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1.
Trends Ecol Evol ; 36(2): 151-163, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33589047

RESUMEN

Half a century ago, Janzen and Connell hypothesized that the high tree species diversity in tropical forests is maintained by specialized natural enemies. Along with other mechanisms, these can cause conspecific negative density dependence (CNDD) and thus maintain species diversity. Numerous studies have measured proxies of CNDD worldwide, but doubt about its relative importance remains. We find ample evidence for CNDD in local populations, but methodological limitations make it difficult to assess if CNDD scales up to control community diversity and thereby local and global biodiversity patterns. A combination of more robust statistical methods, new study designs, and eco-evolutionary models are needed to provide a more definite evaluation of the importance of CNDD for geographic variation in plant species diversity.


Asunto(s)
Árboles , Clima Tropical , Biodiversidad , Bosques , Plantones
2.
Infect Dis Poverty ; 10(1): 1, 2021 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-33397494

RESUMEN

With the coronavirus disease 2019 (COVID-19) pandemic showing no signs of abating, resuming neglected tropical disease (NTD) activities, particularly mass drug administration (MDA), is vital. Failure to resume activities will not only enhance the risk of NTD transmission, but will fail to leverage behaviour change messaging on the importance of hand and face washing and improved sanitation-a common strategy for several NTDs that also reduces the risk of COVID-19 spread. This so-called "hybrid approach" will demonstrate best practices for mitigating the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by incorporating physical distancing, use of masks, and frequent hand-washing in the delivery of medicines to endemic communities and support action against the transmission of the virus through water, sanitation and hygiene interventions promoted by NTD programmes. Unless MDA and morbidity management activities resume, achievement of NTD targets as projected in the WHO/NTD Roadmap (2021-2030) will be deferred, the aspirational goal of NTD programmes to enhance universal health coverage jeopardised and the call to 'leave no one behind' a hollow one. We outline what implementing this hybrid approach, which aims to strengthen health systems, and facilitate integration and cross-sector collaboration, can achieve based on work undertaken in several African countries.


Asunto(s)
/epidemiología , Enfermedades Desatendidas/epidemiología , Enfermedades Desatendidas/prevención & control , África/epidemiología , Enfermedades Endémicas , Salud Global , Humanos , Higiene , Administración Masiva de Medicamentos/métodos , Morbilidad , Pandemias , Equipo de Protección Personal , Saneamiento , Clima Tropical , Medicina Tropical/métodos
3.
J Environ Manage ; 282: 111973, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33461090

RESUMEN

Primary forests in seasonally dry tropical regions have undergone intense land-use/cover change, ranging from widespread shifting agriculture to land clearing for livestock production systems, and selective logging. Despite the importance of tropical dry forests (TDF), little is known about the implications of carbon (C) emissions from deforestation in local, national, and global scales. Therefore, the main objective of this study is to quantify and understand the processes that drive major C losses of this ecosystem in Mexico. Also, we evaluated the applicability of the already published above ground biomass (AGB) maps to quantify and allocate changes in C stocks. The results suggest that biomass maps can be used to capture the patterns of AGB distribution and to identify the driving forces of C emissions. The C losses are more related to socioeconomic drivers than biophysical characteristics like topography and climate. Besides, this study shows that published current AGB maps may be used for landscape management, including conservation and restoration areas.


Asunto(s)
Carbono , Ecosistema , Biomasa , Carbono/análisis , Conservación de los Recursos Naturales , Bosques , México , Árboles , Clima Tropical
4.
Infect Dis Poverty ; 10(1): 2, 2021 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-33397510

