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Diverse Taxa (diverse + taxa)
Selected AbstractsGrazing Intensity and the Diversity of Grasshoppers, Butterflies, and Trap-Nesting Bees and WaspsCONSERVATION BIOLOGY, Issue 6 2002Andreas Kruess The reduction of management intensity can be a useful tool for the long-term conservation of the biological diversity of grasslands. We analyzed floral and faunal diversity on intensively and extensively (unintensively) grazed pastures and on 5- to 10-year-old ungrazed grasslands in northern Germany. Each of the three grassland habitats differing in grazing intensity was replicated six times. We related diverse taxa such as grasshoppers, butterfly adults and lepidopteran larvae, and trap-nesting solitary bees and wasps to vegetation structure. There was an increase of species richness and abundance from pastures to ungrazed grasslands. The percentage of parasitism of the most abundant trap-nesting species, the digger-wasp ( Trypoxylon figulus), was also higher on ungrazed grasslands. Decreased grazing on pastures enhanced species richness for adult butterflies only, whereas the abundance of adult butterflies, solitary bees and wasps, and their natural enemies increased. Although the differences in insect diversity between pastures and ungrazed grassland could be attributed to a greater vegetation height and heterogeneity ( bottom-up effects) on ungrazed areas, the differences between intensively and extensively grazed pastures could not be explained by changes in vegetation characteristics. Hence, intensive grazing appeared to affect the insect communities through the disruption of plant-insect interactions. A mosaic of extensively grazed grassland and grassland left ungrazed for a few years may be a good means by which to maintain biodiversity and the strength of trophic interactions. Resumen: El mantenimiento de pastizales como hábitats distintos depende del manejo regular, generalmente, por medio de pastoreo o segado, pero se sabe que la diversidad de especies declina con el incremento de intensidad de manejo. La reducción de la intensidad de manejo puede ser una herramienta útil para la conservación a largo plazo de la biodiversidad de pastizales. Analizamos la diversidad florística y faunística en pastizales pastoreados intensiva y extensivamente (no intensivos) y en pastizales de 5 a 10 años no pastoreados en el norte de Alemania. Cada uno de los tres hábitats de pastizal diferentes en el grado de pastoreo fue replicado seis veces. Relacionamos diversos taxones como chapulines, mariposas adultas, larvas de lepidópteros y abejas y avispas solitarias con la estructura de la vegetación. Hubo un incremento en la riqueza y abundancia de especies de pastizales pastoreados a no pastoreados. El porcentaje de parasitismo de la especie de avispa más abundante ( Trypoxylon figulus) también fue mayor en pastizales no pastoreados. La reducción del pastoreo incrementó la riqueza de especies de mariposas adultas solamente, mientras que incrementó la abundancia de mariposas adultas, abejas y avispas solitarias y sus enemigos naturales. Aunque las diferencias en la diversidad de insectos entre pastizales pastoreados y no pastoreados pudiera atribuirse a la mayor altura de la vegetación y a la heterogeneidad (efectos abajo-arriba) en áreas no pastoreadas, las diferencias entre pastizales pastoreados intensiva y extensivamente no podría explicarse por cambios en las características de la vegetación. Por consiguiente, el pastoreo intensivo aparentemente afectó a las comunidades de insectos por la disrupción de las interacciones planta-animal. Un mosaico de pastizales pastoreados extensivamente y pastizales sin pastoreo por varios años puede ser una buena estrategia para mantener la biodiversidad y la vigencia de las interacciones tróficas. [source] Using Phylogenetic Diversity Measures to Set Priorities in Conservation: an Example from Southern South AmericaCONSERVATION BIOLOGY, Issue 5 2001Paula Posadas The goal of these ranks for conservation is to consider as many factors as possible that provide additional taxic information, such as taxa richness, taxa distributional patterns, area endemicity, and complementarity between areas. At present there are many measures that consider phylogenetic information, including node-based, genetic-distance, and feature-based measures. We devised a modified phylogenetic node-based index that we call "taxonomic endemicity standardized weight," which considers not only the taxonomic distinctness of the taxa that inhabit a given area but their endemicity as well. Once the standardized weight of the taxonomic endemicity identifies the area of highest priority, complementarity can be used to identify the second area and so on. We used this node-based index to rank priority areas for conservation in southern South America, and we compared the results of our rankings to results based on other node-based indexes. Our index identified Santiago district, in Central Chile province, as the highest priority area for conservation, followed