure of evergreen vs. deciduous elements, the forests are a mixture of deciduous and evergreen tree species. Results Stem density, maximum stem diameter and basal area differed between the old-growth and logged stands, but species composition did not. At lower altitudes, N. alpina was the dominant canopy species in both old-growth and logged stands, but regeneration of N. alpina was significantly different in these stands. At higher altitudes, N. alpina and N. dombeyi were the dominant canopy species in both old-growth and logged stands, and here regeneration patterns of these Nothofagus species were similar. After selective logging, in mixed forests of shade-intolerant Nothofagus and more shade-tolerant trees (such as Laurelia philippiana) there has been a shift in regeneration from more shade-tolerant resprouting species towards Nothofagus. Major and moderate releases in radial growth, indicative of disturbance, occurred in most of the older trees during the last four centuries, and especially during the last 100 years. Growth rates of N. alpina are higher than those of associated shade-tolerant trees, and apparently increase after disturbances. Main conclusions Results suggest that under disturbance regimes dominated by treefall gaps, and additionally canopy openings by selective logging, maintenance of Nothofagus species appears to be associated with complementary differences in growth rate, sprouting capacity, canopy residence time, and longevity. Such small-scale canopy openings may help explain the relative abundance of N. alpina in montane mixed rain forests in the Andean Range, where the maintenance of Nothofagus species in many stands has been attributed to a high frequency of coarse-scale disturbance. My results serve to emphasize that understanding the species coexistence and forest dynamics in Nothofagus forests may require attention to interspecific differences in life-history characteristics. [source] High temporal variation in the assemblage of Lepidopteran larvae on a constant resourceAFRICAN JOURNAL OF ECOLOGY, Issue 4 2009Sini Skippari Abstract We studied variation in the assemblage of lepidopteran larvae between individual trees, and temporal variation in the diversity and species composition of the assemblage in a medium-altitude rainforest in Kibale National Park, Uganda. Monthly samples of lepidopteran larvae were collected from the leaves of Neoboutonia macrocalyx Pax. between January 1995 and December 1996. During this period, a total of 1961 specimens representing 76 lepidopteran morphospecies were found. The numbers of individuals within species varied enormously, ranging from one to 707 individuals. Assemblages of individual trees were highly similar and dominated by geometrid larvae. Temporal variation in herbivore abundance was high. The number of individuals peaked during the major rainy season in 1995 but not in 1996 and was not correlated significantly with rainfall within these 2 years. In contrast, a negative correlation was found between lepidopteran diversity and rainfall that seems to cause a semi-annual trend in diversity with one or two peaks per year. Furthermore, there was seasonality in the similarity of the assemblage. Consequently, the same species were found in the assemblage during certain times of the year. Our study shows that short-term biodiversity assessments can give a skewed picture of the diversity of tropical forests. Résumé Nous avons étudié la variation de l'assemblage de larves de lépidoptères entre différents arbres, et la variation temporelle de la diversité et de la composition des espèces de l'assemblage dans une forêt pluviale de moyenne altitude du Parc National de Kibale, en Ouganda. Des échantillons de larves de lépidoptères furent récoltés tous les mois sur les feuilles de Neoboutonia macrocalyx Pax entre janvier 1995 et décembre 1996. Pendant cette période, nous avons trouvé un total de 1961 spécimens représentant 76 morphoespèces de Lépidoptères. Le nombre d'individus variait énormément selon les espèces, allant de un à 707 individus. Les assemblages des arbres pris individuellement étaient très comparables et dominés par les larves de géométrides. La variation temporelle de l'abondance des herbivores était importante. Le nombre d'individus a culminé lors de la principale saison des pluies de 1995, mais pas en 1996, et il n'y avait pas de corrélation significative avec les chutes de pluies ces deux années-là. Par contre, nous avons trouvé une corrélation négative entre la diversité des lépidoptères et les chutes de pluies qui semblent causer une tendance semi-annuelle de la diversité, avec un ou deux pics par an. De plus, il y avait une saisonnalité dans la similitude des assemblages. Par conséquent, la même espèce se trouvait dans les assemblages à certaines périodes de l'année. Notre étude montre que les évaluations de courte durée de la biodiversité peuvent donner une image