Improving the assessment of predator functional responses by considering alternate prey and predator interactions

Chan, K. Y.; Boutin, Stan; Hossie, Thomas J.; O’Donoghue, Mark; Murray, Dennis L.

doi:10.1002/ecy.1828

Cited by 35 publications

(33 citation statements)

References 55 publications

(175 reference statements)

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“…Interestingly, even in this context, we found no evidence of predator saturation. Hence, our results add to a growing body of research indicating that predators may not become systematically satiated at the highest densities of prey observed in nature (Chan et al 2017;Novak 2010;Preston et al 2018).…”

Section: Discussionsupporting

confidence: 67%

“…In natural systems, our ability to measure functional response is limited by a combination of factors: small sample size, a relatively narrow gradient of observed prey densities, the difficulty to observe predator-prey interactions directly, or the difficulty to estimate predator and prey numbers (Ellis et al 2019;Gilg et al 2006;Suryawanshi et al 2017;Therrien et al 2014). The large variability around predator acquisition rates can also constrains our ability to fully discriminate among functional response shapes, and hence limits our ability to accurately model predator-prey inter-actions in complex and natural ecosystems (Chan et al 2017;O'Donoghue et al 1998;Vucetich et al 2002). Moreover, phenomenological models fail to identify the proximate mechanisms regulating predator acquisition rates.…”

Section: Introductionmentioning

confidence: 99%

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Derivation of predator functional responses using a mechanistic approach in a natural system

Beardsell

Gravel

Berteaux

et al. 2020

Preprint

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The functional response is central to our understanding of any predator-prey system as it establishes the link between trophic levels. Most functional responses are evaluated using phenomenological models linking predator acquisition rate and prey density. However, our ability to measure functional responses using such an approach is often limited in natural systems and the use of inaccurate functions can profoundly affect the outcomes of population and community models. Here, we develop a mechanistic model based on extensive data to assess the functional response of a generalist predator, the arctic fox (<|>Vulpes lagopus</|>), to various tundra prey species (lemmings and the nests of geese, passerines and sandpipers). We found that predator acquisition rates derived from the mechanistic model were consistent with field observations. Although sigmoidal functional responses were previously used to model fox-prey population dynamics, none of our simulations resulted in a saturating response in all prey species. Our results highlight the importance of predator searching components in predator-prey interactions, especially predator speed, while predator acquisition rates were not limited by handling processes. By combining theory with field observations, our study provides support that predator acquisition rate is not systematically limited at the highest prey densities observed in a natural system. We reinforce the idea that functional response categories, typically types I, II, and III, should be considered as particular cases along a continuum. Specific functions derived with a mechanistic approach for a range of densities observed in natural communities should improve our ability to model and understand predator-prey systems.

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Section: Discussionsupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Derivation of predator functional responses using a mechanistic approach in a natural system

Beardsell

Gravel

Berteaux

et al. 2020

Preprint

View full text Add to dashboard Cite

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“…For example, snowshoe hares at lower latitudes, beyond the range of their specialist predator (lynx), often persist at low densities (Hodges, Mills, & Murphy, 2009;Linden, Campa, Roloff, Beyer, & Millenbah, 2011). In regions where lynx are absent, generalist carnivores may exhibit a Type III functional response (density-dependent predation) (Chan et al, 2017;Todd, Keith, & Fischer, 1981) that potentially affords hares a low-density refuge from predation (Holt & Barfield, 2009;Oaten & Murdoch, 1975). Similarly, a low-density refuge may allow moose Alces alces to escape high parasite loads and explain their persistence in some regions along their low-latitude limit in North America (Samuel, 2007).…”

