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1.
Am Nat ; 201(2): 302-314, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36724464

RESUMO

AbstractOne of the most stunning patterns of the distribution of life on Earth is the latitudinal biodiversity gradient. In an influential article, Janzen (1967) predicted that tropical mountains are more effective migration barriers than temperate mountains of the same elevation, because annual temperature variation in the tropics is lower. A great deal of research has demonstrated that the mechanism envisioned by Janzen operates at broad latitudinal scales. However, the extent that the mechanism mediates biodiversity generally, and at smaller scales, is far less understood. We investigated whether climate overlap is associated with genetic similarity between populations within temperate regions using lizards in the Sierra Nevada mountain range of California as a study system. By comparing genetic differentiation between high- and low-elevation populations, we found that in addition to the expected strong pattern of isolation by distance, high climate overlap was negatively associated with genetic differentiation, indicating that population pairs that inhabit climatically similar environments are less genetically differentiated. Moreover, while climate overlap between high- and low-elevation sites is predicted to increase from the equator to temperate regions, we find that in adjacent mountain ranges at the same latitude in temperate regions, climate overlap values can vary widely. This study suggests that in addition to the well-studied main effect of latitude on climate overlap and population differentiation, local climate factors within bioclimatic regions can also influence genetic differentiation between populations and do so by the same general mechanism that operates at larger geographic scales.


Assuntos
Biodiversidade , Clima , Temperatura , Deriva Genética , Clima Tropical
2.
Allergol. immunopatol ; 51(1): 126-132, ene. 2023. tab
Artigo em Inglês | IBECS | ID: ibc-214041

RESUMO

Background: Tropics have some particularities that can impact the natural history and factors associated with allergic diseases. However, few studies described the characteristics of patients with allergic rhinitis (AR) and combined AR and asthma syndrome (CARAS) in Latin American tropical countries. Objective: This study aimed to determine the medical, social, and environmental factors associated with AR and CARAS in children aged 5–18 years treated with immunotherapy in two allergy referral centers in Bogotá (Colombia). Material: and methods: An observational, cross-sectional study was conducted between January 2018 and January 2019. International Study Asthma Allergies Childhood-III and sociodemographic questionnaires were applied to adolescents and parents of children undergoing immunotherapy at the allergy consult in the Hospital Universitario Fundación Santa Fe de Bogotá and UNIMEQ-ORL. Results: Among 830 children aged 5–18 years, 38.1% (n = 316) were women. Up to 63.25% of the population had a positive skin prick test for house dust mites: 63.25% for Dermatophagoides pteronyssinus, 61.81% for Dermatophagoides farinae, and 31.57% for Blomia tropicalis. The factors associated with AR were male sex (PR: 1.31, 95% CI: 1.08–1.57), antibiotic consumption during the first year of life (PR: 0.80; 95% CI: 0.63–0.99), and exposure to dogs (PR: 1.32; 95% CI: 1.06–2.66). The factors associated with CARAS were older age (PR=0.95; 95% CI: 0.95–0.99), acetaminophen consumption over four times a year (PR: 1.31; 95% CI: 1.03–1.55), and antibiotic consumption during the first year of life (PR: 1.21; 95% CI: 1.06–1.34). Conclusion: A high prevalence of B. tropicalis was found in this study. The factors associated with AR and CARAS are like those described in high-income tropical countries. Further studies are needed in low- or middle-income tropical countries to identify modifiable factors associated with allergic diseases (AU)


Assuntos
Humanos , Masculino , Feminino , Pré-Escolar , Criança , Adolescente , Imunoterapia/métodos , Rinite Alérgica/terapia , Asma/terapia , Hipersensibilidade/terapia , Estudos Prospectivos , Clima Tropical , Inquéritos e Questionários , Síndrome
3.
Proc Natl Acad Sci U S A ; 120(3): e2214462120, 2023 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-36623189

