Search results for "Titi"
showing 10 items of 6322 documents
Numerical response of predators to large variations of grassland vole abundance and long‐term community changes
2020
Abstract Voles can reach high densities with multiannual population fluctuations of large amplitude, and they are at the base of predator communities in Northern Eurasia and Northern America. This status places them at the heart of management conflicts wherein crop protection and health concerns are often raised against conservation issues. Here, a 20‐year survey describes the effects of large variations in grassland vole populations on the densities and the daily theoretical food intakes (TFI) of vole predators based on roadside counts. Our results show how the predator community responded to prey variations of large amplitude and how it reorganized with the increase in a dominant predator…
Plant species identities and fertilization influence on arbuscular mycorrhizal fungal colonisation and soil bacterial activities
2016
International audience; Plant species influence soil microbial communities, mainly through their functional traits. However, mechanisms underlying these effects are not well understood, and in particular how plant/ microorganism interactions are affected by plant identities and/or environmental conditions. Here, we performed a greenhouse experiment to assess the effects of three plant species on arbuscular mycorrhizal fungal (AMF) colonization, bacterial potential nitrification (PNA) and denitrification activities (PDA) through their functional traits related to nitrogen acquisition and turnover. Three species with contrasting functional traits and strategies (from exploitative to conservat…
Diversity of foraging strategies and responses to predator interference in seed-eating carabid beetles
2019
12 pages; International audience; The prediction of pest regulation by multi-predator communities often remains challenging because of variable and opposite effects of niche complementarity and predator interference. Carabid communities are regulating weeds in arable fields and include a mix of species ranging from granivores to predators that are obligate omnivores. It is not clear from field studies whether granivore and obligate omnivore species either contribute equally or are complementary in the process of weed suppression, and little is known about the impact of potential predator interference within carabid communities on weed suppression. We compared the weed seed foraging strategy…
Ecological niche features override biological traits and taxonomic relatedness as predictors of occupancy and abundance in lake littoral macroinverte…
2018
The degree to which species ecological and biological traits determine their distribution and abundance has intrigued ecologists for a long time, and it has seen a revival in recent years. This topic is important because it provides information about the determinants of species rarity and their conservation implications. We examined the effects of niche breadth, niche position, biological traits and taxonomic relatedness on the interspecific occupancy–abundance relationship, as well as on occupancy and abundance, in lake littoral macroinvertebrates. We sampled 48 lakes in a boreal lake district, found altogether 155 species, and calculated regional occupancy (as the proportion of sites occu…
Understanding the coexistence of competing raptors by Markov chain analysis enhances conservation of vulnerable species.
2016
Understanding ecological interactions among protected species is crucial for correct management to avoid conflicting outcomes of conservation planning. The occurrence of a superior competitor may drive the exclusion of a subordinate contestant, as in Sicily where the largest European population of the lanner falcon is declining because of potentially competing with the peregrine falcon. We measured the coexistence of these two ecologically equivalent species through null models and randomization algorithms on body sizes and ecological niche traits. Lanners and peregrines are morphologically very similar (Hutchinson ratios <1.3) and show 99% diet overlap, and both of these results predict …
Inhibitory Effect of Azamacrocyclic Ligands on Polyphenol Oxidase in Model and Food Systems
2020
[EN] Enzymatic browning is one of the main problems faced by the food industry due to the enzyme polyphenol oxidase (PPO) provoking an undesirable color change in the presence of oxygen. Here, we report the evaluation of 10 different azamacrocyclic compounds with diverse morphologies as potential inhibitors against the activity of PPO, both in model and real systems. An initial screening of 10 ligands shows that all azamacrocyclic compounds inhibit to some extent the enzymatic browning, but the molecular structure plays a crucial role on the power of inhibition. Kinetic studies of the most active ligand (L2) reveal a S-parabolic I-parabolic noncompetitive inhibition mechanism and a remarkab…
Interactions between invading benthivorous fish and native whitefish in subarctic lakes
2013
SUMMARY 1. Many species are expanding their distribution towards higher latitudes and altitudes in response to climate change. These range shifts are expected to change fish community structure and alter food-web dynamics in subarctic lakes. However, the impacts of invading species on native fish and invertebrate prey communities remain understudied. 2. The trophic ecology of invasive species determines the likelihood of direct resource competition with native taxa. In Northern Europe, perch (Perca fluviatilis), a trophic generalist, and ruffe (Gymnocephalus cernuus), a benthic specialist, are expanding their distribution ranges northwards, colonising lakes inhabited by a native generalist,…
How Long Is Too Long in Contemporary Peer Review? Perspectives from Authors Publishing in Conservation Biology Journals
2015
Delays in peer reviewed publication may have consequences for both assessment of scientific prowess in academics as well as communication of important information to the knowledge receptor community. We present an analysis on the perspectives of authors publishing in conservation biology journals regarding their opinions on the importance of speed in peer-review as well as how to improve review times. Authors were invited to take part in an online questionnaire, of which the data was subjected to both qualitative (open coding, categorizing) and quantitative analyses (generalized linear models). We received 637 responses to a total of 6,547 e-mail invitations sent. Peer-review speed was gene…
Interspecific variation in total phenolic content in temperate brown algae
2017
Marine algae synthesize secondary metabolites such as polyphenols that function as defense and protection mechanisms. Among brown algae, Fucales and Dictyotales (Phaeophyceae) contain the highest levels of phenolic compounds, mainly phlorotannins, that play multiple roles. Four temperate brown algae (Cystoseira amentacea, Cystoseira compressa, Dictyopteris polypodioides and Padina pavonica) were studied for total phenolic contents. Total phenolic content was determined colorimetrically with the Folin-Ciocalteu reagent. Significant differences in total phenolic content were observed between leathery and sheetlike algae and also within each morphological group. Among the four species, the she…
Risk of predation makes foragers less choosy about their food.
2017
18 pages; International audience; Animals foraging in the wild have to balance speed of decision making and accuracy of assessment of a food item's quality. If resource quality is important for maximizing fitness, then the duration of decision making may be in conflict with other crucial and time consuming tasks, such as anti-predator behaviours or competition monitoring. Individuals facing the risk of predation and/or competition should adjust the duration of decision making and, as a consequence, their level of choosiness for resources. When exposed to predation, the forager could either maintain its level of choosiness for food items but accept a reduction in the amount of food items con…