Section: B I Otic Inter Ac Ti On S Vary By Trophi C Le Velmentioning

confidence: 99%

Interactive range‐limit theory (iRLT): An extension for predicting range shifts

Sirén

Morelli

2019

Journal of Animal Ecology

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A central theme of range‐limit theory (RLT) posits that abiotic factors form high‐latitude/altitude limits, whereas biotic interactions create lower limits. This hypothesis, often credited to Charles Darwin, is a pattern widely assumed to occur in nature. However, abiotic factors can impose constraints on both limits and there is scant evidence to support the latter prediction. Deviations from these predictions may arise from correlations between abiotic factors and biotic interactions, as a lack of data to evaluate the hypothesis, or be an artifact of scale. Combining two tenets of ecology—niche theory and predator–prey theory—provides an opportunity to understand how biotic interactions influence range limits and how this varies by trophic level. We propose an expansion of RLT, interactive RLT (iRLT), to understand the causes of range limits and predict range shifts. Incorporating the main predictions of Darwin's hypothesis, iRLT hypothesizes that abiotic and biotic factors can interact to impact both limits of a species’ range. We summarize current thinking on range limits and perform an integrative review to evaluate support for iRLT and trophic differences along range margins, surveying the mammal community along the boreal‐temperate and forest‐tundra ecotones of North America. Our review suggests that range‐limit dynamics are more nuanced and interactive than classically predicted by RLT. Many (57 of 70) studies indicate that biotic factors can ameliorate harsh climatic conditions along high‐latitude/altitude limits. Conversely, abiotic factors can also mediate biotic interactions along low‐latitude/altitude limits (44 of 68 studies). Both scenarios facilitate range expansion, contraction or stability depending on the strength and the direction of the abiotic or biotic factors. As predicted, biotic interactions most often occurred along lower limits, yet there were trophic differences. Carnivores were only limited by competitive interactions (n = 25), whereas herbivores were more influenced by predation and parasitism (77%; 55 of 71 studies). We highlight how these differences may create divergent range patterns along lower limits. We conclude by (a) summarizing iRLT; (b) contrasting how our model system and others fit this hypothesis and (c) suggesting future directions for evaluating iRLT.

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“…The food web for the boreal forest ecosystem at Kluane is given in Boonstra et al (2018). Details of predator-prey interactions in this ecosystem are given in Krebs, Boonstra and Boutin (2001), Krebs et al (2014a), Chan et al (2017), and Boonstra et al (2018) with detailed analyses of data on predator abundance in the Kluane boreal forest. Figure 1 shows the spring density for snowshoe hares from 1977 to 2017 averaged over 3 control grids.…”

Section: Methodsmentioning

confidence: 99%

Hares and Small Rodent Cycles: a 45-year Perspective on Predator-prey Dynamics in the Yukon Boreal Forest

Boonstra

Kenney

Gilbert

2018

Australian Zoologist

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Long-term research is required in ecology to determine patterns of population changes, to suggest limiting factors, and to determine if and how climate change is affecting populations and their communities. In the Kluane region of the Yukon we have monitored control populations of snowshoe hares, mice, and voles from 1973 to 2017 (the longest of any similar time series anywhere in North America) and here we ask what we have observed and learned from these time series. The amplitude of hare cycles may be decreasing over this period. In contrast, the 3-4-year cycles of red backed voles (Myodes rutilus) are becoming more dramatic and the amplitude of their peak years are increasing. Four species of Microtus voles fluctuated independently of red-backed voles prior to 1998, but their peak years became synchronous thereafter, with the dominant species changing from peak to peak. The deer mouse (Peromyscus maniculatus) fluctuated irregularly, completely disappearing from the catch for 5 years in the early 1990s. Weasels were rare for the first 25 years of small rodent changes and marten were absent, but since 2000 marten have colonized and both small predators have become more abundant. Predation drives the snowshoe hare cycle, but it is far from clear that it does so for the small rodents. We suspect that social behaviour is critical for vole cycles, but this supposition has not been tested experimentally. The boreal forests of Canada and Alaska support a boom-bust set of dynamics but the voles fluctuate independently and out of phase with the hares and there is no universal cause.

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Improving the assessment of predator functional responses by considering alternate prey and predator interactions

Cited by 35 publications

References 55 publications

Derivation of predator functional responses using a mechanistic approach in a natural system

Derivation of predator functional responses using a mechanistic approach in a natural system

Interactive range‐limit theory (iRLT): An extension for predicting range shifts

Hares and Small Rodent Cycles: a 45-year Perspective on Predator-prey Dynamics in the Yukon Boreal Forest

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