RESUMO

Logged and structurally degraded tropical forests are fast becoming one of the most prevalent land-use types throughout the tropics and are routinely assumed to be a net carbon sink because they experience rapid rates of tree regrowth. Yet this assumption is based on forest biomass inventories that record carbon stock recovery but fail to account for the simultaneous losses of carbon from soil and necromass. Here, we used forest plots and an eddy covariance tower to quantify and partition net ecosystem CO2 exchange in Malaysian Borneo, a region that is a hot spot for deforestation and forest degradation. Our data represent the complete carbon budget for tropical forests measured throughout a logging event and subsequent recovery and found that they constitute a substantial and persistent net carbon source. Consistent with existing literature, our study showed a significantly greater woody biomass gain across moderately and heavily logged forests compared with unlogged forests, but this was counteracted by much larger carbon losses from soil organic matter and deadwood in logged forests. We estimate an average carbon source of 1.75 ± 0.94 Mg C ha-1 yr-1 within moderately logged plots and 5.23 ± 1.23 Mg C ha-1 yr-1 in unsustainably logged and severely degraded plots, with emissions continuing at these rates for at least one-decade post-logging. Our data directly contradict the default assumption that recovering logged and degraded tropical forests are net carbon sinks, implying the amount of carbon being sequestered across the world's tropical forests may be considerably lower than currently estimated.


Assuntos
Carbono , Ecossistema , Clima Tropical , Biomassa , Atmosfera , Solo
5.
Proc Natl Acad Sci U S A ; 120(5): e2201832120, 2023 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-36689651

RESUMO

Megaherbivores have pervasive ecological effects. In African rainforests, elephants can increase aboveground carbon, though the mechanisms are unclear. Here, we combine a large unpublished dataset of forest elephant feeding with published browsing preferences totaling nearly 200,000 records covering >800 plant species and with nutritional data for 145 species. Elephants increase carbon stocks by: 1) promoting high wood density trees via preferential browsing on leaves from low wood density species, which are more palatable and digestible; and 2) dispersing seeds of trees that are relatively large and have the highest average wood density among tree guilds based on dispersal mode. Loss of forest elephants could cause an increase in abundance of fast-growing low wood density trees and a 6% to 9% decline in aboveground carbon stocks due to regeneration failure of elephant-dispersed trees. These results demonstrate the importance of megaherbivores for maintaining diverse, high-carbon tropical forests. Successful elephant conservation will contribute to climate mitigation at a globally-relevant scale.


Assuntos
Elefantes , Animais , Carbono/metabolismo , Florestas , Árvores/metabolismo , Clima Tropical , Biomassa
6.
Curr Biol ; 33(2): R80-R82, 2023 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-36693316

RESUMO

Tropical deforestation is a significant cause of global biodiversity loss. A new study shows that habitat loss may result in abrupt changes in networks of interacting species. This has major implications for the conservation and restoration of tropical forest ecosystems.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Florestas , Ecologia , Biodiversidade , Clima Tropical
7.
PLoS One ; 18(1): e0279491, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36630378

RESUMO

Many tropical wet forests are species-rich and have relatively even species frequency distributions. But, dominance by a single canopy species can also occur in tropical wet climates and can remain stable for centuries. These are uncommon globally, with the African wet tropics supporting more such communities than the Neotropics or Southeast Asia. Differences in regional evolutionary histories are implied by biogeography: most of Africa's monodominance-forming species are Amherstieae-tribe legumes; monodominance in Neotropical forests occur among diverse taxonomic groups, often legumes, but rarely Amherstieae, and monodominance in Southeast Asian forests occurs mostly among Dipterocarpaceae species. African monodominant forests have been characterized ecologically and taxonomically, but their deep-time history is unknown despite their significant presence and bottom-up ecological influence on diversity. Herein we describe fossil leaflets of Englerodendron mulugetanum sp. nov., an extinct species of the extant genus Englerodendron (Berlinia Clade, Amherstieae, Detarioideae) from the 21.73 Ma Mush Valley site in Ethiopia. We also document a detailed study of associated legume pollen, which originate from a single taxon sharing characters with more than one extant descendant. Taxonomically, the pollen is most comparable to that from some extant Englerodendron species and supports a likely affiliation with the Englerodendron macrofossils. The Mush Valley site provides the first fossil evidence of a monodominant tropical forest in Africa as represented by leaflets and pollen. Previous studies documented >2400 leaves and leaflets from localities at six stratigraphic levels spanning 50,000-60,000 years of nearly continuous deposition within seven meters of section; all but the basal level contain ≥ 50% E. mulugetanum leaflets. Modern leaf litter studies in African mixed vs. monodominant forests indicates the likelihood of monodominance in the forests that surrounded the Mush paleolake, particularly after the basal level. Thus, we provide an early case for monodominance within the Amherstieae legumes in Africa.


