Search results for "TRAS"
showing 10 items of 11623 documents
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…
Differential impact of marine debris ingestion during ontogenetic dietary shift of green turtles in Uruguayan waters
2018
Anthropogenic debris ingestion has been reported for green turtles in all their life stages worldwide. The aim of the present study is to evaluate the marine debris ingestion by green turtles stranded in Uruguayan coast between 2005 and 2013. Debris items were categorized and quantified by frequency of occurrence, relative weight, volume and number of items. A total of 96 dead stranded turtles were analyzed and 70% presented debris in their guts. The majority of debris found were plastic, being hard plastics the most abundant in weight. We found no differences in debris ingestion in stranded turtles a long the Uruguayan coast. However we detected a negative correlation between the presence …
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…
Monitoring the reproductive activity in captive bred female ball pythons (P. regius) by ultrasound evaluation and noninvasive analysis of faecal repr…
2018
The royal python (Python regius) is commonly bred in captivity. To have a successful breeding season, accurate monitoring of the reproductive activity is necessary. The use of non-invasive monitoring methods in exotics is important in order to minimize stress. For this purpose ultrasound has been anecdotally used to monitor royal python reproductive activity. However, there is limited information regarding the reproductive cycle of this species. The aim of the present study is to monitor the female reproductive cycle of the royal python using ultrasonography and gonadal steroid metabolite measurements in the faeces. The reproductive activity of one hundred twenty-nine adult female P. regius…
Diploid Ruppia cirrhosa populations from a southern Mediterranean shallow system
2016
Abstract This paper focuses on the morphology and karyology of representative Ruppia populations from a southern Mediterranean shallow system. The cosmopolitan genus Ruppia L. generally inhabits shallow waters such as coastal lagoons and brackish habitats. Ruppia species are characterised by a simplified morphology and high intraspecific phenotypic plasticity. The chromosome number of Sicilian Ruppia populations is reported here for the first time. The analysed populations showed morphological and reproductive characters of Ruppia cirrhosa (Petagna) Grande but a diploid cytotype (2n = 20). A low fruit production was also observed, suggesting that vegetative reproduction is the main reproduc…
Differences in time and space use between two sympatric Acrocephalus warblers with similar diets
2016
Capsule: We found high diet overlap and different uses of space and time between Moustached Warblers Acrocephalus melanopogon and Reed Warblers Acrocephalus scirpaceus breeding in sympatry at a marshland in Spain. Aims: To study the degree of diet overlap between both species, their space use on a local scale and their breeding phenologies. Methods: We studied the breeding phenologies of the two species by standardized ringing activity. Spatial distribution was investigated by point counts. We determined diet composition from emetic samples and we collected invertebrates by standardized sweep-netting to estimate food availability. Results: Diet and prey selection were similar among species.…
Dispersal flight and colony development in the fungus-growing termites Pseudacanthotermes spiniger and P. militaris
2012
International audience; Pseudacanthotermes spiniger and P. militaris are two African fungus-growing termites (Termitidae, Macrotermitinae) which may become pests in disturbed agrosystems where they often live in sympatry. To study their development and their reproductive strategies, colonies of both species were reared in the laboratory for 20 and 17 years, respectively, after their foundation from reproductive pairs. The first steps of development were in great part similar in both species, although P. spiniger favoured the defence during the juvenile period, while P. militaris tended to favour a rapid development. While P. spiniger colonies did not produce alates until year 7 of colony li…
Different emergence phenology of European grapevine moth (Lobesia botrana, Lepidoptera: Tortricidae) on six varieties of grapes.
2014
AbstractThe phenology of insect emergence affects reproductive success and is especially critical in short-lived species. An increasing number of studies have documented the effects of thermal and other climatic variations and of unpredictable habitats on the timing of adult insect emergence within and between populations and years. Numerous interacting factors may affect the phenology of adult emergence. Host-plant quality and availability is a key factor that has been largely neglected in studies of the phenology of phytophagous insects. The purpose of this study was to determine the effect of host plant characteristics on the rate of larval growth and the pattern of emergence in a wild p…
The effect of low frequency noise on the behaviour of juvenile Sparus aurata.
2020
[EN] Anthropogenic activities are causing increased noise levels in the marine environment. To date, few studies have been undertaken to investigate the effects of different noise frequencies on the behaviour of juvenile fish. In this study, the behavioural changes of juvenile gilthead seabream (Sparus aurata) are evaluated when exposed to white noise filtered in third-octave bands centred at 63, 125, 500, and 1000 Hz (sound pressure level, 140-150 dB re 1 mu& x3a1;a) for 7 h. The group dispersion, motility, and swimming height of the fish were analysed before and during the acoustic emission. Dispersion of the fish was found to reduce immediately upon application of low frequency sound (63…
Population differentiation for adaptive traits and their underlying loci in forest trees : theoretical predictions and experimental results
2000
Population differentiation has been investigated in forest trees since provenance tests were established. A vast amount of results has accumulated in numerous reports and articles about intraspecific variation, that have been summarized in textbooks about forest genetics (Wright 1976). Provenance differences exist for almost any adaptive trait that has been measured in provenance test and for almost any species. These results contrast markedly with data based on biochemical markers as isozymes. As shown by the literature review by Hamrick et al. (1992), forest trees usually exhibit extremely low levels of differentiation for isozymes. Results derived from isozyme surveys are confirmed by ot…