Altitudinal implications in organ size in the Andrew’s toad (Bufo andrewsi)

2019 ◽  
Vol 69 (3) ◽  
pp. 365-376 ◽  
Author(s):  
Li Zhao ◽  
Chun Lan Mai ◽  
Guo Hou Liu ◽  
Wen Bo Liao
Keyword(s):  
Environmental Gradient ◽  
Oxygen Supply ◽  
Environmental Gradients ◽  
Relative Size ◽  
Organ Size ◽  
Phenotypic Flexibility ◽  
Energy Demands ◽  
Morphological And Physiological Traits ◽  
Bufo Andrewsi ◽  
Toad Bufo

Abstract Phenotypic flexibility of morphological and physiological traits within species is a common phenomenon across animal taxa. Hesse’s rule predicts that the size of an organ should exhibit an increase with increasing altitude along environmental gradients due to changes in oxygen supply and energy demands. Here, we test the prediction of Hesse’s rule by investigating geographical variation in the relative size of organs (i.e., heart, lungs, liver, and kidneys) across ten populations of Bufo andrewsi along an environmental gradient. We found that the relative size of these four specific organs did not increase with altitude or latitude across all populations. We also did not find that the relative size of the organs increased with increasing altitude among six populations located at a similar latitude and longitude, which is inconsistent with Hesse’s rule. Our findings suggest that oxygen supply and energy demands do not necessarily affect variation in organ size among populations.

scholarly journals Increasing temporal variance leads to stable species range limits

2021 ◽  
Author(s):  
John W Benning ◽  
Ruth A Hufbauer ◽  
Christopher Weiss-Lehman
Keyword(s):  
Environmental Gradient ◽  
Environmental Gradients ◽  
Local Population ◽  
Evolutionary Model ◽  
Environmental Variation ◽  
Species Range ◽  
Range Limits ◽  
Stable Range ◽  
Species Expansion ◽  
Temporal Variance

What prevents populations of a species from adapting to the novel environments outside the species' geographic distribution? Previous models highlighted how gene flow across spatial environmental gradients determines species expansion vs. extinction and the location of species range limits. However, space is only one of two axes of environmental variation — environments also vary in time, and we know temporal environmental variation has important consequences for population demography and evolution. We used an individual based evolutionary model to explore how temporal stochasticity in environmental conditions influences the spread of populations across a spatial environmental gradient. We find that temporal stochasticity greatly alters our predictions for range dynamics compared to temporally static environments. When temporal variance is equal across the landscape, the fate of species (expansion vs. extinction) is determined by the interaction between the degree of temporal autocorrelation in environmental fluctuations and the steepness of the spatial environmental gradient. When the magnitude of temporal variance changes across the landscape, stable range limits form where this variance becomes large enough to prevent local population adaptation and persistence. These results illustrate the pivotal influence of temporal stochasticity on the likelihood of populations colonizing novel habitats and the location of species range limits.

scholarly journals Southern California margin benthic foraminiferal assemblages across a modern environmental gradient record recent centennial-scale changes in oxygen minimum zone

2019 ◽  
Author(s):  
Hannah M. Palmer ◽  
Tessa M. Hill ◽  
Peter D. Roopnarine ◽  
Sarah E. Myhre ◽  
Katherine R. Reyes ◽  
...  
Keyword(s):  
Water Depth ◽  
San Diego ◽  
Environmental Gradient ◽  
Environmental Gradients ◽  
Oxygen Minimum Zone ◽  
Shannon Index ◽  
Spatial Trends ◽  
Minimum Zone ◽  
Associated Species ◽  
Oxygen Minimum

Abstract. Microfossil assemblages provide valuable records to investigate variability in continental margin biogeochemical cycles, including dynamics of the oxygen minimum zone (OMZ). Analyses of modern assemblages across environmental gradients are necessary to understand relationships between assemblage characteristics and environmental factors. Here, we analyzed five cores from the San Diego Margin (32°42'00'' N, 117°30'00'' W, 300–1175 m water depth) for core top benthic foraminiferal assemblages to understand relationships between community assemblages and spatial hydrographic gradients and down core to identify changes in the oxygen minimum zone through time. Comparisons of benthic foraminiferal assemblages from two size fractions (63–150 and > 150 μm) exhibit similar trends across the spatial/environmental gradient, or in some cases exhibit more pronounced spatial trends in the > 150 μm fraction. We identify two hypoxic associated species (B. spissa and U. peregrina), one oxic associated species (G. subglobosa) and one OMZ edge-associated species (B. argentea). A range of species diversity exists within the modern OMZ (1.5–2.6 H, Shannon Index), suggesting that diversity is not driven by oxygenation alone. Down core analysis of indicator species reveal variability in upper margin of the OMZ (528 m water depth) while the core of the OMZ (800 m) and below the OMZ (1175 m) remained stable in the last 1.5 ka. We document expansion of the upper margin of the OMZ beginning 400 ybp on the San Diego Margin that is synchronous with other regional records of oxygenation.

