scholarly journals Temporally auto-correlated predator attacks structure ecological communities

2021 ◽  
Author(s):  
Sebastian Schreiber
Keyword(s):  
Prey Species ◽  
Species Interaction ◽  
The Other ◽  
Ecological Communities ◽  
Vital Rates ◽  
Predator Density ◽  
Priority Effect ◽  
Predator Attack ◽  
Prey Vulnerability ◽  
Common Resource

For species regulated by a common predator, the P* rule predicts that the prey species that supports the highest mean predator density (P*) excludes the other prey species. This prediction is re-examined in the presence of temporal fluctuations in the vital rates of the interacting species including predator attack rates. When the fluctuations in predator attack rates are temporally uncorrelated, the P* rule still holds even when the other vital rates are temporally auto-correlated. However, when temporal auto-correlations in attack rates are positive but not too strongly, the prey species can coexist due to the emergence of a positive covariance between predator density and prey vulnerability. This coexistence mechanism is similar to the storage effect for species regulated by a common resource. Strongly positive or negative auto-correlations in attack rates generate a negative covariance between predator density and prey vulnerability and a stochastic priority effect can emerge: with non-zero probability either prey species is excluded. These results highlight how temporally auto-correlated species' interaction rates impact the structure and dynamics of ecological communities.

scholarly journals Dynamic population stage structure due to juvenile–adult asymmetry stabilizes complex ecological communities

2021 ◽  
Vol 118 (21) ◽  
pp. e2023709118
Author(s):  
André M. de Roos
Keyword(s):  
Self Regulation ◽  
Interaction Network ◽  
Population Level ◽  
Stage Structure ◽  
Current Theory ◽  
Species Interaction ◽  
Interaction Matrix ◽  
Foraging Efficiency ◽  
Ecological Communities ◽  
The Stability

Natural ecological communities are diverse, complex, and often surprisingly stable, but the mechanisms underlying their stability remain a theoretical enigma. Interactions such as competition and predation presumably structure communities, yet theory predicts that complex communities are stable only when species growth rates are mostly limited by intraspecific self-regulation rather than by interactions with resources, competitors, and predators. Current theory, however, considers only the network topology of population-level interactions between species and ignores within-population differences, such as between juvenile and adult individuals. Here, using model simulations and analysis, I show that including commonly observed differences in vulnerability to predation and foraging efficiency between juvenile and adult individuals results in up to 10 times larger, more complex communities than observed in simulations without population stage structure. These diverse communities are stable or fluctuate with limited amplitude, although in the model only a single basal species is self-regulated, and the population-level interaction network is highly connected. Analysis of the species interaction matrix predicts the simulated communities to be unstable but for the interaction with the population-structure subsystem, which completely cancels out these instabilities through dynamic changes in population stage structure. Common differences between juveniles and adults and fluctuations in their relative abundance may hence have a decisive influence on the stability of complex natural communities and their vulnerability when environmental conditions change. To explain community persistence, it may not be sufficient to consider only the network of interactions between the constituting species.

Emergent Facilitation among Predators on Size-Structured Prey

2013 ◽  
Author(s):  
André M. de Roos ◽  
Lennart Persson
Keyword(s):  
Life History ◽  
Prey Species ◽  
The Other ◽  
Positive Interactions ◽  
Predator Species ◽  
Life History Stages ◽  
Specific Predator ◽  
Specialist Predators

This chapter discusses a variety of positive interactions between predators foraging on different stages of the same prey species, which all emerge owing to the biomass overcompensation that may occur in prey life history stages in response to increased mortality. These interactions include emergent facilitation of specialist predators by generalists that forage on the same prey individuals as the specialists, but in addition forage on smaller or larger prey individuals as well. Furthermore, the chapter shows that two predators that specialize on different life-history stages of prey can facilitate each other to the extent that one predator relies on the presence of the other for its persistence. A stage-specific predator may act as a catalyst species, which promotes and in fact is necessary for the invasion of another predator species, but is subsequently outcompeted by the latter.

