Browsing by Tema "Abiotic component"

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Abiotic and biotic drivers of biomass change in a Neotropical forest
(Wiley, 2017) Masha T. van der Sande; Marielos Peña‐Claros; Nataly Ascarrunz; E.J.M.M. Arets; Juan Carlos Licona; Marisol Toledo; Lourens Poorter
Summary Tropical forests play an important role in the global carbon cycle, but the drivers of net forest biomass change (i.e. net carbon sequestration) are poorly understood. Here, we evaluate how abiotic factors (soil conditions and disturbance) and biotic factors (forest structure, diversity and community trait composition) shape three important demographic processes (biomass recruitment, growth and mortality) and how these underlie net biomass change. To test this, we evaluated 9 years of biomass dynamics using 48 1‐ha plots in a Bolivian tropical moist forest, and measured for the most abundant species eight functional traits that are important for plant carbon gain and loss. Demographic processes were related to the abiotic and biotic factors using structural equation models. Variation in net biomass change across plots was mostly due to stand‐level mortality, but mortality itself could not be predicted at this scale. Contrary to expectations, we found that species richness and trait composition – which is an indicator for the mass‐ratio theory – had little effect on the demographic processes. Biomass recruitment (i.e. the biomass growth by recruiting trees) increased with higher resource availability (i.e. water and light) and with high species richness, probably because of increased resource use efficiency. Biomass growth of larger, established trees increased with higher sand content, which may facilitate root growth of larger trees to deeper soil layers. In sum, diversity and mass‐ratio are of limited importance for the productivity of this forest. Instead, in this moist tropical forest with a marked dry season, demographic processes are most strongly determined by soil texture, soil water availability and forest structure. Only by simultaneously evaluating multiple abiotic and biotic drivers of demographic processes, better insights can be gained into mechanisms playing a role in the carbon sequestration potential of tropical forests and natural systems in general.
Biogeographic patterns and conservation priorities for the dung beetle tribe <scp>P</scp> hanaeini ( <scp>C</scp> oleoptera: <scp>S</scp> carabaeidae: <scp>S</scp> carabaeinae) in <scp>B</scp> olivia
(Wiley, 2012) A. Caroli Hamel‐Leigue; Sebastián K. Herzog; Trond H. Larsen; Darren J. Mann; Bruce D. Gill; W. D. Edmonds; Sacha Spector
Abstract The New World Phanaeini are the best known Neotropical dung beetle tribe and a conservation priority among the Scarabaeinae, an ideal focal taxon for biodiversity research and conservation. We compiled a comprehensive distributional database for 39 phanaeine species in Bolivia and assessed patterns of species richness, body size and endemism in relation to abiotic variables and species richness and body mass of medium to large mammals across nine ecoregions. Pair‐wise linear regressions indicated that phanaeine richness, mean size and endemism are determined by different factors. In all cases mammal body mass had greater explanatory power than abiotic variables or mammal richness. Phanaeine richness was greater in ecoregions with on average smaller mammals and greater mammal richness. Mean phanaeine size increased with mean body mass of the largest herbivorous and omnivorous mammals. Endemism was greater in ecoregions with on average smaller herbivorous and omnivorous mammals. On average, smaller phanaeines had more restricted distributions than larger species; ecoregional endemism and mean body size were negatively correlated. Large phanaeines probably depend on large mammals to provide adequate food resources. Greater richness of smaller mammal species may allow for greater temporal and spatial resource partitioning and therefore greater phanaeine species richness. Low numbers of large mammal species may favour the persistence of geographically restricted phanaeine species by reducing interspecific competition with larger, more geographically widespread and presumably dominant phanaeines. Cerrado, Southwest Amazonia and Yungas are priority ecoregions for phanaeine conservation due to high total and endemic species richness.