faussée de la diversité des forêts tropicales. [source] Temporal variation in glucocorticoid levels during the resting phase is associated in opposite way with maternal and paternal melanic colorationJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 10 2010A. ROULIN Abstract Sex-dependent selection can help maintain sexual dimorphism. When the magnitude of selection exerted on a heritable sex trait differs between the sexes, it may prevent each sex to reach its phenotypic optimum. As a consequence, the benefit of expressing a sex trait to a given value may differ between males and females favouring sex-specific adaptations associated with different values of a sex trait. The level of metabolites regulated by genes that are under sex-dependent selection may therefore covary with the degree of ornamentation differently in the two sexes. We investigated this prediction in the barn owl, a species in which females display on average larger black spots on the plumage than males, a heritable ornament. This melanin-based colour trait is strongly selected in females and weakly counter-selected in males indicating sex-dependent selection. In nestling barn owls, we found that daily variation in baseline corticosterone levels, a key hormone that mediates life history trade-offs, covaries with spot diameter displayed by their biological parents. When their mother displayed larger spots, nestlings had lower corticosterone levels in the morning and higher levels in the evening, whereas the opposite pattern was found with the size of paternal spots. Our study suggests a link between daily regulation of glucocorticoids and sex-dependent selection exerted on sexually dimorphic melanin-based ornaments. [source] Temporal variation of heterozygosity-based assortative mating and related benefits in a lesser kestrel populationJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 12 2009J. ORTEGO Abstract Heterozygosity as a target of mate choice has received much attention in recent years and there is growing evidence supporting its role in the evolution of mate preferences. In this study we analyse mating patterns in relation to heterozygosity in a lesser kestrel (Falco naumanni) population intensively monitored over six study years (2002,2007). The magnitude of heterozygosity-based assortative mating varied over time, being particularly patent in the last study years (2006, 2007). We have found evidence that this mating pattern entails both direct and indirect-genetic benefits. Clutch size increased with female heterozygosity and more heterozygous males raised a higher number of fledglings particularly in those years when the strength of the heterozygosity-based assortative mating was markedly higher. In the last study year, parent,offspring correlation of heterozygosity was stronger and higher than the expected if individuals would have randomly mated with respect to heterozygosity. Overall, our results offer empirical support to the heterozygous mate hypothesis of sexual selection but suggest that genetic diversity may act as a temporally variable target for mate choice. [source] Social structure of a polygynous tent-making bat, Cynopterus sphinx (Megachiroptera)JOURNAL OF ZOOLOGY, Issue 2 2000Jay F. Storz Abstract The social structure of an Old World tent-making bat Cynopterus sphinx (Megachiroptera), was investigated in western India. A combination of census and mark,recapture data over 2 years (1996,98) was used to infer the form of the mating system, compositional stability of social groups and mode of new social group formation. The breeding population of C. sphinx was subdivided into diurnal roosting colonies, each of which contained one to five discrete roosting groups and often one or more solitary bats in adjacent roosts. Bats most frequently roosted in stem tents constructed in the flower/fruit clusters of the kitul palm Caryota urens. Temporal variation in social structure was assessed using visual census data for a subset of the study population over 3 years (1995,98) spanning six consecutive reproductive periods. The sex and age composition of diurnal roosting groups indicated a polygynous harem-forming mode of social organization, as groups invariably contained a single adult male, 1,37 reproductive females and their dependent young (n= 33 harems). Harem size averaged 6.1 adults in the wet season (n= 19, sd= 3.5) and 13.6 adults in the dry season (n= 14, sd= 8.5). The same harem social configuration was maintained year-round, despite a high degree of synchrony and seasonality in the timing of reproduction. Juveniles of both sexes dispersed after weaning and sexually immature bats were never present in harems at the time of parturition. Adult females often remained associated as roostmates from one parturition period to the next, and group cohesion was unaffected by turnover of harem males. Adult females frequently transferred among roosts within