Search results for "covariation"

Variation and covariation in infectivity, virulence and immunodepression in the host-parasite association Gammarus pulex-Pomphorhynchus laevis.

2009

Parasites often manipulate host immunity for their own benefit, either by exacerbating or suppressing the immune response and this may directly affect the expression of parasite virulence. However, genetic variation in immunodepression, which is a prerequisite to its evolution, and the relationship between immunodepression and virulence, have rarely been studied. Here, we investigated the variation among sibships of the acanthocephalan parasite, Pomphorhynchus laevis , in infecting and in immunodepressing its amphipod host, Gammarus pulex . We also assessed the covariation between infectivity, parasite-induced immune depression and host mortality (parasite virulence). We found that infecti…

Cross-taxon congruence and relationships to stand characteristics of vascular plants, bryophytes, polyporous fungi and beetles in mature managed bore…

2018

Abstract Multi-taxon analyses of ecological assemblages are needed when the effects of forestry on biodiversity are examined. Management usually simplifies the structure of forests, which results in quantitative and qualitative declines in many microhabitats and species associated with them. In Fennoscandia, most forests are managed for industrial use of wood, but relatively little is known about the relationships between structural components and biodiversity in managed forests. Abundance, composition or species number of different species groups reacting similarly to variation in their environment would be a useful tool e.g. in estimating responses of species that are more difficult to sa…

The Amino Acid Transporter JhI-21 Coevolves with Glutamate Receptors, Impacts NMJ Physiology, and Influences Locomotor Activity in Drosophila Larvae

2015

AbstractChanges in synaptic physiology underlie neuronal network plasticity and behavioral phenomena, which are adjusted during development. The Drosophila larval glutamatergic neuromuscular junction (NMJ) represents a powerful synaptic model to investigate factors impacting these processes. Amino acids such as glutamate have been shown to regulate Drosophila NMJ physiology by modulating the clustering of postsynaptic glutamate receptors and thereby regulating the strength of signal transmission from the motor neuron to the muscle cell. To identify amino acid transporters impacting glutmatergic signal transmission, we used Evolutionary Rate Covariation (ERC), a recently developed bioinforma…

Implications of heat waves on immune defence, life history traits, and adaptive potential : a snail's perspective

2014

Dynamic Energy Budget model parameter estimation for the bivalve Mytilus californianus: Application of the covariation method

2014

Dynamic Energy Budget (DEB) models serve as a powerful tool for describing the flow of energy through organisms from assimilation of food to utilization for maintenance, growth and reproduction. The DEB theory has been successfully applied to several bivalve species to compare bioenergetic and physiological strategies for the utilization of energy. In particular, mussels within the Mytilus edulis complex (M. edulis, M. galloprovincialis, and M. trossulus) have been the focus of many studies due to their economic and ecological importance, and their worldwide distribution. However, DEB parameter values have never been estimated for Mytilus californianus, a species that is an ecological domin…

Analyse et Estimations Spectrales des Processus alpha-Stables non-Stationnaires

2006

In this work a new spectral representation of a symmetric alpha-stable processes is introduced. It is based on a covariation pseudo-additivity and Morse-Transue's integral with respect to a bimesure built by using pseudo-additivity property. This representation, specific to S$\alpha$S processes, is analogous to the covariance of second order processes. On the other hand, it generalizes the representation established for stochastic integrals with respect to symmetric alpha-stable process of independent increments. We provide a classification of non-stationary harmonizable processes; this classification is based on the bimesure structure. In particular, we defined and investigated periodicall…

Age-Related Adaptations of Lower Limb Intersegmental Coordination During Walking

2019

Lower-limb intersegmental coordination is a complex component of human walking. Aging may result in impairments of motor control and coordination contributing to the decline in mobility inducing loss of autonomy. Investigating intersegmental coordination could therefore provide insights into age-related changes in neuromuscular control of gait. However, it is unknown whether the age-related declines in gait performance relates to intersegmental coordination. The aim of this study was to evaluate the impact of aging on the coordination of lower limb kinematics and kinetics during walking at a conformable speed. We then assessed the body kinematics and kinetics from gait analyses of 84 volunt…

Covariation between reading and arithmetic skills from grade 1 to grade 7

2017

This study examined the extent to which reading and arithmetic skills show covariation at Grade 1 and at Grade 7, to what extent this covariation is time-invariant or time-specific, and to what extent different antecedents will predict these time-invariant and time-specific portions of the covariation. The reading and arithmetic skills of a total of 1335 Finnish children were assessed at the end of Grade 1 and then again at the end of Grade 7. Phonological awareness, letter knowledge, rapid automatized naming (RAN), counting, and parental education levels were measured in kindergarten; working memory at Grade 1 and nonverbal reasoning at Grade 3. The results showed that reading and arithmet…

Global Groundwater-Vegetation Relations

2017

Groundwater is an integral component of the water cycle, and it also influences the carbon cycle by supplying moisture to ecosystems. However, the extent and determinants of groundwater-vegetation interactions are poorly understood at the global scale. Using several high-resolution data products, we show that the spatial patterns of ecosystem gross primary productivity and groundwater table depth are correlated during at least one season in more than two-thirds of the global vegetated area. Positive relationships, i.e., larger productivity under shallower groundwater table, predominate in moisture-limited dry to mesic conditions with herbaceous and shrub vegetation. Negative relationships, …