scholarly journals Dietary innovations spurred the diversification of ruminants during the Caenozoic

2014 ◽  
Vol 281 (1776) ◽  
pp. 20132746 ◽  
Author(s):  
Juan L. Cantalapiedra ◽  
Richard G. FitzJohn ◽  
Tyler S. Kuhn ◽  
Manuel Hernández Fernández ◽  
Daniel DeMiguel ◽  
...  
Keyword(s):  
Global Climate ◽  
Mixed Feeding ◽  
Evolutionary Transitions ◽  
Feeding Styles ◽  
Ecological Flexibility ◽  
Climate Shifts ◽  
Adaptive Radiations ◽  
Global Temperature Change ◽  
Major Factors ◽  
Mixed Feeder

Global climate shifts and ecological flexibility are two major factors that may affect rates of speciation and extinction across clades. Here, we connect past climate to changes in diet and diversification dynamics of ruminant mammals. Using novel versions of Multi-State Speciation and Extinction models, we explore the most likely scenarios for evolutionary transitions among diets in this clade and ask whether ruminant lineages with different feeding styles (browsing, grazing and mixed feeding) underwent differential rates of diversification concomitant with global temperature change. The best model of trait change had transitions from browsers to grazers via mixed feeding, with appreciable rates of transition to and from grazing and mixed feeding. Diversification rates in mixed-feeder and grazer lineages tracked the palaeotemperature curve, exhibiting higher rates during the Miocene thermal maxima. The origination of facultative mixed diet and grazing states may have triggered two adaptive radiations—one during the Oligocene–Miocene transition and the other during Middle-to-Late Miocene. Our estimate of mixed diets for basal lineages of both bovids and cervids is congruent with fossil evidence, while the reconstruction of browser ancestors for some impoverished clades—Giraffidae and Tragulidae—is not. Our results offer model-based neontological support to previous palaeontological findings and fossil-based hypothesis highlighting the importance of dietary innovations—especially mixed feeding—in the success of ruminants during the Neogene.

EXE: a Climatically Sensitive Model to Study Climate Change and CO2 Enhancement Effects on Forests

1992 ◽  
Vol 40 (5) ◽  
pp. 717 ◽  
Author(s):  
P Martin
Keyword(s):  
Atmospheric Chemistry ◽  
General Circulation ◽  
Global Climate ◽  
Circulation Model ◽  
Resource Exploitation ◽  
Momentum Exchange ◽  
Ecological Dynamics ◽  
The North ◽  
Natural Resource Exploitation ◽  
Major Factors

Vegetation plays a significant role in determining the local and regional hydrology of ice-free continental surfaces and the dynamics of the atmosphere above it. Vegetation also influences the global climate directly by affecting atmospheric chemistry. In particular, it partially controls the carbon cycle. In turn, vegetation is influenced by climate and changes in the ambient concentration of CO2. This may have important consequences for agriculture and natural resource exploitation. A formal recognition of atmosphere/biosphere interrelationships is crucial but insufficient. Systematic investigations of the interactions between climate, plant physiology and ecology are badly needed. In this spirit, this paper presents the results of numerical simulations performed with the Energy, water and momentum eXchange, and Ecological dynamics (EXE) model at a local scale over periods of 400-800 (simulation) years. EXE constitutes a first attempt to couple a physiologically based water budget and an explicit treatment of ecological dynamics. In principle, EXE could be forced by the output of an atmospheric general circulation model (GCM). Within this context, the paper demonstrates through the examples it analyses that both potential stomata1 response to CO2 and the possible range of changes in atmospheric relative humidity are likely major factors in determining the ecosystem response to greenhouse warming. Consequently, they should be considered in future studies of this kind. The paper also provides explanations regarding the movement of ecotones, defined as the transition zones between different vegetation assemblages. Taking the North American forest/prairie boundary as a case study, the analysis of the results shows how, in a greenhouse warmed world, St Paul, MN, might look like North Platte, NE. Finally, building on the previous example by using two different models, this study illustrates that results can be strongly model dependent and encourages extreme caution in their interpretation.

scholarly journals Regional emission metrics for short-lived climate forcers from multiple models

