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61.
Parasitic plants rely completely or partially on host plant, namely holoparasitic or hemiparasitic, respectively. The effect of parasitism on host plants is not fully known. Misodendrum punctulatum (Misodendraceae) is the most common hemiparasite species in the southernmost forests of Chile and Argentina, and it has been identified as an important sanitary problem in forestry. In this study we evaluated the M. punctulatum effect on growth rates and architecture of pure Nothofagus pumilio (Nothofagaceae) forests in southern South America (52°10′S; 71°55′W). We established three plots of 30 × 30 m, and 10 cores were extracted from diameter at breast height (d.b.h. = 1.3 m) from living trees in each plot, using increment borers. Tree rings were measured, and anova was used to compare the annual growth rate of both infected and uninfected N. pumilio. The results showed that N. pumilio trees severely infected by M. punctulatum reduce growth rates in contrast with uninfected individuals (P < 0.05). Besides, trees with high‐infection levels evidenced deterioration in its architecture, showing asymmetric and suppressed canopies, according to ad hoc numerical indexes. This study provides a starting point to understand the parasite–host relationship in the Patagonian forests of southern Chile.  相似文献   
62.
Few studies have found strong evidence to suggest that ecotones promote species richness and diversity. In this study we examine the responses of a high‐Andean bird community to changes in vegetation and topographical characteristics across an Andean tree‐line ecotone and adjacent cloud forest and puna grassland vegetation in southern Peru. Over a 6‐month period, birds and vegetation were surveyed using a 100 m fixed‐width Distance Sampling point count method. Vegetation analyses revealed that the tree‐line ecotone represented a distinctive high‐Andean vegetation community that was easily differentiated from the adjacent cloud forest and puna grassland based on changes in tree‐size characteristics and vegetation cover. Bird community composition was strongly seasonal and influenced by a pool of bird species from a wider elevational gradient. There were also clear differences in bird community measures between tree‐line vegetation, cloud forest and puna grassland with species turnover (β‐diversity) most pronounced at the tree‐line. Canonical Correspondence Analysis revealed that the majority of the 81 bird species were associated with tree‐line vegetation. Categorizing patterns of relative abundance of the 42 most common species revealed that the tree‐line ecotone was composed primarily of cloud forest specialists and habitat generalists, with very few species from the puna grassland. Only two species, Thlypopsis ruficeps and Anairetes parulus, both widespread Andean species more typical of montane woodland vegetation edges, were categorized as ecotone specialists. However, our findings were influenced by significant differences in species detectability between all three vegetation communities. Our study highlights the importance of examining ecotones at an appropriate spatial and temporal scale. Selecting a suitable distance between sampling points based on the detection probabilities of the target bird species is essential to obtain an unbiased picture of how ecotones influence avian richness and diversity.  相似文献   
63.
Abstract: Since 1997 the Mexican government has promoted Management Units for Conservation and Sustainable Use of Wildlife (UMAs) on private and community lands as an economically attractive mean for the conservation of biodiversity. To date, compliance of UMAs with stated sustainability goals has not been evaluated. Thus, we designed multicriteria evaluation framework based on the stated objectives of the national UMA program and applied it to a sample of 6 UMAs operating in peasant communities near or in the Calakmul Biosphere Reserve in Campeche, Mexico. Evaluation criteria covered thematic areas of environment, economy, social development, and laws and rules. We formulated 15 criteria with 29 indicators, and 133 verifiers. Data for the verifiers were based on direct observation, interviews with key actors in the peasant communities, participation in regional meetings, scrutiny of government reports, and databases. We calculated sustainability indexes by weighting, summing, and standardizing verifiers to percentage scales, and aggregating to the successive higher hierarchical levels of the evaluation framework. We found an average overall sustainability index of 45.7% for the UMAs evaluated. Scores were highest for the environment thematic area (55.2%), followed by economy (43.4%), social development (42.3%), and laws and rules (41.7%). We observed particularly low indicators for management strategies, habitat monitoring, environmental education, and knowledge of wildlife laws. We conclude that the contribution of UMAs to the conservation and sustainable use of biodiversity could be improved by a number of actions. These include developing wildlife management educational programs with a strong environmental legislation component, the correct enforcement of wildlife laws, and creating country-wise links among academic and governmental institutions promoting the work with regional and national wildlife experts.  相似文献   
64.
The taxonomy and nomenclature of the genus Huperzia Bernh. in the Azores and Madeira have been reviewed. Plants collected in the Azores and Madeira were characterized morphologically. The independence between two endemic species common to Madeira and the Azores Islands –Huperzia suberecta (Lowe) Tardieu and Huperzia dentata (Herter) Holub – is clearly shown. A clear‐cut morphological separation between these taxa and Huperzia selago (L.) Bernh. ex Schrank & Mart. of continental Europe is established. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 522–533.  相似文献   
65.