Marine Parasites and Disease in the Era of Global Climate Change

2021 ◽  
Vol 13 (1) ◽  
pp. 397-420
Author(s):  
James E. Byers
Keyword(s):  
Climate Change ◽  
Current Knowledge ◽  
Global Climate ◽  
Ecological Communities ◽  
Vital Rates ◽  
Ecological Processes ◽  
Performance Curves ◽  
Temperature Climate ◽  
Induced Changes ◽  
Host Parasite

Climate change affects ecological processes and interactions, including parasitism. Because parasites are natural components of ecological systems, as well as agents of outbreak and disease-induced mortality, it is important to summarize current knowledge of the sensitivity of parasites to climate and identify how to better predict their responses to it. This need is particularly great in marine systems, where the responses of parasites to climate variables are less well studied than those in other biomes. As examples of climate's influence on parasitism increase, they enable generalizations of expected responses as well as insight into useful study approaches, such as thermal performance curves that compare the vital rates of hosts and parasites when exposed to several temperatures across a gradient. For parasites not killed by rising temperatures, some simple physiological rules, including the tendency of temperature to increase the metabolism of ectotherms and increase oxygen stress on hosts, suggest that parasites’ intensity and pathologies might increase. In addition to temperature, climate-induced changes in dissolved oxygen, ocean acidity, salinity, and host and parasite distributions also affect parasitism and disease, but these factors are much less studied. Finally, because parasites are constituents of ecological communities, we must consider indirect and secondary effects stemming from climate-induced changes in host–parasite interactions, which may not be evident if these interactions are studied in isolation.

Coppicing ability of 20 Eucalyptus species grown at two high-altitude sites in South Africa

2003 ◽  
Vol 33 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Keith M Little ◽  
Robin AW Gardner
Keyword(s):  
South Africa ◽  
High Altitude ◽  
Species Interaction ◽  
The Other ◽  
Eucalyptus Species ◽  
Mpumalanga Province ◽  
Kwazulu Natal ◽  
Potential Alternative ◽  
Alternative Species ◽  
Growing Conditions

In the 1980s, Eucalyptus macarthurii and E. nitens were planted in the colder, higher altitude areas of South Africa to meet the increased demand for pulpwood. To find possible alternatives, six site × species interaction trials were planted in 1990–1991. Based on volume performance and pulping properties, E. badjensis, E. benthamii, E. oreades, E. nobilis, E. smithii, and E. fraxinoides were identified as having good commercial potential. Although the performance of the parent crop is important, the ability to coppice is advantageous because of lower reestablishment costs. To determine this, the ability for these species to coppice was assessed at 10 months after felling at two of the trial sites with widely different growing conditions (Broadholms in Mpumalanga province and Draycott in KwaZulu-Natal province). More than 80% of the living stumps of E. benthamii, E. smithii, E. quadrangulata, E. macarthurii, E. badjensis, E. dunnii, E. cypellocarpa, E. saligna, and E. elata had coppiced at both sites. At Draycott, an exposed, dry site, both E. smithii and E. benthamii could be considered as potential alternative species to E. nitens, because besides having good volume, both species coppiced well. At Broadholms, a more protected and slightly wetter site, the significantly better volume of E. fraxinoides (which did not coppice well) when compared with the other species would mean that a substantial saving in reestablishment costs via coppice regeneration would have to be made before one could consider this method of reestablishment.

scholarly journals An Enhanced Supervisory Control Strategy for Periodicity Mutual Exclusions in Discrete Event Systems Based on Petri Nets

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Zhongyuan Jiang ◽  
Huan Wang ◽  
Xiaoliang Chen ◽  
Mingwei Tang ◽  
Jianhong Ye
Keyword(s):  
Control Strategy ◽  
Supervisory Control ◽  
Discrete Event Systems ◽  
Discrete Event ◽  
Mutual Exclusion ◽  
The Other ◽  
Structural Conversion ◽  
Event Systems ◽  
Common Resource ◽  
The Common

