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Srivastava, D. S., Céréghino, R., Trzcinski, M. K., MacDonald, A. A. M., Marino, N. A. C., Mercado, D. A., et al. (2020). Ecological response to altered rainfall differs across the Neotropics. Ecology, 101(4), e02984.
Abstract: There is growing recognition that ecosystems may be more impacted by infrequent extreme climatic events than by changes in mean climatic conditions. This has led to calls for experiments that explore the sensitivity of ecosystems over broad ranges of climatic parameter space. However, because such response surface experiments have so far been limited in geographic and biological scope, it is not clear if differences between studies reflect geographic location or the ecosystem component considered. In this study, we manipulated rainfall entering tank bromeliads in seven sites across the Neotropics, and characterized the response of the aquatic ecosystem in terms of invertebrate functional composition, biological stocks (total invertebrate biomass, bacterial density) and ecosystem fluxes (decomposition, carbon, nitrogen). Of these response types, invertebrate functional composition was the most sensitive, even though, in some sites, the species pool had a high proportion of drought-tolerant families. Total invertebrate biomass was universally insensitive to rainfall change because of statistical averaging of divergent responses between functional groups. The response of invertebrate functional composition to rain differed between geographical locations because (1) the effect of rainfall on bromeliad hydrology differed between sites, and invertebrates directly experience hydrology not rainfall and (2) the taxonomic composition of some functional groups differed between sites, and families differed in their response to bromeliad hydrology. These findings suggest that it will be difficult to establish thresholds of “safe ecosystem functioning” when ecosystem components differ in their sensitivity to climatic variables, and such thresholds may not be broadly applicable over geographic space. In particular, ecological forecast horizons for climate change may be spatially restricted in systems where habitat properties mediate climatic impacts, and those, like the tropics, with high spatial turnover in species composition. © 2020 by the Ecological Society of America
Keywords: contingency; distributed experiment; freshwater; global change biology; macroinvertebrates; phytotelmata; precipitation; aquatic ecosystem; climate change; climate conditions; ecosystem response; extreme event; functional group; invertebrate; Neotropical Region; rainfall; species pool; Bacteria (microorganisms); Invertebrata; rain; animal; climate change; drought; ecosystem; invertebrate; Animals; Climate Change; Droughts; Ecosystem; Invertebrates; Rain
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Leitão, R. P., Zuanon, J., Villéger, S., Williams, S. E., Baraloto, C., Fortunel, C., et al. (2016). Rare species contribute disproportionately to the functional structure of species assemblages. Proceedings of the Royal Society B: Biological Sciences, 283(1828).
Abstract: There is broad consensus that the diversity of functional traits within species assemblages drives several ecological processes. It is also widely recognized that rare species are the first to become extinct following human-induced disturbances. Surprisingly, however, the functional importance of rare species is still poorly understood, particularly in tropical species-rich assemblages where the majority of species are rare, and the rate of species extinction can be high. Here, we investigated the consequences of local and regional extinctions on the functional structure of species assemblages. We used three extensive datasets (stream fish from the Brazilian Amazon, rainforest trees from French Guiana, and birds from the Australian Wet Tropics) and built an integrative measure of species rarity versuscommonness, combining local abundance, geographical range, andhabitat breadth. Using different scenarios of species loss, we found a disproportionate impact of rare species extinction for the three groups, with significant reductions in levels of functional richness, specialization, and originality of assemblages, which may severely undermine the integrity of ecological processes. The whole breadth of functional abilities within species assemblages, which is disproportionately supported by rare species, is certainly critical in maintaining ecosystems particularly under the ongoing rapid environmental transitions. © 2016 The Author(s) Published by the Royal Society. All rights reserved.
Keywords: Conservation; Extinction; Functional diversity; Null models; Rarity index; Tropical biodiversity
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Garcia-Davila, C., Aldana Gomero, D., Renno, J. - F., Diaz Soria, R., Hidalgo Pizango, G., Flores Llampazo, G., et al. (2020). Molecular evidence for three genetic species of Dipteryx in the Peruvian Amazon. Genetica, 148(1), 1–11.
Abstract: There is a high international demand for timber from the genus Dipteryx, or “shihuahuaco” as it is known in Peru. Developing tools that allow the identification and discrimination of Dipteryx species is therefore important for supporting management of natural populations and to underpin legal trade of its timber. The objective of this study was the molecular characterization of Dipteryx species in the Peruvian Amazonia. Two plastid regions (cpDNA: trnH–psbA and matK) were sequenced and 11 microsatellite markers (nDNA) were genotyped for 32 individuals identified as Dipteryx charapilla, D. micrantha morphotype 1 and D. micrantha morphotype 2. Using the concatenated sequences of the plastid genes, we identified ten haplotypes that were not shared between the species or between the D. micrantha morphotypes. Haplotypic diversity was greater in D. micrantha morphotype 2 and D. charapilla than in D. micrantha morphotype 1, which presented only one haplotype with a wide distribution in Peru. The microsatellites allowed the discrimination of the same three clades and identified diagnostic alleles for each clade. These results allowed us to demonstrate that the two morphotypes of D. micrantha are different at both the plastid and nuclear markers, which supports the existence of three genetically distinct species in Peru. This study provides information for the genetic discrimination of Dipteryx species and emphasises the importance of conserving the genetic variability of this genus in the Peruvian Amazonia. © 2019, Springer Nature Switzerland AG.