2016 ◽  
Vol 16 (11) ◽  
pp. 7451-7468 ◽  
Author(s):  
Borgar Aamaas ◽  
Terje K. Berntsen ◽  
Jan S. Fuglestvedt ◽  
Keith P. Shine ◽  
Nicolas Bellouin
Keyword(s):  
East Asia ◽  
Radiative Forcing ◽  
Climate Models ◽  
Global Climate ◽  
Climate Impact ◽  
Ozone Precursors ◽  
Direct Forcing ◽  
Rf Values ◽  
Global Temperature Change ◽  
The Impact

Abstract. For short-lived climate forcers (SLCFs), the impact of emissions depends on where and when the emissions take place. Comprehensive new calculations of various emission metrics for SLCFs are presented based on radiative forcing (RF) values calculated in four different (chemical-transport or coupled chemistry–climate) models. We distinguish between emissions during summer (May–October) and winter (November–April) for emissions in Europe and East Asia, as well as from the global shipping sector and global emissions. The species included in this study are aerosols and aerosol precursors (BC, OC, SO2, NH3), as well as ozone precursors (NOx, CO, VOCs), which also influence aerosols to a lesser degree. Emission metrics for global climate responses of these emissions, as well as for CH4, have been calculated using global warming potential (GWP) and global temperature change potential (GTP), based on dedicated RF simulations by four global models. The emission metrics include indirect cloud effects of aerosols and the semi-direct forcing for BC. In addition to the standard emission metrics for pulse and sustained emissions, we have also calculated a new emission metric designed for an emission profile consisting of a ramping period of 15 years followed by sustained emissions, which is more appropriate for a gradual implementation of mitigation policies.For the aerosols, the emission metric values are larger in magnitude for emissions in Europe than East Asia and for summer than winter. A variation is also observed for the ozone precursors, with largest values for emissions in East Asia and winter for CO and in Europe and summer for VOCs. In general, the variations between the emission metrics derived from different models are larger than the variations between regions and seasons, but the regional and seasonal variations for the best estimate also hold for most of the models individually. Further, the estimated climate impact of an illustrative mitigation policy package is robust even when accounting for the fact that the magnitude of emission metrics for different species in a given model is correlated. For the ramping emission metrics, the values are generally larger than for pulse or sustained emissions, which holds for all SLCFs. For SLCFs mitigation policies, the dependency of metric values on the region and season of emission should be considered.

scholarly journals A global environmental crisis 42,000 years ago

Science ◽  
2021 ◽  
Vol 371 (6531) ◽  
pp. 811-818
Author(s):  
Alan Cooper ◽  
Chris S. M. Turney ◽  
Jonathan Palmer ◽  
Alan Hogg ◽  
Matt McGlone ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Climate Modeling ◽  
Global Climate ◽  
Environmental Crisis ◽  
Global Environmental ◽  
Climate Shifts ◽  
Magnetic Inversion ◽  
Global Impacts ◽  
Extinction Events ◽  
Magnetic Poles

Geological archives record multiple reversals of Earth’s magnetic poles, but the global impacts of these events, if any, remain unclear. Uncertain radiocarbon calibration has limited investigation of the potential effects of the last major magnetic inversion, known as the Laschamps Excursion [41 to 42 thousand years ago (ka)]. We use ancient New Zealand kauri trees (Agathis australis) to develop a detailed record of atmospheric radiocarbon levels across the Laschamps Excursion. We precisely characterize the geomagnetic reversal and perform global chemistry-climate modeling and detailed radiocarbon dating of paleoenvironmental records to investigate impacts. We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.

scholarly journals Seasonal dietary changes increase the abundances of savanna herbivore species

2020 ◽  
Vol 6 (40) ◽  
pp. eabd2848
Author(s):  
A. Carla Staver ◽  
Gareth P. Hempson
Keyword(s):  
Theoretical Models ◽  
Mixed Feeding ◽  
Population Declines ◽  
African Savanna ◽  
Historical Pattern ◽  
Population Sizes ◽  
Herbivore Species ◽  
Diet Shifts ◽  
Dietary Strategies ◽  
Mixed Feeder