Biology, ecology and demography of the tropical treehopper <scp>E</scp> nnya maculicornis ( <scp>H</scp> emiptera: <scp>M</scp> embracidae): relationships between female fitness, maternal care and oviposition sites
(Wiley, 2017) Liliana Alejandra Cáceres Sanchez; Daniel Torrico-Bazoberry; ROMINA COSSIO; KENIA REQUE; Sandra Aguilar; Hermann M. Niemeyer; Carlos F. Pinto
1. Treehoppers ( H emiptera: M embracidae) exhibit a wide range of social behaviours related to maternal care and nymphal aggregation. Maternal care represents an investment in terms of time and energy leading to trade‐offs which bear a strong relationship with parity and can thus affect population dynamics. These trade‐offs can be modulated by biotic and abiotic features of the oviposition site. 2. Preliminary observations on E nnya maculicornis ( M embracidae: S imilinae: P olyglyptini) show that females generally lay a single egg mass, and occasionally two or three egg masses, and that maternal care is a plastic trait because some females abandoned their egg mass before it hatched while other females remained with their offspring after egg hatching. These features make this species an interesting model to study the relationship between female fitness, maternal care and ecological factors such as oviposition site. 3. The biology and natural history of E . maculicornis are described and the relationships in question analysed using demographic parameters estimated by matrix models. E nnya maculicornis showed sexual dimorphism and a longer developmental period than other species of the same tribe. Females exhibited maternal care that increased offspring survival, and preferred mature over young host leaves for oviposition. Finite rate of increase ( λ ) values were lower than 1, suggesting a tendency towards population decrease. 4. The results represent the first detailed description of the life history and ecology for a species of this genus. Additionally, new hypotheses for treehopper sexual dimorphism, oviposition site choice and the ecological effects on population dynamics are proposed.
Biotic and Abiotic Drivers of Phenotypic Diversity in the Genus Lupinus (Fabaceae)
(Multidisciplinary Digital Publishing Institute, 2026) Mateo Burke Irazoque; Monica Moraes R; Sissi Lozada-Gobilard
The genus Lupinus (Fabaceae) represents an exceptional model system for studying evolutionary processes mediated by pollinators and environmental factors. This review synthesizes evidence on phenotypic variability of floral traits, trait selection by biotic and abiotic factors, and the eco-evolutionary implications of these interactions. Pollinators shape floral traits through specialized selection that optimizes pollination efficiency while maintaining plasticity toward autogamy under pollinator scarcity. At the same time, abiotic pressures drive adaptations to climate and elevation, which Lupinus achieves through phenotypic plasticity, such as adjusting flowering time, and through mutualisms with soil microbes that reduce abiotic stress. Ecological implications reveal contrasting dynamics, where native species sustain specialized pollination networks, while invasive species such as L. polyphyllus Lindl. disrupt these interactions through competitive exclusion. Thus, these two factors collectively drive Lupinus phenotypic diversity through specialized adaptations and plasticity. Finally, we emphasize the need for integrated studies combining genomics and ecological modeling to decipher the adaptive mechanisms of this genus.
Bracken fern facilitates tree seedling recruitment in tropical fire-degraded habitats
(Elsevier BV, 2014) Silvia C. Gallegos; Isabell Hensen; Francisco Saavedra; Matthias Schleuning
Chemical properties of foliar metabolomes represent a key axis of functional trait variation in forests of the tropical Andes
(Royal Society, 2026) Sierra Chadwick; David Henderson; Arden Perkins; Leslie Cayola; Alfredo Fuentes; Belen Alvestegui; Nathan Muchhala; J. Sebastián Tello; Martin Volf; J. Wilson Myers
Plants interact with their environment through diverse specialized metabolites that protect them from abiotic stressors, like drought or radiation, and biotic stressors, like herbivores or pathogens. However, few studies have considered the chemical properties of metabolites as a potential axis of functional trait variation along environmental gradients. Here, we examined how the chemical properties of foliar metabolomes, such as mean aromaticity, hydrophobicity and polarity, as well as commonly used morphological traits, vary with climate and elevation among 16 forest plots in the tropical Andes of Bolivia. We found that chemical properties were weakly related to morphological traits among tree species, yet both varied significantly with climate and elevation. In particular, abundance-weighted mean hydrophobicity decreased, and polar surface area increased with elevation and in colder and drier climates. Additionally, co-occurring species showed increasing chemical similarity with elevation for the most-aromatic and most-polar metabolites. These results suggest that abiotic stress associated with colder, drier climates and solar radiation acts as a filter for metabolome chemical properties. This contrasts with chemical dissimilarity observed at lower elevations, which is likely driven by pressure from host-specialized enemies in warmer, wetter climates. Our results introduce the possibility that chemical defences may be constrained by abiotic stressors.
