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1.
Adaptations to tube dwelling in the Bivalvia 总被引:1,自引:0,他引:1
ENRICO SAVAZZI 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1982,15(3):275-297
Tube-dwelling Bivalvia, which enclose themselves in secondary calcareous envelopes (crypts) , evolved polyphyletically within the Gastrochaenacea, Pholadacea and Clavagellacea. The adaptive strategies for maintaining a suitable life position within a soft sediment were the main factor affecting the evolution of these forms. These basic strategies (boring in or cementation to bioclasts; construction of long vertical crypts anchored within the sediment by their own length; elongation and bending of the siphonal extremity of the crypt to reach to the surface after disturbances; passive reorientation by water currents; neo-formation of motile structures) were adopted convergently by representatives of the three superfami-lies. □ Mollusca, Pelecypoda, tube dwelling, functional morphology, ecology. 相似文献
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JOSEP PENUELAS JORDI SARDANS JOAN LLUSIÀ SUSAN M. OWEN JOFRE CARNICER THOMAS W. GIAMBELLUCA ENRICO L. REZENDE MASHURI WAITE ÜLO NIINEMETS 《Global Change Biology》2010,16(8):2171-2185
Plant‐invasive success is one of the most important current global changes in the biosphere. To understand which factors explain such success, we compared the foliar traits of 41 native and 47 alien‐invasive plant species in Oahu Island (Hawaii), a location with a highly endemic flora that has evolved in isolation and is currently vulnerable to invasions by exotic plant species. Foliar traits, which in most cases presented significant phylogenetic signal, i.e. closely related species tended to resemble each other due to shared ancestry, separated invasive from native species. Invasive species had lower leaf mass per area and enhanced capacities in terms of productivity (photosynthetic capacity) and nutrient capture both of macro‐ (N, P, K) and microelements (Fe, Ni, Cu and Zn). All these differences remain highly significant after removing the effects of phylogenetic history. Alien‐invasive species did not show higher efficiency at using limiting nutrient resources, but they got faster leaf economics returns and occupied a different biogeochemical niche, which helps to explain the success of invasive plants and suggests that potential increases in soil nutrient availability might favor further invasive plant success. 相似文献
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Semiempirical modeling of abiotic and biotic factors controlling ecosystem respiration across eddy covariance sites 总被引:1,自引:0,他引:1
MIRCO MIGLIAVACCA MARKUS REICHSTEIN ANDREW D. RICHARDSON ROBERTO COLOMBO MARK A. SUTTON GITTA LASSLOP ENRICO TOMELLERI GEORG WOHLFAHRT NUNO CARVALHAIS ALESSANDRO CESCATTI MIGUEL D. MAHECHA LEONARDO MONTAGNANI DARIO PAPALE SÖNKE ZAEHLE ALTAF ARAIN ALMUT ARNETH T. ANDREW BLACK ARNAUD CARRARA SABINA DORE DAMIANO GIANELLE CAROLE HELFTER DAVID HOLLINGER WERNER L. KUTSCH PETER M. LAFLEUR YANN NOUVELLON CORINNA REBMANN HUMBERTO R.
Da ROCHA MIRCO RODEGHIERO OLIVIER ROUPSARD MARIA‐TERESA SEBASTIÀ GUENTHER SEUFERT JEAN‐FRANCOISE SOUSSANA MICHIEL K.
