Mass Extinctions and the Structure and Function of Ecosystems

2013 ◽  
Vol 19 ◽  
pp. 115-156 ◽  
Author(s):  
Pincelli M. Hull ◽  
Simon A. F. Darroch

Mass extinctions shape the history of life and can be used to inform understanding of the current biodiversity crisis. In this paper, a general introduction is provided to the methods used to investigate the ecosystem effects of mass extinctions (Part I) and to explore major patterns and outstanding research questions in the field (Part II). The five largest mass extinctions of the Phanerozoic had profoundly different effects on the structure and function of ecosystems, although the causes of these differences are currently unclear. Outstanding questions and knowledge gaps are identified that need to be addressed if the fossil record is to be used as a means of informing the dynamics of future biodiversity loss and ecosystem change.

2017 ◽  
Author(s):  
Charley J. Hubbard ◽  
Marcus T. Brock ◽  
Linda T.A. van Diepen ◽  
Loïs Maignien ◽  
Brent E. Ewers ◽  
...  

AbstractPlants alter chemical and physical properties of soil, and thereby influence rhizosphere microbial community structure. The structure of microbial communities may in turn affect plant performance. Yet, outside of simple systems with pairwise interacting partners, the plant genetic pathways that influence microbial community structure remain largely unknown, as are the performance feedbacks of microbial communities selected by the host plant genotype. We investigated the role of the plant circadian clock in shaping rhizosphere community structure and function. We performed 16S rRNA gene sequencing to characterize rhizosphere bacterial communities of Arabidopsis thaliana between day and night time points, and tested for differences in community structure between wild-type (Ws) vs. clock mutant (toc1-21, ztl-30) genotypes. We then characterized microbial community function, by growing wild-type plants in soils with an overstory history of Ws, toc1-21 or ztl-30 and measuring plant performance. We observed that rhizosphere community structure varied between day and night time points, and clock misfunction significantly altered rhizosphere communities. Finally, wild-type plants germinated earlier and were larger when inoculated with soils having an overstory history of wild-type in comparison to clock mutant genotypes. Our findings suggest the circadian clock of the plant host influences rhizosphere community structure and function.


2021 ◽  
Vol 32 ◽  
pp. ii-xiv
Author(s):  
Paul Montagna

Chance and good luck led to a career studying how freshwater inflow drives estuary processes. In 1986, someone asked me: How much fresh water has to flow to a bay for it to be healthy? The question shaped my career. There is probably no better place on Earth to compare effects caused by inflow differences than the Texas coast, because the major estuarine systems lie in a climatic gradient where runoff decreases 56—fold from the Louisiana border in the northeast to the Mexico border in the southwest. This estuary—comparison experiment was used to study inflow effects. The science evolved from the idea in the 1990’s that organisms responded directly to inflow rates to the domino theory in the 2000’s of indirect effects where inflow drives estuary conditions and that organisms respond to those habitat conditions. Today it is hypothesized that climate drives hydrology, which drives estuary dynamics; and thus, climatic factors can indirectly shape estuarine structure and function. Assuming change along the inflow gradient is analogous to effects of altering estuaries over time, we can now predict ecosystem change with changing climate or land—use change.


2016 ◽  
Vol 2016 ◽  
pp. 191-197
Author(s):  
Nicole Haitzinger

This paper is concerned with resonances of the tragic in twentieth-century central-European dance theatet, to be discussed with particular reference to Pina Bausch's 1975 Orpheus and Eurydice. In my study Resonances of the Tragic: Between Event and Affect (2015), I have argued that in terms of a history of the “longue durée,” the evocation of the tragic occurs in a field of tension between technique, the mise-en-scène, and conceptions, as well as procedures and moments of interruption, of suspension, of disruption and of the indeterminable resulting from ecstatic corporeality. Its structure and function can generate an event in the emphatic sense of the term; consequently, it provides a paradigm for recognizing structures of form and of an aesthetic of reception, structures emerging from individual constellations of the fictional and choric, absence and presence. From the perspective of dance studies, the tragic emanates from the representation of horrendous monstrosity testing the limits of what can be imagined by means of the moved body in all senses of the word; but how exactly does Bausch produce the qualities of the ambivalent, ambiguous, and paradoxical—and, consequently, the tragic?


2016 ◽  
Vol 21 (4) ◽  
pp. 212-219 ◽  
Author(s):  
Sandy Toogood

Purpose The purpose of this paper is to provide a commentary on Patterson and Berry’s paper “Reflections on culture, structure and function of an intensive support service centred on positive behavioural support”. Design/methodology/approach This paper reviews key ideas presented in Patterson and Berry’s article relative to the recent history of service delivery in the UK and the growing interest being shown in positive behaviour support. Findings Patterson and Berry’s article adds to a modest literature on specialist support services and should stimulate further descriptions of service models and the concepts underpinning them. Originality/value The literature on specialist support service models is limited and this addition should be relevant to a wide range of clinicians, consumers and commissioners.