Chemical properties of foliar metabolomes represent a key axis of functional trait variation in forests of the tropical Andes
(2025) Sedio, Brian; Chadwick, Sierra; Henderson, David; Forrister, Dale; Cayola, Leslie; Fuentes, Alfredo; Alvestegui, Belén; Muchhala, Nathan; Tello, J. Sebastián; Volf, Martin
Plants interact with their environment through diverse specialized metabolites that protect them from abiotic stressors like drought or radiation and biotic stressors like herbivores or pathogens. However, few studies have considered the chemical properties of metabolites as a potential axis of functional trait variation along environmental gradients. Here, we examined how the chemical properties of foliar metabolomes, such as mean aromaticity, hydrophobicity, and polarity, as well as commonly used morphological traits, vary with climate and elevation among 16 forest plots in the tropical Andes of Bolivia. We found that chemical properties were weakly related to morphological traits among tree species, yet both varied significantly with climate and elevation. In particular, abundance-weighted mean hydrophobicity decreased, and polar surface area increased with elevation and in colder and drier climates. Additionally, co-occurring species showed increasing chemical similarity with elevation for the most-aromatic and most-polar metabolites. These results suggest that abiotic stress associated with colder, drier climates and solar radiation acts as a filter for metabolome chemical properties. This contrasts with chemical dissimilarity observed at lower elevations, which is likely driven by pressure from host-specialized enemies in warmer, wetter climates. Our results introduce the possibility that chemical defenses may be constrained by abiotic stressors. Morphological traits and foliar metabolome chemical properties for each species-by-plot are reported in Dataset S1. Community-weighted mean values are reported in Dataset S2. The structural similarities among 20,571 metabolites are reported as a Qemistree dendrogram in .tre phylogeny format as Dataset S3. Masses, molecular formulae, predicted structures, classifications, and chemical properties and sample-level abundances for 20,571 unique metabolites are provided in Dataset S4.
Dendrochronological investigation of the high Andean tree species Polylepis besseri and implications for management and conservation
(Springer Science+Business Media, 2010) Edgar E. Gareca; Milton Fernández; Sharon Stanton
Dietary-morphological relationships in fish assemblages of small forested streams in the Bolivian Amazon
(EDP Sciences, 2007) Carla Ibañez; Pablo A. Tedesco; Rémy Bigorne; Bernard Hugueny; Marc Pouilly; Claudia Zepita; José Zubieta; Thierry Oberdorff
We explored the relationships between diet and morphology in 30 fish species from forested tropical streams of the Bolivian Amazon. These species were first assigned to eight broad trophic guilds based on stomach contents analysis. The relationships between diet and morphology were then examined using Redundancy Analysis, after having checked for potential phylogenetical effects. Results show that, independently of any phylogenetic constraints, some of the trophic guilds could be grossly predicted from few relevant morphological attributes (i.e. relative intestinal length, standard length and mouth orientation) and thus suggest a significant link between diet and morphology. In other words, species having similar diet tend to converge to some extent on some morphological attributes. This link was nevertheless rather weak, suggesting that even if morphology may set limits to patterns of resource use, these limits are broad enough to allow fishes changing their choice of prey resources to respond to local biotic and/or abiotic conditions.