the same colony, and harems underwent periodic fissions and fusions. The founding of new harems most often resulted from the fissioning of previously cohesive harems within the same colony. However, some harems contained disproportionate numbers of yearling females, indicating that new groups are also founded by nulliparous females of the same age cohort. A significant degree of heterogeneity in age composition among harems was revealed in the 1998 dry season, but was unrelated to age-stratification of tent roosts. Although formation of new harems may be non-random with respect to age composition of the founders, founding events are not restricted to newly created tents and often involve recolonization of previously occupied roosts. [source] Temporal variation in contamination of pine engraver beetles with Fusarium circinatum in native Monterey pine forests in CaliforniaPLANT PATHOLOGY, Issue 6 2008N. Erbilgin The relative importance of beetle species associated with Fusarium circinatum -infected Monterey pines was investigated in three Monterey pine forests along the coast of central California, USA from April to November in 2004 and 2005. Fusarium circinatum was frequently isolated from Ips mexicanus and I. plastographus. The mean percentage isolation based upon numbers of I. mexicanus and I. plastographus carrying propagules of F. circinatum was 17·7 and 10·9% in 2004 and 16·7 and 17·3% in 2005, respectively. The mean percentage isolation was high in the spring and early summer and low in late summer and autumn in all three locations for both species. Isolation was higher from beetles emerging from harvested F. circinatum -infected pine-stems than for trapped beetles, 42·4% for I. mexicanus and 45·9% for I. plastographus. The mean (± SE) propagule load of trapped I. mexicanus was 269·5 (± 14·1) in 2004 and 281·7 (± 35·7) in 2005 and was 216·1 (± 28·9) in 2004 and 251·9 (± 28·4) in 2005 for I. plastographus. Mean propagule loads decreased from May to November in all locations for both species. Propagule loads of beetles emerged from infected stems were lower than that of trapped beetles, with means of 89·4 (± 23·2) and 93·0 (± 23·2) for I. mexicanus and I. plastographus, respectively. Thus beetles must acquire fungal propagules from more than one infected host. These results also suggest that higher contamination rates and propagule loads in spring and early summer may indicate a higher risk of pitch canker transmission, relative to late summer or autumn. [source] Temporal variation in the genetic structure of host-associated populations of the small ermine moth Yponomeuta padellus (Lepidoptera, Yponomeutidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2000LÉON E. L. RAIJMANN Temporal changes in allele frequencies were studied in host-associated populations of the small ermine moth Yponomeuta padellus. At one site, populations from three host plants (Sorbus aucuparia, Amelanchier larnarckii, and Crataegus spp.) were sampled annually during a four-year-period and analysed with 20 polymorphic allozyme markers. At two other sites, allele frequencies at 5- 6 enzyme loci of Y. padellus populations from two different host plants were also tested for consistency over a 13-year-pcriod. Significant allele frequency changes occurred in the short-term analysis, whereas allele frequencies remained relatively stable through time in the long-term analyses. Furthermore, allele frequencies of Y. padellus populations from Crataegus spp. were relatively stable compared to the other host populations. The role of the agents responsible for the observed patterns is discussed. [source] Tonically active neurons in the primate striatum and their role in the processing of information about motivationally relevant eventsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2002Paul ApicellaArticle first published online: 11 DEC 200 Abstract Analysis of recordings of single neuronal activity in the striatum of monkeys engaged in behavioural tasks has shown that tonically active neurons (TANs) can be distinguished by their distinct spontaneous firing and functional properties. As TANs are assumed to be cholinergic interneurons, the study of their physiological characteristics allows us to gain an insight into the role of a particular type of local-circuit neuron in the processing of information at the striatal level. In monkeys performing various behavioural tasks, the change in the activity of TANs, unlike the diversity of task-related activations exhibited by the phasically active population of striatal neurons, involves a transient depression of the tonic firing related to environmental events of motivational significance. Such events include primary rewards and stimuli that have acquired a reward value during associative learning. These neurons also respond to an aversive air puff, indicating that their responsiveness is not restricted to appetitive conditions. Another