RESUMEN

BACKGROUND: The damage inflicted by the coronavirus diseases 2019 (COVID-19) pandemic upon humanity is and will continue to be considerable. Unprecedented progress made in global health over the past 20 years has reverted and economic growth has already evaporated, giving rise to a global recession, the likes of which we may not have experienced since the Second World War. Our aim is to draw the attention of the neglected tropical disease (NTD) community towards some of the major emerging economic opportunities which are quickly appearing on the horizon as a result of COVID-19. MAIN TEXT: This scoping review relied on a literature search comprised of a sample of articles, statements, and press releases on initiatives aimed at mitigating the impact of COVID-19, while supporting economic recovery. Of note, the donor scenario and economic development agendas are highly dynamic and expected to change rapidly as the COVID-19 pandemic unfolds, as are donor and lender priorities. CONCLUSIONS: The NTD community, particularly in low- and middle-income countries (LMICs), will need to work quickly, diligently, and in close collaboration with decision-makers and key stakeholders, across sectors at national and international level to secure its position. Doing so might enhance the odds of grasping potential opportunities to access some of the massive resources that are now available in the form of contributions from corporate foundations, trust funds, loans, debt relieve schemes, and other financial mechanisms, as part of the ongoing and future economic development agendas and public health priorities driven by the COVID-19 pandemic. This paper should serve as a starting point for the NTD community to seek much needed financial support in order to sustain and revitalize control and elimination efforts pertaining to NTDs in LMICs.


Asunto(s)
/economía , Enfermedades Desatendidas/economía , Enfermedades Desatendidas/epidemiología , Estatus Económico , Salud Global , Humanos , Pandemias , Pobreza , Salud Pública , Factores de Riesgo , Clima Tropical , Naciones Unidas , Organización Mundial de la Salud
5.
Science ; 371(6528): 458-459, 2021 01 29.
Artículo en Inglés | MEDLINE | ID: mdl-33510010
6.
Ambio ; 50(1): 215-228, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32152906

RESUMEN

Analysing the drivers of deforestation and forest degradation in conservation landscapes can provide crucial information for conservation management. While rates of forest loss can be measured through remote sensing, on the ground information is needed to confirm the commodities and actors behind deforestation. We administered a questionnaire to Wildlife Conservation Society's landscape managers to assess the deforestation drivers in 28 tropical conservation landscapes. Commercial and subsistence agriculture were the main drivers of deforestation, followed by settlement expansion and infrastructure development. Rice, rubber, cassava and maize were the crops most frequently cited as drivers of deforestation in these emblematic conservation landscapes. Landscape managers expected deforestation trends to continue at similar or greater magnitude in the future, calling for urgent measures to mitigate these trends.


Asunto(s)
Conservación de los Recursos Naturales , Bosques , Agricultura , Árboles , Clima Tropical
7.
Sci Total Environ ; 754: 142202, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33254844

RESUMEN

Biological nitrogen fixation (BNF) is a fundamental part of nitrogen cycling in tropical forests, yet little is known about the contribution made by free-living nitrogen fixers inhabiting the often-extensive forest canopy. We used the acetylene reduction assay, calibrated with 15N2, to measure free-living BNF on forest canopy leaves, vascular epiphytes, bryophytes and canopy soil, as well as on the forest floor in leaf litter and soil. We used a combination of calculated and published component densities to upscale free-living BNF rates to the forest level. We found that bryophytes and leaves situated in the canopy in particular displayed high mass-based rates of free-living BNF. Additionally, we calculated that nearly 2 kg of nitrogen enters the forest ecosystem through free-living BNF every year, 40% of which was fixed by the various canopy components. Our results reveal that in the studied tropical lowland forest a large part of the nitrogen input through free-living BNF stems from the canopy, but also that the total nitrogen inputs by free-living BNF are lower than previously thought and comparable to the inputs of reactive nitrogen by atmospheric deposition.