Differential adaptation of two varieties of common bean to abiotic stress
(Oxford University Press, 2006) X. Carolina Lizana; Mark Wentworth; Juan‐Pablo Martínez; Daniel Villegas; Rodrigo Meneses; Erik H. Murchie; Claudio Pastenes; Bartolomeo Lercari; P. Vernieri; Peter Horton
The yield of 24 commercial varieties and accessions of common bean (Phaseolus vulgaris) has been determined at different sites in Chile and Bolivia. Statistical analysis was performed in order to characterize whether a particular variety was more or less stable in yield under different environmental conditions. Amongst these, two varieties have been identified for more detailed study: one variety has a higher than average yield under unstressed conditions but is strongly affected by stress, and another has a reduced yield under unstressed conditions but is less affected by stress. The contrasting rate of abscission of the reproductive organs under drought stress was clearly consistent with these differences. The more tolerant genotype shows a great deal of plasticity at the biochemical and cellular level when exposed to drought stress, in terms of stomatal conductance, photosynthetic rate, abscisic acid synthesis, and resistance to photoinhibition. By contrast, the former lacks such plasticity, but shows an enhanced tendency for a morphological response, the movement of leaves, which appears to be its principal response to drought stress.
Differential effect of shade, water and soil type on emergence and early survival of three dominant species of the Atacama Desert
(Wiley, 2016) Ramiro Pablo López; Francisco A. Squeo; Julio R. Gutiérrez
Abstract Understanding the regeneration niche of species may allow us to gain insight into how communities are structured. In deserts, the regeneration niche is usually related to spaces beneath shrubs where shade cast by shrubs creates microenvironments that benefit seedlings and where even small amounts of rain may favour germination and establishment. Shade and water may also interact with different types of soils. However, species may have different requirements for germination and seedling survival. We could expect that shrub species with different drought tolerances exhibit different responses to the combination of these factors. We ask if responses of dominant species of the Atacama Desert to abiotic factors (shade, water and soil type) are related to their drought tolerance, a topic not exhaustively explored in shrubs growing in true deserts. We conducted two factorial experiments. The first one was designed to evaluate how shade (microhabitat) in combination with water may affect germination (emergence) and early survival. In the second experiment, we assessed the influence of shade in relation to soil type. Each species responded distinctively to the three variables under study, but in general, their emergence responses were more influenced by water (more water, greater emergence) than by microhabitat or soil type. Survival was influenced both by microhabitat and by water and was higher under shade and abundant water. Soil type affected only one of our species in terms of emergence. Species responses in general depended on their tolerance to stress. In one species, there was indication of a seed–seedling conflict. Our results show similar species responses to environmental constraints but also more or less unique responses that are related to their tolerance to drought and which may ultimately permit species coexistence. We found that shade may not be important for germination but may be crucial for survival in dry years.
Disadvantages of living in a populous neighborhood for sit‐and‐wait predators: Competition for space reduces pit‐trap size in antlion larvae
(Wiley, 2020) Alejandro G. Farji‐Brener; Agostina S. Juncosa‐Polzella; Daniela Madrigal-Tejada; Diego Centeno‐Alvarado; Mariana Hernández‐Soto; Mayori Soto‐Huaira; Sebastián Gutiérrez‐Cruz
Abstract The study of how trap design responds to biotic and abiotic conditions can help to understand the selective forces affecting the foraging of trap‐building organisms. We experimentally tested whether pit design can be modified by intraspecific competition for space in larvae of Myrmeleon crudelis , a common sit‐and‐wait predator that digs conical pit traps in the soil to capture walking arthropods. In a tropical forest in Costa Rica, we measured pit dimensions, larval body size, and the level of competition (i.e., density of neighboring traps) in 40 antlion larvae. These larvae were then taken to the laboratory and allowed to build new traps in individual containers. We measured within‐individual changes in the size of traps in the field and in the laboratory, and related these to the level of competition experienced in the field. Larvae with relatively high levels of competition in the field showed a greater increase in the size of their pits in the laboratory. This change was independent of larval size. Larvae with none or few neighbors in the field showed little change in their pit sizes, whereas those with higher competition levels increased their diameter and depth up to 1,400% and 1,000%, respectively. Our results demonstrate that, at least in high‐density aggregations, pit design is restricted by competition in addition to the constraints imposed by body size. This work suggests that biotic interactions can play a role in the design of extended phenotypes in sit‐and‐wait predators that live in dense aggregations.
