Paper on quantifying growth autocorrelation published

Brooks, M. McCoy, M.W., and B. M. Bolker. (2013). A method for detecting positive growth autocorrelation without marking individuals. PloS one 8 (10), e76389

Nice Blog Review: Link

 

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Long Overdue Update – New Papers Published

Silliman, B. R., M. W. McCoy, C. Angelini, R. D. Holt,  J. N. Griffin, and J. van de Koppel. 2013. Consumer Fronts, Spatial Processes, and Ecosystem Structure and Stability. Annual Review of Ecology, Evolution, and Systematics 44 (1)

Silliman, B.R., M.W. McCoy, G.C. Trussell, C.M. Crain, P.J. Ewanchuk, and M.D. Bertness. (2013). Non-linear interactions between consumers and flow determine the probability of plant community dominance on Maine rocky shores. PloS one 8 (8), e67625

Touchon J. C., M. W. McCoy, J. R. Vonesh, and K.M. Warkentin. (2013) Effects of plastic hatching timing carry over through metamorphosis in red-eyed treefrogs. Ecology 94 (4), 850-860.

van Wesenbeeck, B. K., J. N. Griffin, M. van Koningsveld, K.B. Gedan, M. W. McCoy, B. R. Silliman. (2013) “Nature-based coastal defenses: can biodiversity help?” in P. Kareiva and S. Levin, editors. Encyclopedia of Biodiversity. Elsevier.

Cruze, L., Hamlin, H. J., Kohno, S., McCoy, M. W., & Guillette Jr, L. J. (2013). Evidence of Steroid Hormone Activity in the Chorioallantoic Membrane of a Turtle (Pseudemys nelsoni). General and Comparative Endocrinology.

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Paper published: Quantifying predation risk

PLoS One – Prey Responses to Predator Chemical Cues: Disentangling the Importance of the Number and Biomass of Prey Consumed

To effectively balance investment in predator defenses versus other traits, organisms must accurately assess predation risk. Chemical cues caused by predation events are indicators of risk for prey in a wide variety of systems, but the relationship between how prey perceive risk in relation to the amount of prey consumed by predators is poorly understood. While per capita predation rate is often used as the metric of relative risk, studies aimed at quantifying predator-induced defenses commonly control biomass of prey consumed as the metric of risk. However,…(read more)

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Paper published: Emergent effects of multiple predators on prey survival

Link: Ecology Letters

Predator-prey relationships define food webs and determine how much and how fast energy is transferred through ecosystems. Because most species are prey of multiple species of predators, it is essential to understand how effects of different predators combine to influence prey dynamics. Furthermore, species that are higher on the food chain often suffer greater effects from activities such as harvesting, habitat fragmentation, toxin bioaccumulation, and habitat degradation; thus understanding how decreasing predator diversity affects the rest of the ecosystem will be paramount. Ecologists have been investigating how the effects of multiple predators combine to affect foodwebs for more than 30 years. Recent reviews have shown that predators sometimes kill more and sometimes kill less prey than expected based on their independent effects. These unpredictable or emergent effects can arise, for example, when predators work cooperatively to subdue prey (leading to risk enhancement for prey) or when predators interfere with one another while foraging (leading to risk reduction prey). However, in this study we show that past models used to generate the null expectations for how predator effects should combine are biased. Previous models for predicting the combined effects of predators made two implicit (and generally unacknowledged assumptions): 1) that prey mortality rates were constant over the duration of the study; and 2) that prey density did not change over the course of the experiment. Both assumptions were likely violated in almost all studies. For example, most predators have functional response that lead to increasing prey mortality as prey density declines.

In a paper published on Sept. 23 2012 in the journal Ecology Letters, we showed that current models that predict how the effects of multiple predators combine are biased.  Moreover, we show that the direction and magnitude of the bias depends on the study design and experimental duration.

This study calls into question dozens of studies and much of what we thought we had learned over the past 30+ years about how predator effects combine to influence prey mortality and other foodweb properties. Importantly, the implications of our findings are not isolated to only affecting our understanding effects of multiple predators. Indeed, our understanding of species diversity on a variety of ecological processes and ecosystem functions may be vulnerable to the same critique, which applies whenever changing densities are combined with some form of density-dependence. Finally, our paper provided a road map for moving forward that will improve our ability to understand and predict the importance of diversity on key ecological processes.

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