Mutual exclusion problems widely exist in discrete event systems in which several processes will compete for the common resource for maintaining their normal running. This competition is mutually exclusive. However, a special behavior, that is, periodic mutual exclusion behavior, is important for many discrete event systems. Once a process obtains the common resource, it will consecutively obtain the common resource in the following several competitions. The other processes should wait for the release of the common resource. All processes will compete for the common resource again after the common resource is released. These competitions have obvious periodicity. In this paper, a methodology is proposed to design periodic mutual exclusion supervisors to control the periodic mutual exclusion behavior in discrete event systems. Moreover, two original structural conversion concepts, calledk-derivation andk-convergence processes, are proposed to construct the periodic mutual exclusion supervisors. The discussion results show that many undesirable execution sequences are forbidden since the periodic mutual exclusion behavior is controlled by the proposed periodic mutual exclusion supervisors. Finally, an example is used to illustrate the proposed methodology.

Observations on spermatogenesis, sperm phenotype, and fertility in white-tailed × mule deer hybrids and a yak × cow hybrid

1988 ◽  
Vol 66 (7) ◽  
pp. 1664-1671 ◽  
Author(s):  
William D. Wishart ◽  
Francis Hrudka ◽  
Sheila M. Schmutz ◽  
Peter F. Flood
Keyword(s):  
Sperm Morphology ◽  
Parental Species ◽  
Mule Deer ◽  
Odocoileus Hemionus ◽  
Species Interaction ◽  
The Other ◽  
Sperm Production ◽  
Histological Techniques ◽  
Normal Sperm ◽  
Testicular Differentiation

Fertility, spermatogenesis, and sperm phenotype were investigated in three hybrid deer (Odocoileus virginianus dacotensis × Odocoileus hemionus hemionus) and a yak × domestic cow hybrid (Bos mutus (grunniens) × Bos primigenius (taurus)) using histological techniques. All of the hybrids studied were infertile but varied in the degree of testicular differentiation, spermatogenic activity, and sperm production. The hybrid yak was the least developed and the white-tailed deer × F1 hybrid was the most advanced. F1 backcrossing improved spermatogenesis, output, and morphology of sperm, but not the fertility of the donor, indicating that normal sperm morphology alone does not assure fertility. Two deer hybrids that produced sperm differed in sperm phenotype from each other and from the parental species. Interaction of a Y chromosome from one species and autosomal sex-determining genes from the other species is suggested as a possible explanation of sterility in male hybrids.

scholarly journals The Maintenance of Public Order at Sea and the Nationality of Ships

1960 ◽  
Vol 54 (1) ◽  
pp. 25-116 ◽  
Author(s):  
Mybes S. McDougal ◽  
William T. Burke ◽  
Ivan A. Vlasic
Keyword(s):  
International Law ◽  
The Other ◽  
Law Of The Sea ◽  
Public Order ◽  
Common Resource

Most comprehensively viewed, the international law of the sea comprises two very different sets of principles. One set of principles, establishing certain basic, overriding community goals, prescribes for all states the widest possible access to, and the fullest enjoyment of, the shared use of the great common resource of the oceans. The other set of principles, commonly described as jurisdictional, expresses certain implementing policies designed economically to secure the basic community goals of shared use by establishing a shared competence among states in a domain largely free from the exclusive public order of any particular state.

scholarly journals Vulnerable species interactions are important for the stability of mutualistic networks

2019 ◽  
Author(s):  
Benno I. Simmons ◽  
Hannah S. Wauchope ◽  
Tatsuya Amano ◽  
Lynn V. Dicks ◽  
William J. Sutherland ◽  
...  
Keyword(s):  
Species Interactions ◽  
Species Coexistence ◽  
Species Interaction ◽  
Interaction Networks ◽  
Ecological Communities ◽  
Ecological Context ◽  
Intrinsic Properties ◽  
Network Stability ◽  
Starting Point ◽  
The Stability