Asunto(s)
Fijación del Nitrógeno , Suelo , Ecosistema , Bosques , Nitrógeno , Árboles , Clima Tropical
8.
Mol Phylogenet Evol ; 154: 106962, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-32950682

RESUMEN

The stipple-throated antwrens of the genus Epinecrophylla (Aves: Thamnophilidae) are represented by eight species primarily found in the lowlands of the Amazon Basin and the Guiana Shield. The genus has a long and convoluted taxonomic history, with many attempts made to address the taxonomy and systematics of the group. Here we employ massively parallel sequencing of thousands of ultraconserved elements (UCEs) to provide both the most comprehensive subspecies-level phylogeny of Epinecrophylla antwrens and the first population-level genetic analyses for most species in the genus. Most of our results are robust to a diversity of phylogenetic and population genetic methods, but we show that even with thousands of loci we are unable to fully resolve the relationships between some western Amazonian species in the haematonota group. We uncovered phylogenetic relationships between taxa and patterns of population structure that are discordant with both morphology and current taxonomy. For example, we found deep genetic breaks between taxa in the ornata group that are currently regarded as species, and in the haematonota and leucophthalma groups we found paraphyly at the species and subspecies levels, respectively. As has been found in many Amazonian taxa, our phylogenetic results show that the major river systems of the Amazon Basin appear to have an effect on the genetic structure and range limits within Epinecrophylla. Our population genetics analyses showed extensive admixture between some taxa despite their deep genetic divergence. We present a revised taxonomy for the group and suggest areas for further study.


Asunto(s)
Passeriformes/clasificación , Filogenia , Clima Tropical , Animales , Secuencia de Bases , Genética de Población , Genoma Mitocondrial , Geografía , Passeriformes/genética , Polimorfismo de Nucleótido Simple/genética , Análisis de Componente Principal , Especificidad de la Especie
9.
Mol Phylogenet Evol ; 154: 106971, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33035682

RESUMEN

Subtribe Galipeinae (tribe Galipeeae) is the most diverse group of Rutaceae (the orange family) in the Neotropics, with 27 genera and ca. 130 species. The largest genus in the subtribe is Conchocarpus, with ca. 50 species, distributed from Central America to southern Brazil, and is particularly diverse in the Brazilian Atlantic Forest. The circumscription of the genus was recently changed to accommodate the species of Almeidea. However, even with this inclusion, Conchocarpus did not appear as monophyletic because the position of C. concinnus, which appeared in a clade with the other genera of Galipeinae rather than in the clade with the other species of Conchocarpus. The objective of the present study is to investigate the phylogenetic position of four other species of Conchocarpus (hereafter called "C. gauchaudianus group") that share morphological traits and geographical distribution with C. concinnus suggesting a close phylogenetic affinity. Phylogenetic analyses were based on morphological and molecular data from nuclear regions ITS-1 and ITS-2 as well as plastid regions trnL-trnF and rps-16, and were conducted with parsimony and Bayesian inference as optimization criteria. Results showed Conchocarpus as polyphyletic with its species divided in two clades, one, herein called "the Conchocarpus sensu stricto group," includes the type species C. macrophyllus, and the other "the Conchocarpus gaudichaudianus group" includes C. concinnus. The latter group is here recognized as a new genus, Dryades, the name given by Carl Friederich von Martius (1794-1868) to the Domain of the Atlantic Forest in Brazil, inspired by the tree nymphs in Greek mythology. Floral structure and leaf morphology provided further support to the findings of phylogenetic analysis. A description of the new genus, new combinations, a key to the species of the new genus, discussions of the affinities of the species are also provided, as well as data on the conservation status of the species of Dryades. Additionally, new data on floral structure of C. heterophyllus, C. macrophyllus and C. minutiflorus (all from the Conchocarpus sensu stricto group) are provided.


