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41.
ALISTAIR S. JUMP JOSEP PEÑUELAS LAURA RICO † ELISENDA RAMALLO MARC ESTIARTE JOSÉ A. MARTÍNEZ-IZQUIERDO† FRANCISCO LLORET‡ 《Global Change Biology》2008,14(3):637-643
Rapid climate change will impose strong directional selection pressures on natural plant populations. Climate-linked genetic variation in natural populations indicates that an evolutionary response is possible. We investigated such a response by comparing individuals subjected to elevated drought and warming treatments with individuals establishing in an unmanipulated climate within the same population. We report that reduction in seedling establishment in response to climate manipulations is nonrandom and results from the selection pressure imposed by artificially warmed and droughted conditions. When compared against control samples, high single-locus genetic divergence occurred in drought and warming treatment samples, with genetic differentiation up to 37 times higher than background (mean neutral locus) genetic differentiation. These loci violate assumptions of selective neutrality, indicating the signature of natural selection by drought. Our results demonstrate that rapid evolution in response to climate change may be widespread in natural populations, based on genetic variation already present within the population. 相似文献
42.
ENRIQUE E. MONTAMAT SANDRA DURAND JOSE L. BOCCO GLORIA M. DE LUCA D'ORO ANTONIO BLANCO 《The Journal of eukaryotic microbiology》1999,46(2):155-159
Analysis of zymograms of extracts of Trypanosoma cruzi isolated from different hosts in Argentina allowed characterization of 12 zymodemes or "isozymic strains," only six of which were found in human patients. Two of these six zymodemes (Z1 and Z12) were widely distributed and found in more than 80% of human patients. These two "major natural clones" differed significantly in pathogenic activity. Because the groupings obtained by studying enzymes and kinetoplast DNA (kDNA) were similar, it is possible to identify the zymodeme by analyzing kDNA. A 290-bp fragment was amplified by PCR using primers for the sequences flanking the hypervariable regions of kDNA minicircles. Labeled probes for this fragment, prepared from Z1 and Z12 reference stocks, hybridized specifically with PCR-amplified kDNA from parasite stocks, allowing identification of zymodemes. 相似文献
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CHRISTOPHER B. ANDERSON JUAN L. CELIS‐DIEZ BARBARA J. BOND GUILLERMO MARTÍNEZ PASTUR CHRISTIAN LITTLE JUAN J. ARMESTO CLAUDIO GHERSA AMY AUSTIN TOMAS SCHLICHTER ANTONIO LARA MARTIN CARMONA ENRIQUE J. CHANETON JULIO R. GUTIERREZ RICARDO ROZZI KRISTIN VANDERBILT GUILLERMO OYARCE ROBERTO J. FERNÁNDEZ 《Austral ecology》2012,37(5):529-536
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R. EDUARDO PALMA ENRIQUE RODRÍGUEZ‐SERRANO ERIC RIVERA‐MILLA CRISTIAN E. HERNANDEZ JORGE SALAZAR‐BRAVO MARIA I. CARMA SEBASTIAN BELMAR‐LUCERO PABLO GUTIERREZ‐TAPIA HORACIO ZEBALLOS TERRY L. YATES 《Zoological Journal of the Linnean Society》2010,160(3):551-566
Sequences from two mitochondrial genes (cytochrome b and NADH1) were used to produce a molecular phylogeny for 12 named and two undescribed species of the genus Oligoryzomys. All analyses placed Oligoryzomys microtis as the most basal taxon, a finding consistent with previous studies that suggested the west‐central Amazon as a centre of origin for the tribe Oryzomyini to which Oligoryzomys belongs. Biogeographically, this suggests that Oligoryzomys had a South American origin, and later advanced northwards, entering Central America and Mexico more recently. Different analyses have provided consistent support for several additional clades that did not necessarily agree with the species groups hypothesized by previous studies. A molecular clock derived for these data suggests an origin for the genus of 6.67 Mya, with most speciation within the genus occurring between 3.7 and 1.5 Mya. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 551–566. 相似文献
45.
NOEMÍ MAZÍA ENRIQUE J. CHANETON CRISTINA DELLACANONICA LUCIANO DIPAOLO THOMAS KITZBERGER 《Ecological Entomology》2012,37(3):193-203
1. Endemic herbivory can influence forest ecosystem function, but how annual productivity consumption relates to seasonal resource utilisation by folivore guilds remains poorly understood. 2. Monthly changes in leaf damage and foliage traits were monitored in ‘dry’ and ‘wet’Nothofagus pumilio (Fagales: Nothofagaceae) deciduous forests in northern Patagonia, Argentina. Herbivore‐induced leaf abscission was assessed and foliar productivity consumption was measured in the canopy and in litterfall harvests. 3. Seasonal damage ranged from 8% to 32% in dry forest, but remained below 5% in wet forest although foliar quality was higher in the latter. In dry forest, dominant guilds were temporally separated; leaf miners consumed younger foliage in spring to early summer, whereas leaf tiers prevailed in late summer to autumn. In wet forest, damage created by external chewers was concentrated in early summer. 4. Insect damage induced premature leaf abscission, especially in dry forest. Although foliar production in wet forest doubled that in dry forest, the percentage of productivity lost to folivores was higher in dry (14–20%) than in wet (1.2–1.8%) forest. 5. The overall greater impact of herbivory in dry forest canopies countered the expectation that consumption would increase with plant productivity and nutritional quality. Lower temperatures and a shorter growing season are likely to constrain folivory in wet forest stands. 相似文献
46.
