scholarly journals Extreme climatic event drives range contraction of a habitat-forming species

2013 ◽  
Vol 280 (1754) ◽  
pp. 20122829 ◽  
Author(s):  
Dan A. Smale ◽  
Thomas Wernberg
Keyword(s):  
Structural Changes ◽  
Species Distributions ◽  
Ecological Change ◽  
Ecosystem Structure ◽  
Discrete Events ◽  
Marginal Populations ◽  
Range Contraction ◽  
Range Edge ◽  
Ecosystem Level ◽  
Underlying Mechanisms

Species distributions have shifted in response to global warming in all major ecosystems on the Earth. Despite cogent evidence for these changes, the underlying mechanisms are poorly understood and currently imply gradual shifts. Yet there is an increasing appreciation of the role of discrete events in driving ecological change. We show how a marine heat wave (HW) eliminated a prominent habitat-forming seaweed, Scytothalia dorycarpa , at its warm distribution limit, causing a range contraction of approximately 100 km (approx. 5% of its global distribution). Seawater temperatures during the HW exceeded the seaweed's physiological threshold and caused extirpation of marginal populations, which are unlikely to recover owing to life-history traits and oceanographic processes. Scytothalia dorycarpa is an important canopy-forming seaweed in temperate Australia, and loss of the species at its range edge has caused structural changes at the community level and is likely to have ecosystem-level implications. We show that extreme warming events, which are increasing in magnitude and frequency, can force step-wise changes in species distributions in marine ecosystems. As such, return times of these events have major implications for projections of species distributions and ecosystem structure, which have typically been based on gradual warming trends.

Abstract P604: Astrocyte-dependent Regulation of Vascular Tone: Role in Hypertension

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Juan Manuel Ramiro-Diaz ◽  
Ki Jung Kim ◽  
Jessica A Filosa
Keyword(s):  
Vascular Tone ◽  
Structural Changes ◽  
Neurovascular Unit ◽  
Brain Slices ◽  
Vascular Cognitive Impairment ◽  
Vascular Density ◽  
Aqp4 Expression ◽  
Functional Changes ◽  
Functional Studies ◽  
Underlying Mechanisms

Clinical studies support that untreated hypertension (HT) accelerates the development of vascular cognitive impairment (VCI). Yet, the underlying mechanisms for VCI are not known. In a recent study we demonstrated the role of astrocytes in the regulation of parenchymal arteriole (PA) steady-state vascular tone. Here we hypothesized hypertension results in structural and functional changes to the neurovascular unit resulting in enhanced astrocytic TRPV4 channel-dependent Ca 2+ increases contributing to augmented pressure-induced PA constriction . Functional studies were conducted in brain slices from angiotensin II (AngII) treated mice (600 ng/Kg/min, 28 days). PA arterioles within brain slices were perfused and pressurized and myogenic-evoked diameter changes measured using video microscopy. In addition, using the GLAST-CreERT2 ; R26-lsl-GCaMP3 mice we measure myogenic-evoked Ca 2+ changes in perivascular astrocytes. We demonstrate that HT increases pressure-induced PA tone by 11.14% at 30 mmHg and 12.97% at 60 mmHg (10.88 to 22.02 and 15.46 to 28.43% of tone, P<0.05 and P<0.01, respectively). In ANG II-treated mice, PA myogenic-evoked responses significantly increased astrocytic Ca 2+ oscillations frequency (119.4%, 0.0366 to 0.0803 Hz, P<0.0001). A significant increase in astrocytic Ca 2+ oscillation frequency was also observed after 2 min of AngII (500 nM) bath application (44.8%, 0.0366 to 0.053 Hz, P<0.01) in brain slices from AngII treated mice. Furthermore, using the model of spontaneous hypertensive rat (SHR) we observed that HT differentially increases vascular density and the number of vascular pericytes in cortical layers with highest neuronal densities (L III-V). Finally, while aquaporin 4 (AQP4) expression pattern was not different in the gray matter of SHR compared with WKY rats, a significant increase in unpolarized AQP4 expression was observed in the white matter of SHR. Taken together, this evidence indicates that HT induces functional and structural changes to the neurovascular unit favoring the development of regional brain hypoperfusion likely contributing to the development of VCI.

scholarly journals Chimpanzee (Pan troglodytes verus) density and environmental gradients at their biogeographical range edge

2020 ◽  
Author(s):  
Erin G. Wessling ◽  
Paula Dieguez ◽  
Manuel Llana ◽  
Liliana Pacheco ◽  
Jill D. Pruetz ◽  
...  
Keyword(s):  
Pan Troglodytes ◽  
Habitat Heterogeneity ◽  
Environmental Gradients ◽  
Abiotic Factors ◽  
Habitat Characteristics ◽  
Pan Troglodytes Verus ◽  
Range Limit ◽  
Range Edge ◽  
Food Species ◽  
Underlying Mechanisms