African savannas are home to the world’s last great megafaunal communities, but despite ongoing population declines, we only poorly understand the constraints on savanna herbivore abundances. Seasonal diet shifts (except migration) have received little attention, despite a diversity of possible dietary strategies. Here, we first formulate two theoretical models that predict that both mixed feeding and migratory grazing increase population sizes. These predictions are borne out in comprehensive data across African savanna parks: Mixed feeders are the most abundant herbivores in Africa, alongside a few migratory grazer populations. Overall, clear mixed-feeder dominance may reflect a historical pattern or may instead mirror a general global decline in specialists. Regardless, mixed feeders dominate the savannas of the present and future.

scholarly journals Factors Affecting the Salinity Intrusion at the Paddy Field in Thua Thien Hue Province, Vietnam

2021 ◽  
Author(s):  
Nguyen Phuc Khoa ◽  
Nguyen Thanh Dien ◽  
Nguyen Huu Ngu ◽  
Hoang Dinh Trung
Keyword(s):  
Paddy Field ◽  
Global Climate ◽  
Soil Samples ◽  
Paddy Fields ◽  
Salinity Intrusion ◽  
Factors Affecting ◽  
Shrimp Pond ◽  
The Status ◽  
Water And Soil Samples ◽  
Major Factors

Background: Several coastal regions in Vietnam have been suffered from salinity intrusion as a consequence of global climate change. However, there are limited studies on saline intrusion in Vietnam. This paper aimed to investigate the salinity intrusion of water and soil samples in paddy fields along Tam Giang lagoon, Thua Thien Hue province and clarify the factors affecting the salinity level. Methods: We measured the salinity concentrations (EC, Electrical conductivity) of water and soil samples in paddy fields at different distances (400, 600, 800, 1000 and 1200 m) from Tam Giang lagoon. The multiple regression analysis was performed to figure out the factors affecting the salinity concentrations. Result: The salinity concentrations of water were assessed as 48% high saline (10-25 dS m-1), 34% moderately saline (2-10 dS m-1), 2% slightly saline (0.7-2 dS m-1) and 15% non-saline ( less than 0.7 dS m-1). As for surface soil in paddy field, 14.3% moderately saline (4-8 dS m-1), 35.4% slightly saline (2-4 dS m-1) and 50.3% non-saline (0-2 dS m-1) were measured. A significantly positive correlation was found between salinity concentrations of water and soil (n = 175, r = 0.886, p less than 0.01). The distances from salinity sources, Tam Giang lagoon and shrimp pond, were major factors affecting the salinity concentrations. The paddy fields near Tam Giang lagoon and shrimp pond have higher salinity concentrations compared to those areas close to the residential area. The surface water in the paddy field within 1000 m from the salinity source was assessed as saline that might harm the paddy soil and rice production. The results of this study provide highly useful information for local policymakers and farmers about the status of salinity intrusion in paddy land.

scholarly journals A Simple Equation for Regional Climate Change and Associated Uncertainty

2008 ◽  
Vol 21 (7) ◽  
pp. 1589-1604 ◽  
Author(s):  
Filippo Giorgi
Keyword(s):  
Climate Change ◽  
Global Climate ◽  
Regional Climate ◽  
Regional Climate Change ◽  
First Century ◽  
Temperature And Precipitation ◽  
Regional Temperature ◽  
Global Temperature Change ◽  
Simple Equations ◽  
Precipitation Changes

Abstract Simple equations are developed to express regional climate changes for the twenty-first century and associated uncertainty in terms of the global temperature change (GTC) without a dependence on the underlying emission pathways. The equations are applied to regional temperature and precipitation changes over different regions of the world, and relevant parameters are calculated using the latest multimodel ensemble of global climate change simulations. Examples are also shown of how to use the equations to develop probability density functions (PDFs) of regional climate change based on PDFs of GTC. The main advantage of these equations is that they can be used to estimate regional changes from GTC obtained either from simple and intermediate complexity models or from target CO2 stabilization concentrations.

scholarly journals The surface climatology of the eastern Mediterranean region obtained in a three-member ensemble climate change simulation experiment