Asunto(s)
Segregación Cromosómica , Bosques , Rutaceae/clasificación , Clima Tropical , Teorema de Bayes , Brasil , América Central , Flores/anatomía & histología , Fenotipo , Filogenia , Hojas de la Planta/anatomía & histología , Rutaceae/embriología , Especificidad de la Especie
10.
Aquat Toxicol ; 231: 105718, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33360235

RESUMEN

Climate change and oil pollution pose a major threat to tropical marine ecosystems and to the coastal communities relying on their resources. The Gulf of Guinea is severely affected by multiple human induced stressors, but the potential impacts of these on marine productivity remain unknown. We investigated the combined effects of heatwaves (climate stressor) and the polycyclic aromatic hydrocarbon pyrene (proxy for oil) on the copepod Centropages velificatus. We quantified survival, reproduction and fecal pellet production of females exposed to concentrations of 0, 10, 100 and 100+ nM (saturated) pyrene under simulated heatwaves of different thermal intensity (+3 °C and +5 °C above control treatment temperature). Thermal stress due to both moderate and intensive heatwaves resulted in reduced survival and egg production. The negative effects of pyrene were only measurable at the high pyrene concentrations. However, thermal stress increased the sensitivity of C. velificatus to pyrene, indicating a synergistic interaction between the two stressors. We document that the interaction of multiple stressors can result in cumulative impacts that are stronger than expected based on single stressor studies. Further research is urgently needed to evaluate the combined impact of climatic and anthropogenic stressors on the productivity of coastal ecosystems, particularly in the tropical areas.


Asunto(s)
Cambio Climático , Contaminación por Petróleo/análisis , Clima Tropical , Zooplancton/fisiología , Animales , Copépodos/efectos de los fármacos , Copépodos/fisiología , Heces , Femenino , Humanos , Pirenos/toxicidad , Reproducción/efectos de los fármacos , Análisis de Supervivencia , Contaminantes Químicos del Agua/toxicidad
11.
Sci Total Environ ; 756: 143939, 2021 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-33310218

RESUMEN

We present the first annually resolved and statistically reliable tree-ring δ18O (δ18OT) chronologies for the three South Asian tropical moist forest tree species (Chukrasia tabularis A. Juss., Toona ciliata M. Roem., and Lagerstroemia speciosa Roxb.) which differ in their shade tolerance and resistance to water stress. We found significantly higher mean δ18OT values in light-demanding T. ciliata than in intermediate shade tolerant C. tabularis and shade tolerant L. speciosa (p < 0.001). δ18OT in C. tabularis was mainly influenced by pre-monsoon vapor pressure deficit (VPD; r = -0.54, p < 0.01) and post monsoon maximum temperature (Tmax) (r = 0.52, p < 0.01). δ18OT in T. ciliata was strongly negatively correlated with a dry season drought index PDSI (r = -0.65, p < 0.001) and VPD (r = -0.58, p < 0.001). Pre-monsoon Tmax was strongly positively linked with δ18OT in L. speciosa (r = 0.65, p < 0.001), indicating that climatic influences on δ18OT are species-specific and vary among tree functional types. Although there was a week correlation between local precipitation and δ18OT in our studied species, we found a strong correlation between δ18OT and precipitation at a larger spatial scale. Linear mixed effect models revealed that multiple factors improved model performance only in C. tabularis, yielding the best model, which combined VPD and Tmax. The top models in T. ciliata and L. speciosa included only the single factors PDSI and Tmax, highlighting that the way C. tabularis interacts with climate is more complex when compared with other two species. Our analyses suggest that stable oxygen isotope composition in tree rings of South Asian tropical moist forest trees are a suitable proxy of local and regional climate variability and are an important tool for understanding the physiological mechanisms associated with the global hydrological cycle.


Asunto(s)
Sequías , Bosques , Oxígeno , Isótopos de Oxígeno/análisis , Temperatura , Clima Tropical
12.
Chemosphere ; 262: 127772, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32799140