Van Der MOLEN 《Global Change Biology》2011,17(1):390-409
In this study we examined ecosystem respiration (RECO) data from 104 sites belonging to FLUXNET, the global network of eddy covariance flux measurements. The goal was to identify the main factors involved in the variability of RECO: temporally and between sites as affected by climate, vegetation structure and plant functional type (PFT) (evergreen needleleaf, grasslands, etc.). We demonstrated that a model using only climate drivers as predictors of RECO failed to describe part of the temporal variability in the data and that the dependency on gross primary production (GPP) needed to be included as an additional driver of RECO. The maximum seasonal leaf area index (LAIMAX) had an additional effect that explained the spatial variability of reference respiration (the respiration at reference temperature Tref=15 °C, without stimulation introduced by photosynthetic activity and without water limitations), with a statistically significant linear relationship (r2=0.52, P<0.001, n=104) even within each PFT. Besides LAIMAX, we found that reference respiration may be explained partially by total soil carbon content (SoilC). For undisturbed temperate and boreal forests a negative control of total nitrogen deposition (Ndepo) on reference respiration was also identified. We developed a new semiempirical model incorporating abiotic factors (climate), recent productivity (daily GPP), general site productivity and canopy structure (LAIMAX) which performed well in predicting the spatio‐temporal variability of RECO, explaining >70% of the variance for most vegetation types. Exceptions include tropical and Mediterranean broadleaf forests and deciduous broadleaf forests. Part of the variability in respiration that could not be described by our model may be attributed to a series of factors, including phenology in deciduous broadleaf forests and management practices in grasslands and croplands. 相似文献
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Abstract Sprouting vigour is determined by the plant amount of reserves and intrinsic growth rate of plants. While the first factor has been well studied, the second is far less understood. Although a higher growth rate would imply a higher sprouting vigour, fast‐growing species may have less below‐ground reserves, and thus, a lower sprouting potential. The relative importance of both opposite effects was little explored in the literature. To analyse the influence of growth rate on sprouting vigour, one growth season after a fire we measured plant height of the old (pre‐fire) and new (post‐fire) tissue in 194 individuals of 14 woody species from a woodland in central Argentina. We calculated a mean value of pre‐ and post‐fire height for each species, and obtained from a data‐base potential height at maturity, wood density (WD) and specific leaf area (SLA), as surrogates of intrinsic growth rate. We performed a forward stepwise multiple regression using WD and SLA, together with mean pre‐fire height or potential height as independent variables, and mean post‐fire height (as an indicator of resprout vigour) as the dependent variable. Interactions were also tested. Pre‐fire height, WD and their interaction term were the variables that best explained post‐fire height. We also analysed the relationship between pre‐ and post‐fire size for each species independently by fitting hyperbolic functions. Then we correlated both parameters of the functions to species characteristics (WD, SLA, potential height and mean pre‐fire height). Both parameters of the hyperbolic functions were significantly correlated only with WD, but not with the other species characteristics. All results together indicate that species with low WD (i.e. high potential growth rate) regrow more vigorously than species with high WD when pre‐fire individuals were tall. In contrast, when pre‐fire individuals were small, WD had no influence on sprout vigour. A trade‐off between allocation of biomass to underground reserves and shoot growth seems to be responsible for the patterns obtained. For small individuals, below‐ground reserves seem to play a more important role than inherent growth rate (here measured through WD) in determining the sprouting vigour, while for large individuals, growth rate seems more important than reserves. 相似文献
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ENRICO SAVAZZI 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1990,23(2):195-212
Savazzi, E. 1990 04 15: Biological aspects of theoretical shell morphology. Lethaia . Vol. 23 , pp. 195–212. Oslo. ISSN 0024–1164
Among the available methods in theoretical shell morphology. moving-frame method, produce the broadest range of shell shapes and appear to emulate most closely the biological processes involved in shell morphogenesis and growth. In addition, moving-frame methods can easily be enhnneed in both respects by adding operations that are similar in nature to the original procedures. Improvements beyond this point. however. require a qualitative change in approach. The focus of attention must he transferred from the shell lo the soft parts involved in shell construction. This may be done by (1) regarding the soft parts a5 pneus. and (2) controlling their shape and metabolism through morphogenetic programme based on biochemical reactions. * Theoretical morphology. functional morphology, modelling. computer graphics, Mollusca. Gastropoda. Bivalvia. Brachiopoda . 相似文献
