Search results for "vid"
showing 10 items of 14131 documents
Visible implant elastomer (VIE) success in early larval stages of a tropical amphibian species
2020
AbstractAnimals are often difficult to distinguish at an individual level, but being able to identify individuals can be crucial in ecological or behavioral studies. In response to this challenge, biologists have developed a range of marking (tattoos, brands, toe-clips) and tagging (PIT, VIA, VIE) methods to identify individuals and cohorts. Animals with complex life cycles are notoriously hard to mark because of the distortion or loss of the tag across metamorphosis. In frogs, few studies have attempted larval tagging and none have been conducted on a tropical species. Here, we present the first successful account of VIE tagging in early larval stages (Gosner stage 25) of the dyeing poison…
Plankton Tracker: A novel integrated system to investigate the dynamic sinking behavior in phytoplankton
2020
Abstract Phytoplankton sinking is an important property that can determine community composition, affecting nutrient and light absorption in the photic zone, and influencing biogeochemical cycling via material loss to the deep ocean. To date, the difficulty in exploring the sinking processes is partly due to methodological limitations in measuring phytoplankton sinking rate. However, in the last decade, works have illustrated various methods based on some non-invasive and low perturbing approaches (laser scanner, video-microscopy, fluorescence spectroscopy). In this study, we review the methods for sinking rate estimation and describe the Plankton Tracker, a novel integrated system to inves…
Nest defence against avian brood parasites is promoted by egg-removal events in a cowbird–host system
2011
Recent studies of birds have found that the antiparasite behaviour of host species is modified by social learning. We tested whether individual or social learning modifies the nest defence of yellow warblers, Setophaga petechia, against the parasitic brown-headed cowbird, Molothrus ater. Using field experiments, we exposed warblers to simulated events of nest parasitism and predation, or allowed them to observe conspecifics mobbing a cowbird. Intensity of nest defence by yellow warblers was greater after simulated threats at their nest than after they had observed mobbing of cowbirds by conspecifics. Warblers defended their nests more aggressively when they perceived a cowbird as an egg pre…
Anti-brood Parasite Defences: The Role of Individual and Social Learning
2017
In this chapter, we consider the ways in which learning is involved in the anti-brood parasitism defences that hosts deploy across the nesting cycle. Brood parasitism varies in space and through time, and hosts have accordingly evolved plastic defences that can be tuned to local conditions. Hosts can achieve their defence plasticity by individual and social learning, as well as by experience-independent mechanisms. While these mechanisms can profoundly affect the coevolutionary dynamics between hosts and their brood parasites, our understanding of how they feature across the host nesting cycle is far from complete. Hosts can actively defend themselves against brood parasitism via a variety …
Brown bear behaviour in human-modified landscapes: The case of the endangered Cantabrian population, NW Spain
2018
Large carnivores are recolonizing parts of their historical range in Europe, a heavily modified human landscape. This calls for an improvement of our knowledge on how large carnivores manage to coexist with humans, and on the effects that human activity has on large carnivore behaviour, especially in areas where carnivore populations are still endangered. Brown bears Ursus arctos have been shown to be sensitive to the presence of people and their activities. Thus, bear conservation and management should take into account potential behavioural alterations related to living in human-modified landscapes. We studied the behaviour of brown bears in the Cantabrian Mountains, NW Spain, where an en…
Binding Site Alteration Is Responsible for Field-Isolated Resistance to Bacillus thuringiensis Cry2A Insecticidal Proteins in Two Helicoverpa Species
2010
Background Evolution of resistance by target pests is the main threat to the long-term efficacy of crops expressing Bacillus thuringiensis (Bt) insecticidal proteins. Cry2 proteins play a pivotal role in current Bt spray formulations and transgenic crops and they complement Cry1A proteins because of their different mode of action. Their presence is critical in the control of those lepidopteran species, such as Helicoverpa spp., which are not highly susceptible to Cry1A proteins. In Australia, a transgenic variety of cotton expressing Cry1Ac and Cry2Ab (Bollgard II) comprises at least 80% of the total cotton area. Prior to the widespread adoption of Bollgard II, the frequency of alleles conf…
Impact of sewage pollution on two species of sea urchins in the Mediterranean Sea (Cortiou, France): radial asymmetry as a bioindicator of stress.
2015
9 pages; International audience; BackgroundThe surroundings of the Cortiou sewage are among the most polluted environments of the French Mediterranean Sea (Marseilles, France). So far, no studies have precisely quantified the impact of pollution on the development of organisms in this area.MethodsWe used a fluctuating asymmetry (FA) measure of developmental instability (DI) to assess environmental stress in two species of radially symmetric sea urchins (Arbacia lixula and Paracentrotus lividus). For six sampling sites (Cortiou, Riou, Maire, East Maire, Mejean, and Niolon), levels of FA were calculated from continuous and discrete skeletal measures of ambulacral length, number of pore pairs …
Sandbar shark aggregation in the central Mediterranean Sea and potential effects of tourism
2021
An aggregation of sandbar sharks Carcharhinus plumbeus occurs every summer around the remote uninhabited islet of Lampione (Pelagie Islands Marine Protected Area, south-western Mediterranean Sea), attracting an increasing number of tourists for a shark watching experience. Despite the ecological and socio-economic importance of this rare occurrence in Mediterranean waters, there is a lack of scientific data and lack of information as to the potential impact of tourist activities on the presence and behaviour of this shark species. Using baited underwater videos, this study provides the first assessment of this shark aggregation, as well as a preliminary evaluation of the potential effects t…
Some like it deep : Intraspecific niche segregation in ruffe (Gymnocephalus cernua)
2017
Generalist fishes commonly show intraspecific niche segregation along the littoral–pelagic resource axis in lakes. Recent studies have shown that the deep, cold and seemingly unproductive profundal zone can also offer underutilised resources and facilitate specialised individuals, and can contribute to lake food webs via methane-derived carbon pathways. Despite numerous examples from salmonid fish species, such intraspecific niche segregation along a littoral–profundal resource axis has not been reported in percids or other predominantly littoral benthivorous fishes. Here, we describe a case of ruffe (Gymnocephalus cernua: Percidae) populations consisting of shallow- and deep-water dwelling…
Size-dependent predation of the mesopredator Marthasterias glacialis (L.) (Asteroidea)
2016
Asteroids are largely recognized as important predators in all of the world’s oceans and for this reason, they play a crucial role in shaping the structure and functioning of benthic ecosystems. The spiny starfish Marthasterias glacialis is generally considered a voracious predator of molluscs, in particular bivalves. Using field observations and carbon (δ13C) and nitrogen (δ15N) stable isotopes, we explored possible changes in diet in relation to size of M. glacialis. Data were collected at Ustica Island (Southern Tyrrhenian Sea) from June 2008 to June 2010. M. glacialis showed a size shift in feeding preferences due to different use of food items: bivalves, Columbella rustica, Euthria cor…