scholarly journals Upstream trophic structure modulates downstream community dynamics via resource subsidies

2017 ◽  
Vol 7 (15) ◽  
pp. 5724-5731 ◽  
Author(s):  
Eric Harvey ◽  
Isabelle Gounand ◽  
Chelsea J. Little ◽  
Emanuel A. Fronhofer ◽  
Florian Altermatt
Keyword(s):  
Trophic Structure ◽  
Community Dynamics ◽  
Resource Subsidies

scholarly journals Studying insect diversity in the tropics

1999 ◽  
Vol 354 (1391) ◽  
pp. 1811-1824 ◽  
Author(s):  
H. C. J. Godfray ◽  
O. T. Lewis ◽  
J. Memmott
Keyword(s):  
Food Webs ◽  
Trophic Structure ◽  
Community Dynamics ◽  
Experimental Studies ◽  
Leaf Miner ◽  
Insect Diversity ◽  
Insect Community ◽  
Structure Of Communities ◽  
Modern Ecology ◽  
The Tropics

Understanding the extent and causes of insect diversity in the humid tropics is one of the major challenges in modern ecology. We review some of the current approaches to this problem, and discuss how future progress may be made. Recent calculations that there may be more than 30 million species of insect on earth have focused attention on the magnitude of this problem and stimulated several new lines of research (although the true figure is now widely thought to be between five and ten million species). We discuss work based on insecticidal fogging surveys; studies of herbivore and parasitoid specificity; macroecological approaches; and the construction of food webs. It is argued that progress in estimating insect diversity and in understanding insect community dynamics will be enhanced by building local inventories of species diversity, and in descriptive and experimental studies of the trophic structure of communities. As an illustration of work aimed at the last goal, we discuss the construction and analysis of quantitative host–parasitoid food webs, drawing on our work on leaf miner communities in Central America.

scholarly journals Upstream trophic structure modulates downstream community dynamics via resource subsidies

2016 ◽  
Author(s):  
Eric Harvey ◽  
Isabelle Gounand ◽  
Chelsea Little ◽  
Emanuel A. Fronhofer ◽  
Florian Altermatt
Keyword(s):  
Community Structure ◽  
Species Interactions ◽  
Community Dynamics ◽  
Physical Structure ◽  
Trophic Levels ◽  
Resource Subsidies ◽  
Biological Communities ◽  
Natural Systems ◽  
Resource Flows ◽  
Downstream Communities

AbstractIn many natural systems, the physical structure of the landscape dictates the flow of resources. Despite mounting evidence that communities’ dynamics can be indirectly coupled by reciprocal among-ecosystem resource flows, our understanding of how directional resource flows might indirectly link biological communities is limited. We here propose that differences in community structure upstream should lead to different downstream dynamics, even in the absence of dispersal. We report an experimental test of the effect of upstream community structure on downstream community dynamics in a simplified but highly controlled setting, using protist microcosms. We implemented directional flows of resources, without dispersal, from a standard resource pool into upstream communities of contrasting interaction structure and then to further downstream communities of either one or two trophic levels. Our results demonstrate that different types of species interactions in upstream habitats may lead to different population sizes and levels of biomass in these upstream habitats. This, in turn, leads to varying levels of detritus transfer (dead biomass) to the downstream communities, thus influencing their population densities and trophic interactions in predictable ways. Our results suggest that the structure of species interactions in directionally structured ecosystems can be a key mediator of alterations to downstream habitats. Alterations to upstream habitats can thus cascade down to downstream communities, even without dispersal.

scholarly journals Persistence and stability of interacting species in response to climate warming: The role of trophic structure

2020 ◽  
Author(s):  
Taranjot Kaur ◽  
Partha Sharathi Dutta
Keyword(s):  
Food Web ◽  
Climate Warming ◽  
Food Chain ◽  
Trophic Structure ◽  
Community Dynamics ◽  
Threshold Temperature ◽  
Individual Species ◽  
Past Century ◽  
Interacting Species ◽  
Species Dynamics