Assuntos
Fabaceae , Etiópia , Árvores , Florestas , Evolução Biológica , Verduras , Clima Tropical
8.
Philos Trans R Soc Lond B Biol Sci ; 378(1867): 20210076, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36373921

RESUMO

Seed dispersal by animals is key for restoration of tropical forests because it maintains plant diversity and accelerates community turnover. Therefore, changes in seed dispersal during forest restoration can indicate the recovery of species interactions, and yet these changes are rarely considered in forest restoration planning. In this study, we examined shifts in the importance of different seed dispersal modes during passive restoration in a tropical chronosequence spanning more than 100 years, by modelling the proportion of trees dispersed by bats, small birds, large birds, flightless mammals and abiotic means as a function of forest age. Contrary to expectations, tree species dispersed by flightless mammals dominated after 20 years of regeneration, and tree richness and abundance dispersed by each mode mostly recovered to old growth levels between 40 and 70 years post-abandonment. Seed dispersal by small birds declined over time during regeneration, while bat dispersal played a minor role throughout all stages of succession. Results suggest that proximity to old growth forests, coupled with low hunting, explained the prevalence of seed dispersal by animals, especially by flightless mammals at this site. We suggest that aspects of seed dispersal should be monitored when restoring forest ecosystems to evaluate the reestablishment of species interactions. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.


Assuntos
Quirópteros , Dispersão de Sementes , Animais , Ecossistema , Florestas , Árvores , Sementes , Aves , Clima Tropical
9.
Oecologia ; 201(1): 199-212, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36520222

RESUMO

There is often a vertical stratification of the vegetation in tropical forests, where each forest stratum has a unique set of environmental conditions, including marked differences in habitat heterogeneity, physical complexity, and microclimate. Additionally, many tropical forests are highly seasonal, and we need to consider the temporal variation in environmental conditions when assessing the functional aspects of their organisms. Here, we tested the hypothesis that vertical stratification and seasonality shape tropical ants' functional ecology and that there are differences in the functional trait diversity and composition between arboreal and ground-dwelling ant communities. We collected ants in the arboreal and ground strata in the rainy and dry seasons in six different areas, measuring seven morphological traits to characterize their functional ecology and diversity. Irrespective of the season, we found a distinct functional composition between arboreal and ground-dwelling ants and a higher functional richness on the ground. However, ground ants were more functionally redundant than arboreal ants. The differences in functional richness and redundancy between ant inhabiting strata and season could also be observed in the community-weighted mean traits: arboreal and ground ant traits can be distinguished in Weber's length, mandible length, eye length, and eye position on the head capsule. The differences in these functional traits are mainly related to the ants' feeding habits and the complexity of their foraging substrates. Overall, by providing the first systematic comparison of continuous traits between arboreal and ground-dwelling ants, our study opens new investigation paths, indicating important axes of functional diversification of tropical ants.