striking feature of the TANs is that their responses can be modulated by predictions about stimulus timing. Temporal variations in event occurrence have been found to favour the responses of TANs, whereas the responses are diminished or abolished in the presence of external cues that predict the time at which events will occur. These data suggest that the TANs respond as do detectors of motivationally relevant events, but they also demonstrate that these neurons are influenced by predictive information based on past experience with a given temporal context. TANs represent a unique subset of striatal neurons that might serve a modulatory function, monitoring for temporal relationships between environmental events. [source] Pelagic and benthic net production of dissolved inorganic carbon in an unproductive subarctic lakeFRESHWATER BIOLOGY, Issue 3 2007JAN ÅBERG Summary 1. Both the pelagic and benthic net dissolved inorganic carbon (DIC) productions were measured in situ on four occasions from June to September 2004, in the unproductive Lake Diktar-Erik in subarctic Sweden. The stable isotopic signal (,13C) of respired organic material was estimated from hypolimnion water data and data from a laboratory incubation using epilimnion water. 2. Both pelagic and benthic habitats were net heterotrophic during the study period, with a total net DIC production of 416 mg C m,2 day,1, of which the pelagic habitat contributed approximately 85%. The net DIC production decreased with depth both in the pelagic water and in the sediments, and most of the net DIC production occurred in the upper water column. 3. Temporal variations in both pelagic and benthic DIC production were small, although we observed a significant decrease in pelagic net DIC production after the autumn turnover. Water temperature was the single most important factor explaining temporal and vertical variations in pelagic DIC production. No single factor explained more than 10% of the benthic net DIC production, which probably was regulated by several interacting factors. 4. Pelagic DIC production, and thus most of the whole-lake net production of DIC, was mainly due to the respiration of allochthonous organic carbon. Stable isotope data inferred that nearly 100% of accumulated DIC in the hypolimnion water had an allochthonous carbon source. Similarly, in the laboratory incubation using epilimnion water, c. 85% of accumulated DIC was indicated to have an allochthonous organic carbon source. [source] Temporal variations of physical and hydrochemical properties of springs in the Mid-Levels area, Hong Kong: results of a 1-year comprehensive monitoring programmeHYDROLOGICAL PROCESSES, Issue 8 2008Chi-Man Leung Abstract Springs and seeps occur in the spaces around Po Hing Fong Street in the Mid-Levels area, Hong Kong. Most of the springs occur through the drainage weepholes on retaining walls at the street. This paper first examines the geology and history of the springs. The paper then reports the findings from a 1-year comprehensive spring monitoring programme. The temporal variations of flow rate, physiochemical parameters and hydrochemistry of the springs are discussed. The average temperatures of the springs were close to the mean air temperature, although there was a systematic lag time of 40 to 50 days between the peak air temperature and highest water temperatures. Spring waters from two rows of weepholes in the retaining wall showed significantly different physical and hydrochemical responses to the changes in rainfall and temperature, though their vertical distance is only about 1 m. The results suggest that water from the upper row of weepholes may represent a recharge source that is shallow or close to the spring outlets, whereas that from the lower row of weepholes may represent a recharge source that is much deeper or further up the hill. Although the spring flows increased rapidly after rainstorms, analysis of the total dissolved solids showed a delayed response to rainstorm events. The concentration of individual ions in the spring water varied in a unique way in response to rainstorm events. It is clear that the presence of underground man-made drainage systems and the leakage from water mains in the study area may add complexity to the solute responses and transport mechanisms. Further studies are required to constrain the impacts of these man-made structures on the hydrogeology of the springs. Copyright © 2007 John Wiley & Sons, Ltd. [source] Nesting area fidelity and survival of female Common Goldeneyes Bucephala clangula: are they density-dependent?IBIS, Issue 3 2002Ingo Ludwichowski The breeding histories of 218 female Common Goldeneyes Bucephala clangula were recorded between 1971 and 2000 in a study area in Schleswig-Holstein, northern Germany. Females were first recorded breeding at a median age of 2 years usually in their area of hatching (philopatry). One hundred and