ENRIQUE GARCÍA-BARROS 《Biological journal of the Linnean Society. Linnean Society of London》2000,70(2):251-284
The interspecific relationships between egg size and body size in butterflies (Papilionoidea and Hesperiidae), and between size and egg and larval development time, larval trophic specificity, foodplant structure, climate, and phenology were investigated based on a sample of more than 1180 species. The independent contrasts mediod was used to avoid taxonomy-dependent results. Egg size is allometrically related to adult wing length by a slope of 0.43. Based on a subset of species, fecundity is correlated to adult body size, and there is evidence for a compromise between egg number and egg size (relative to adult size) across species. Butterfly size increases in correlation to the mean annual temperature of me species geographic range, but decreases in relation to increased aridity (or die length of the dry season). Larger butterflies tend to have longer larval development times, use large or structurally complex host plants, and are more likely to lay their eggs in batches, irrespective of climate. Larger eggs tend to develop more slowly, and give rise to larvae with longer developmental periods that will result in larger adults. No evidence was found to support a relationship between butterfly body size and polyphagy. A complex pattern of interrelationships links body size (and egg size) to other traits, although correlations other than mat between egg size and body size are generally low. The results suggest the necessity of separating climate and seasonality into components that are relevant to insect life histories in comparative studies. 相似文献
47.
ISABEL SOTO-CRUZ JANET M. OLIVER ENRIQUE ORTEGA 《Journal of receptor and signal transduction research》2013,33(1):67-81
Aggregation of the multichain (α β γ2) high-affinity IgE receptor (Fcε RI) initiates a signaling cascade that results in the release of allergic mediators. The cytoplasmic tails of the Fcε RI-β and -γ subunits contain immunoreceptor tyrosine-based activation motifs (ITAMs). Phosphorylation of the γ ITAM mediates activation of Syk kinase and is sufficient for triggering the responses induced by Fcε RI crosslinking. Phosphorylation of the β ITAM is insufficient to mediate cell activation. The rat β ITAM contains three tyrosines (Tyr218, Tyr224, and Tyr228) with an intermediate noncanonical tyrosine. Synthetic peptides based on the ITAM of the Fcε RI-β subunit were used to investigate the role of each phosphotyrosine in the binding of signaling proteins to this motif. Among the proteins that bind to phosphorylated β ITAM are Syk, Grb2, Shc, SHIP, and SHP-1, and binding does not depend on previous cell activation. Nonphosphorylated peptides do not bind these proteins. Syk binding to β -peptides is dependent on the number and position of phosphotyrosines in the ITAM. Phosphorylation of Tyr218 seems to be most important for Syk binding. Recruitment of Syk and other signaling proteins to the β -subunit might be important for its amplifier role. 相似文献
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ANA SOFIA SOARES-CORDEIRO SIMON P. DRISCOLL TILL K. PELLNY ENRIQUE OLMOS MARIA CELESTE ARRABAÇA & CHRISTINE H. FOYER 《Plant, cell & environment》2009,32(12):1833-1844
Photosynthesis and associated signalling are influenced by the dorso-ventral properties of leaves. The degree of adaxial/abaxial symmetry in stomatal numbers, photosynthetic regulation with respect to light orientation and the total section areas of the bundle sheath (BS) cells and the surrounding mesophyll (M) cells on the adaxial and abaxial sides of the vascular bundles were compared in two C4 [ Zea mays (maize) and Paspalum dilatatum ] and one C3 [ Triticum turgidum (Durum wheat)] monocotyledonous species. The C3 leaves had a higher degree of dorso-ventral symmetry than the C4 leaves. Photosynthetic regulation was the same on each side of the wheat leaves, as were stomatal numbers and the section area of the BS relative to that of the M cells (BS/M section area ratio). In contrast, photosynthetic regulation in maize and P. dilatatum leaves showed a marked surface-specific response to light orientation. Compared to the adaxial sides of the C4 monocotyledonous leaves, the abaxial surfaces had more stomata and the BS/M section area ratio was significantly higher. Differences in dorso-ventral structure, particularly in Kranz anatomy, serve not only to maximize photosynthetic capacity with respect light orientation in C4 monocotyledonous leaves but also allow adaxial and abaxial-specific signalling from the respective M cells. 相似文献
50.
PATRICIA CABEZAS ENRIQUE MACPHERSON ANNIE MACHORDOM 《Zoological Journal of the Linnean Society》2009,156(3):465-493
The family Galatheidae is among the most diverse families of anomuran decapod crustaceans, and the South‐West Pacific is a biodiversity hot spot for these squat lobsters. Attempts to clarify the taxonomic and evolutionary relationships of the Galatheidae on the basis of morphological and molecular data have revealed the existence of several cryptic species, differentiated only by subtle morphological characters. Despite these efforts, however, relationships among genera are poorly understood, and the family is in need of a detailed systematic review. In this study, we assess material collected in different surveys conducted in the Solomon Islands, as well as comparative material from the Fiji Islands, by examining both the morphology of the specimens and two mitochondrial markers (cytochrome oxidase subunit I, COI, and 16S rRNA). These two sources of data revealed the existence of eight new species of squat lobster, four of which were ascribed to the genus Munida, two to the genus Paramunida, one to the genus Plesionida, and the last species was ascribed to the genus Agononida. These eight species are described along with phylogenetic relationships at the genus level. Our findings support the taxonomic status of the new species, yet the phylogenetic relationships are not yet fully resolved. Further molecular analysis of a larger data set of species, and more conserved genes, will help clarify the systematics of this group. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 465–493. 相似文献