AbstractOver the past century, the Earth has experienced roughly 0.4–0.8°C rise in the average temperature and which is projected to increase between 1.4–5.8°C by the year 2100. The increase in the Earth’s temperature directly influences physiological traits of individual species in ecosystems. However, the effect of these changes in community dynamics, so far, remains relatively unknown. Here we show that the consequences of warming (i.e., increase in the global mean temperature) on the interacting species persistence or extinction are correlated with their trophic complexity and community structure. In particular, we investigate different nonlinear bioenergetic tri-trophic food web modules, commonly observed in nature, in the order of increasing trophic complexity; a food chain, a diamond food web and an omnivorous interaction. We find that at low temperatures, warming can destabilize the species dynamics in the food chain as well as the diamond food web, but it has no such effect on the trophic structure that involves omnivory. In the diamond food web, our results indicate that warming does not support top-down control induced co-existence of intermediate species. However, in all the trophic structures warming can destabilize species up to a threshold temperature. Beyond the threshold temperature, warming stabilizes species dynamics at the cost of the extinction of higher trophic species. We demonstrate the robustness of our results when a few system parameters are varied together with the temperature. Overall, our study suggests that variations in the trophic complexity of simple food web modules can influence the effects of climate warming on species dynamics.

Testing ecological release as a compensating mechanism for mass mortality in a keystone predator

2020 ◽  
Vol 637 ◽  
pp. 59-69 ◽  
Author(s):  
J Sullivan-Stack ◽  
BA Menge
Keyword(s):  
Community Dynamics ◽  
Limiting Factor ◽  
Sea Star ◽  
Top Predator ◽  
Oregon Coast ◽  
Ecological Release ◽  
Keystone Predator ◽  
Pisaster Ochraceus ◽  
Wasting Syndrome

Top predator decline has been ubiquitous across systems over the past decades and centuries, and predicting changes in resultant community dynamics is a major challenge for ecologists and managers. Ecological release predicts that loss of a limiting factor, such as a dominant competitor or predator, can release a species from control, thus allowing increases in its size, density, and/or distribution. The 2014 sea star wasting syndrome (SSWS) outbreak decimated populations of the keystone predator Pisaster ochraceus along the Oregon coast, USA. This event provided an opportunity to test the predictions of ecological release across a broad spatial scale and determine the role of competitive dynamics in top predator recovery. We hypothesized that after P. ochraceus loss, populations of the subordinate sea star Leptasterias sp. would grow larger, more abundant, and move downshore. We based these predictions on prior research in Washington State showing that Leptasterias sp. competed with P. ochraceus for food. Further, we predicted that ecological release of Leptasterias sp. could provide a bottleneck to P. ochraceus recovery. Using field surveys, we found no clear change in density or distribution in Leptasterias sp. populations post-SSWS, and decreases in body size. In a field experiment, we found no evidence of competition between similar-sized Leptasterias sp. and P. ochraceus. Thus, the mechanisms underlying our predictions were not in effect along the Oregon coast, which we attribute to differences in habitat overlap and food availability between the 2 regions. Our results suggest that response to the loss of a dominant competitor can be unpredictable even when based in theory and previous research.

The Township, the Pregnant Girl and the Church: Community Dynamics, Gender and Social Control in Early Nineteenth-century Scotland

2019 ◽  
Vol 10 (1) ◽  
pp. 41-67
Author(s):  
Elizabeth Ritchie
Keyword(s):  
Nineteenth Century ◽  
Rural Communities ◽  
Social Control ◽  
Community Dynamics ◽  
Church Discipline ◽  
Sexual Offences ◽  
Early Nineteenth Century ◽  
Female Community ◽  
The Church ◽  
Unmarried Girl

In 1814 in a small Highland township an unmarried girl, ostracised by her neighbours, gave birth. The baby died. The legal precognition permits a forensic, gendered examination of the internal dynamics of rural communities and how they responded to threats to social cohesion. In the Scottish ‘parish state’ disciplining sexual offences was a matter for church discipline. This case is situated in the early nineteenth-century Gàidhealtachd where and when church institutions were less powerful than in the post-Reformation Lowlands, the focus of most previous research. The article shows that the formal social control of kirk discipline was only part of a complex of behavioural controls, most of which were deployed within and by communities. Indeed, Scottish communities and churches were deeply entwined in terms of personnel; shared sexual prohibitions; and in the use of shaming as a primary method of social control. While there was something of a ‘female community’, this was not unconditionally supportive of all women nor was it ranged against men or patriarchal structures.

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