Abstract: A growing international concern for the welfare of animals, combined with the need to capture and handle specific species for conservation, management, or recreational purposes, is increasing the need for scientific evaluation of capture methods. We evaluated the efficiency, selectivity, and injury of cable restraint devices and cage-traps for capture of red foxes (Vulpes vulpes) in 4 sites of Castilla y León (Spain) during spring of 2006. All traps performed similarly at all sites, with no apparent site and trap interactions. Fox capture rates and mechanical efficiencies of the Belisle® (Edouard Belisle, Saint Veronique, PQ, Canada) and Collarum® (Wildlife Control Supplies, East Granby, CT; mention of product names does not infer endorsement) were similar, but both had higher capture rates than the cage-trap. Similar to previous studies, the Collarum was 100% selective for canids and had a selectivity of 94.4 overall, which was higher than that for the Belisle (63.4); both Collarum and Belisle were much more selective than the cage-trap (21.4). Fox injuries were statistically indistinguishable using injury scores, but the Collarum and the Belisle surpassed international standards for humane trapping; an insufficient number of animals were captured in cage-traps to allow evaluation. Both the Collarum and the Belisle may be useful for the capture of foxes in Spain, but training and experience with each may be necessary to ensure the highest efficiency while preventing injuries, especially to nontarget species. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):830–836; 2008)  相似文献   
66.
We present a phylogenetic and taxonomic study of the morphology and biology of the terminal‐instar larval stage of 19 species representing all the genera of Torymidae parasitoids of gall wasps in Europe, with the single exception of Megastigmus. The genera studied include Adontomerus Nikol'skaya, Idiomacromerus Crawford, Chalcimerus Steffan & Andriescu, Glyphomerus Förster, Pseudotorymus Masi and Torymus Dalman. We primarily used chaetotaxy and some head structures. The terminal‐instar larvae of all studied species are thoroughly described for the first time and illustrated with SEM images. We provide diagnostic characters for the family and the genera studied, and keys to genera and species for the identification of torymid larvae associated with cynipid galls. The majority of the torymid larvae studied are solitary monophagous parasitoids. Finally, to assess the potential use of larval characters in systematic studies of the family, a phylogenetic analysis of the studied taxa based on 42 larval morphological characters is proposed and compared with the current taxonomy of Torymidae. Our results suggest that body chaetotaxy, and characters of the head and mouthparts could be used for genera and species discrimination. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 676–721.  相似文献   
67.
Comparison of the diversity and community structure of Coleoptera (Passalidae) collected in Los Tuxtlas, Veracruz, Mexico, in primary and secondary tropical forest has been carried out. The saproxylophagous beetles studied can be differentiated according to their presence in three distinct microhabitats of rotting logs: underbark, sapwood—heartwood and microhabitat generalists. Over the 2-year study period, 12 passalid species were recorded (six Passalini and six Proculini) represented by a total of 2971 individuals, collected from 234 rotting logs. The rarefaction method, the lognormal species—abundance relationship, and the nonparametric jackknife method were used to compare species richness between the habitats. The data were also fitted to log series, truncated lognormal, geometric, and broken-stick species abundance models to detect changes in community structure. The community composition of Passalidae in Los Tuxtlas did not differ ostensibly between the primary and secondary forests. Neither the mean number of individuals nor the biomass per log differed significantly. Furthermore, there were no significant differences between the two habitats in terms of the number of underbark, sapwood/heartwood, and microhabitat generalist species. Different richness estimators indicated that the primary forest community is only slightly richer. The slight decrease in richness of the secondary forest is related to a decrease in dominance by certain species, as well as to a more balanced abundance distribution, which is adequately described by the broken-stick model. Complementary explanations for this pattern may be: (1) that logging reduces the abundance of dominant species, thus preventing competitive exclusion in the secondary forest; and (2) that passalid diversity is not regulated by the diversity of tree species.  相似文献   
68.
Nectar samples were collected from Silene colorata Poiret (Caryophyllaceae), in three different populations from south-western Spain: Zahara de la Sierra (Cádiz), Bornos (Cádiz) and Bormujos (Seville). Samples were analysed for amino acids by reverse-phase high-performance liquid chromatography with precolumn phenylisotiocyanate (PITC) derivatization. The method has the advantage of being highly sensitive, capable of detecting nanogram (ng) quantities of amino acids. Eighteen amino acids were identified and quantified. The mean number of amino acids in a nectar sample was 14 (SD = 2.8). Six amino acids (threonine, alanine, arginine, proline, tyrosine and methionine) were detected in all samples, accounting for 83% of the total amino acids content; proline and arginine were the most abundant amino acids, accounting for 40% and 20% of the total amino acids, respectively. The mean amounts of amino acids in nectar samples per population were 824, 782 and 356 µ m in Zahara de la Sierra, Bornos and Bormujos, respectively. Environmental variations such as temperature and sunlight are factors influencing the metabolic processes of nectar production. Our results may contradict the theory that the chemical constituents of floral nectar vary according to the kinds of pollinators.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 49–56.  相似文献   
69.
Morphological variation of the Y chromosome has been observed in different populations. This variation is mostly related to the heteromorphic Yq12 band, which is composed of a variable block of constitutive heterochromatin. The Yqh+ heteromorphism has a worldwide frequency of 2.85% and is considered clinically innocuous. The aim of this study was to identify the ancestry of the Yqh+ heteromorphism present in individuals from western Mexico. For this purpose, 17 Y-chromosome single nucleotide polymorphisms were analysed by multiplex polymerase chain reaction and SNaPshot assays. In 28 Yqh+ males, only five haplogroups were observed; with a haplogroup diversity of 0.4841 ± 0.1094, which was less than that observed in a study of unselected Mexican mestizo population. Differences were specifically conferred by the high frequencies of haplogroups R1b1 and P*(xQ,R), and by the absence of the Amerindian haplogroup Q (Q*(xQ1a3a) plus Q1a3a) from the Yqh+ group. This study suggests a post-1492 incorporation for Yqh+ chromosomes into the Mexican northwestern population.  相似文献   
70.
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