scholarly journals Oxygen supply capacity breathes new life into critical oxygen partial pressure (Pcrit)

2021 ◽  
Vol 224 (8) ◽  
Author(s):  
Brad A. Seibel ◽  
Alyssa Andres ◽  
Matthew A. Birk ◽  
Alexandra L. Burns ◽  
C. Tracy Shaw ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Supply ◽  
Accurate Determination ◽  
Maximum Energy ◽  
Hypoxia Tolerance ◽  
Energy Demands ◽  
Critical Oxygen ◽  
Supply Capacity

ABSTRACT The critical oxygen partial pressure (Pcrit), typically defined as the PO2 below which an animal's metabolic rate (MR) is unsustainable, is widely interpreted as a measure of hypoxia tolerance. Here, Pcrit is defined as the PO2 at which physiological oxygen supply (α0) reaches its maximum capacity (α; µmol O2 g−1 h−1 kPa−1). α is a species- and temperature-specific constant describing the oxygen dependency of the maximum metabolic rate (MMR=PO2×α) or, equivalently, the MR dependence of Pcrit (Pcrit=MR/α). We describe the α-method, in which the MR is monitored as oxygen declines and, for each measurement period, is divided by the corresponding PO2 to provide the concurrent oxygen supply (α0=MR/PO2). The highest α0 value (or, more conservatively, the mean of the three highest values) is designated as α. The same value of α is reached at Pcrit for any MR regardless of previous or subsequent metabolic activity. The MR need not be constant (regulated), standardized or exhibit a clear breakpoint at Pcrit for accurate determination of α. The α-method has several advantages over Pcrit determination and non-linear analyses, including: (1) less ambiguity and greater accuracy, (2) fewer constraints in respirometry methodology and analysis, and (3) greater predictive power and ecological and physiological insight. Across the species evaluated here, α values are correlated with MR, but not Pcrit. Rather than an index of hypoxia tolerance, Pcrit is a reflection of α, which evolves to support maximum energy demands and aerobic scope at the prevailing temperature and oxygen level.

scholarly journals Grassland communities of Stol mountain (eastern Serbia ): Vegetation and environment al relationships

2013 ◽  
Vol 65 (1) ◽  
pp. 211-227 ◽  
Author(s):  
Svetlana Acic ◽  
U. Silc ◽  
S. Vrbnicanin ◽  
Svjetlana Cupac ◽  
G. Topisirovic ◽  
...  
Keyword(s):  
Species Composition ◽  
Environmental Gradient ◽  
Environmental Gradients ◽  
Detrended Correspondence Analysis ◽  
Ecological Indicator ◽  
Vegetation Types ◽  
Indicator Values ◽  
Grassland Vegetation ◽  
Data Set ◽  
Grassland Communities

The systematic survey of grassland communities was performed on Mt. Stol (eastern Serbia). The main aims of the research were to: (1) determine grassland vegetation types of the researched area; (2) correlate the impacts of the soil and environmental conditions on the occurrence of certain plant communities, and (3) comment on the conservational value of the grasslands in the researched area. The data set included 60 phytosociological relev?s of grasslands recorded between 2001 and 2004. The main environmental gradients of species composition were analyzed by Detrended Correspondence Analysis (DCA). For the ecological interpretation of ordination axes, ecological indicator values were used. Three associations were distinguished: Danthonietum calycinae, Asperulo-Agrostietum vulgaris and Ranunculo bulbosi- Arrhenatheretum elatioris belonging to two alliances and two classes: Chrysopogono-Danthonion - Festuco-Brometea and Arrhenatherion - Molinio-Arrhenatheretea. The results of the DCA support our assumption that the main environmental gradient in the species composition of the grasslands is related to nutrients and moisture. The conservational value of grasslands in the researched area is discussed.

scholarly journals Integrity of fluvial fish communities is subject to environmental gradients in mountain streams, Sierra de Aroa, north Caribbean coast, Venezuela

2006 ◽  
Vol 4 (3) ◽  
pp. 319-328 ◽  
Author(s):  
Douglas Rodríguez-Olarte ◽  
Ahyran Amaro ◽  
Jorge Coronel ◽  
Donald C. Taphorn B.
Keyword(s):  
Environmental Gradient ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Fish Communities ◽  
Physical Habitat ◽  
Heterogeneous Habitat ◽  
Components Analysis ◽  
The Relationship ◽  
Different Levels ◽  
Habitat Parameters