Among the available methods in theoretical shell morphology. moving-frame method, produce the broadest range of shell shapes and appear to emulate most closely the biological processes involved in shell morphogenesis and growth. In addition, moving-frame methods can easily be enhnneed in both respects by adding operations that are similar in nature to the original procedures. Improvements beyond this point. however. require a qualitative change in approach. The focus of attention must he transferred from the shell lo the soft parts involved in shell construction. This may be done by (1) regarding the soft parts a5 pneus. and (2) controlling their shape and metabolism through morphogenetic programme based on biochemical reactions. * Theoretical morphology. functional morphology, modelling. computer graphics, Mollusca. Gastropoda. Bivalvia. Brachiopoda . 相似文献
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NICOLA TOMASI TOBIAS KRETZSCHMAR LUCA ESPEN LAURE WEISSKOPF ANJA THOE FUGLSANG MICHAEL GJEDDE PALMGREN GÜNTER NEUMANN ZENO VARANINI ROBERTO PINTON ENRICO MARTINOIA & STEFANO CESCO 《Plant, cell & environment》2009,32(5):465-475
White lupin ( Lupinus albus L.) is able to grow on soils with sparingly available phosphate (P) by producing specialized structures called cluster roots. To mobilize sparingly soluble P forms in soils, cluster roots release substantial amounts of carboxylates and concomitantly acidify the rhizosphere. The relationship between acidification and carboxylate exudation is still largely unknown. In the present work, we studied the linkage between organic acids (malate and citrate) and proton exudations in cluster roots of P-deficient white lupin. After the illumination started, citrate exudation increased transiently and reached a maximum after 5 h. This effect was accompanied by a strong acidification of the external medium and alkalinization of the cytosol, as evidenced by in vivo nuclear magnetic resonance (NMR) analysis. Fusicoccin, an activator of the plasma membrane (PM) H+ -ATPase, stimulated citrate exudation, whereas vanadate, an inhibitor of the H+ -ATPase, reduced citrate exudation. The burst of citrate exudation was associated with an increase in expression of the LHA1 PM H+ -ATPase gene, an increased amount of H+ -ATPase protein, a shift in pH optimum of the enzyme and post-translational modification of an H+ -ATPase protein involving binding of activating 14-3-3 protein. Taken together, our results indicate a close link in cluster roots of P-deficient white lupin between the burst of citrate exudation and PM H+ -ATPase-catalysed proton efflux. 相似文献
7.
ENRICO SAVAZZI 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1989,22(1):31-48
Savazzi, Enrico 1989 01 15: Burrowing mechanisms and sculptures in Recent gastropods. Lethaia , Vol. 22, pp. 31–48. Oslo. ISSN 0024–1164.
Burrowing was observed in 32 gastropod species, belonging to 8 families, from Italy and the Philippines. Most species burrow by repeating a three-phase sequence: (1) digging with the foot, (2) dragging the shell forward and downward, and (3) rocking the shell around its longitudinal axis. Minor specific differences in the burrowing dynamics are common, and totally different mechanisms also occur. Burrowing sculptures consisting of terraces or asymmetrical tubercles are observed in the majority of the studied species. Characteristics of the burrowing process explain some cases of apparent divergence of burrowing sculptures from the paradigm. Burrowing sculptures in the Gastropoda should be expected to occur mostly among medium-slender, rather than markedly high-spired, shell morphologies. □ Mollusca, Gastropoda, Cerithiidae, Nassariidae, Mitridae, Costellariidae, Conidae, Terebridae, Turridae, Hydro-biidae, shell, sculpture, burrowing, functional morphology, ecology, behaviour, Holocene, Indo-Pacific. Philippines, Mediterranean, Italy . 相似文献
Burrowing was observed in 32 gastropod species, belonging to 8 families, from Italy and the Philippines. Most species burrow by repeating a three-phase sequence: (1) digging with the foot, (2) dragging the shell forward and downward, and (3) rocking the shell around its longitudinal axis. Minor specific differences in the burrowing dynamics are common, and totally different mechanisms also occur. Burrowing sculptures consisting of terraces or asymmetrical tubercles are observed in the majority of the studied species. Characteristics of the burrowing process explain some cases of apparent divergence of burrowing sculptures from the paradigm. Burrowing sculptures in the Gastropoda should be expected to occur mostly among medium-slender, rather than markedly high-spired, shell morphologies. □ Mollusca, Gastropoda, Cerithiidae, Nassariidae, Mitridae, Costellariidae, Conidae, Terebridae, Turridae, Hydro-biidae, shell, sculpture, burrowing, functional morphology, ecology, behaviour, Holocene, Indo-Pacific. Philippines, Mediterranean, Italy . 相似文献
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