scholarly journals Leaf evolution in Southern Hemisphere conifers tracks the angiosperm ecological radiation

2011 ◽  
Vol 279 (1727) ◽  
pp. 341-348 ◽  
Author(s):  
Ed Biffin ◽  
Timothy J. Brodribb ◽  
Robert S. Hill ◽  
Philip Thomas ◽  
Andrew J. Lowe
Keyword(s):  
Leaf Morphology ◽  
Terrestrial Ecosystems ◽  
Time Constraints ◽  
Ecological Radiation ◽  
Leaf Evolution ◽  
Climatic Range ◽  
Bayesian Relaxed Clock ◽  
The Tropics ◽  
Relaxed Clock ◽  
Lineage Diversification

The angiosperm radiation has been linked to sharp declines in gymnosperm diversity and the virtual elimination of conifers from the tropics. The conifer family Podocarpaceae stands as an exception with highest species diversity in wet equatorial forests. It has been hypothesized that efficient light harvesting by the highly flattened leaves of several podocarp genera facilitates persistence with canopy-forming angiosperms, and the angiosperm ecological radiation may have preferentially favoured the diversification of these lineages. To test these ideas, we develop a molecular phylogeny for Podocarpaceae using Bayesian-relaxed clock methods incorporating fossil time constraints. We find several independent origins of flattened foliage types, and that these lineages have diversified predominantly through the Cenozoic and therefore among canopy-forming angiosperms. The onset of sustained foliage flattening podocarp diversification is coincident with a declining diversification rate of scale/needle-leaved lineages and also with ecological and climatic transformations linked to angiosperm foliar evolution. We demonstrate that climatic range evolution is contingent on the underlying state for leaf morphology. Taken together, our findings imply that as angiosperms came to dominate most terrestrial ecosystems, competitive interactions at the foliar level have profoundly shaped podocarp geography and as a consequence, rates of lineage diversification.

Age estimation for the genus Cymbidium (Orchidaceae: Epidendroideae) with implementation of fossil data calibration using molecular markers (ITS2 & matK) and phylogeographic inference from ancestral area reconstruction

2016 ◽  
Vol 14 (06) ◽  
pp. 1660001 ◽  
Author(s):  
Ruchishree Konhar ◽  
Manish Debnath ◽  
Jean Valrie Marbaniang ◽  
Devendra Kumar Biswal ◽  
Pramod Tandon
Keyword(s):  
Life Forms ◽  
Ancestral Area ◽  
Tropical Regions ◽  
Ancestral Area Reconstruction ◽  
History Of ◽  
Public Repositories ◽  
Bayesian Relaxed Clock ◽  
The Tropics ◽  
Fossil Data ◽  
Relaxed Clock

Intercontinental dislocations between tropical regions harboring two-thirds of the flowering plants have always drawn attention from taxonomists and biogeographers. One such family belonging to angiosperms is Orchidaceae with an herbaceous habit and high species diversity in the tropics. Here, we investigate the evolutionary and biogeographical history of the genus Cymbidium, which represents a monophyletic subfamily (Epidendroideae) of the orchids and comprises 50 odd species that are distinctly distributed in tropical to temperate regions. Much is not known about correlations among the level of CAM activity (one of the photosynthetic pathways often regarded as an adaptation to water stress in land plants), habitat, life forms, and phylogenetic relationships of orchids from an evolutionary perspective. A relatively well-resolved and highly supported phylogeny for Cymbidium orchids is reconstructed based on sequence analysis of ITS2 and matK regions from the chloroplast DNA available in public repositories viz. GenBank at NCBI. This study examines a genus level analysis by integrating different molecular matrices to existing fossil data on orchids in a molecular Bayesian relaxed clock employed in BEAST and assessed divergence times for the genus Cymbidium with a focus on evolutionary history of photosynthetic characters. Our study has enabled age estimations (45Ma) as well as ancestral area reconstruction for the genus Cymbidium using BEAST by addition of previously analyzed two internal calibration points.

scholarly journals On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?