We examined physical habitat and fish assemblages in rivers of the Aroa Mountains (Venezuela) with different levels of environmental protection due to the creation of Yurubí National Park within the drainage. We developed an Index of Biotic Integrity (IBI) and evaluated it using principal components analysis (PCA) and canonical correspondence analysis (CCA). Tributary rivers were divided into classes according to their origin (protected by the park) and physical characteristics of each, including substrate. Fishes were captured using standardized electrofishing. Fish communities showed greater species richness in heterogeneous habitat and protected rivers but overall abundance was higher in unprotected and impacted rivers. The IBI was sensitive to these differences and the scores were higher in protected rivers. The IBI detected degree of disturbance of fish communities without direct consideration of habitat parameters measured. The PCA revealed a gradient in substrate heterogeneity. Similarly, CCA revealed differences in fish assemblage composition along the environmental gradient and that varied with protection status of the river. The relationship between PCA and IBI scores was highly significant (r² = 0.61, P < 0.0001). The PCA and CCA analysis moderately validated the structure and predictability of IBI; but it is still necessary to refine the model and to extend its application for more time and over a wider area.

scholarly journals Separate the wheat from the chaff: genomic scan for local adaptation in the red coralCorallium rubrum

2018 ◽  
Author(s):  
M. Pratlong ◽  
A. Haguenauer ◽  
K. Brener ◽  
G. Mitta ◽  
E. Toulza ◽  
...  
Keyword(s):  
Local Adaptation ◽  
Environmental Gradient ◽  
Environmental Gradients ◽  
High Rate ◽  
Corallium Rubrum ◽  
Red Coral ◽  
Geographical Regions ◽  
Adaptive Processes ◽  
Tests Of Association ◽  
Candidate Loci

ABSTRACTGenomic data allow an in-depth and renewed study of local adaptation. The red coral (Corallium rubrum, Cnidaria) is a highly genetically structured species and a promising model for the study of adaptive processes along an environmental gradient. Here, we used RAD-Sequencing in order to study the vertical genetic structure of this species and to search for signals of local adaptation to depth and thermal regime in the red coral. Previous studies have shown different thermotolerance levels according to depth in this species which could correspond to genetic or environmental differences. We designed a sampling scheme with six pairs of ‘shallow vs deep’ populations distributed in three geographical regions as replicates. Our results showed significant differentiation among locations and among sites separated by around 20 m depth. The tests of association between genetics and environment allowed the identification of candidate loci under selection but with a potentially high rate of false positive. We discuss the methodological obstacles and biases encountered for the detection of selected loci in such a strongly genetically structured species. On this basis, we also discuss the significance of the candidate loci for local adaptation detected in each geographical region and the evolution of red coral populations along environmental gradients.A colony of red coral,Corallium rubrum, near Marseille. Photo: F. Zuberer / OSU Pythéas / CNRS

scholarly journals Southern California margin benthic foraminiferal assemblages record recent centennial-scale changes in oxygen minimum zone

2020 ◽  
Vol 17 (11) ◽  
pp. 2923-2937
Author(s):  
Hannah M. Palmer ◽  
Tessa M. Hill ◽  
Peter D. Roopnarine ◽  
Sarah E. Myhre ◽  
Katherine R. Reyes ◽  
...  
Keyword(s):  
Water Depth ◽  
San Diego ◽  
Environmental Gradient ◽  
Environmental Gradients ◽  
Oxygen Minimum Zone ◽  
Shannon Index ◽  
Spatial Trends ◽  
Minimum Zone ◽  
Associated Species ◽  
Oxygen Minimum

Abstract. Microfossil assemblages provide valuable records to investigate variability in continental margin biogeochemical cycles, including dynamics of the oxygen minimum zone (OMZ). Analyses of modern assemblages across environmental gradients are necessary to understand relationships between assemblage characteristics and environmental factors. Five cores were analyzed from the San Diego margin (32∘42′00′′ N, 117∘30′00′′ W; 300–1175 m water depth) for core top benthic foraminiferal assemblages to understand relationships between community assemblages and spatial hydrographic gradients as well as for down-core benthic foraminiferal assemblages to identify changes in the OMZ through time. Comparisons of benthic foraminiferal assemblages from two size fractions (63–150 and >150 µm) exhibit similar trends across the spatial and environmental gradient or in some cases exhibit more pronounced spatial trends in the >150 µm fraction. A range of species diversity exists within the modern OMZ (1.910–2.586 H, Shannon index), suggesting that diversity is not driven by oxygenation alone. We identify two hypoxic-associated species (B. spissa and U. peregrina), one oxic-associated species (G. subglobosa) and one OMZ edge-associated species (B. argentea). Down-core analysis of indicator species reveals variability in the upper margin of the OMZ (528 m water depth) while the core of the OMZ (800 m) and below the OMZ (1175 m) remained stable in the last 1.5 kyr. We document expansion of the upper margin of the OMZ beginning 400 BP on the San Diego margin that is synchronous with other regional records of oxygenation.

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