Statistical Analysis With Missing Data (2nd ed.) (Book)

Christensen, R. (2002), Plane Answers to Complex Questions: The Theory of Linear Models (3rd ed.), New York: Springer-Verlag. Crocker, D. C. (1980), Review of Linear Regression Analysis, by G. A. F. Seber, Technometrics, 22, 130. Datta, B. N. (1995), Numerical Linear Algebra and Applications, Paci c Grove, CA: Brooks/Cole. Draper, N. R. (2002), “Applied Regression Analysis Bibliography Update 2000–2001,” Communications in Statistics: Theory and Methods, 2051– 2075. Golub, G. H., and Van Loan, C. F. (1996), Matrix Computations (3rd ed.), Baltimore, MD: Johns Hopkins University Press. Graybill, F. A. (2000), Theory and Application of the Linear Model, Paci c Grove, CA: Brooks/Cole. Hocking, R. R. (2003), Methods and Applications of Linear Models: Regression and the Analysis of Variance (2nd ed.), New York: Wiley. Porat, B. (1993), Digital Processing of Random Signals, Englewood Cliffs, NJ: Prentice-Hall. Ravishanker, N., and Dey, D. K. (2002), A First Course in Linear Model Theory, Boca Raton, FL: Chapman and Hall/CRC. White, H. (1984), Asymptotic Theory for Econometricians, Orlando, FL: Academic Press.

Generalized Estimating Equations

Individual differences in the energy cost of self-maintenance (resting metabolic rate, RMR) are substantial and the focus of an emerging research area. These differences may influence fitness because self-maintenance is considered as a life-history component along with growth and reproduction. In this review, we ask why do some individuals have two to three times the ‘maintenance costs’ of conspecifics, and what are the fitness consequences? Using evidence from a range of species, we demonstrate that diverse factors, such as genotypes, maternal effects, early developmental conditions and personality differences contribute to variation in individual RMR. We review evidence that RMR is linked with fitness, showing correlations with traits such as growth and survival. However, these relationships are modulated by environmental conditions (e.g. food supply), suggesting that the fitness consequences of a given RMR may be context-dependent. Then, using empirical examples, we discuss broad-scale reasons why variation in RMR might persist in natural populations, including the role of both spatial and temporal variation in selection pressures and trans-generational effects. To conclude, we discuss experimental approaches that will enable more rigorous examination of the causes and consequences of individual variation in this key physiological trait.

https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2011.1778

What causes intraspecific variation in resting metabolic rate and what are its ecological consequences

The conflicting relationships between aphids and men: a review of aphid damage and control strategies.

Dengue virus causes ∼50–100 million infections per year and thus is considered one of the most aggressive arthropod-borne human pathogen worldwide. During its replication, dengue virus induces dramatic alterations in the intracellular membranes of infected cells. This phenomenon is observed both in human and vector-derived cells. Using high-resolution mass spectrometry of mosquito cells, we show that this membrane remodeling is directly linked to a unique lipid repertoire induced by dengue virus infection. Specifically, 15% of the metabolites detected were significantly different between DENV infected and uninfected cells while 85% of the metabolites detected were significantly different in isolated replication complex membranes. Furthermore, we demonstrate that intracellular lipid redistribution induced by the inhibition of fatty acid synthase, the rate-limiting enzyme in lipid biosynthesis, is sufficient for cell survival but is inhibitory to dengue virus replication. Lipids that have the capacity to destabilize and change the curvature of membranes as well as lipids that change the permeability of membranes are enriched in dengue virus infected cells. Several sphingolipids and other bioactive signaling molecules that are involved in controlling membrane fusion, fission, and trafficking as well as molecules that influence cytoskeletal reorganization are also up regulated during dengue infection. These observations shed light on the emerging role of lipids in shaping the membrane and protein environments during viral infections and suggest membrane-organizing principles that may influence virus-induced intracellular membrane architecture.

/pdf/dengue-virus-infection-perturbs-lipid-homeostasis-in-2azx1ghq3e.pdf

Dengue Virus Infection Perturbs Lipid Homeostasis in Infected Mosquito Cells.

