Unexpected Effects of Predators Upon Their Prey: The Case of the American Alligator

Bondavalli, Cristina; Ulanowicz, Robert E.

doi:10.1007/s100219900057

Cited by 88 publications

(44 citation statements)

References 38 publications

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“…Thus, the applicability of the interaction milieu concept should also be validated in more complex ecosystems. More complex food webs (e.g., with strong intraguild predation) and indirect interactions (e.g., apparent competition) can lead to unexpected effects on performance of component species (Bondavalli and Ulanowicz 1999;Wootton 2002). Moreover, food webs also differ greatly in how long food chains extend.…”

Section: How To Extend the Concept Of Interaction Milieu To More Compmentioning

confidence: 99%

Interaction Milieu Explains Performance of Species in Simple Food Webs along an Environmental Gradient

Ellers¹

2011

TOECOLJ

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Species interact with each other in a complex network of relationships that can be modeled as an interaction milieu, i.e. a biotic background with which the species interacts. The interaction milieu is given by the frequency distribution of traits that are important to a given interaction; hence this approach provides a direct link between organism performance, abiotic environmental conditions and interspecific interactions. In this study, we investigate how performance of component species is affected by the interaction milieu along an environmental gradient. We specifically addressed two questions: 1) can the interaction milieu shift species performance away from the niche optimum?, and 2) do species have a higher invasive potential if they have divergent trait values compared to the interaction milieu? We developed a model where a target species showing a given performance response curve to an environmental gradient, i.e., generalist or specialist, interacts with predators and competitors. The predictions of the model were compared with empirical findings on the abundance patterns of species along a salinity gradient in a green beach ecosystem. Green beaches are characterized by their strong gradients and spatial variability in abiotic factors, and their relatively simple food web consisting of Collembola species and their spider predators. First, our results showed that interaction milieu can displace species from their fundamental niche optimum. This led to abundance patterns that cannot be predicted by species performance response curves alone, emphasizing the importance to include ecological interactions. Second, species failed to invade their preferred part of the gradient if predators or competitors shared the target species' preference. Future studies should explore if the concept of interaction milieu can be generalized across trophic levels, and search for traits that are important on deciding the outcome of ecological interactions. Furthermore, the identification of the relevant response traits and their frequency distribution, in combination with trait plasticity of species in interaction milieus might be a step forward to link evolutionary principles to ecological networks, and vice versa.

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Section: How To Extend the Concept Of Interaction Milieu To More Compmentioning

confidence: 99%

Interaction Milieu Explains Performance of Species in Simple Food Webs along an Environmental Gradient

Ellers¹

2011

TOECOLJ

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“…Parallel direct interactions result in the huge number of indirect effects among species. Some of these are positive, some are negative, and the mixed sign of the net effects is a major challenge to understanding and predicting (Palomares et al, 1995;Bondavalli and Ulanowicz, 1999;Yodzis, 2000). Moreover, indirect effects can be surprisingly strong (Palomares et al, 1995) and surprisingly far-reaching (Estes et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Short Communication: Systems-based conservation and conflicts between species protection programs

Jordán

Báldi

2013

Web Ecol.

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Abstract. Although the conflict between conservation efforts and economic growth is a major topic of conservation science, the conflicts between different conservation projects are much less documented and represented in the literature. We provide an overview of some case studies where these conflicts arise and discuss how to manage and solve them. We argue that conflicts are unavoidable, and that we can find optimal and efficient solutions only by studying the holistic, macroscopic properties of whole socio-ecological systems. Novel computational solutions offer simple and efficient simulation toolkits providing indicators that can support strategic and integrative decisions from a systems perspective.

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“…While empirical results are also highlighting the important roles of indirect effects (e.g. Wootton, 1994;Berger et al, 2008;Diekotter et al, 2007;Menendez et al, 2007;Letnic et al, 2009;Walsh and Reznick, 2010), network analysis shows how the integral of indirect interactions across a whole web of interactions can transform the effective relationships between species so that they tend to be more positive (Ulanowicz and Puccia, 1990;Patten, 1991;Fath and Patten, 1998;Bondavalli and Ulanowicz, 1999), and more evenly distribute the system resources (Fath and Patten, 1999a;Borrett and Salas, 2010) and control (Schramski et al, 2006.…”

Section: Introductionmentioning

confidence: 99%

Equivalence of the realized input and output oriented indirect effects metrics in Ecological Network Analysis

Borrett¹,

Freeze²,

Salas³

2011

Ecological Modelling

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A new understanding of the consequences of how ecosystem elements are interconnected is emerging from the development and application of Ecological Network Analysis. The relative importance of indirect effects is central to this understanding, and the ratio of indirect flow to direct flow (I/D) is one indicator of their importance. Two methods have been proposed for calculating this indicator. The unit approach shows what would happen if each system member had a unit input or output, while the realized technique determines the ratio using the observed system inputs or outputs. When using the unit method, the input oriented and output oriented ratios can be different, potentially leading to conflicting results. However, we show that the input and output oriented I/D ratios are identical using the realized method when the system is at steady state. This work is a step in the maturation of Ecological Network Analysis that will let it be more readily testable empirically and ultimately more useful for environmental assessment and management.

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Unexpected Effects of Predators Upon Their Prey: The Case of the American Alligator

Cited by 88 publications

References 38 publications

Interaction Milieu Explains Performance of Species in Simple Food Webs along an Environmental Gradient

Interaction Milieu Explains Performance of Species in Simple Food Webs along an Environmental Gradient

Short Communication: Systems-based conservation and conflicts between species protection programs

Equivalence of the realized input and output oriented indirect effects metrics in Ecological Network Analysis

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