by Maule, Malvinas, and districts of Subantarctic province. Malvinas exhibits greater complementarity relative to Santiago than Maule does, however, so Malvinas is ranked second in priority. Indexes based on phylogenetic information measure the evolutionary component of biodiversity and allow one to identify areas that will ensure the preservation of evolutionary potential and phylogenetically rare taxa. The modified index we propose is sensitive to taxic distinctness and endemicity as well and allows information from diverse taxa to be combined (i.e., different cladograms). The use of complementarity allows for preservation of the maximum quantity of taxa in a minimal number of protected areas. Resumen: Las medidas de diversidad filogenética jerarquiza a las áreas para prioridades de conservación de biodiversidad con base en información codificada en filogenias (cladogramas), La meta de estas categorías de conservación requiere tomar en consideración tantos factores que proporcionan información adicional (riqueza de taxones, patrones de distribución de los taxones, endemicidad del área y complementariedad entre áreas) como sea posible. Actualmente hay muchas medidas que consideran información filogenética (basadas en nodos, distancia genética y basadas en características). Diseñamos un índice filogenético modificado basado en nodos que denominamos "peso estandarizado de endemicidad taxonómica", el cual considera no solo la peculiaridad genética de los taxa que habitan una región determinada sino también su endemicidad. Una vez que el peso estandarizado de endemicidad identifica el área de mayor prioridad, la complementariedad se puede usar para identificar la segunda área y así sucesivamente. Utilizamos este índice basado en nodos para jerarquizar áreas prioritarias para conservación en el sur de América del Sur, y comparamos los resultados de nuestras jerarquizaciones con resultados obtenidos con otros índices basados en nodos. Nuestro índice identificó al distrito de Santiago, en la provincia de Chile Central, como el área de mayor prioridad para conservación, seguido por Maule, Malvinas y distritos de la provincia Subantártica. Sin embargo, Malvinas presenta mayor complementariedad en relación con Santiago que el Maule y, por tanto, Malvinas ocupa la segunda prioridad. Los índices basados en información filogenética miden el componente evolutivo de la biodiversidad y permiten la identificación de áreas que aseguran la preservación de taxones con potencial evolutivo y filogenéticamente peculiares. El índice modificado que proponemos es sensible tanto a la peculiaridad de los taxones como a la endemicidad y permite combinar información de diversos taxones (i.e. cladogramas diferentes). El uso de la complementariedad permite la preservación de la mayor cantidad de taxones en un número mínimo de áreas protegidas. [source] GENETIC ANALYSIS OF A CHROMOSOMAL HYBRID ZONE IN THE AUSTRALIAN MORABINE GRASSHOPPERS (VANDIEMENELLA, VIATICA SPECIES GROUP)EVOLUTION, Issue 1 2009Takeshi Kawakami Whether chromosomal rearrangements promote speciation by providing barriers to gene exchange between populations is one of the long-standing debates in evolutionary biology. This question can be addressed by studying patterns of gene flow and selection in hybrid zones between chromosomally diverse taxa. Here we present results of the first study of the genetic structure of a hybrid zone between chromosomal races of morabine grasshoppers Vandiemenella viatica, P24(XY) and viatica17, on Kangaroo Island, Australia. Chromosomal and 11 nuclear markers revealed a narrow hybrid zone with strong linkage disequilibrium and heterozygote deficits, most likely maintained by a balance between dispersal and selection. Widths and positions of clines for these markers are concordant and coincident, suggesting that selection is unlikely to be concentrated on a few chromosomes. In contrast, a mitochondrial marker showed a significantly wider cline with centre offset toward the P24(XY) side. We argue that the discordance between the mitochondrial and nuclear/chromosomal clines and overall asymmetry of the clines suggest a secondary origin of the contact zone and potential movement of the zone after contact. Genome-wide scans using many genetic markers and chromosomal mapping of these markers are needed to investigate whether chromosomal differences directly reduce gene flow after secondary contact. [source] Substrate specificity of a maize ribosome-inactivating protein differs across diverse taxaFEBS JOURNAL, Issue 7 2000Julie E. Krawetz The superfamily of ribosome-inactivating proteins (RIPs) consists of toxins that catalytically inactivate ribosomes at a universally conserved region of the large ribosomal RNA. RIPs carry out a single N-glycosidation event that alters the binding site of the translational elongational factor eEF1A and causes a cessation of protein synthesis that leads to subsequent cell death. Maize RIP1 is a kernel-specific RIP with the unusual property of being produced as a zymogen, proRIP1. ProRIP1 