Distribution of Ephemeroptera in the Andean Part of the Rio Beni Drainage Basin (Bolivia): Regional Pattern or Control at the Local Scale?
(2001) Giovanna Rocabado; J.G. Wasson; Faviany Lino
Ecological drivers of avian community assembly along a tropical elevation gradient
(Wiley, 2020) Flavia Montaño‐Centellas; Bette A. Loiselle; Morgan W. Tingley
Community assembly theory hypothesizes that two main niche‐based processes act to shape composition and organization of biological assemblages: abiotic filtering and biological interactions. Here, we conducted repeated surveys of bird abundance along an undisturbed elevational gradient in the tropical Andes to investigate 1) signals of deterministic processes driving community assembly and 2) potential mechanisms by which these forces operate (temperature, habitat complexity, fruit and insect availability), while correcting for imperfect detection and modeling species abundances with N‐mixture models. We observed strong signals of abiotic filtering driving functionally and phylogenetically clustered assemblages towards higher elevations, and a weaker signal of limiting similarity resulting in few overdispersed assemblages at lower elevations. Whereas the decay in species richness with increasing elevation was explained by temperature, trait and phylogenetic dispersion were explained by both temperature and vegetation structure, implying that an interplay of abiotic and biotic mechanisms determines abundance‐based community structure in our montane assemblages. Interestingly, trait and phylogenetic dispersion consistently decreased until ~3000 m but increased above this elevation, highlighting a potential role of competition in resource‐scarce habitats. Combined, our findings suggest abiotic filters are still the main process shaping montane biotas across elevations, whereas resource availability might act locally upon assemblages further modifying them. Our study challenges recent studies in tropical mountains that suggest that biotic filters are a stronger force than abiotic filters in shaping tropical montane assemblages, and exemplifies how accounting for imperfect detection might overcome potential biases in detecting environmental filtering signals in community assembly studies.
Effects of liana load, tree diameter and distances between conspecifics on seed production in tropical timber trees
(Elsevier BV, 2008) Jacob Nabe‐Nielsen; Johannes Kollmann; Marielos Peña‐Claros
Enhanced facilitation at the extreme end of the aridity gradient in the Atacama Desert: a community‐level approach
(Wiley, 2016) Ramiro Pablo López; Francisco A. Squeo; Cristina Armas; Douglas Kelt; Julio R. Gutiérrez
Plant facilitation is now recognized as an important process in severe environments. However, there is still no agreement on how facilitation changes as conditions become increasingly severe. The classic stress gradient hypothesis (SGH) predicts a monotonic increase in facilitation, which rises in frequency as conditions approach the extreme end of the environmental gradient. However, few studies have evaluated the validity of the SGH at the community level, the level at which it was formulated. Moreover, few studies have tested the SGH at either extreme of the gradient, and very few have excluded the effect of livestock on community response to stress. In line with the SGH, we hypothesized that several spatial pattern summary statistics would change monotonically from the least to the most arid sites, indicating increasingly aggregated patterns. In this study, we performed an evaluation of the SGH both within communities of shrub species and across a large portion of the Atacama Desert, and we isolated the abiotic component of the SGH. Our environmental gradient covered an extreme aridity gradient (< 20-130 mm annual precipitation). To perform point pattern analysis, we established 13 sites with environmental conditions representing four distinct levels of this gradient. Further, we conducted species co-occurrence analyses at 19 sites along the gradient. Both sets of analyses showed stronger positive spatial associations among plants at the most extreme end of the gradient. This was true regardless of whether we included all individuals, only small individuals located around large ones, or individuals in species pairs. Moreover, species tended to show greater co-occurrence as environmental severity increased. This increase in aggregation in the plant community seems to correlate with an increase in the strength of positive interspecific interactions, rather than greater clustering within each species. These monotonic increases in species co-occurrence and spatial association in more severe environments are consistent with some of the predictions of SGH, and collectively these results suggest that as the climate becomes more arid, positive species pairs interactions tend to be prevalent in the community.