RESUMEN

This study utilized the freshwater amphipod (Hyalella azteca) for the indication of contamination risk levels of sediment-associated contaminants in the Erren (ER1∼ER10) and Sanye Rivers (SY1∼SY5) which were contaminated by metal scrap and smelting industries for decades. Toxicity identification evaluations involving the manipulation of pore water and whole-sediment samples were conducted to identify causative pollutants. Impacts on the aquatic environment were then evaluated in order to explore how industrial development led to contaminant accumulation in sediments and resulted in biological effects. A whole-sediment TIE indicated that the major toxicant at sampling sites ER8 and SY5 was ammonia and that its toxicity was significantly reduced by the addition of zeolite. Toxicity at sampling sites ER4 and ER9 was induced by ammonia and heavy metals (Zn, Cd, Cr, As), whereas Cr was at toxic levels at ER6. ∑PAHs was another major class of contaminants at site ER2. Metals (Zn, Ni, Pb, Cd, Cr, and As) were identified as major toxic contaminants at three sites (ER3, SY1, and SY3). The application of TIEs confirmed that a causative toxicant can be identified and that its measured toxicity correlated with its concentration. In conclusion, a TIE approach was successful in demarcating most effective contaminant groups (ammonia, heavy metals, and non-polar organic compounds) in whole-sediment cores, their porewaters and potential toxicities from a highly polluted river after remediation in southern Taiwan to an invertebrate animal model H. azteca.


Asunto(s)
Anfípodos/efectos de los fármacos , Monitoreo del Ambiente/métodos , Sedimentos Geológicos/química , Ríos/química , Contaminantes Químicos del Agua/toxicidad , Amoníaco/análisis , Amoníaco/toxicidad , Animales , Agua Dulce/química , Metales Pesados/análisis , Metales Pesados/toxicidad , Hidrocarburos Policíclicos Aromáticos/análisis , Hidrocarburos Policíclicos Aromáticos/toxicidad , Taiwán , Clima Tropical , Contaminantes Químicos del Agua/análisis , Zeolitas/química
13.
J Environ Manage ; 279: 111805, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33316643

RESUMEN

Tropical secondary forests play a prominent role in conserving biodiversity and providing ecosystem services, but their recovery can be slow and their succession trajectory is distinct from old-growth forests. Thinning is an essential silvicultural approach to enhance the recovery rate and timber production of forests. However, the selection of trees to thin has been mainly based on size class rather than on species identity. There is little empirical or experimental evidence of species-focused thinning with the goal of altering species composition. We examined the effects of thinning on community structure, demographic rates, species richness and functional diversity of woody plants in a detailed investigation of 60-year-old secondary tropical lowland rain forest on Hainan Island, South China. The density and basal area of trees ≥5 cm DBH (diameter at breast height) increased significantly after five years' recovery with no significant change for saplings (DBH < 5 cm). Species composition after thinning changed significantly and mid-to late-successional species of both saplings and trees were more abundant after five years' recovery. The relative growth rates (RGR) and recruitment rates were significantly higher in thinning plots for both saplings and trees, and RGRs increased by 127% and 48%, respectively. The mortality rate decreased by 13% for trees and increased by 47% for saplings in thinning plots compared to the control. The community weighted mean (CWM) of the specific leaf area (SLA) of saplings showed a significantly decreasing trend while CWMs of wood density (WD) and mean maximum height (Hmax) of saplings increased after thinning. By contrast, CWMs of SLA and Hmax of trees were significantly higher, but WD was significantly lower- in thinning plots than the control. RGR and recruitment rate of saplings and trees increased significantly as thinning intensity increased. However, the thinning intensity had a weak or nil effect on the mortality rate. Our results support the selective removal and girdling of pioneer and mid-successional species in a way that could accelerate recovery and improve the growth and recruitment of late-successional species in tropical secondary forests. Thinning at a relatively low intensity can maintain species diversity and alter species functional composition. This outcome shows promise for improved future management of tropical forests in human-modified tropical forest landscapes.


Asunto(s)
Ecosistema , Clima Tropical , Biodiversidad , China , Demografía , Bosques , Humanos , Persona de Mediana Edad , Bosque Lluvioso , Árboles
14.
Ecol Lett ; 24(3): 451-463, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33316132

RESUMEN

Extreme drought events have negative effects on forest diversity and functioning. At the species level, however, these effects are still unclear, as species vary in their response to drought through specific functional trait combinations. We used long-term demographic records of 21,821 trees and extensive databases of traits to understand the responses of 338 tropical dry forests tree species to ENSO2015 , the driest event in decades in Northern South America. Functional differences between species were related to the hydraulic safety-efficiency trade-off, but unexpectedly, dominant species were characterised by high investment in leaf and wood tissues regardless of their leaf phenological habit. Despite broad functional trait combinations, tree mortality was more widespread in the functional space than tree growth, where less adapted species showed more negative net biomass balances. Our results suggest that if dry conditions increase in this ecosystem, ecological functionality and biomass gain would be reduced.