Evolutionary loss of traits can result from negative selection on a specific phenotype, or if the trait is selectively neutral, because the phenotype associated with the trait has become redundant. Even essential traits may be lost, however, if the resulting phenotypic deficiencies can be compensated for by the environment or a symbiotic partner. Here we demonstrate that loss of an essential me-tabolic trait in parasitic wasps has evolved through environmental compensation. We tested 24 species for the ability to synthesize lipids de novo and collected additional data from the literature. We found the majority of adult parasitoid species to be incapable of synthesizing lipids, and phylogenetic analyses showed that the evolution of lack of lipogenesis is concurrent with that of parasitism in insects. Exploitive host manipulation, in which the host is forced to synthesize lipids to the benefit of the parasitoid, presumably facilitates loss of lipogenesis through environmental compensation. Lipogenesis re-evolved in a small number of parasitoid species, particularly host generalists. The wide range of host species in which generalists are able to develop may impede effective host manipulation and could have resulted in regaining of lipogenic ability in generalist parasitoids. As trait loss through environmental compensation is unnoticed at the phenotypic level, it may be more common than currently anticipated, especially in species involved in intricate symbiotic relationships with other species.

/pdf/loss-of-lipid-synthesis-as-an-evolutionary-consequence-of-a-1hjpq8s288.pdf

Loss of lipid synthesis as an evolutionary consequence of a parasitic lifestyle.

Summary 1. Ectotherm organisms are known to be plastic in their responses to temperature. Individuals developing at low temperatures usually achieve a larger body size through a lower growth rate (‘Temperature Size Rule’, TSR) and, when compared at the adult stage in a common environment, have a higher metabolic rate than those developing at higher temperatures (‘Thermal Compensation Hypothesis’, TCH). 2. For such plastic individuals, increased metabolic rate may incur a switch in the energetic allocation between competing functions such as maintenance and reproduction. Consequently, this differential allocation is expected to affect the animals’ foraging behaviour. 3. This study investigates the effect of developmental temperatures and temperature experienced as adults on metabolic rate, life-history traits and foraging behaviour of females of the parasitic wasp Aphidius rhopalosiphi. For this purpose, individuals were reared at 10, 15, 20 and 25 � C. At emergence, we checked if their traits followed the TSR. We then placed all females in a common environment (20 � C), measured their metabolic rate and examined if a switch of energetic allocation occurred between longevity and ⁄ or egg load. Finally, we examined the physiological consequences of temperature on their host patch exploitation behaviour. 4. First, our results showed that traits at emergence followed the TSR. Second, metabolic rates of individuals developing at low temperatures were higher, following the TCH and leading to a reduction in longevity but an increase in oviposition rate. Finally, we showed that patch exploitation behaviours conformed to the predictions of state-dependent foraging models and that hosts which were not exposed to different temperatures, modified their behavioural defences. 5. To our knowledge, this is the first study to demonstrate adaptive thermal developmental plasticity in metabolic rates and its consequences on thermal plasticity of life-history traits and foraging behaviour in ectotherms.

https://besjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1365-2435.2010.01813.x

Thermal plasticity of metabolic rates linked to life‐history traits and foraging behaviour in a parasitic wasp

1. In the context of global change, modifications in winter conditions may disrupt the seasonal phenology patterns of organisms, modify the synchrony of closely interacting species and lead to unpredictable outcomes at different ecological scales.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/een.12792

How climate change affects the seasonal ecology of insect parasitoids

Evolutionary ecology of the interactions between aphids and their parasitoids.

Climatic changes result in an increased in mean temperature and in a higher incidence of extreme weather events such as heat and cold waves. For ectotherms, such as insect parasitoids, the ability to remain active under extreme climatic conditions is a significant key to fitness. The body size of individuals, and in particular their surface to volume ratio, may play a role in their resistance to thermal conditions. The thermal tolerances are investigated of two closely-related sympatric parasitoid species [Aphidius avenae Haliday and Aphidius rhopalosiphi De Stefani-Perez (Hymenoptera: Aphidiinae)] that have a similar ecology but differ in body size and phenologies. The critical thermal limits of individuals are assessed in both sexes of each parasitoid species and the influence of surface-volume ratios on their thermal tolerances. Aphidius avenae is less resistant to low temperatures and more resistant to high temperatures than A. rhopalosiphi. The lower surface to volume ratio of A. avenae individuals may help them to remain active in summer when experiencing heat waves. However, body size is not the sole factor that plays a role in differences of thermal tolerance between species and body size may not be an adaptation to extreme temperatures but rather a by-product of developmental regulation. Closely related sympatric species from the same ecological guild can have different thermal tolerances that may allow them to occur within the same habitat. The present study also highlights the importance of clearly defining how to measure critical thermal limits to determine the thermal tolerance of a species.

Cécile Le Lann

Papers

Loss of lipid synthesis as an evolutionary consequence of a parasitic lifestyle.

Thermal plasticity of metabolic rates linked to life‐history traits and foraging behaviour in a parasitic wasp

How climate change affects the seasonal ecology of insect parasitoids

Evolutionary ecology of the interactions between aphids and their parasitoids.

Thermal tolerance of sympatric hymenopteran parasitoid species: does it match seasonal activity?