ABSTRACTIdentifying ecological gradients at the range edge of a species is an essential step in revealing the underlying mechanisms and constraints that limit the species’ geographic range. We aimed to describe the patterns of variation in chimpanzee (Pan troglodytes verus) density and habitat characteristics perpendicular to the northern edge of their range and to investigate potential environmental mechanisms underlying chimpanzee distribution in a savanna-mosaic habitat. We estimated chimpanzee densities at six sites forming a 126 km latitudinal gradient at the biogeographical range edge of the western chimpanzee in the savanna-mosaic habitats of southeastern Senegal. To accompany these data, we used systematically placed vegetation plots to characterize the habitats at each site for habitat heterogeneity, tree density and size, floral assemblages, among other variables. We found that both biotic and abiotic factors are potential determinants of the chimpanzee range limit in this ecoregion. Specifically, chimpanzee-occupied landscapes at the limit had smaller available floral assemblages, less habitat heterogeneity, and contained fewer closed canopy habitats in which chimpanzees could seek refuge from high temperatures than landscapes farther from the range limit. This pattern was accompanied by a decline in chimpanzee density with increasing proximity to the range limit. Our results provide several indications of the potential limits of food species diversity, thermal refuge, and water availability to the chimpanzee niche and the implications of these limits for chimpanzee biogeography, especially in the face of climate change predictions, as well as to species distributional modeling more generally.

Imaging Morphogenesis: Technological Advances and Biological Insights

Science ◽  
2013 ◽  
Vol 340 (6137) ◽  
pp. 1234168 ◽  
Author(s):  
Philipp J. Keller
Keyword(s):  
Structural Changes ◽  
Imaging Techniques ◽  
Spatial Scales ◽  
Image Data ◽  
Physical Models ◽  
Data Sets ◽  
Full Potential ◽  
Technological Advances ◽  
Complex Image ◽  
Underlying Mechanisms

Morphogenesis, the development of the shape of an organism, is a dynamic process on a multitude of scales, from fast subcellular rearrangements and cell movements to slow structural changes at the whole-organism level. Live-imaging approaches based on light microscopy reveal the intricate dynamics of this process and are thus indispensable for investigating the underlying mechanisms. This Review discusses emerging imaging techniques that can record morphogenesis at temporal scales from seconds to days and at spatial scales from hundreds of nanometers to several millimeters. To unlock their full potential, these methods need to be matched with new computational approaches and physical models that help convert highly complex image data sets into biological insights.

scholarly journals “Walking in Two Worlds”: Towards an Indigenist Ecological Systems Model for Group Therapy

2020 ◽  
Author(s):  
Jillian Fish ◽  
Glenn Hirsch ◽  
Moin Syed
Keyword(s):  
Indigenous Peoples ◽  
Counseling Psychology ◽  
Structural Changes ◽  
Clinical Intervention ◽  
Ecological Systems ◽  
Ecological Change ◽  
Integrative Framework ◽  
Indigenous Epistemologies ◽  
Systems Model ◽  
Ecological Systems Model

Walking in two worlds is a common metaphor Indigenous peoples use to describe their experiences navigating the differences between Indigenous and Western epistemological and ontological worldviews across various contexts. Despite wide support for this phenomena, there have been few attempts to address Indigenous-Western cultural incongruities through structural changes in counseling psychology, though we are well-equipped as a profession to do so. Thus, we propose for counseling psychology to move towards an Indigenist Ecological Systems Model (IESM; MASKED, 2018) as an integrative framework for promoting Indigenous epistemologies and ontologies in science and practice. We provide a brief overview of IESM and a direct application of the model through a case illustration of Walking in Two Worlds, a psychotherapy group for Indigenous peoples. With IESM, we describe creating an Indigenous-informed clinical intervention that leverages Indigenous epistemologies and ontologies, prompting real ecological change. We conclude with implications IESM has for counseling psychology.

scholarly journals Fear, human shields and the redistribution of prey and predators in protected areas

2007 ◽  
Vol 3 (6) ◽  
pp. 620-623 ◽  
Author(s):  
Joel Berger
Keyword(s):  
North America ◽  
Protected Areas ◽  
Species Distributions ◽  
Unintended Consequence ◽  
Anthropogenic Effects ◽  
Ecological Change ◽  
Large Carnivores ◽  
Brown Bears ◽  
Human Presence ◽  
Landscape Use