2019 ◽  
Author(s):  
Brendan Byrne ◽  
Dylan B. A. Jones ◽  
Kimberly Strong ◽  
Saroja M. Polavarapu ◽  
Anna B. Harper ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Net Ecosystem Exchange ◽  
Terrestrial Ecosystems ◽  
Atmospheric Co2 ◽  
Strong Correlations ◽  
Climate Anomalies ◽  
Temperature And Precipitation ◽  
The Tropics ◽  
Emergent Constraint ◽  
The Impact

Abstract. Interannual variations in temperature and precipitation impact the carbon balance of terrestrial ecosystems, leaving an imprint in atmospheric CO2. Quantifying the impact of climate anomalies on the net ecosystem exchange (NEE) of terrestrial ecosystems can provide a constraint to evaluate terrestrial biosphere models against, and may provide an emergent constraint on the response of terrestrial ecosystems to climate change. We investigate the spatial scales over which interannual variability in NEE can be constrained using atmospheric CO2 observations from the Greenhouse Gases Observing Satellite (GOSAT). NEE anomalies are calculated by performing a series of inversion analyses using the GEOS-Chem model to assimilate GOSAT observations. Monthly NEE anomalies are compared to proxies, variables which are associated with anomalies in the terrestrial carbon cycle, and to upscaled NEE estimates from FLUXCOM. Strong agreement is found in the timing of anomalies in the GOSAT flux inversions with soil temperature and FLUXCOM. Strong correlations are obtained (P  RNINO3.4) in the tropics on continental and larger scales, and in the northern extratropics on sub-continental scales during the summer (R2 ≥ 0.49). These results, in addition to a series of observing system simulation experiments that were conducted, provide evidence that GOSAT flux inversions can isolate anomalies in NEE on continental and larger scales. However, in both the tropics and northern extratropics, the agreement between the inversions and the proxies/FLUXCOM is sensitive to the flux inversion configuration. Our results suggest that regional scales are likely the minimum scales that can be resolved in the tropics using GOSAT observations, but obtaining robust NEE anomaly estimates on these scales may be difficult.

scholarly journals Evaluating molecular clock calibrations using Bayesian analyses with soft and hard bounds

2007 ◽  
Vol 3 (3) ◽  
pp. 275-279 ◽  
Author(s):  
Kate L Sanders ◽  
Michael S.Y Lee
Keyword(s):  
Molecular Clock ◽  
Cross Validation ◽  
Molecular Dating ◽  
Limiting Factor ◽  
Bayesian Analyses ◽  
Clock Analysis ◽  
Bayesian Relaxed Clock ◽  
Posterior Estimate ◽  
Relaxed Clock

A limiting factor in many molecular dating studies is shortage of reliable calibrations. Current methods for choosing calibrations (e.g. cross-validation) treat them as either correct or incorrect, whereas calibrations probably lie on a continuum from highly accurate to very poor. Bayesian relaxed clock analysis permits inclusion of numerous candidate calibrations as priors: provided most calibrations are reliable, the model appropriate and the data informative, the accuracy of each calibration prior can be evaluated. If a calibration is accurate, then the analysis will support the prior so that the posterior estimate reflects the prior; if a calibration is poor, the posterior will be forced away from the prior. We use this approach to test two fossil dates recently proposed as standard calibrations within vertebrates. The proposed bird–crocodile calibration (approx. 247 Myr ago) appears to be accurate, but the proposed bird–lizard calibration (approx. 255 Myr ago) is substantially too recent.

scholarly journals Soil Texture, Organic Matter and Nutrients Affect Production of Acacia in Northeast Vietnam

2020 ◽  
pp. 33-41
Author(s):  
Pham Tien Dung ◽  
Do Van Ban ◽  
Pham Quang Tuyen ◽  
Phung Dinh Trung ◽  
Nguyen Huy Hoang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Texture ◽  
Soil Nutrient ◽  
Terrestrial Ecosystems ◽  
Growth Speed ◽  
Volume Production ◽  
Acacia Hybrid ◽  
Life On Earth ◽  
The Tropics ◽  
Lower Production