Keywords: D. micrantha; Dipteryx charapilla; Genetic diversity; Microsatellites; Sequencing; Shihuahuaco; microsatellite DNA; plant DNA; allele; Dipteryx; DNA sequence; genetic variation; genetics; genotype; haplotype; Peru; phylogeny; plastid; river; species difference; Alleles; Dipteryx; DNA, Plant; Genetic Variation; Genotype; Haplotypes; Microsatellite Repeats; Peru; Phylogeny; Plastids; Rivers; Sequence Analysis, DNA; Species Specificity
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Rahali, H., Ghanem, N., Griffe, L., Rahali, R., & Stien, D. (2004). A general approach to the quantification of resin-bound functional groups by NMR. New J. Chem., 28(11), 1344–1346.
Abstract: There has been a continuing need for sensitive, accurate and rapid methods to monitor functional loading of insoluble supports for solid phase synthesis. The present articles reports our findings regarding functional group loading quantification using H-1 NMR. Results obtained for supported amino, hydroxyl and NH-Fmoc groups are in agreement with those calculated using well-established methods and demonstrate that the strategy of looking, either at the excess reagent left in solution (NH2 and OH), or at the protecting group derivatives released from the polymer (Fmoc), is a viable approach to resin loading quanti. cation.
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Szilagyi, A., Scheuring, I., Edwards, D. P., Orivel, J., & Yu, D. W. (2009). The evolution of intermediate castration virulence and ant coexistence in a spatially structured environment. Ecol. Lett., 12(12), 1306–1316.
Abstract: Theory suggests that spatial structuring should select for intermediate levels of virulence in parasites, but empirical tests are rare and have never been conducted with castration (sterilizing) parasites. To test this theory in a natural landscape, we construct a spatially explicit model of the symbiosis between the ant-plant Cordia nodosa and its two, protecting ant symbionts, Allomerus and Azteca. Allomerus is also a castration parasite, preventing fruiting to increase colony fecundity. Limiting the dispersal of Allomerus and host plant selects for intermediate castration virulence. Increasing the frequency of the mutualist, Azteca, selects for higher castration virulence in Allomerus, because seeds from Azteca-inhabited plants are a public good that Allomerus exploits. These results are consistent with field observations and, to our knowledge, provide the first empirical evidence supporting the hypothesis that spatial structure can reduce castration virulence and the first such evidence in a natural landscape for either mortality or castration virulence.
Keywords: Cooperation; evolution of virulence; host-pathogen; mutualism; myrmecophyte; parasite; rock-paper-scissors; spatial games; tolerance; trade-off
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Esquivel-Muelbert, A., Phillips, O. L., Brienen, R. J. W., Fauset, S., Sullivan, M. J. P., Baker, T. R., et al. (2020). Tree mode of death and mortality risk factors across Amazon forests. Nat. Commun., 11(5515).
Abstract: The carbon sink capacity of tropical forests is substantially affected by tree mortality. However, the main drivers of tropical tree death remain largely unknown. Here we present a pan-Amazonian assessment of how and why trees die, analysing over 120,000 trees representing > 3800 species from 189 long-term RAINFOR forest plots. While tree mortality rates vary greatly Amazon-wide, on average trees are as likely to die standing as they are broken or uprooted—modes of death with different ecological consequences. Species-level growth rate is the single most important predictor of tree death in Amazonia, with faster-growing species being at higher risk. Within species, however, the slowest-growing trees are at greatest risk while the effect of tree size varies across the basin. In the driest Amazonian region species-level bioclimatic distributional patterns also predict the risk of death, suggesting that these forests are experiencing climatic conditions beyond their adaptative limits. These results provide not only a holistic pan-Amazonian picture of tree death but large-scale evidence for the overarching importance of the growth–survival trade-off in driving tropical tree mortality. © 2020, The Author(s).
Keywords: bioclimatology; carbon sink; ecological modeling; growth; holistic approach; mortality; mortality risk; risk factor; survival; trade-off; tropical forest; article; climate; controlled study; forest; growth rate; human; mortality rate; mortality risk; survival; biological model; biomass; Brazil; carbon sequestration; ecology; ecosystem; environmental monitoring; growth, development and aging; proportional hazards model; risk factor; tree; tropic climate; Amazonia; carbon dioxide; Biomass; Brazil; Carbon Dioxide; Carbon Sequestration; Ecology; Ecosystem; Environmental Monitoring; Forests; Models, Biological; Proportional Hazards Models; Risk Factors; Trees; Tropical Climate
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Scotti, I., Gugerli, F., Pastorelli, R., Sebastiani, F., & Vendramin, G. G. (2008). Maternally and paternally inherited molecular markers elucidate population patterns and inferred dispersal processes on a small scale within a subalpine stand of Norway spruce (Picea abies [L.] Karst.). For. Ecol. Manage., 255(11), 3806–3812.