Protected areas form crucial baselines to judge ecological change, yet areas of Africa, Asia and North America that retain large carnivores are under intense economic and political pressures to accommodate massive human visitation and attendant infrastructure. An unintended consequence is the strong modulation of the three-way interaction involving people, predators and prey, a dynamic that questions the extent to which animal distributions and interactions are independent of subtle human influences. Here, I capitalize on the remarkable 9-day synchronicity in which 90% of moose neonates in the Yellowstone Ecosystem are born, to demonstrate a substantive change in how prey avoid predators; birth sites shift away from traffic-averse brown bears and towards paved roads. The decade-long modification was associated with carnivore recolonization, but neither mothers in bear-free areas nor non-parous females altered patterns of landscape use. These findings offer rigorous support that mammals use humans to shield against carnivores and raise the possibility that redistribution has occurred in other mammalian taxa due to human presence in ways we have yet to anticipate. To interpret ecologically functioning systems within parks, we must now also account for indirect anthropogenic effects on species distributions and behaviour.

scholarly journals Peripheral Mechanisms of Neuropathic Pain—The Role of Neuronal and Non-Neuronal Interactions and Their Implications for Topical Treatment of Neuropathic Pain

2021 ◽  
Vol 14 (2) ◽  
pp. 77
Author(s):  
Magdalena Kocot-Kępska ◽  
Renata Zajączkowska ◽  
Joanna Mika ◽  
Jerzy Wordliczek ◽  
Jan Dobrogowski ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Nerve Injury ◽  
Structural Changes ◽  
Neuronal Cells ◽  
Special Focus ◽  
Peripheral Sensitization ◽  
Peripheral Neuropathic Pain ◽  
Topical Analgesics ◽  
Underlying Mechanisms

Neuropathic pain in humans arises as a consequence of injury or disease of somatosensory nervous system at peripheral or central level. Peripheral neuropathic pain is more common than central neuropathic pain, and is supposed to result from peripheral mechanisms, following nerve injury. The animal models of neuropathic pain show extensive functional and structural changes occurring in neuronal and non-neuronal cells in response to peripheral nerve injury. These pathological changes following damage lead to peripheral sensitization development, and subsequently to central sensitization initiation with spinal and supraspinal mechanism involved. The aim of this narrative review paper is to discuss the mechanisms engaged in peripheral neuropathic pain generation and maintenance, with special focus on the role of glial, immune, and epithelial cells in peripheral nociception. Based on the preclinical and clinical studies, interactions between neuronal and non-neuronal cells have been described, pointing out at the molecular/cellular underlying mechanisms of neuropathic pain, which might be potentially targeted by topical treatments in clinical practice. The modulation of the complex neuro-immuno-cutaneous interactions in the periphery represents a strategy for the development of new topical analgesics and their utilization in clinical settings.

Stroboscopic neutron diffraction from spatially modulated systems

2003 ◽  
Vol 218 (2) ◽  
Author(s):  
G. Eckold ◽  
H. Gibhardt ◽  
D. Caspary ◽  
P. Elter ◽  
K. Elisbihani
Keyword(s):  
Neutron Diffraction ◽  
Time Scales ◽  
Structural Changes ◽  
Structural Response ◽  
Relaxation Processes ◽  
Time Resolved ◽  
Transient States ◽  
Underlying Mechanisms ◽  
Lock In ◽  
Kinetics Of

AbstractThe combination of stroboscopic techniques and neutron diffraction can be used to study the kinetics of structural changes in condensed matter on a microscopic level. Transient states may be identified and characterized on time-scales down to the microsecond regime. Hence, valuable information about the underlying mechanisms can be obtained from time-resolved experiments. Particularly interesting subjects for this type of investigation are spatially modulated systems which undergo phase transitions or phase separation. The potential of stroboscopic neutron diffraction is demonstrated using three different examples in which samples are periodically perturbed by the variation of temperature, mechanical stress or electric field and their structural response is characterized by time-resolved diffraction. Spinodal decomposition in ionic crystals of the silver-alkali halide type is shown to be dominated by two different processes on different time-scales. The stress-induced phase transition into the incommensurate phase of quartz involves relaxation processes which are reflected by different kinetic behaviours of Bragg peaks and satellite reflections, respectively. Finally, metastable transient states are observed during the field induced lock-in transition in ferroelectric Rb

scholarly journals Mutation accumulation and the formation of range limits

2015 ◽  
Vol 11 (1) ◽  
pp. 20140871 ◽  
Author(s):  
Roslyn C. Henry ◽  
Kamil A. Bartoń ◽  
Justin M. J. Travis
Keyword(s):  
Growth Rate ◽  
Deleterious Effect ◽  
Environmental Gradient ◽  
Species Distributions ◽  
Mutation Accumulation ◽  
Range Limits ◽  
Deleterious Mutations ◽  
Mutation Load ◽  
Limited Growth ◽  
Marginal Populations

The dynamics of range formation are important for understanding and predicting species distributions. Here, we focus on a process that has thus far been overlooked in the context of range formation; the accumulation of mutation load. We find that mutation accumulation severely reduces the extent of a range across an environmental gradient, especially when dispersal is limited, growth rate is low and mutations are of intermediate deleterious effect. Our results illustrate the important role deleterious mutations can play in range formation. We highlight this as a necessary focus for further work, noting particularly the potentially conflicting effects dispersal may have in reducing mutation load and simultaneously increasing migration load in marginal populations.