two of 140 females (73%) re-nested only in one of the 13 nesting areas (clusters of nestboxes) for all their known life of up to 13 breeding seasons. The remaining 38 individuals moved between different nesting areas at least once between breeding attempts. The two oldest females were still breeding at a minimum age of 15 years (i.e. 13 years between first and last recorded breeding attempt). Temporal variations in annual survival rates of adult females could best be explained by a model with annual survival rate varying independently and randomly about a mean of 0.830 (se = ±0.023) with an estimated sd of ±0.092 (95% CI = 0.064, 0.138). No trend in the annual survival rate was detected over the study period of 30 years, although the presence of a moderate trend could not be ruled out. The absence of any discernible trend in survival at a time when the population size increased substantially indicates little, if any, density-dependence in survival of female Goldeneyes during this study. [source] Species diversity and population dynamics of rodents in a farm-fallow field mosaic system in Central TanzaniaAFRICAN JOURNAL OF ECOLOGY, Issue 2 2010Rhodes H. Makundi Abstract A Capture-Mark-Recapture study was undertaken in Central Tanzania to compare variations in community structure and population dynamics of rodents in two types of habitats. The study was conducted in fallow field mosaic habitat dominated by perennial and annual grasses (grid BEA) and a more heterogeneous habitat (grid BEB) which was previously woodland cleared of most trees with vegetation dominated by shrubs, bushes, scattered trees and perennial grass. The relative abundance of rodents in BEA was: Mastomys natalensis (73.5%) > Aethomys chrysophilus (8.9%) > Gerbilliscus vicina (7.3%) > Arvicanthis neumanni (6.1%) > Acomys spinosissimus (4.1%) and for grid BEB: M. natalensis (67.6%) > G. vicina (11.2%) > A. neumanni (10.3%) > A. chrysophilus (7.6%) > A. spinosissimus (2.9%). Graphiurus sp., Mus minutoides, Saccostomus mearnsi, Lemniscomys striatus and L. griselda were rare and only occasionally trapped in BEB. Spatial variations in population density were non-significant except for A. chrysophilus. Significant temporal variations within grids were observed, with synchrony of population peaks for some species. The rare species boosted species richness of grid BEB rather artificially, without significantly contributing to higher species diversity. Temporal variations in Simpson's Diversity indices between grids were non-significant except for three out of twenty-one trapping sessions. Résumé Une étude par capture , marquage , recapture fut entreprise dans le centre de la Tanzanie pour comparer les variations de la structure des communautés et de la dynamiques des populations de rongeurs dans deux types d'habitats. L'étude fut menée dans un habitat composé d'une mosaïque de prairies en jachères dominé par des herbes pérennes et annuelles (grille BEA) et dans un habitat plus hétérogène (grille BEB) qui était auparavant une forêt, défrichée de la plupart de ses arbres et dominée par des buissons, des arbustes, des arbres épars et des herbes pérennes. L'abondance relative des rongeurs dans BEA était la suivante : Mastomys natalensis (73,5%) > Aethomys chrysophilus (8,9%) > Gerbilliscus vicina (7,3%) > Arvicanthis neumanni (6,1%) > Acomys spinosissimus (4,1%), et pour la grille BEB: M natalensis (67,6%) > G. vicina (11,2%) > A. neumanni (10,3%) > A. chrysophilus (7,6%) > A. spinosissimus (2,9%). Graphiurus sp. Mus minutoides, Saccostomus mearnsi, Lemniscomys striatus et L. griseldaétaient rares et n'étaient que rarement capturés dans BEB. Les variations spatiales de la densité de population n'étaient pas significatives sauf pour A. chrysophilus. Des variations temporelles significatives furent observées à l'intérieur des grilles, ainsi qu'une synchronisation des pics de population pour certaines espèces. Les espèces rares renforçaient de façon plutôt artificielle la richesse en espèces de la grille BEB, sans contribuer significativement à une plus grande diversité des espèces. Des variations temporelles des indices de diversité de Simpson entre les grilles n'étaient pas significatives sauf pour trois des 21 sessions de captures. [source] Ectodomain shedding of membrane-anchored heparin-binding EGF like growth factor and subcellular localization of the C-terminal fragment in the cell cycleJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2005Fujio Toki Heparin-binding EGF-like growth factor (HB-EGF) is initially synthesized as a type I transmembrane protein (proHB-EGF). The proHB-EGF is shed by specific metalloproteases, releasing the N-terminal fragment into the extracellular space as a soluble growth factor (HB-EGF) and the C-terminal fragment (HB-EGF-C) into the intracellular space, where it prevents transcriptional repression by the promyelocytic leukemia zinc finger protein (PLZF). The