FRAIR: an R package for fitting and comparing consumer functional responses

This is the author accepted manuscript. The final version is available from Wiley / British Ecological Society via the DOI in this record.1.Consumer‐resource interactions (i.e. the functional response) underpin decades of ecological advancements. However, selecting, fitting and comparing functional response models using appropriate methods remains a non‐trivial endeavour. 2.The R package frair provides tools for selecting and differentiating various forms of consumer functional response models, a consistent interface for fitting and visualising response curves, and a selection of statistically robust methods for comparing fitted parameters. 3.Using real data from crustacean predator‐prey systems, we demonstrate the utility of frair, highlighting best practice and common analytical mistakes.Pūnaha Hihiko Vision Mātauranga Capability.European Union INTERREG IVA Programme and Department of Environment, Northern Ireland (DOENI)Natural Environment Research Counci

Route planning with transportation network maps: an eye-tracking study.

Planning routes using transportation network maps is a common task that has received little attention in the literature. Here, we present a novel eye-tracking paradigm to investigate psychological processes and mechanisms involved in such a route planning. In the experiment, participants were first presented with an origin and destination pair before we presented them with fictitious public transportation maps. Their task was to find the connecting route that required the minimum number of transfers. Based on participants' gaze behaviour, each trial was split into two phases: (1) the search for origin and destination phase, i.e., the initial phase of the trial until participants gazed at both origin and destination at least once and (2) the route planning and selection phase. Comparisons of other eye-tracking measures between these phases and the time to complete them, which depended on the complexity of the planning task, suggest that these two phases are indeed distinct and supported by different cognitive processes. For example, participants spent more time attending the centre of the map during the initial search phase, before directing their attention to connecting stations, where transitions between lines were possible. Our results provide novel insights into the psychological processes involved in route planning from maps. The findings are discussed in relation to the current theories of route planning

Fruit-Surface Flavonoid Accumulation in Tomato Is Controlled by a SlMYB12-Regulated Transcriptional Network

The cuticle covering plants' aerial surfaces is a unique structure that plays a key role in organ development and protection against diverse stress conditions. A detailed analysis of the tomato colorless-peel y mutant was carried out in the framework of studying the outer surface of reproductive organs. The y mutant peel lacks the yellow flavonoid pigment naringenin chalcone, which has been suggested to influence the characteristics and function of the cuticular layer. Large-scale metabolic and transcript profiling revealed broad effects on both primary and secondary metabolism, related mostly to the biosynthesis of phenylpropanoids, particularly flavonoids. These were not restricted to the fruit or to a specific stage of its development and indicated that the y mutant phenotype is due to a mutation in a regulatory gene. Indeed, expression analyses specified three R2R3-MYB–type transcription factors that were significantly down-regulated in the y mutant fruit peel. One of these, SlMYB12, was mapped to the genomic region on tomato chromosome 1 previously shown to harbor the y mutation. Identification of an additional mutant allele that co-segregates with the colorless-peel trait, specific down-regulation of SlMYB12 and rescue of the y phenotype by overexpression of SlMYB12 on the mutant background, confirmed that a lesion in this regulator underlies the y phenotype. Hence, this work provides novel insight to the study of fleshy fruit cuticular structure and paves the way for the elucidation of the regulatory network that controls flavonoid accumulation in tomato fruit cuticle

Substrate preferences of coexisting invasive amphipods, Dikerogammarus villosus and Dikerogammarus haemobaphes, under field and laboratory conditions

This is an Open Access Article. It is published by Springer under the Creative Commons Attribution 4.0 International Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/Two Ponto-Caspian amphipods, Dikerogammarus villosus and Dikerogammarus haemobaphes, have expanded their geographical ranges from eastern Europe into Great Britain in recent years. This study represents one of the first examining the distribution and habitat preferences of coexisting populations of D. haemobaphes and D. villosus via field and laboratory experiments in the UK. Field surveys of a recently invaded lowland reservoir in the UK are complimented with ex situ laboratory mesocosm experiments examining the substrate preferences of coexisting populations of D. villosus and D. haemobaphes. Results from the field study indicated that D. haemobaphes dominated the macroinvertebrate community within the reservoir and demonstrated a strong affinity for large cobble and artificial substrates. D. villosus occurred at lower abundances but displayed a strong preference for coarse cobble substrates. A third invasive amphipod, Crangonyx pseudogracilis, was largely confined to sand/silt habitats. Laboratory mesocosm experiments clearly supported the field observations of D. villosus and D. haemobaphes with both species demonstrating a preference for cobble substrates. Results from the study highlight the importance of characterising physical habitat when investigating biological invasions and suggest that habitat availability may influence the extent and speed at which range expansion of new amphipod invaders occurs

Functional response comparisons among freshwater amphipods: ratio-dependence and higher predation for Gammarus pulex compared to the non-natives Dikerogammarus villosus and Echinogammarus berilloni

International audienceAbstractThe invasive Ponto–Caspian amphipod Dikerogammarus villosus strongly impairs the structure of recipient freshwater communities, mostly through predation of a wide range of invertebrates. Useful insights on the ecological impact of an invader can be provided by comparing its functional response (FR)—namely the relationship between resource use and resource availability—to that of trophic analogs from the recipient communities. We applied this method and derived the FR of D. villosus, the native Gammarus pulex, and Echinogammarus berilloni, another gammarid that is also undergoing range expansion, feeding on live dipteran larvae. We tested a range of predator densities to account for mutual interference among predators, assuming that predators do not forage alone in their natural environment. We also analysed the predators’ spatial distribution to investigate whether spatial behaviour might be at the origin of interference. For the three gammarid species, the per capita predation rate was a function of the prey-to-predator ratio and showed a decelerating rise to an asymptote. There was no difference in searching efficiency between the three species while prey handling time was significantly lower in G. pulex than in D. villosus and E. berilloni, leading to a higher food intake for the native at high prey densities. Differences in morphology and behaviour between the three gammarids might explain our results. Indeed, D. villosus tended to aggregate more than the other two gammarid species, which promotes conspecific interactions. Our findings suggest that mutual interference between conspecifics is a fundamental shaper of gammarid predation. Time spent interacting with conspecifics is likely to decrease the biotic pressure of the Killer shrimp D. villosus. From a broader perspective, in addition to higher predation risk, parasitism, habitat complexity or climatic variables, the presence of conspecifics of the predator (i.e. predator density) is another factor that has the potential to alter FR comparisons