Assuntos
Formigas , Árvores , Animais , Clima Tropical , Ecossistema , Florestas
10.
Zoology (Jena) ; 156: 126065, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36502738

RESUMO

Congeneric species often coexist in sympatry using behavioral and morphological adaptations to reduce competition and interspecific interference, but reproductive patterns behind coexistence remain unknown. We analyzed the gonadal morphology and development, reproductive cycle, and population structure of two sympatric congeneric fishes to evaluate the degree of overlap and differentiation of the reproductive biology between species in a Neotropical river. Development of testes and ovaries were similar between species, both showing asynchronous gonadal development, large diameter of gametes and synthesis of mucosubstances by follicle cells to form adhesive eggs. Although the morphometry of germ cells did not present differences, the zona radiata of mature eggs in Hypostomus garmani was markedly thicker than H. francisci, which suggests different spawning habitats. Both species have greater reproductive activity in the rainy season, concomitant with increase in water temperature, however H. garmani initiates and ends its reproduction earlier than H. francisci, indicating a differentiation of reproductive periods. Sexually mature males and females of H. francisci reproduced at a larger mean size then H. garmani. The two congeneric species had a similar abundance and sex ratios in the study area. Results show that although the species exhibited broad overlap of reproductive traits, a spatial and temporal differentiation of the reproductive biology was present. This study contributes to understanding reproductive mechanisms that may facilitate coexistence between congeneric sympatric species.


Assuntos
Peixes-Gato , Simpatria , Animais , Feminino , Masculino , Peixes-Gato/anatomia & histologia , Peixes-Gato/fisiologia , Gônadas , Reprodução , Rios , Clima Tropical , Tamanho Corporal
11.
Proc Natl Acad Sci U S A ; 120(1): e2214972120, 2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36580592

RESUMO

Regression learning is one of the long-standing problems in statistics, machine learning, and deep learning (DL). We show that writing this problem as a probabilistic expectation over (unknown) feature probabilities - thus increasing the number of unknown parameters and seemingly making the problem more complex-actually leads to its simplification, and allows incorporating the physical principle of entropy maximization. It helps decompose a very general setting of this learning problem (including discretization, feature selection, and learning multiple piece-wise linear regressions) into an iterative sequence of simple substeps, which are either analytically solvable or cheaply computable through an efficient second-order numerical solver with a sublinear cost scaling. This leads to the computationally cheap and robust non-DL second-order Sparse Probabilistic Approximation for Regression Task Analysis (SPARTAn) algorithm, that can be efficiently applied to problems with millions of feature dimensions on a commodity laptop, when the state-of-the-art learning tools would require supercomputers. SPARTAn is compared to a range of commonly used regression learning tools on synthetic problems and on the prediction of the El Niño Southern Oscillation, the dominant interannual mode of tropical climate variability. The obtained SPARTAn learners provide more predictive, sparse, and physically explainable data descriptions, clearly discerning the important role of ocean temperature variability at the thermocline in the equatorial Pacific. SPARTAn provides an easily interpretable description of the timescales by which these thermocline temperature features evolve and eventually express at the surface, thereby enabling enhanced predictability of the key drivers of the interannual climate.


Assuntos
El Niño Oscilação Sul , Clima Tropical , Entropia , Temperatura , Algoritmos
12.
Parasitol Res ; 122(2): 571-583, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36515752

RESUMO

We applied a step-down factor analysis (SDFA) and multi-site generalised dissimilarity modelling (MS-GDM) to local flea communities harboured by small mammals (i.e., collected at small sampling sites over a short time period) in two South American regions (Patagonia and the Northwestern Argentina) with the aim of understanding whether these communities were assembled via niche-based or dispersal-based processes. The SDFA allows us to determine whether clusters of flea assemblages across different types of climates, vegetation and soils can be distinguished (suggesting niche-based assembly). MS-GDM allows us to determine whether a substantial proportion of the variation in flea species turnover is explained by specific climate-associated, vegetation-associated and soil-associated variables (indicating niche-based assembly) or host turnover (indicating dispersal-based assembly). Mapping of assemblages on climate, vegetation and soil maps, according to their loadings on axis 1 or axis 2 of the SDFA, did not provide clear-cut results. Clusters of similar loadings could be recognized within some, but not other, climate, vegetation and soil types. However, MS-GDM demonstrated that the effect of environmental variables (especially air temperature) on flea compositional turnover was much stronger than that of host turnover, indicating the predominance of niche-based processes in local community assembly. A comparison of our results with those on the mechanisms that drive species assembly in regional communities allows us to conclude that local and regional communities result from the joint action of niche-based and dispersal-based processes, with the former more important at a smaller spatial scale and the latter at a larger spatial scale.