goal of the present study was to characterize regulation of proHB-EGF shedding and study its temporal variations in HB-EGF-C localization throughout the cell cycle. Quantitative combination analyses of cell surface proHB-EGF and HB-EGF in conditioned medium showed that proHB-EGF shedding occurred during the G1 cell cycle phase. Laser scanning cytometry (LSC) revealed that HB-EGF-C was internalized into the cytoplasm during the late G1 phase and accumulated in the nucleus beginning in the S phase. Subsequent nuclear export of PLZF occurred during the late S phase. Further, HB-EGF-C was localized around the centrosome following breakdown of the nuclear envelope and was localized to the interzonal space with chromosome segregation in the late M phase. Temporal variations in HB-EGF localization throughout the cell cycle were also characterized by time-lapse imaging of cells expressing YFP-tagged proHB-EGF, and these results were consistent with those obtained in cytometry studies. These results indicate that proHB-EGF shedding and subsequent HB-EGF-C signaling are related with progression of the cell cycle and may provide a clue to understand the unique biological significance of non-receptor-mediated signaling of proHB-EGF in cell growth. © 2004 Wiley-Liss, Inc. [source] Late Quaternary upwelling off tropical NW Africa: new micropalaeontological evidence from ODP Hole 658C,JOURNAL OF QUATERNARY SCIENCE, Issue 3 2006Simon K. Haslett Abstract Planktonic foraminifera and radiolaria have been analysed in a Late Quaternary (40,0,ka) sediment sequence from Ocean Drilling Program (ODP) Hole 658C located under a coastal upwelling system near Cap Blanc, offshore northwest Africa, in order to document the palaeoceanographic history of the area. Temporal variations in species abundance and faunal assemblage analysis reveal a tripartite phased sequence of palaeoceanographic change through the Late Quaternary. Phase 1 spans 40,14.5,ka and is characterised by moderate upwelling, but Heinrich event 2 is distinguished as a brief episode of strengthened upwelling. Phase 2 begins with a change in a number of variables at ca. 14.5,ka and extends to ca. 5.5,ka. This phase is characterised by a general strengthening of upwelling, but may be subdivided into three minor phases including (a) the recognition of the Younger Dryas, marked by a temporary reduction in upwelling strength, followed by (b) an intensification of upwelling, and (c) upwelling and high productivity between 8 and 5.5,ka. This phase of upwelling corresponds with maximum Holocene cooling, possibly triggered by the collapse of the Laurentide ice sheet. Phase 3 extends from 5.5 to 0,ka and is characterised by weak upwelling and significant calcite dissolution. These phases are related to climatic events, particularly the African Humid Period (AHP), which is coincident with Phase 2. The AHP is characterised by increased precipitation, linked to an intensification of the African monsoon that enhances North East Trade Wind-driven coastal upwelling and is associated with the expansion of continental vegetation across North Africa. Copyright © 2006 John Wiley & Sons, Ltd. [source] Improved Plasma Spray Torch Stability Through Multi-Electrode DesignCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7 2007J. Schein Abstract Coating production by thermal plasma spray is dependent on the residence time of particles in the plasma jet produced by the gas flow inside a plasma torch. To ensure a high fraction of well-molten particles to be accelerated towards the substrate a long reproducible residence time is needed. This can be achieved by a long plasma jet with little or no temporal variation in length and temperature. While single electrode plasma torches need an unstable attachment of the anodic arc root in order to avoid excess erosion, which also causes an unstable plasma jet, multi-electrode torches allow operation with fixed anode attachments by subdividing the anode current by the number of electrodes used, and thereby thus reducing the power input for each separated arc root. Once the steady anode attachment has been obtained the produced plasma jet exhibits a steady characteristic, but also looses rotational symmetry. The separation can be achieved by using either multi anode or multi cathode geometry with appropriate electrical control. Both version have been produced with 3 electrodes each resulting in two systems known as the Delta Gun (3 anodes) and Triplex (3 cathodes). (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spatial and temporal variation of abundance, biomass and diversity within marine reserves in the PhilippinesDIVERSITY AND DISTRIBUTIONS, Issue 4 2010Jonathan A. Anticamara Abstract Aim, The objective of this study was to investigate the influence of protection duration (years of fishing closure) and location (distance from shore) on reef fish diversity. Location, Danajon Double