Soil provides nutrients, water, and growing space for plants, and thus is the basis for life on earth. Soil nutrient availability impacts productivity of terrestrial ecosystems i.e. forest. However, support for this phenomenon in the tropics remains elusive. In this study, the effects of soil properties including texture, organic matter and nutrients on production of Acacia hybrid and A. mangium plantations in Northeast Vietnam were studied. Thirtythree sample plots of 500 m2 (20 m × 25 m) each were established in plantations of 1–14 years old for measuring stem diameter at breast height and height for all Acacia trees. In each plot, a 0–30 cm depth soil sample was taken for analyzing soil texture, organic matter, and nutrients. While allometry was used to estimate standing volume (production) of all measured stems. The results indicated that both species had rapid growth until 8th year after planting, then growth speed decreases as age increasing. The ratio of loam particles in soil controls production of both species, as higher loam ratios lead to lower production in terms of the standing volume. While higher phosphorous availability in the soil will lead to higher production of A. mangium but not A. hybrid. There weren’t any relationships between production and soil nitrogen and potassium for both species. It is concluded that A. hybrid and A. mangium should be logged at the age earlier than 8 years old for pulpwood to maximize production, rapid reinvestment, and benefit return. Fertilizing phosphorus to acacia plantations should be conducted to increase production, while potassium and nitrogen should not be applied.

scholarly journals Carbon leaks from flooded land: do we need to re-plumb the inland water active pipe?

2018 ◽  
Author(s):  
Gwenaël Abril ◽  
Alberto V. Borges
Keyword(s):  
Ecosystem Respiration ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Inland Waters ◽  
Organic C ◽  
Wetland Ecosystems ◽  
High Productivity ◽  
Biogeochemical Models ◽  
Waterlogged Soils ◽  
The Tropics

Abstract. At the global scale, inland waters are a significant source of atmospheric carbon (C), particularly in the tropics. The active pipe concept predicts that C emissions from streams, lakes and rivers are largely fuelled by terrestrial ecosystems. The traditionally recognized C transfer mechanisms from terrestrial to aquatic systems are surface runoff and groundwater drainage. We present here a series of arguments that support the idea that land flooding is an additional significant process that fuels inland waters with C at the global scale. Whether the majority of CO2 emitted by rivers comes from floodable land (approximately 10 % of the continents) or from well-drained land is a fundamental question that impacts our capacity to predict how these C fluxes might change in the future. Using classical concepts in ecology, we propose, as a necessary step forward, an update of the active pipe concept that differentiates floodable land from drained land. Contrarily to well-drained land, wetlands combine strong hydrological connectivity with inland waters, high productivity assimilating CO2 from the atmosphere, direct transfer of litter and exudation products to water and waterlogged soils, a generally dominant allocation of ecosystem respiration below the water surface and a slow gas exchange rate at the water-air interface. These properties force plants to pump atmospheric C to wetland waters and, when hydrology is favourable, to inland waters as organic C and dissolved CO2. This wetland CO2 pump may contribute disproportionately to CO2 emissions from inland waters, particularly in the tropics, and consequently at the global scale. In future studies, more care must be taken in the way that vertical and horizontal C fluxes are conceptualized along watersheds and 2D-models that adequately account for the hydrological export of all C species are necessary. In wetland ecosystems, significant effort should be dedicated to quantifying the components of primary production and respiration in air, water and waterlogged soils, and these metabolic rates should be used in coupled hydrological-biogeochemical models. The construction of a global typology of wetlands also appears necessary to adequately integrate continental C fluxes at the global scale.

scholarly journals Age estimation for Asian Cymbidium (Orchidaceae: Epidendroideae) with implementation of fossil data calibration using molecular markers (ITS2 & matK) implying phylogeographic inference