Assuntos
Sifonápteros , Animais , Mamíferos , Solo , Clima Tropical , Argentina , Ecossistema , Biodiversidade
14.
PeerJ ; 10: e14535, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36540804

RESUMO

The question whether or not tropical lianas infest host trees randomly or they exert host selection has implications for the structure and dynamics of tropical rainforests, particularly if colonization by lianas impacts host fitness. In this study, we present evidence that the Neotropical liana Marcgravia longifolia (Marcgraviaceae) infests host trees non-randomly. We identified host trees to species or genus level for 87 of the 100 M. longifolia individuals found in the study area of the Estación Biológica Quebrada Blanco (EBQB) in north-eastern Peruvian Amazonia. Data on host availability were taken from two 1-ha plots sampled at EBQB as part of a large-scale tree inventory in western Amazonia. Of the total of 88 tree genera with two or more individuals present in the inventory, 18 were represented amongst hosts. Host genera with a probability of colonization higher than expected by chance were Eschweilera (Lecythidaceae), Pouteria (Sapotaceae), Brosimum (Moraceae), and Hymenaea (Fabaceae). These findings suggest that M. longifolia exerts some level of host selectivity, but the mechanisms for this are completely unknown. Given the large number of animal species (41 bird species, three primate species) that are dispersing the seeds of M. longifolia and that have diverse ecological strategies, directed seed dispersal is unlikely to account for the observed patterns of host infestation.


Assuntos
Floresta Úmida , Clima Tropical , Animais , Probabilidade , Sementes , Peru
15.
Nature ; 612(7941): 707-713, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36517596

RESUMO

Old-growth tropical forests are widely recognized as being immensely important for their biodiversity and high biomass1. Conversely, logged tropical forests are usually characterized as degraded ecosystems2. However, whether logging results in a degradation in ecosystem functions is less clear: shifts in the strength and resilience of key ecosystem processes in large suites of species have rarely been assessed in an ecologically integrated and quantitative framework. Here we adopt an ecosystem energetics lens to gain new insight into the impacts of tropical forest disturbance on a key integrative aspect of ecological function: food pathways and community structure of birds and mammals. We focus on a gradient spanning old-growth and logged forests and oil palm plantations in Borneo. In logged forest there is a 2.5-fold increase in total resource consumption by both birds and mammals compared to that in old-growth forests, probably driven by greater resource accessibility and vegetation palatability. Most principal energetic pathways maintain high species diversity and redundancy, implying maintained resilience. Conversion of logged forest into oil palm plantation results in the collapse of most energetic pathways. Far from being degraded ecosystems, even heavily logged forests can be vibrant and diverse ecosystems with enhanced levels of ecological function.


Assuntos
Aves , Metabolismo Energético , Cadeia Alimentar , Agricultura Florestal , Florestas , Mamíferos , Clima Tropical , Animais , Biodiversidade , Biomassa , Aves/fisiologia , Bornéu , Mamíferos/fisiologia , Óleo de Palmeira , Árvores/crescimento & desenvolvimento , Ecologia
17.
Nature ; 612(7940): 483-487, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36477532