Asunto(s)
Sequías , Clima Tropical , Ecosistema , Bosques , América del Norte , Hojas de la Planta , Árboles , Agua
15.
PLoS One ; 15(12): e0237051, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33382693

RESUMEN

Hourly temperature was measured for approximately one year at 17 stations in three caves in Quintana Roo, Mexico. Thirteen of these stations were in the extensive twilight zones of all three caves. All seventeen stations showed seasonality in temperature with a 3°C drop during the Nortes season. Two of the caves, Muévelo Sabrosito and Muévelo Rico, showed greater variability during the winter months while in Río Secreto (Tuch) variability was greatest during the rainy season. Río Secreto is less open to the surface than the other two. All sites also showed a daily temperature cycle, although it was very faint in some Río Secreto (Tuch) sites. While temperature variability is diminished relative to surface variation, its temporal pattern is worthy of further study.


Asunto(s)
Cuevas/química , Temperatura , Clima Tropical , Ecosistema , México , Lluvia , Estaciones del Año
16.
PLoS One ; 15(12): e0243932, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33315909

RESUMEN

Across the tropics, large-bodied mammals have been affected by selective logging in ways that vary with levels of timber extraction, collateral damage, species-specific traits and secondary effects of hunting, as facilitated by improved access through logging roads. In Peninsular Malaysia, 3.0 million hectares or 61 percent of its Permanent Reserved Forests is officially assigned for commercial selective logging. Understanding how wildlife adapts and uses logged forest is critical for its management and, for threatened species, their conservation. In this study, we quantify the population status of four tropical ungulate species in a large selectively logged forest reserve and an adjacent primary forest protected area. We then conduct finer scale analyses to identify the species-specific factors that determine their occurrence. A combined indirect sign-camera trapping approach with a large sampling effort (2,665 km and 27,780 trap nights surveyed) covering a wide area (560 km2) generated species-specific detection probabilities and site occupancies. Populations of wild boar were widespread across both logged and primary forests, whereas sambar and muntjac occupancy was lower in logged forest (48.4% and 19.2% respectively), with gaur showing no significant difference. Subsequent modelling revealed the importance of conserving lower elevation habitat in both habitat types, particularly <1,000 m asl, for which occupancies of sambar, muntjac and gaur were typically higher. This finding is important because 75 percent (~13,400 km2) of Peninsular Malaysia's Main Range Forest (Banjaran Titiwangsa) is under 1,000 m asl and therefore at risk of being converted to industrial timber plantations, which calls for renewed thinking around forest management planning.


Asunto(s)
Conservación de los Recursos Naturales , Especies en Peligro de Extinción , Agricultura Forestal , Mamíferos/fisiología , Animales , Biodiversidad , Bovinos , Ecosistema , Bosques , Malasia , Ciervo Muntjac/fisiología , Especificidad de la Especie , Clima Tropical , Grabación en Video
17.
Proc Natl Acad Sci U S A ; 117(52): 33358-33364, 2020 12 29.
Artículo en Inglés | MEDLINE | ID: mdl-33318167

