Search results for "Statistic"
showing 10 items of 12520 documents
Fire benefits flower beetles in a Mediterranean ecosystem
2018
Despite the abundance of plants that benefit from fire in Mediterranean ecosystems, little is known about the possible presence of fire-favoured insects (other than bark beetles). For two years we sampled invertebrates after two large wildfires in eastern Spain and demonstrate that two flower beetle species, Protaetia morio and P. oblonga (Cetoniidae), show a pyrophilous behaviour. These beetles were much more numerous after the fires than in unburnt plots around the fire perimeter; in addition, these species tended to increase in number with the distance from the fire perimeter and with fire recurrence, especially P. morio. These results were maintained for the two postfire years sampled. …
Can number and size of offspring increase simultaneously?--a central life-history trade-off reconsidered.
2011
Abstract Background To maximize their fitness, parents are assumed to allocate their resources optimally between number and size of offspring. Although this fundamental life-history trade-off has been subject to long standing interest, its genetic basis, especially in wild mammals, still remains unresolved. One important reason for this problem is that a large multigenerational pedigree is required to conduct a reliable analysis of this trade-off. Results We used the REML-animal model to estimate genetic parameters for litter size and individual birth size for a common Palearctic small mammal, the bank vole (Myodes glareolus). Even though a phenotypic trade-off between offspring number and …
Predicting and testing functional responses: An example from a tardigrade–nematode system
2008
Abstract Numerous studies have empirically measured consumer functional responses or theoretically developed response models, but whether these models can quantitatively predict observed data has hardly been tested. We perform such a test for the terrestrial predator–prey system Macrobiotus richtersi (Tardigrada)– Acrobeloides nanus (Nematoda). For two different size classes of A. nanus , we report a functional response as measured in the laboratory and quantitatively compare it to predictions of three models with different degrees of complexity: (1) the disc equation which does not include satiation effects; (2) the steady-state satiation (SSS) equation which assumes a constant level of pr…
The effects of data collection and observation methods on uncertainty of social networks in wild primates
2020
International audience; In social species, network centralities of group members shape social transmission and other social phenomena. Different factors have been found to influence the measurement of social networks, such as data collection and observation methods. In this study, we collected data on adults and juveniles and examined the effect of data collection method (ad libitum sampling vs. focal animal sampling) and observation method (interaction—grooming; play—vs. association—arm‐length; 2 m; 5 m proximities—) on social networks in wild vervet monkeys. First, we showed using a bootstrapping method, that uncertainty of ad libitum grooming and play matrices were lesser than uncertaint…
Advantage of rare infanticide strategies in an invasion experiment of behavioural polymorphism
2012
Killing conspecific infants (infanticide) is among the most puzzling phenomena in nature. Stable polymorphism in such behaviour could be maintained by negative frequency-dependent selection (benefit of rare types). However, it is currently unknown whether there is genetic polymorphism in infanticidal behaviour or whether infanticide may have any fitness advantages when rare. Here we show genetic polymorphism in non-parental infanticide. Our novel invasion experiment confirms negative frequency-dependent selection in wild bank vole populations, where resource benefits allow an infanticidal strategy to invade a population of non-infanticidal individuals. The results show that infanticidal beh…
Pairing context determines condition-dependence of song rate in a monogamous passerine bird.
2013
Condition-dependence of male ornaments is thought to provide honest signals on which females can base their sexual choice for genetic quality. Recent studies show that condition-dependence patterns can vary within populations. Although long-term association is thought to promote honest signalling, no study has explored the influence of pairing context on the condition-dependence of male ornaments. In this study, we assessed the influence of natural variation in body condition on song rate in zebra finches ( Taeniopygia guttata ) in three different situations: during short and long encounters with an unfamiliar female, and within heterosexual mated pairs. We found consistent individual diff…
Odor intensity measurements in gas chromatography-olfactometry using cross modality matching : evaluation of training effects
1999
International audience
Chemical fingerprints suggest direct familiarisation rather than phenotype matching during olfactory recognition in Australian sea lions (Neophoca ci…
2019
International audience; Olfaction is one of the most commonly used senses for communication among animals and is of particular importance to mother-offspring recognition in mammals. The use of smell in offspring recognition has been well studied, however, we often lack information about the underlying mechanistic basis for olfactory recognition. Using gas chromatography–mass spectrometry (GC–MS), we examine chemical profiles of two different colonies of Australian sea lions (Neophoca cinerea) and assess similarity of chemical fingerprints in mother-pup pairs. This analysis allows us to examine whether a chemical base for phenotype matching exists in this species. Our results showed no GC-de…
Environmental Quality Assessment of Bizerte Lagoon (Tunisia) Using Living Foraminifera Assemblages and a Multiproxy Approach.
2015
This study investigated the environmental quality of the Bizerte Lagoon (Tunisia) through an integrated approach that combined environmental, biogeochemical, and living benthic foraminiferal analyses. Specifically, we analyzed the physicochemical parameters of the water and sediment. The textural, mineralogical, and geochemical characteristics of the sediment, including total organic carbon, total nitrogen, simultaneously extracted metals (SEM), acid volatile sulfides (AVS), chlorophyll a, CaCO3, and changes in bacterial populations and carbon isotopes were measured. The SEM/AVS values indicated the presence of relatively high concentrations of toxic metals in only some areas. Foraminiferal…
Forest snail faunas from Transylvania (Romania) and their relationship to the faunas of Central and Northern Europe
2011
Forty-three forest sites in seven sampling areas in mountainous parts of Transylvania were sampled to obtain inventories of their snail faunas, and to make comparisons between these and the faunas of similar sites further north along the Carpathian chain. Sampling areas ran from close to the Ukrainian border in the north to Retezat in the south-west. Altogether, 83 species were found, as well as between 19 and 40 species at individual sites. Sites within the same sampling area had more species in common than in among-area comparisons, although differences between areas did not relate to the distance between them. Such differences appear to be related more to ecological factors than to geogr…