RESUMO

Recent observations suggest that the large carbon sink in mature and recovering forests may be strongly limited by nitrogen1-3. Nitrogen-fixing trees (fixers) in symbiosis with bacteria provide the main natural source of new nitrogen to tropical forests3,4. However, abundances of fixers are tightly constrained5-7, highlighting the fundamental unanswered question of what limits new nitrogen entering tropical ecosystems. Here we examine whether herbivory by animals is responsible for limiting symbiotic nitrogen fixation in tropical forests. We evaluate whether nitrogen-fixing trees experience more herbivory than other trees, whether herbivory carries a substantial carbon cost, and whether high herbivory is a result of herbivores targeting the nitrogen-rich leaves of fixers8,9. We analysed 1,626 leaves from 350 seedlings of 43 tropical tree species in Panama and found that: (1) although herbivory reduces the growth and survival of all seedlings, nitrogen-fixing trees undergo 26% more herbivory than non-fixers; (2) fixers have 34% higher carbon opportunity costs owing to herbivory than non-fixers, exceeding the metabolic cost of fixing nitrogen; and (3) the high herbivory of fixers is not driven by high leaf nitrogen. Our findings reveal that herbivory may be sufficient to limit tropical symbiotic nitrogen fixation and could constrain its role in alleviating nitrogen limitation on the tropical carbon sink.


Assuntos
Florestas , Herbivoria , Fixação de Nitrogênio , Nitrogênio , Árvores , Clima Tropical , Animais , Carbono/metabolismo , Sequestro de Carbono , Nitrogênio/metabolismo , Panamá , Folhas de Planta , Plântula , Árvores/classificação , Árvores/metabolismo
19.
Sci Rep ; 12(1): 18544, 2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36329120

RESUMO

Biodiversity decline in the tropics requires the implementation of comprehensive landscape management where agricultural systems are necessarily an integral element of biodiversity conservation. This study evaluates the potential for taxonomic biodiversity conservation within an intensive livestock-agricultural-forest mosaic landscape in Catacamas, Honduras. Tree sampling was performed in 448 plots set up within different forest and agricultural land uses: secondary forests, agroforestry coffee plantations, agriculture, pastures, live fences and riparian forest. All trees with a minimum diameter at breast height of 10 cm were identified and measured. We characterized their tree structure and diversity, and compared tree diversity between the different uses. The results indicate a high degree of tree species diversity: 375 species identified, belonging to 74 families among the 15,096 trees inventoried across 84.2 hectares, including many rare species (40% of the species registered three individuals or fewer). Biodiversity indices for agroforestry coffee were found equivalent to those for natural secondary forests in the Catacamas landscape. Combining biodiversity conservation and agricultural production is possible in human-pressured tropical landscapes through tree cover maintenance. Enrichment practices combining local producers and technical knowledge may improve tree diversity in agricultural landscapes by prioritizing a mix of forest and introduced tree species (rare and with multiple uses).


Assuntos
Agricultura , Florestas , Humanos , Honduras , Biodiversidade , Conservação dos Recursos Naturais , Ecossistema , Clima Tropical
20.
Environ Monit Assess ; 195(1): 66, 2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36329327

RESUMO

Selective logging disrupts forests, changing their structure and species composition. Long-term monitoring helps in identifying the factors influencing it and aids in designing management plans. We conducted a quantitative re-assessment of trees ≥ 30 cm girth at breast height in four 1 ha plots in logged and two 1 ha plots in adjacent unlogged compartments of Uppangala forest continuum in the Western Ghats, India to compare the structural and compositional changes after a decade (2010-2021). Altogether, four species disappeared and three species were newly recruited. Mean species richness and stem density of both the forest sites decreased. Logged plots showed a slight increase in basal area (2.5%) and biomass (5.1%), whereas unlogged plots showed a decline in basal area (3.92%) and biomass (2.9%). As compared to unlogged plots, all the demographic rates were higher for logged forest sites. Across the six individual plots, the growth rates varied significantly owing to wood density and forest strata categories. Non-metric multidimensional scaling (NMDS) identified three groups with significant difference in species composition, where logged and unlogged plots have a distinct composition except for one plot. Although species richness and stem diversity remained stable, the species composition is different 37 years after logging, and the impacts of logging are still evident in the forest.


Assuntos
Agricultura Florestal , Clima Tropical , Agricultura Florestal/métodos , Monitoramento Ambiental , Florestas , Árvores , Índia
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