Barrier Reef, Bohol, Philippines. Methods, Reef fish abundance and size structure, by species, were obtained monthly using replicated underwater visual belt transects (n = 8; 70 × 5-m belt transects) over 3 years (2002,2005) at eight sites that included six marine reserves and two unprotected reef areas. We analysed species accumulation curves, diversity indices and abundance,biomass comparison (ABC) curves within and across the study sites to assess the influence of protection duration and location. Results, Analyses showed that longer protection duration impacted reef fish diversity at both inshore and offshore sites by shifting ABC curves from higher abundance than biomass curves at fished sites to higher biomass than abundance curves at most of the protected sites. Protection duration did not significantly influence either the rate of species accumulation within sites or the 12 diversity indices measured across the study sites. The offshore sites consistently showed higher rates of species accumulation and diversity indices values than inshore sites with similar protection duration. One protected offshore young marine reserve site that has been assessed as the least well-managed showed patterns more consistent with the fished sites. Main conclusions, Analyses showed that protection duration mainly impacted diversity by increasing the dominance of large-bodied species and enhancing total biomass. Besides protection duration, reserve location influenced species accumulation curves and diversity indices. [source] Grasshopper (Orthoptera: Acridoidea) species diversity in the Pampas, ArgentinaDIVERSITY AND DISTRIBUTIONS, Issue 2 2000María Marta Cigliano Abstract., A study was conducted to describe the major features of geographical and temporal variation in the diversity of grassland grasshopper species (Orthoptera: Acridoidea) in different sites of the Pampas, Argentina. Species richness and relative abundance were assessed at 12 sites in eastern La Pampa and western Buenos Aires provinces, from 1994 through 1999. Mean species richness at the regional level was 10, and 34 grasshopper species were collected throughout of the study. Comparison with grasshopper species diversity from the Great Plains of North America is discussed. An evaluation of the proportions of species in each of the three distribution groups (broad, intermediate and narrow) revealed that, over all sites, broadly distributed species made up 14.7% of species composition and intermediately and narrowly distributed species made up 26.5% and 58.8%, respectively. The three top-ranked species in the studied sites were Dichroplus elongatus, D. pratensis and Staurorhectus longicornis. Results showed that, contrary to what was expected, one of the widely distributed species in the region (i.e. Baeacris punctulatus) does not always constitute one of the most abundant species. Finally, the loss of one of the historically most common species in the Pampas, D. maculipennis, is also discussed. [source] Estimation of temporal variation in splash detachment in two Japanese cypress plantations of contrasting ageEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2010Y. Wakiyama Abstract To elucidate splash erosion processes under natural rainfall conditions, temporal variations in splash detachment were observed using a piezoelectric saltation sensor (H11B; Sensit Co., Portland, ND, USA). Preliminary laboratory tests of Sensit suggested that they were suitable for field observations. Field observations were conducted between July and September 2006 in 21- and 36-year-old Japanese cypress (Chamaecyparis obtusa) plantations with mean stand heights of 9·2,m and 17·4,m, respectively. Splash detachment (in g m,2) was measured seven times using splash cups, and raindrop kinetic energy (in J,m,2,mm,1) in both stands was measured using laser drop-sizing (LD) gauges. Sensit was installed to record saltation counts, which were converted to temporal data of splash detachment (splash rate; in g m,2 10,min,1) using the relationship between splash detachment and saltation counts. Surface runoff was monitored using runoff plots of 0·5,m width and 2·0,m length to obtain temporal data of flow depth (in millimeters). Both total splash detachment and raindrop kinetic energy were larger in the older stand. Increased splash rates per unit throughfall were found in both stands after rainless durations longer than approximately one day in both stands. However, a lower splash rate was found in the 21-year stand after rainfall events. During extreme rainstorms, the 21-year stand showed a low runoff rate and a decline in the splash rate, while the 36-year stand showed a higher splash rate and increased flow depth. The piezoelectric sensor proved to be a useful means to elucidate splash erosion processes in field conditions. Copyright © 2010 John Wiley & Sons, Ltd. 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