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Same Trees (same + tree)
Selected AbstractsHouse Finch Carpodacus mexicanus roosting behaviour during the non-breeding season and possible effects of mycoplasmal conjunctivitisIBIS, Issue 1 2007ANDRÉ A. DHONDT We studied House Finch Carpodacus mexicanus roosting behaviour during the non-breeding season using radiotracking and direct observations in Ithaca, NY, USA. In contrast to what has been reported in the literature and in contrast to what should be expected from Newton's European studies of cardueline finches, House Finches roost in small groups (mean 3.5; maximum 11) and do not display at roost sites. Seventy-seven per cent of the birds re-used the same tree on successive observations. In winter, birds re-used the same roost tree more often than in the autumn, and birds with mycoplasmal conjunctivitis tended to move more between roost trees than did birds without conjunctivitis. A small number of radiotagged birds that roosted in the same tree were observed together in the daytime more often than by chance, suggesting the existence of social bonds between birds (some same sex) during the non-breeding season. In the autumn the birds often roosted in leafed deciduous trees and closer to their daytime feeding locations than they did in winter. In winter all birds roosted in evergreen trees. It is possible that the reliable and predictable food sources at feeding sites offered by the public might have changed House Finch roosting behaviour. [source] Variation of haplotype distributions of two genomic regions of Citrus tristeza virus populations from eastern SpainMOLECULAR ECOLOGY, Issue 2 2003F. D'Urso Abstract Genetic variation in natural populations of Citrus tristeza virus (CTV) was studied using haplotypes detected by single-strand conformation polymorphism (SSCP) analysis of two genomic regions (p20 gene and segment A, located in ORF1a). Analysis of 254 samples from 125 trees, collected at 12 different sites, yielded 8 different haplotypes for p20 and 5 for segment A. The most frequent haplotype of p20 was predominant at all sites, but several sites differed in the predominance of segment A haplotypes. At most sites, the homozygosity observed for the p20 gene tended to be higher than expected in a neutral evolution, whereas the opposite was true for segment A. Comparison of the populations at different sites showed that 44 of the 66 possible population pairs were genetically distinct for segment A, but only six pairs differed for the p20 gene. Analysis of molecular variance grouping trees by site, scion variety, rootstock or age, showed that variation in segment A was significantly affected by site, tree age and rootstock, and that variation between trees in each group and within trees was even more important. In contrast, variation in p20 was affected only by site and rootstock, each factor contributing to < 2% of the variation. The data suggest that sequence variations in segment A must be functionally less important and that it has less evolutionary constraints than p20. Detection of different haplotypes in neighbour trees or in samples from the same tree may help explain part of the variability observed in CTV symptom expression. [source] Brief communication: Puncture and crushing resistance scores of Tana river mangabey (Cercocebus galeritus) diet itemsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009Julie Wieczkowski Abstract Cercocebus mangabeys are characterized by dental traits that have been interpreted as adaptations to eat hard diet items. Although there are data that mangabeys include a large proportion of fruit and especially seeds in their diets, no hardness measurements have been done on mangabeys' food items. This study measured puncture and crushing resistance of food items in the diet of the Tana River mangabey (C. galeritus). Feeding data were collected by the use of scan samples from one mangabey group from August 2000 to July 2001 and from July 2005 to June 2006. Food items were collected during the latter period only, and from the same tree in or under which mangabeys had been observed eating. A portable agricultural fruit tester was used to measure the puncture resistance of fruit and a valve spring tester was used to measure the crushing resistance of seeds. The average puncture resistance of fruit was 1.7 kg/mm2, and the average crushing resistance of seeds was 12.8 kg. There were no correlations between puncture resistance, crushing resistance, or all resistance scores and frequency contribution to the diet. Resistance scores measured in this study were within the range of hardness scores of fruit and exceeded hardness scores of seeds eaten by other hard object feeders. Although this study supports the interpretation that Cercocebus dental traits are adaptations to hard object feeding, future research should investigate other material properties of food, as well as the role hard diet items play in niche separation and as fallback foods. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] Systemic induced resistance in Monterey pineFOREST PATHOLOGY, Issue 2 2001Bonello The pathogenic fungus Fusarium circinatum causes pitch canker of pines. This study shows that Monterey pine (Pinus radiata), one of the most economically important pine species in the world and the main host in California, responds to infection by Fusarium circinatum in a manner consistent with systemic induced resistance. Repeated mechanical inoculations of the same trees in the field produced progressively smaller lesions over a period of 2 years, with mean lesion length decreasing significantly from 2.89 ± 0.42 cm to 1.04 ± 0.17 cm. In the greenhouse, predisposing inoculations with the pathogen induced a significant lesion length reduction, from 5.5 ± 0.21 cm in control trees to 4.46 ± 0.36 cm in predisposed trees over a period of 6 weeks. Under constant environmental conditions in a growth chamber, predisposing inoculations also induced a significant reduction in lesion size, from 3.01 ± 0.15 cm to 2.55 ± 0.18 cm over a period of 4 weeks. This is the first unequivocal report of systemic induced resistance in a conifer. Résistance systémique induite chez le Pinus radiata Fusarium circinatum est l'agent causal du ,pitch canker' des pins. Le Pinus radiata est l'un des pins les plus importants économiquement dans le monde, et le principal hôte de la maladie en Californie. Cette étude montre que P. radiata réagit régulièrement à l'infection de Fusarium circinatum d'une façon qui peut être de la résistance systémique induite. Des inoculations mécaniques répétées sur de mêmes arbres en nature ont produit progressivement des lésions dont la taille diminuait au cours d'une période de deux ans; la longueur des lésions diminuait significativement de 2.89 ± 0.42 cm à 1.04 ± 0.17 cm. En serre, des inoculations de pré-conditionnement avec le parasite ont entraîné une réduction significative de la longueur des lésions, de 5.5 ± 0.21 cm chez les témoins à 4.46 ± 0.36 cm chez les arbres pré-conditionnés, au cours d'une période de six semaines. En conditions environnementales constantes en chambre climatique, les inoculations de pré-conditionnement ont aussi induit une réduction significative de la taille des lésions, de 3.01 ± 0.15 cm à 2.55 ± 0.18 cm, en une période de 4 semaines. Ceci est la première mention non équivoque d'une résistance systémique induite chez un conifère. Induzierte systemische Resistenz in Monterey-Kiefer Der pathogene Pilz Fusarium circinatum verursacht einen Krebs an Kiefern (pitch canker). Die vorliegende Untersuchung zeigt, dass die Monterey-Kiefer (Pinus radiata), eine der ökonomisch wichtigsten Kiefernarten der Welt und Hauptwirt in Kalifornien, auf Infektionen durch Fusarium circinatum mit induzierter systemischer Resistenz reagiert. Wiederholte mechanische Inokulationen der gleichen Bäume im Feld führten zu zunehmend kleineren Läsionen über einen Beobachtungszeitraum von zwei Jahren. Die Länge der Läsionen nahm von 2.89 ± 0.42 cm auf 1.04 ± 0.17 cm signifikant ab. Im Gewächshaus bewirkten prädisponierende Inokulationen mit dem Pathogen eine signifikante Reduktion der Läsionslänge von 5.5 ± 0.21 cm in den Kontrollen auf 4.46 ± 0.36 cm in den prädisponierten Pflanzen über einen Beobachtungszeitraum von sechs Wochen. Prädisponierende Inokulationen bewirkten auch unter konstanten Umweltbedingungen in einer Klimakammer eine signifikante Abnahme der Läsionsgrösse von 3.01 ± 0.15 cm auf 2.55 ± 0.18 über eine Periode von vier Wochen. Es handelt sich hier um den ersten eindeutigen Nachweis von induzierter systemischer Resistenz bei einer Konifere. [source] Bark beetle-mediated fungal infections of susceptible trees induce resistance to subsequent infections in a dose dependent mannerAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2009Nadir Erbilgin Abstract 1,Experiments were conducted to determine whether propagule loads on the twig beetles Pityophthorus setosus and Pityophthorus carmeli (Coleoptera: Scolytidae) influence the pathogen infection of the host tree in the Monterey pine- Fusarium circinatum system. 2,On an average, F. circinatum was isolated from 2.6% and 3.3% of trapped P. setosus and P. carmeli, respectively, although the isolation percentages varied over the season, being highest in the spring and lowest in late summer and fall for both species. Mean pathogen load was 13.4 and 22.6 propagules per beetle, on P. setosus and P. carmeli, respectively, and decreased from May to November for both species. The pathogen was also isolated from approximately 55% of both beetle species that emerged from infected branches. Mean propagule load on emerged P. setosus and P. carmeli was 39 and 66.5, respectively. 3,On the basis of these data, beetle species were treated with one of three propagule loads (low, medium, high) and caged onto live branches to determine whether they could transmit the pathogen. At all propagule loads, both species transmitted the pathogen, and transmission percentage and lesion length, a measure of tree susceptibility, were positively correlated with propagule load. 4,To investigate further whether the previous transmission by beetles could affect response of the same trees to subsequent infection with F. circinatum, different branches were inoculated on the same trees used in the transmission study, and lesion lengths were measured. Lesion lengths were lower on trees that had been previously exposed to beetles treated with high or medium propagule loads than on trees that had previously been exposed to beetles treated with low propagule loads. This suggests that the initial infection by beetles carrying high or medium propagule loads induced resistance to subsequent infections of the host, whereas infections caused by beetles with low propagule loads did not. [source] Competition as a structuring force in leaf miner communitiesOIKOS, Issue 6 2009Ayco J. M. Tack The role of competition in structuring communities of herbivorous insects is still debated. Despite this, few studies have simultaneously investigated the strength of various forms of competition and their effect on community composition. In this study, we examine the extent to which different types of competition will affect the presence and abundance of individual leaf miner species in local communities on oak trees Quercus robur. We first use a laboratory experiment to quantify the strength of intra- and interspecific competition. We then conduct a large-scale field experiment to determine whether competition occurring in one year extends to the next. Finally, we use observational