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The assessment of relative model performance using information criteria like AIC and BIC has become routine among functional-response studies, reflecting trends in the broader ecological literature. Such information criteria allow comparison across diverse models because they penalize each model's fit by its parametric complexity--in terms of their number of free parameters--which allows simpler models to outperform similarly fitting models of higher parametric complexity. However, criteria like AIC and BIC do not consider an additional form of model complexity, referred to as geometric complexity, which relates specifically to the mathematical form of the model. Models of equivalent parametric complexity can differ in their geometric complexity and thereby in their ability to flexibly fit data. Here we use the Fisher Information Approximation to compare, explain, and contextualize how geometric complexity varies across a large compilation of single-prey functional-response models--including prey-, ratio-, and predator-dependent formulations--reflecting varying apparent degrees and forms of non-linearity. Because a model's geometric complexity varies with the data's underlying experimental design, we also sought to determine which designs are best at leveling the playing field among functional-response models. Our analyses illustrate (1) the large differences in geometric complexity that exist among functional-response models, (2) there is no experimental design that can minimize these differences across all models, and (3) even the qualitative nature by which some models are more or less flexible than others is reversed by changes in experimental design. Failure to appreciate model flexibility in the empirical evaluation of functional-response models may therefore lead to biased inferences for predator-prey ecology, particularly at low experimental sample sizes where its impact is strongest. We conclude by discussing the statistical and epistemological challenges that model flexibility poses for the study of functional responses as it relates to the attainment of biological truth and predictive ability. [ABSTRACT FROM AUTHOR]

Asimina triloba is replacing shade-tolerant Acer saccharum as the most abundant seedling in many Ac. saccharum-dominated forests in the midwestern USA. Selective browsing of Ac. saccharum by Odocoileus virginianus and avoidance of As. triloba contributes to this increased As. triloba abundance. However, shade tolerance may also be a factor contributing to increasing As. triloba. We tested our hypothesis that As. triloba is more shade tolerant than Ac. saccharum. Fraxinus quadrangulata is less shade tolerant than As. triloba and Ac. saccharum; however, other than As. triloba, it was the only species that increased stems per hectare in the seedling stratum from 2003 to 2008. We evaluated leaf photosynthetic traits to assess shade tolerance of these three species. Light response curves (LRCs) of As. triloba, Ac. saccharum, and F. quadrangulata saplings were measured under a dense Ac. saccharum canopy in situ using a portable infrared gas analyzer and were tested for fit to rectangular hyperbola, nonrectangular hyperbola, and exponential LRC models. Multivariate analysis of covariance, with estimated ambient irradiance and leaf temperature as covariates, tested interspecific differences in gas exchange properties: (Rd [dark respiration], α [LRC initial slope], and AMAX [maximum photosynthetic rate]). Multivariate contrasts indicated that F. quadrangulata had significantly higher rates of photosynthesis than the two other species, indicating lesser shade tolerance, whereas As. triloba had greater initial light response (α values) than Ac. saccharum, which confers an advantage to As. triloba under low light conditions. These results implicate greater shade tolerance by As. triloba as another contributor to its increasing dominance in the understory. [ABSTRACT FROM AUTHOR]

Simple Summary: Aedes mosquitoes with larvae that develop in water-filled containers are prominent vectors of disease and are often targets of mosquito control. Laboratory studies and theory suggest that survival of larvae to adulthood decreases as the density of larvae increases. Theory further suggests that this density effect may interact with mosquito control, such that mortality from mosquito control may sometimes increase production of adults. To understand whether such an effect is likely in nature, we conducted field studies of three Aedes species at five sites. Our field studies determined the typical range of densities in the field and quantified the shape of the survival-density relationship. We find that observed larval densities and survival-density relationships vary substantially, often resulting in the prediction that adult production would be unaffected, or even increased, by imposing mortality on larvae. Maximum larval density at a site is strongly and positively related to the likelihood of these counter-productive predicted outcomes. Our results indicate that we cannot assume that killing larvae will result in fewer adults. Effectiveness of mosquito control may be improved by a thorough understanding of how a local mosquito population will respond to achievable levels of larval mortality from mosquito control. Population density can affect survival, growth, development time, and adult size and fecundity, which are collectively known as density-dependent effects. Container Aedes larvae often attain high densities in nature, and those densities may be reduced when larval control is applied. We tested the hypothesis that density-dependent effects on survival are common and strong in nature and could result in maximal adult production at intermediate densities for Aedes aegypti, Aedes albopictus, and Aedes triseriatus. We surveyed naturally occurring densities in field containers, then introduced larvae at a similar range of densities, and censused the containers for survivors. We analyzed the survival-density relationships by nonlinear regressions, which showed that survival-density relationships vary among seasons, sites, and species. For each Aedes species, some sites and times yielded predictions that larval density reduction would yield the same (compensation), or more (overcompensation), adults than no larval density reduction. Thus, larval control targeting these Aedes species cannot always be assumed to yield a reduction in the number of adult mosquitoes. We suggest that mosquito control targeting larvae may be made more effective by: Imposing maximum mortality; targeting populations when larval abundances are low; and knowing the shape of the survival-density response of the target population. [ABSTRACT FROM AUTHOR]