Enhancing the Sustainability of Quinoa Production and Soil Resilience by Using Bioproducts Made with Native Microorganisms
(Multidisciplinary Digital Publishing Institute, 2013) Noel Ortuño; José A. Castillo; Mayra Claros; O. Navia; Marlene Angulo; Daniel Barja; Claudia Gutiérrez; Violeta C. Angulo
Microorganisms are involved in a network of interactions with plants, promoting growth and acting as biocontrol agents against diseases. In this work, we studied native microorganisms associated with quinoa plants (Chenopodium quinoa) and the application of these organisms to the organic production of quinoa in the Andean Altiplano. Quinoa is a non-cereal grain native to the Andean highlands and is highly nutritious and gluten-free. As such, the international demand for quinoa has increased substantially in recent years. We isolated native endophytic bacteria that are able to fix nitrogen, solubilize phosphate and synthesize a phytohormone and native strains of Trichoderma, a fungus typically used for increasing plant growth and tolerance to biotic and abiotic stresses. Greenhouse assays and field trials allowed for selecting promissory bacterial isolates, mostly belonging to Bacillus and Paenibacillus genera, that increased plant length, panicle weight and grain yield. Selected microbial isolates were large-scale multiplied in simple and inexpensive culture media and then formulated to obtain bioproducts that were distributed among local farmers. Thus, we developed a technology for the exploitation of beneficial microbes, offering promising and environmentally friendly strategies for the organic production of quinoa without perturbing the native microbial diversity of Andean soils and making them more resilient to the adverse effects of climatic change and the over-production of quinoa.
Environmental heterogeneity and dispersal processes influence post-logging seedling establishment in a Chiquitano dry tropical forest
(Elsevier BV, 2015) Robin Corrià-Ainslie; J. Julio Camarero; Marisol Toledo
Evaluación de los Niveles de Contaminación por Plomo y Arsénico en muestras de Suelos y productos Agrícolas Procedentes de la región cercana al Complejo metalúrgico Vinto
(2009) Maritza Mercado; María Eugenia García; Jorge Quintanilla
This article completes the previous studies made in the zone of the metallurgical complex Vinto in Oruro - Bolivia, corroborating that its ecosystem is contaminated in both biotic and abiotic samples. / Este articulo completa los estudios realizados anteriormente en la zona de la metalurgica Vinto en Oruro - Bolivia, comprobandolo un ecosistema contaminado, pues asi lo estan sus factores bioticos y abioticos.
First insight into microbial diversity and ion concentration in the Uyuni salt flat, Bolivia
(University of Puerto Rico at Mayaguez, 2016) Cesar A. Pérez-Fernández; Mercedes Iriarte; Wilber Hinojosa-Delgadillo; Andrea Veizaga-Salinas; Raúl J. Cano; Jessica C. Rivera; Gary A. Toranzos
The most important hypersaline environment in Bolivia is the Uyuni salt flat. It is the largest salt flat in the world and, it presents certain unique chemical characteristics and composition on its surface such as a gradient of ion concentrations from south to north. The autochthonous microbial communities in these salt flats have yet to be studied in detail, and it is not clear if these communities are somehow homogeneous across in the ca. 10,000 km2 flat. The present study was done in order to describe the structure of the microbial communities and determine any possible correlations with abiotic factors. Total DNA was extracted from rock salt samples obtained at different locations, and 16S rDNA followed by Terminal Restriction Fragment Length Polymorphism (T-RFLP) analyses. Statistical analyses of the communities indicated that the highest diversity indices were found in the southern area, and the microbial communities were clustered in three groups for bacteria and in two groups for archaea. This variation could be explained by different concentrations of lithium and calcium, in addition to other abiotic variables on the surface crust. Our results indicate that even under extreme hypersaline conditions abiotic factors such as wind or geological activity may determine the composition of the resident microbiota.