AbstractSpecies are central to ecology and conservation. However, it is the interactions between species that generate the functions on which ecosystems and humans depend. Despite the importance of interactions, we lack an understanding of the risk that their loss poses to ecological communities. Here, we quantify risk as a function of the vulnerability (likelihood of loss) and importance (contribution to network stability in terms of species coexistence) of 4330 mutualistic interactions from 41 empirical pollination and seed dispersal networks across six continents. Remarkably, we find that more vulnerable interactions are also more important: the interactions that contribute most to network stability are those that are most likely to be lost. Furthermore, most interactions tend to have more similar vulnerability and importance across networks than expected by chance, suggesting that vulnerability and importance may be intrinsic properties of interactions, rather than only a function of ecological context. These results provide a starting point for prioritising interactions for conservation in species interaction networks and, in areas lacking network data, could allow interaction properties to be inferred from taxonomy alone.

scholarly journals Interaction capacity underpins community diversity

2020 ◽  
Author(s):  
Masayuki Ushio
Keyword(s):  
Interspecific Interactions ◽  
Experimental Studies ◽  
Interaction Strength ◽  
Single Species ◽  
Species Interaction ◽  
Community Diversity ◽  
Ecological Communities ◽  
Total Dna ◽  
Mathematical Equations ◽  
The Mean

AbstractHow patterns in community diversity emerge is a long-standing question in ecology. Theories and experimental studies suggested that community diversity and interspecific interactions are interdependent. However, evidence from multitaxonomic, high-diversity ecological communities is lacking because of practical challenges in characterizing speciose communities and their interactions. Here, I analyzed time-varying causal interaction networks that were reconstructed using 1197 species, DNA-based ecological time series taken from experimental rice plots and empirical dynamic modeling, and show that species interaction capacity, namely, the sum of interaction strength that a single species gives and receives, underpins community diversity. As community diversity increases, the number of interactions increases exponentially but the mean species interaction capacity of a community becomes saturated, weakening interaction among species. These patterns are explicitly modeled with simple mathematical equations, based on which I propose the “interaction capacity hypothesis”, namely, that species interaction capacity and network connectance are proximate drivers of community diversity. Furthermore, I show that total DNA concentrations and temperature influence species interaction capacity and connectance nonlinearly, explaining a large proportion of diversity patterns observed in various systems. The interaction capacity hypothesis enables mechanistic explanations of community diversity, and how species interaction capacity is determined is a key question in ecology.

scholarly journals Towards a Conceptual Understanding of Groundwater Ecology

2012 ◽  
Vol 1 (3) ◽  
pp. 493
Author(s):  
H.O Nwankwoala
Keyword(s):  
Conceptual Understanding ◽  
Chemical Properties ◽  
The Other ◽  
Ecological Communities ◽  
Groundwater Hydrology ◽  
Future Perspectives ◽  
Natural Ecosystems ◽  
Ecological Processes ◽  
Physico Chemical ◽  
Groundwater Ecology

In recent times, ecohydrology and hydroecology are making a mark on theenvironmental agenda, as evidenced by the proliferation of these terms in theacademic literature. There is an increasing recognition that groundwater is essentialto many ecological communities. Surface ecological processes (such asevapotranspiration) significantly impact hydrological responses and relatedhydrochemical function. Thus, the relation of groundwater hydrology to patternsand processes in ecology is a ‘two-way street’ where understanding the feedback ofone to the other serves as a powerful lens through which to evaluate and explainthe functioning of natural ecosystems. Influxes of groundwater to lakes, rivers, andwetlands can change whole-system physico-chemical properties such astemperature and salinity, while also providing more subtle influences onmicroenvironments and their ecological processes. The recognition of thesignificance and power of this tandem has not always been followed with effectiveinterdisciplinary science. The ecological, hydrological, and physico-chemical linksbetween groundwater, surface water and associated ecosystems are seldom fullyunderstood even though true characterization and wise management will require amultidisciplinary approach. This means biologists need to understand theimportance of magnitude and timing of groundwater flows for their system, whichrequires the skills of hydrogeologists to achieve. Hydrogeologists, in turn, mustunderstand how and why groundwater influences ecological processes so that theirexpertise is brought to bear at a scale commensurate to the ecological researchquestion. In this paper therefore, an overview of general concepts, research effortsand future perspectives are presented. More importantly, the paper asserts that it isnot simply the integration of hydrology and ecology that will determine the futureprospects for ecohydrology/hydroecology, but the way in which this integrativescience is conducted.

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