RESUMEN

Forests are the largest terrestrial biomass pool, with over half of this biomass stored in the highly productive tropical lowland forests. The future evolution of forest biomass depends critically on the response of tree longevity and growth rates to future climate. We present an analysis of the variation in tree longevity and growth rate using tree-ring data of 3,343 populations and 438 tree species and assess how climate controls growth and tree longevity across world biomes. Tropical trees grow, on average, two times faster compared to trees from temperate and boreal biomes and live significantly shorter, on average (186 ± 138 y compared to 322 ± 201 y outside the tropics). At the global scale, growth rates and longevity covary strongly with temperature. Within the warm tropical lowlands, where broadleaf species dominate the vegetation, we find consistent decreases in tree longevity with increasing aridity, as well as a pronounced reduction in longevity above mean annual temperatures of 25.4 °C. These independent effects of temperature and water availability on tree longevity in the tropics are consistent with theoretical predictions of increases in evaporative demands at the leaf level under a warmer and drier climate and could explain observed increases in tree mortality in tropical forests, including the Amazon, and shifts in forest composition in western Africa. Our results suggest that conditions supporting only lower tree longevity in the tropical lowlands are likely to expand under future drier and especially warmer climates.


Asunto(s)
Longevidad , Temperatura , Árboles/anatomía & histología , Árboles/fisiología , Clima Tropical , Ecosistema , Geografía , Modelos Teóricos , Árboles/crecimiento & desarrollo , Agua
18.
Proc Natl Acad Sci U S A ; 117(52): 33365-33372, 2020 12 29.
Artículo en Inglés | MEDLINE | ID: mdl-33318195

RESUMEN

Climate change is increasing global temperatures and intensifying the frequency and severity of extreme heat waves. How organisms will cope with these changes depends on their inherent thermal tolerance, acclimation capacity, and ability for evolutionary adaptation. Yet, the potential for adaptation of upper thermal tolerance in vertebrates is largely unknown. We artificially selected offspring from wild-caught zebrafish (Danio rerio) to increase (Up-selected) or decrease (Down-selected) upper thermal tolerance over six generations. Selection to increase upper thermal tolerance was also performed on warm-acclimated fish to test whether plasticity in the form of inducible warm tolerance also evolved. Upper thermal tolerance responded to selection in the predicted directions. However, compared to the control lines, the response was stronger in the Down-selected than in the Up-selected lines in which evolution toward higher upper thermal tolerance was slow (0.04 ± 0.008 °C per generation). Furthermore, the scope for plasticity resulting from warm acclimation decreased in the Up-selected lines. These results suggest the existence of a hard limit in upper thermal tolerance. Considering the rate at which global temperatures are increasing, the observed rates of adaptation and the possible hard limit in upper thermal tolerance suggest a low potential for evolutionary rescue in tropical fish living at the edge of their thermal limits.


Asunto(s)
Evolución Biológica , Cambio Climático , Clima Tropical , Pez Cebra/fisiología , Aclimatación/fisiología , Animales , Temperatura
19.
Nat Commun ; 11(1): 6347, 2020 12 11.
Artículo en Inglés | MEDLINE | ID: mdl-33311511

RESUMEN

Tropical forests are being deforested worldwide, and the remaining fragments are suffering from biomass and biodiversity erosion. Quantifying this erosion is challenging because ground data on tropical biodiversity and biomass are often sparse. Here, we use an unprecedented dataset of 1819 field surveys covering the entire Atlantic Forest biodiversity hotspot. We show that 83-85% of the surveys presented losses in forest biomass and tree species richness, functional traits, and conservation value. On average, forest fragments have 25-32% less biomass, 23-31% fewer species, and 33, 36, and 42% fewer individuals of late-successional, large-seeded, and endemic species, respectively. Biodiversity and biomass erosion are lower inside strictly protected conservation units, particularly in large ones. We estimate that biomass erosion across the Atlantic Forest remnants is equivalent to the loss of 55-70 thousand km2 of forests or US$2.3-2.6 billion in carbon credits. These figures have direct implications on mechanisms of climate change mitigation.


Asunto(s)
Biodiversidad , Biomasa , Ecología , Bosques , Clima Tropical , Argentina , Brasil , Ciclo del Carbono , Cambio Climático , Conservación de los Recursos Naturales , Ecosistema , Paraguay , Especificidad de la Especie , Árboles
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