2007 ◽  
Vol 12 ◽  
pp. 67-80 ◽  
Author(s):  
S. O. Krichak ◽  
P. Alpert ◽  
K. Bassat ◽  
P. Kunin
Keyword(s):  
Climate Change ◽  
Climate Model ◽  
Eastern Mediterranean ◽  
Global Climate ◽  
Global Climate Model ◽  
Regional Climate ◽  
Eastern Mediterranean Region ◽  
Climate Change Simulation ◽  
Precipitation Increase ◽  
Major Factors

Abstract. Two configurations of RegCM3 regional climate model (RCM) have been used to downscale results of two atmosphere-ocean global climate model (AOGCM) simulations of the current (1961–1990) and future climates (2071–2100) over the eastern Mediterranean (EM) region. The RCM domain covering the EM region from northern Africa to central part of Asia Minor with grid spacing of 50 km was used. Three sets of RCM simulations were completed. Results of the RCM experiment support earlier projections of a temperature (annual precipitation) increase (decrease) to the end of 21st century over the EM. The roles of several major factors in controlling uncertainty of the climate change estimates are evaluated. The main uncertainty factors appear to be associated with possible inadequacies in RCM description of the EM-climate-controlling developments over remotely located areas as well as those in the simulations of the global climate and its trends by the AOGCMs.

scholarly journals Montane Meadows as a Microcosm for Predicting Global Change

2005 ◽  
Vol 29 ◽  
pp. 70-73
Author(s):  
D. Debinski
Keyword(s):  
Environmental Changes ◽  
Global Climate ◽  
Warning System ◽  
Distribution Patterns ◽  
Atmospheric Composition ◽  
Ecological Changes ◽  
Climate Shifts ◽  
Terrestrial Habitats ◽  
Montane Meadows ◽  
Changes Over Time

The last decade has witnessed intensifying, abrupt global climate change. Despite this impact, we know little about when, what, and how changes occur. Most climate research is limited to studies of the abiotic environment, focusing on atmospheric composition and carbon fluxes. These studies fail to provide adequate indicators of climate changes and their impact on habitats and species. Recent and intensifying ecological changes have generated interest in (Root et al. 2003, Thomas et al. 2004), and the need for tools that can help to prepare for global climate shifts. Changes in ecological (biotic) communities are excellent indicators of climate shifts, providing models to predict changes over time. Montane meadows, defined here as persistently non­forested habitats in mountain ecosystems, make up a small percentage of terrestrial habitats, but they are likely to exhibit changes much more rapidly than most other areas. These meadows are arrayed along a hydrological gradient (from hydric to mesic to xeric) and inhabited by short-lived plants and highly mobile animal species that can exhibit quick changes in distribution patterns relative to environmental changes. Thus, they can provide an early warning system for other ecosystems across the globe. Currently, the extent and range of climatic changes that will occur in montane meadows are unknown.

Sex ratio variation in gynodioecious species of Echium endemic to the Canary Islands

Botany ◽  
2010 ◽  
Vol 88 (2) ◽  
pp. 211-216 ◽  
Author(s):  
Marcel E. Dorken
Keyword(s):  
Sex Ratio ◽  
Canary Islands ◽  
Adaptive Radiation ◽  
Life Form ◽  
Important Determinant ◽  
Oceanic Islands ◽  
Evolutionary Transitions ◽  
Seed Fertility ◽  
Evolutionary Changes ◽  
Adaptive Radiations

Species of Echium from the Canary Islands represent an adaptive radiation of plants involving evolutionary changes in habitat and life form. Alongside these changes, evolutionary transitions of the sexual system have occurred: approximately one quarter of Echium species from the Canary Islands are dimorphic for gender, paralleling other adaptive radiations of plants on oceanic islands, such as Schiedea in Hawaii. Here, I report on the variation in the frequency of female plants among eight gynodioecious populations representing four species of Echium on the island of Tenerife, and provide preliminary estimates of the seed fertility of females and hermaphrodites, which is an important determinant of the sex ratio for gynodioecious species. Across populations, female frequencies ranged between 6% and 54%, a much wider range than had previously been reported for gynodioecious species of Echium on the Canary Islands. Substantial frequencies of female plants occurred, even though no differences in the seed fertility of females and hermaphrodites were detected.

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