Metallothionein-I- and -II-deficient mice display increased susceptibility to cadmium-induced fetal growth restriction

2013 ◽  
Vol 305 (6) ◽  
pp. E727-E735 ◽  
Author(s):  
Johanna Selvaratnam ◽  
Haiyan Guan ◽  
James Koropatnick ◽  
Kaiping Yang
Keyword(s):  
Fetal Growth ◽  
Fetal Growth Restriction ◽  
Structural Changes ◽  
Molecular Mechanisms ◽  
Glucose Transporter ◽  
Cadmium Exposure ◽  
Growth Restriction ◽  
Glut1 Expression ◽  
Pregnant Mice ◽  
Underlying Mechanisms

Maternal cadmium exposure induces fetal growth restriction (FGR), but the underlying mechanisms remain largely unknown. The placenta is the main organ known to protect the fetus from environmental toxins such as cadmium. In this study, we examine the role of the two key placental factors in cadmium-induced FGR. The first is placental enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which is known to protect the fetus from exposure to high cortisol levels and subsequently FGR, and the second the cadmium binding/sequestering proteins metallotheionein (MT)-I and -II. Using the MT-I/II −/− mouse model, pregnant mice were administered cadmium, following which pups and placentas were collected and examined. MT-I/II−/− pups exposed to cadmium were significantly growth restricted, but neither placental weight nor 11β-HSD2 was altered. Although cadmium administration did not result in any visible structural changes in the placenta, increased apoptosis was detected in MT-I/II−/− placentas following cadmium exposure, with a significant increase in levels of both p53 and caspase 3 proteins. Additionally, glucose transporter (GLUT1) was significantly reduced in MT-I/II−/− placentas of pups exposed to cadmium, whereas zinc transporter (ZnT-1) remained unaltered. Taken together, these results demonstrate that MT-I/II−/− mice are more vulnerable to cadmium-induced FGR. The present data also suggest that increased apoptosis and reduced GLUT1 expression in the placenta contribute to the molecular mechanisms underlying cadmium-induced FGR.

scholarly journals Environmental correlates of peatland carbon fluxes in a thawing landscape: do transitional thaw stages matter?

2015 ◽  
Vol 12 (1) ◽  
pp. 445-480 ◽  
Author(s):  
A. Malhotra ◽  
N. T. Roulet
Keyword(s):  
Temperature Sensitivity ◽  
Structural Changes ◽  
Co2 Flux ◽  
Apparent Temperature ◽  
Ecosystem Structure ◽  
Environmental Correlates ◽  
C Storage ◽  
Discontinuous Permafrost ◽  
Significant Area ◽  
And Function

Abstract. Peatlands in discontinuous permafrost regions occur as a mosaic of wetland types, each with variable sensitivity to climate change. Permafrost thaw further increases the spatial heterogeneity in ecosystem structure and function in peatlands. Carbon (C) fluxes are well characterized in end-member thaw stages such as fully intact or fully thawed permafrost but remain unconstrained for transitional stages that cover a significant area of thawing peatlands. Furthermore, changes in the environmental correlates of C fluxes, due to thaw are not well described: a requirement for modeling future changes to C storage of permafrost peatlands. We investigated C fluxes and their correlates in end-member and a number of transitional thaw stages in a sub-arctic peatland. Across peatland lumped CH4 and CO2 flux data had significant correlations with expected correlates such as water table depth, thaw depth, temperature, photosynthetically active radiation and vascular green area. Within individual thaw states, bivariate correlations as well as multiple regressions between C flux and environmental factors changed variably with increasing thaw. The variability in directions and magnitudes of correlates reflects the range of structural conditions that could be present along a thaw gradient. These structural changes correspond to changes in C flux controls, such as temperature and moisture, and their interactions. Temperature sensitivity of CH4 increased with increasing thaw in bivariate analyses, but lack of this trend in multiple regression analyses suggested cofounding effects of substrate or water limitation on the apparent temperature sensitivity. Our results emphasize the importance of incorporating transitional stages of thaw in landscape level C budgets and highlight that end-member or adjacent thaw stages do not adequately describe the variability in structure-function relationships present along a thaw gradient.

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