2007 ◽  
Vol 23 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Brian Dolan

✓Anatomical and physiological understandings of the structure and function of the brain have worked to establish it as the “seat of the soul.” As an organ of reflection, meditation, and memory, the brain becomes synonymous with what defines the “self” through the existence of consciousness—of mind. Thus, the brain has been associated with a range of transcendent concepts—the soul, spirit, mind, and consciousness—that all relate in fundamental ways to each other both in terms of their perceived location within the brain and because of the way each works ultimately to define the person to whom the brain belongs. In this article, the author provides a brief exploration of how interrelated these categories have been when seen in the context of ancient, Renaissance, early modern, and modern philosophical and medical concerns; how the brain has variously been perceived as home to these intimate states of being; and how practitioners from the neurosciences have reflected on these questions. The author provides novel insights into the interrelationships of philosophy, theology, and medicine by examining these issues through the lens of the history of neuroscience.


2007 ◽  
Vol 293 (5) ◽  
pp. H2667-H2679 ◽  
Author(s):  
Charlotte Hwa ◽  
William C. Aird

In 1628, William Harvey provided definitive evidence that blood circulates. The notion that blood travels around the body in a circle raised the important question of how nutrients pass between blood and underlying tissue. Perhaps, Harvey posited, arterial blood pours into the flesh as into a sponge, only then to find its way into the veins. Far from solving this problem, Marcello Malpighi's discovery of the capillaries in 1661 only added to the dilemma: surely, some argued, these entities are little more than channels drilled into tissues around them. As we discuss in this review, it would take over 200 years to arrive at a consensus on the basic structure and function of the capillary wall. A consideration of the history of this period provides interesting insights into not only the central importance of the capillary as a focus of investigation, but also the enormous challenges associated with studying these elusive structures.


2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Toshio Takahashi ◽  
Masayuki Hatta

The peptide-signaling molecules (<50 amino acid residues) occur in a wide variety of invertebrate and vertebrate organisms, playing pivotal roles in physiological, endocrine, and developmental processes. While some of these peptides display similar structures in mammals and invertebrates, others differ with respect to their structure and function in a species-specific manner. Such a conservation of basic structure and function implies that many peptide-signaling molecules arose very early in the evolutionary history of some taxa, while species-specific characteristics led us to suggest that they also acquire the ability to evolve in response to specific environmental conditions. In this paper, we describe GLWamide-family peptides that function as signaling molecules in the process of muscle contraction, metamorphosis, and settlement in cnidarians. The peptides are produced by neurons and are therefore referred to as neuropeptides. We discuss the importance of the neuropeptides in both developmental and physiological processes in a subset of hydrozoans, as well as the potential use as a seed compound in drug development and aspects related to the protection of corals.


1974 ◽  
Vol 186 (1084) ◽  
pp. 191-215 ◽  

It is fifty years, this year, since insulin was successfully used to treat patients suffering from diabetes. It is thirty years since A. C. Chibnall gave the Bakerian lecture on ‘Amino acid analysis and the structure of proteins’, (1942), including insulin, and ten years since F. G. Young gave the Croonian lecture on ‘Insulin and its action’ (1962). It is difficult not to feel that this is a particularly appropriate moment at which to discuss, once again, insulin, its chemistry and biochemistry, its structure and function. Chibnall did, of course, warn us in 1942 to beware of the ‘hypnotic power of numerology’. The most serious reason for discussing insulin today is not the existence of the recurring anniversaries (other dates are more important in the history of the study of insulin), but the fact that we still do not know how it works in living creatures. Very recently we have acquired a great wealth of new information about the actual arrangement in space of the atoms in insulin molecules in crystals. We can begin to answer many of the questions chemists and biochemists have been asking about the behaviour of insulin for years past. It seems useful to give here some of these answers in the hope that they may guide further experiments towards the complete understanding of the action of insulin that still eludes us.


2016 ◽  
Vol 2016 ◽  
pp. 180-190
Author(s):  
Georgiana Gore ◽  
Andrée Grau ◽  
Maria Koutsouba

This paper is concerned with resonances of the tragic in twentieth-century central-European dance theatet, to be discussed with particular reference to Pina Bausch's 1975 Orpheus and Eurydice. In my study Resonances of the Tragic: Between Event and Affect (2015), I have argued that in terms of a history of the “longue durée,” the evocation of the tragic occurs in a field of tension between technique, the mise-en-scène, and conceptions, as well as procedures and moments of interruption, of suspension, of disruption and of the indeterminable resulting from ecstatic corporeality. Its structure and function can generate an event in the emphatic sense of the term; consequently, it provides a paradigm for recognizing structures of form and of an aesthetic of reception, structures emerging from individual constellations of the fictional and choric, absence and presence. From the perspective of dance studies, the tragic emanates from the representation of horrendous monstrosity testing the limits of what can be imagined by means of the moved body in all senses of the word; but how exactly does Bausch produce the qualities of the ambivalent, ambiguous, and paradoxical—and, consequently, the tragic?


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