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We explored mechanisms determining the upper altitudinal limit of ephemeropterans from two different genera: Leptohyphes Eaton, 1882 (Leptohyphidae) and Lachlania Hagen, 1868 (Oligoneuriidae). For this, we (1) surveyed the two taxa in 165 stream sites along a wide altitudinal gradient; (2) sampled benthic fauna at short altitudinal intervals along a stream, from 2780 to 3150 m above sea level; (3) collected adults at the lowest and highest sites; and (4) transplanted nymphs from the lowest to the highest study site in our stream to determine survival over time. Densities of the two taxa declined gradually with altitude and both disappeared between 2950 and 3080 m a.s.l. The upper altitudinal limit in the stream seemed to be most closely related to mean oxygen saturation, temperature, and current velocity. Adults were collected where the nymphs were found, but not at the upstream site where the nymphs were absent, implying limited upstream dispersal of adults and some of the altitudinal constraint lying at the adult stage. Short-term survival of transplanted nymphs was lower than that of controls, suggesting that the distribution was limited at the juvenile stage, and that at least some of the altitudinal constraint is related to the abiotic stream environment. 相似文献
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Empirical evidence for large‐scale human impact on intertidal aggregations,larval supply and recruitment of Pyura praeputialis around the Bay of Antofagasta,Chile
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Patricio H. Manríquez Juan Carlos Castilla Verónica Ortiz María Elisa Jara 《Austral ecology》2016,41(6):701-714
In northern Chile, Pyura praeputialis is an invasive species inhabiting rocky intertidal and subtidal habitats restricted exclusively to the Bay of Antofagasta where it forms extensive aggregations. The negative impact of Pyura gathering on mid‐intertidal abundances of this species has recently been reported at the south‐eastern end of this bay. In the present study we have increased sampling sites to cover the entire bay toward the north‐western end and the northern section, where a coastal marine reserve for the scallop fishery partially restricts shellfish gathering. Therefore, the sampling sites were chosen to represent different levels of shellfish gathering access along the northern shore of the bay. Long‐term monitoring (1999–2014) of changes in tunicate cover and the abundances of larvae and recruits at seven sites are reported. The opening of a remodelled artificial and recreational beach in 2012, on the central‐eastern shore of the bay, has increased accessibility to rocky intertidal platforms that started to be massively visited by Pyura gatherers from the summer of 2013. This allowed for the implementation of an intensive short‐term monitoring program of changes in tunicate cover and the abundances of their larvae and recruits. When gathering access was present the reduction in intertidal cover was generalized to the entire bay and followed by reductions in larvae and recruits. However, these reductions were not found in sites with more restricted gathering access. We conclude that continuous extraction by Pyura gatherers followed by reductions of conspecific larvae and recruits are the main drivers behind the reduced abundance of P. praeputialis in the entire bay of Antofagasta. Thus, if gathering is not stopped important ecosystem services provided by this tunicate in the bay may be threatened. Similar consequences may be expected if other massive and irreversible reductions in other species of the Pyura complex, that inhabit other coasts in the southern hemisphere, occur. The controversy concerning the impacts of invasive species and whether they cause negative, positive or neutral impacts to original ecosystems and fisheries is discussed. 相似文献
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Juan Antonio Surez‐Cuenca Rogelio Robledo‐Nolasco Marco Antonio Alcntara‐Melndez Luis Javier Díaz Hernndez Eduardo Vera‐Gmez Alejandro Hernndez‐Patricio Karla Susana Snchez‐Díaz Juan Ariel Buendía‐Gutirrez Alejandra Contreras‐Ramos Atzin Su Ruíz‐Hernndez Rebeca Prez‐Cabeza de Vaca Paul Mondragn‐Tern 《Journal of cellular and molecular medicine》2019,23(7):4844-4849
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Dalmiro Borzone Mas Patricio F. Alvarenga Pablo A. Scarabotti 《Journal of fish biology》2019,95(5):1298-1310
We analysed the influence of ecological factors, phylogenetic history and trade-offs between traits on the life-history variation among 10 loricariid species of the middle Paraná River. We measured eight life-history variables and classified the life-history strategies following the equilibrium–periodic–opportunistic (EPO) model. Principal-component analysis of life-history traits segregated species along a gradient from small opportunistic (low fecundity, low parental investment) to large equilibrium (low-medium fecundity, high parental investment) species. A clear periodic strategist was absent in the analysed assemblage. Variation partitioning by canonical phylogenetic ordination analysis showed both a component of variation uniquely explained by phylogenetic history (PH; 32.2%) and a component shared between PH and ecological factors (EF; 37%). The EPO model is a useful tool for predicting correlations among life-history traits and understanding potential demographic responses of species to environmental variation. Life-history patterns observed throughout Loricariidae suggests that this family has diversified across all three endpoint strategies of the EPO model. Our study indicates that evolutionary lineage affiliation at the level of subfamily can be a strong predictor of the life-history strategy used by each species. 相似文献
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Patricio Hernáez Erick Villegas-Castro Rafael Campos Duarte Marcelo Antonio Amaro Pinheiro 《Invertebrate reproduction & development.》2019,63(2):88-99
Year-round continuous reproduction in tropical regions is an established paradigm in marine ecology. In this study, we tested this paradigm using the ghost shrimp Callichirus seilacheri from the tropical eastern Pacific as a model species. We also examined size-frequency distribution, sex ratio, and recruitment cycle to contribute to the biological knowledge of this species. To this end, a total of 456 individuals of C. seilacheri were collected during 12 months of sampling. Population structure was symmetrical for both sexes, and the overall sex ratio did not differ from evenness. Males outnumbered females in smaller size classes, though, revealing a potential sex-dependent mortality in small individuals. The breeding pattern followed the well-marked seasonal regime of the region, with ovigerous females registered during the rainy season. While natural variation in the seawater temperature had no influence on reproduction of this species, changes in water salinity possibly triggered the appearance of egg-bearing females in the population. Recruitment occurred throughout the year but was more intense during the dry season, following the appearance of ovigerous females. The adaptability of the life cycle of C. seilacheri to the seasonal climate provides further evidence that reproduction in tropical species is not always continuous. 相似文献
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Separate taurine and chloride efflux pathways activated during regulatory volume decrease 总被引:6,自引:0,他引:6
Stutzin Andres; Torres Ruben; Oporto Macarena; Pacheco Patricio; Eguiguren Ana Luisa; Cid L. Pablo; Sepulveda Francisco V. 《American journal of physiology. Cell physiology》1999,277(3):C392
Organic osmolyte and halide permeability pathways activated inepithelial HeLa cells by cell swelling were studied by radiotracer efflux techniques and single-cell volume measurements. The replacement of extracellular Cl byanions that are more permeant through the volume-activated Cl channel, as indicated byelectrophysiological measurements, significantly decreasedtaurine efflux. In the presence of less-permeant anions, an increase intaurine efflux was observed. Simultaneous measurement of the125I, used as a tracer forCl, and[3H]taurine effluxshowed that the time courses for the two effluxes differed. InCl-rich medium the increasein I efflux was transient,whereas that for taurine was sustained. OsmosensitiveCl conductance, assessed bymeasuring changes in cell volume, increased rapidly after hypotonicshock. The influx of taurine was able to counteractCl conductance-dependentcell shrinkage but only ~4 min after triggering cell swelling. Thistaurine-induced effect was blocked by DIDS. Differences in anionsensitivity, the time course of activation, and sensitivity to DIDSsuggest that the main cell swelling-activated permeability pathways fortaurine and Cl are separate. 相似文献