Abstract: The within-population spatial structure of genetic diversity is shaped by demographic processes, including historical accidents such as forest perturbations. Information drawn from the analysis of the spatial distribution of genetic diversity is therefore inherently linked to demographic-historical processes that ultimately determine the fate of populations. All adult trees and saplings in a 1.4-ha plot within a mixed Norway spruce (Picea abies [L.] Karst) stand were characterised by means of chloroplast (paternally inherited) markers, and a large sub-sample of these were genotyped at mitochondrial (maternally inherited) molecular markers. These data were used to analyse the spatial distribution of genetic variation and to compare the patterns corresponding to the two marker types. The plot presented non-homogeneous local stem density in the younger cohorts, and the indirect effect of this source of variation on the spatial genetic structure was investigated. Results suggest that (i) spatially limited seed dispersal induced patchiness in genotype distribution, while pollen flow had a homogenising effect; (ii) deviations from random spatial structure were stronger in the demographically most stable portions of the stand, while they were weaker where sudden bursts of regeneration occurred; (iii) spatially overlapping adult and sapling cohorts displayed the same spatial genetic structure (stronger on stable areas, weaker in portions of the stand undergoing events of intense regeneration), which was substantiated by the influence of local demographic processes. Regeneration dynamics as modulated by demography thus influences the distribution of genetic diversity within the stand both in the younger life stages and in the adult population. (C) 2008 Elsevier B.V. All rights reserved.
Keywords: chloroplast microsatellites; mitochondrial minisatellites; pollen/seed dispersal; demography; spatial autocorrelation
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Leroy, C., Gril, E., Si Ouali, L., Coste, S., Gérard, B., Maillard, P., et al. (2019). Water and nutrient uptake capacity of leaf-absorbing trichomes vs. roots in epiphytic tank bromeliads. Environ. Exp. Bot., 163, 112–123.
Abstract: The water and nutrient uptake mechanisms used by vascular epiphytes have been the subject of a few studies. While leaf absorbing trichomes (LATs) are the main organ involved in resource uptake by bromeliads, little attention has been paid to the absorbing role of epiphytic bromeliad roots. This study investigates the water and nutrient uptake capacity of LATs vs. roots in two epiphytic tank bromeliads Aechmea aquilega and Lutheria splendens. The tank and/or the roots of bromeliads were watered, or not watered at all, in different treatments. We show that LATs and roots have different functions in resource uptake in the two species, which we mainly attributed to dissimilarities in carbon acquisition and growth traits (e.g., photosynthesis, relative growth rate, non-structural carbohydrates, malate), to water relation traits (e.g., water and osmotic potentials, relative water content, hydrenchyma thickness) and nutrient uptake (e.g., 15 N-labelling). While the roots of A. aquilega did contribute to water and nutrient uptake, the roots of L. splendens were less important than the role played by the LATs in resource uptake. We also provide evidenced for a synergistic effect of combined watering of tank and root in the Bromelioideae species. These results call for a more complex interpretation of LATs vs. roots in resource uptake in bromeliads. © 2019 Elsevier B.V.
Keywords: 15 N labelling; Carbon metabolism; Nutrient uptake; Plant performance; Tank bromeliad; Water status; Aechmea
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Bremaud, I., Minato, K., Langbour, P., & Thibaut, B. (2010). Physico-chemical indicators of inter-specific variability in vibration damping of wood. Ann. For. Sci., 67(7), 707.
Abstract: The vibration damping coefficient (tan delta) of wood is an important property for acoustical uses, including musical instruments. Current difficulties in the availability of some of the preferred species call for diversification, but this comes up against the lack of systematic damping coefficient data. Keeping in mind the possible factors affecting tans, could we predict its variations between species, by using indicators that are either easily measured and/or readily available for many species? Vibrational properties, equilibrium moisture content and colorimetric parameters were assessed on 94 wood types belonging to 76 species. Experimental results were then related to data on chemical contents and physical properties from the CIRAD database. The “standard” relationship between tan delta and specific modulus of elasticity (E'/rho) explained only half of the variations. Deviations from this trend were correlated to extractives content, yet effects were not directly quantitative. Damping deviations were also correlated to colour and moisture-related properties, especially so with fibre saturation point. By taking into account a combination of moisture-related properties, colour – or extractives content, and the “standard” relationship between tans and E'/rho, we could propose simple predictive models which explain up to 89% of observed variations in tan delta between 48 species.
Keywords: damping coefficient; diversity of woods; extractives; physical properties; vibrational properties
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ter Steege, H., Pitman, N. C. A., Sabatier, D., Baraloto, C., Salomão, R. P., Guevara, J. E., et al. (2013). Hyperdominance in the Amazonian Tree Flora. Science, 342(6156), 1243092.
Abstract: The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species—less diverse than the North American tree flora—accounts for half of the world’s most diverse tree community.
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