2013 ◽  
Author(s):  
Devendra K Biswal ◽  
Jean V Marbaniang ◽  
Pramod Tandon
Keyword(s):  
Land Plants ◽  
Tropical Regions ◽  
The Public ◽  
Plant Group ◽  
History Of ◽  
Bayesian Relaxed Clock ◽  
The Tropics ◽  
Fossil Data ◽  
Relationship Of ◽  
First Time

Abstract: Intercontinental dislocations between tropical regions harboring two-thirds of the flowering plants have always drawn attention from taxonomists and bio-geographers. The focus had always been on woody land plants rather than on herbs. Orchidaceae is one such family belonging to angiosperms, with an herbaceous habit and high species diversity in the tropics. Here, we investigate the evolutionary and bio-geographical history of the genus Cymbidium, which represents a monophyletic subfamily (Epidendroideae) of the orchids and comprises 50 odd species that are disjunctly distributed in tropical to temperate regions. A relatively well-resolved and highly supported phylogeny of Cymbidiums was reconstructed based on sequence analyses of internal transcribed spacer (ITS2) regions and maturaseK (matK) from the chloroplast region available on the public domain in GenBank at NCBI. Crassulacean acid metabolism (CAM) is one of the photosynthetic pathways regarded as adaptation to water stress in land plants. Hardly any information exists on correlations among the level of CAM activity, habitat, life form, and phylogenetic relationship of a plant group from an evolutionary perspective. This study examines a genus level analyses by integrating ITS and matK data to all fossil data available on orchids in a molecular Bayesian relaxed clock employed in BEAST and assessed divergence times for the genus Cymbidium with a focus on evolutionary plasticity of photosynthetic characters. Our study has enabled age estimations for the genus Cymbidum (12Ma) for the first time using BEAST by addition of previously analyzed two internal calibration points.

scholarly journals Wood decomposition in aquatic and terrestrial ecosystems in the tropics: contrasting biotic and abiotic processes

2018 ◽  
Vol 95 (1) ◽  
Author(s):  
Jennifer M Jones ◽  
Katy D Heath ◽  
Astrid Ferrer ◽  
Shawn P Brown ◽  
Thomas Canam ◽  
...  
Keyword(s):  
Terrestrial Ecosystems ◽  
Wood Decomposition ◽  
The Tropics

scholarly journals Biological Sinks for Carbon Dioxide – An Option for Agroforestry Systems in the Tropics

2015 ◽  
pp. 129-141 ◽  
Author(s):  
Friedhelm Goltenboth ◽  
Paciencia Milan
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Terrestrial Ecosystems ◽  
Agroforestry Systems ◽  
Average Temperature ◽  
The Core ◽  
Carbon Dioxide Concentrations ◽  
Core Questions ◽  
The Tropics ◽  
Business As Usual

One of the core questions, that need to be answered in the present discussion about climate change, is how the increase of carbon dioxide content in the atmosphere can be minimized if not stopped. This Greenhouse Gas (GHG) is the main reason for the increase of average temperature. Under business as usual (BAU) conditions an increase in temperature between 1.7-4.5֯C is expected during the next 100 years. One option to counter this trend is through reforestation and the conservation of forests functioning as carbon sinks. Estimates are giving an amount of 60 Petagram (Pg) or 60 Gigatons (Gt) as exchange of carbon between the terrestrial ecosystems and the atmosphere annually. Tropical forests and agroforestry systems show promising options in the process of binding atmospheric carbon dioxide. The use of agroforestry methods, like the Rainforestation Farming strategy, open very interesting options due to ecological and economical advantages, while contributing to the reduction of carbon dioxide concentrations.

Bayesian relaxed clock estimation of divergence times in foraminifera

2011 ◽  
Vol 61 (1) ◽  
pp. 157-166 ◽  
Author(s):  
Mathieu Groussin ◽  
Jan Pawlowski ◽  
Ziheng Yang
Keyword(s):  
Divergence Times ◽  
Clock Estimation ◽  
Bayesian Relaxed Clock ◽  
Relaxed Clock
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