field data to examine the extent to which mechanisms of competition uncovered in the two experiments actually reflect into patterns of co-occurrence in nature. In our experiment, we found direct competition at the leaf-level to be stronger among conspecific than among heterospecific individuals. Indirect competition among conspecifics lowered the survival and weight of larvae of T. ekebladella, both at the branch and the tree-level. In contrast, indirect competition among heterospecifics was only detected in one out of three species pairs examined. In the field experiment, the presence of a given moth species in one year affected the relative abundance of leaf miner species in the next year. Nevertheless, patterns of competition observed in these experiments did not translate into repulsion among free-ranging leaf miners: conspecific larvae of four leaf-mining species were aggregated on the same trees, shoots and leaves. In contrast, heterospecific larvae were only aggregated at the tree-level. We propose that despite the fact that leaf miners do compete and that such effects extend through time, the incidence and strength of competition is relatively small at realistic densities. Hence, competition will likely be of minor importance in shaping the distribution of leaf miners in a natural setting. [source] Are tree trunks habitats or highways?AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2002A comparison of oribatid mite assemblages from hoop-pine bark, litter Abstract Oribatid mites (Acari: Oribatida) are among the most diverse and abundant inhabitants of forest soil and litter, but also have species-rich assemblages on bark and in the canopies of trees. It is unclear whether the trunk of a tree acts simply as a ,highway' for movement of mites into and out of the canopy, or whether the trunk has a distinctive acarofauna. We compare oribatid assemblages from the trunk bark of hoop pine (Araucaria cunninghamii) with those from litter collected beneath the same trees. A 1.0 by 0.5 m area of bark was sampled from three trees at each of five sites using a knockdown insecticide. A 1-L sample of leaf litter was collected as close as possible to the base of each sampled tree. Mites were extracted using Tullgren funnels, identified to genus and morphospecies, and counted. Assemblages were almost 100% distinct, with only one oribatid morphospecies (Pseudotocepheus sp.) collected from both litter and bark. Litter had a higher taxon richness than bark in total and per sample, but oribatids made up a greater percentage of the acarofauna in the bark samples. We had expected that the more consistent physical substrate of bark would be reflected in greater similarity of oribatid faunas on trunks than in litter; however, the opposite proved to be the case. We conclude that hoop-pine trunks are habitats rather than highways for oribatid mites. Based on the observed higher turnover among bark faunas, tree trunks may represent habitat islands whose colonisation by particular oribatid species is more stochastic than that of the more continuous ,sea' of litter. [source] Inner-crown Microenvironments of Two Emergent Tree Species in a Lowland Wet Forest,BIOTROPICA, Issue 2 2005Catherine L. Cardelús ABSTRACT Vascular epiphyte communities, comprising up to 25 percent of tropical forest flora, contribute to plant diversity and thus ecosystem-level processes; however, one of the proximal determinants of those communities, microclimate, is little studied. Here we present the first comprehensive study of microclimates in the inner crowns of two emergent tree species, Hyeronima alchorneoides and Lecythis ampla, at La Selva Biological Station, Costa Rica. We examined photon flux density, temperature, vapor pressure, and humidity in inner-crown branches during the wet and dry seasons and during the wet-season leafless phase of Lecythis. In both seasons, the percentage daily PFD in foliated Lecythis crowns (9%, wet season; 11%, dry season) was significantly higher than in Hyeronima crowns (5%, both seasons), with the leafless wet-season PFD of Lecythis reaching 23 percent of full sun. Temperature and vapor pressure varied less in Hyeronima than in Lecythis crowns during the dry season. Microenvironmental conditions for epiphytes within Hyeronima crowns were more spatially and temporally homogeneous and were more buffered from ambient conditions than within Lecythis crowns. Growing conditions within the crowns of the same trees and among different trees were measurably different and are likely to affect the structure and composition of the resident epiphyte communities. RESUMEN Las epífitas vasculares representan el 25 por ciento de la flora vascular en bosques tropicales. Sin embargo, existe poca información sobre el microclima en que estas plantas habitan. Comparamos flujo fotosintético (PFD), temperatura, presión de vapor y humedad en las ramas interiores de dos especies de árboles emergentes, Hyeronima alchorneoides y Lecythis ampla, en la Estación Biológica La Selva, Costa Rica. En cada estación, se encontró una diferencia significativa entre el por ciento PFD en el dosel de Lecythis (9%, estación lluviosa; 11%, estación seca) y el por ciento PFD registrado en Hyeronima (5.6%, los dos estaciones), con por ciento PFD de Lecythis en la época sin hojas llegando a 23 por ciento. Las copas de Hyeronima mostraron menos variación en temperatura y presión de vapor que las copas de Lecythis durante la época seca. El microclima en el dosel de Hyeronima fue más homogéneo espacialmente y temporalmente y más regulado en comparación con el microclima en Lecythis. Las condiciones de crecer en el dosel de un árbol y entre diferentes árboles son diferentes, y probablemente afectan la estructura y composición de las comunidades de epífitas. [source] | ||||||||||