accumulates during seed development and becomes active during germination when cellular proteases remove acidic residues from a central domain and both termini. These deletions also result in RIP activation in vitro. However, the effectiveness of RIP1 activity against target ribosomes remains species-dependent. To determine the potential efficiency of maize RIP1 as a plant defense protein, we used quantitative RNA gel blots to detect products of RIP activity against intact ribosomal substrates from various species. We determined the enzyme specificity of recombinant maize proRIP1 (rproRIP1), papain-activated rproRIP1 and MOD1 (an active deletion mutant of rproRIP1) against ribosomal substrates with differing levels of RIP sensitivity. The rproRIP1 had no detectable enzymatic activity against ribosomes from any of the species assayed. The papain-activated rproRIP1 was more active than MOD1 against ribosomes from either rabbit or the corn pathogen, Aspergillus flavus, but the difference was much more marked when rabbit ribosomes were used as a substrate. The papain-activated rproRIP1 was much more active against rabbit ribosomes than homologous Zea mays ribosomes and had no detectable effect on Escherichia coli ribosomes. [source] Population differences in behaviour are explained by shared within-population trait correlationsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2010JONATHAN N. PRUITT Abstract Correlations in behavioural traits across time, situation and ecological context (i.e. ,behavioural syndromes' or ,personality') have been documented for a variety of behaviours, and in diverse taxa. Perhaps the most controversial inference from the behavioural syndromes literature is that correlated behaviour may act as an evolutionary constraint and evolutionary change in one's behaviour may necessarily involve shifts in others. We test the two predictions of this hypothesis using comparative data from eighteen populations of the socially polymorphic spider, Anelosimus studiosus (Araneae, Theriidae). First, we ask whether geographically distant populations share a common syndrome. Second, we test whether population differences in behaviour are correlated similarly to within-population trait correlations. Our results reveal that populations separated by as much as 36° latitude shared similar syndromes. Furthermore, population differences in behaviour were correlated in the same manner as within-population trait correlations. That is, population divergence tended to be along the same axes as within-population covariance. Together, these results suggest a lack of evolutionary independence in the syndrome's constituent traits. [source] Circadian rhythms in plants: a millennial viewPHYSIOLOGIA PLANTARUM, Issue 4 2000C. Robertson McClung Circadian rhythms are endogenous rhythms with periods of approximately 24 h. These rhythms are widespread both within any given organism and among diverse taxa. As genetic and molecular biological studies, primarily in a subset of model organisms, have begun to identify the components of circadian systems, there is optimism that we will soon achieve a detailed molecular understanding of circadian timing mechanisms. Although plants have provided many examples of rhythmic outputs, and our understanding of photoreceptors of circadian input pathways is well-advanced, plants have lagged behind other groups of organisms in the identification of components of the central circadian oscillator. However, there are now a number of promising candidates for components of plant circadian clocks, and it seems probable that we will soon know the details of a plant central oscillator. Moreover, there is also accumulating evidence that plants and other organisms house multiple circadian clocks, both in different tissues and, quite probably, within individual cells. This provides an unanticipated level of complexity with the potential for interaction among these multiple oscillators. [source] Insects ,Down Under', Diversity, endemism and evolution of the Australian insect fauna: examples from select ordersAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 3 2004Andrew D Austin In addition, a number of groups are noticeably absent or depauperate on the continent. Many groups found in Australia show characteristic Gondwanan distribution patterns on the southern continents. There are extensive radiations on the plant families Myrtaceae and Mimosaceae, a specialised arid/semiarid fauna, and diverse taxa associated with rainforests and seasonally wet tropical regions. The fauna is also poorly studied, particularly when compared with the flora and vertebrate groups. However, studies in the last two decades have provided a more comprehensive picture of the size of the fauna, relationships, levels of endemism, origins and its evolution. Here we provide an overview of these and other aspects of Australian insect diversity, focusing on six groups, the Thysanoptera and the five megadiverse orders Hemiptera, Coleoptera, Diptera, Lepidoptera and Hymenoptera. [source] | ||||||||||