scholarly journals Substantial intraspecific variation in energy budgets: biology or artefact?

2021 ◽  
Author(s):  
Tomos Potter ◽  
David N Reznick ◽  
Tim Coulson
Keyword(s):  
Intraspecific Variation ◽  
Life Histories ◽  
Interspecific Variation ◽  
Energy Budgets ◽  
Parameter Estimates ◽  
Dynamic Energy Budget ◽  
Trinidadian Guppy ◽  
Parameter Values ◽  
Biological Differences ◽  
Growth And Reproduction

Dynamic energy budget (DEB) models provide a mechanistic description of life-histories in terms of fluxes of energy through biological processes. In these models, life-histories are a function of environmental conditions and of fundamental traits of the organism relating to the acquisition, allocation, and use of energy. These traits are described by the parameters of the DEB model, which have been estimated for over 2500 species. Recent work has aimed to compare species on the basis of differences in DEB parameters. We show that caution is required in such analyses, because (i) parameter estimates vary considerably as an artefact of the types of data used to fit the models, and (ii) there is substantial intraspecific variation in parameter values, reflecting biological differences among populations. We show that similar patterns of growth and reproduction can be reproduced with very different parameter sets. Our results imply that direct comparison of DEB parameters across populations or species may be invalid. However, valid comparisons are possible if differences in the types of data used to fit the models are taken into account. We estimated DEB parameters for 16 populations of Trinidadian guppy, identifying differences in resource allocation and metabolic rate consistent with evolved life-history differences among these populations. Variation in parameter values was substantial: if intraspecific variation in DEB parameters is greater than currently measured levels of interspecific variation, the detection of broad-scale patterns in energy budgets across species will be challenging.

Individual Growth and Reproduction

2019 ◽  
pp. 38-56
Author(s):  
Ken H. Andersen
Keyword(s):  
Life History ◽  
Growth Model ◽  
Life Histories ◽  
Maximum Size ◽  
Individual Growth ◽  
Energy Budgets ◽  
Asymptotic Size ◽  
The Individual ◽  
Growth And Reproduction

This chapter develops descriptions of how individuals grow and reproduce. More specifically, the chapter seeks to determine the growth and reproduction rates from the consumption rate, by developing an energy budget of the individual as a function of size. To that end, the chapter addresses the question of how an individual makes use of the energy acquired from consumption. It sets up the energy budgets of individuals by formulating the growth model using so-called life-history invariants, which are parameters that do not vary systematically between species. While the formulation of the growth model in terms of life-history invariants is largely successful, there is in particular one parameter that is not invariant between life histories: the asymptotic size (maximum size) of individuals in the population. This parameter plays the role of a master trait that characterizes most of the variation between life histories.

Population size structure and sex ratios in some woodlice (Crustacea: Oniscidae) from southern Africa

1994 ◽  
Vol 10 (2) ◽  
pp. 261-271 ◽  
Author(s):  
J. M. Dangerfield ◽  
S. R. Telford
Keyword(s):  
Population Size ◽  
Southern Africa ◽  
Life Histories ◽  
Mating Systems ◽  
Size Structure ◽  
Sex Ratios ◽  
Interspecific Variation ◽  
Sexual Competition ◽  
Population Size Structure ◽  
Adult Sex Ratio

ABSTRACTThe population size structure and adult sex ratio were recorded for four indigenous and one introduced species of terrestrial isopod from southern Africa. Interspecific variation was considerable with either discrete or continuous distributions indicative of the production of separate cohorts or continuous recruitment. Intraspecific variation was also considerable particularly in species such as Aphiloscia vilis which can be found in diverse habitats. Sex ratios were consistently female biased, a result consistent with observations made on temperate species. These observations, and a consideration of sexual dimorphism based on body mass, suggest that phenotypic plasticity may be an important tactic in the life histories of tropical woodlice and that in some populations the potential exists for strong sexual competition and complex mating systems.

Kinetics and physiological characteristics of autotrophic dentrification by denitrifying sulfur bacteria

2000 ◽  
Vol 42 (3-4) ◽  
pp. 59-68 ◽  
Author(s):  
S.-E. Oh ◽  
K.-S. Kim ◽  
H.-C. Choi ◽  
J. Cho ◽  
I.S. Kim
Keyword(s):  
Gas Production ◽  
Parameter Estimates ◽  
Production Volume ◽  
Autotrophic Denitrification ◽  
Nonlinear Regression Analysis ◽  
Monod Equation ◽  
Sulfur Bacteria ◽  
The Media ◽  
Parameter Values ◽  
Mixotrophic Conditions

To study the kinetics and physiology of autotrophic denitrifying sulfur bacteria, a steady-state anaerobic master culture reactor (MCR) was operated for over six months under a semi-continuous mode and nitrate limiting conditions using nutrient/mineral/buffer (NMB) medium containing thiosulfate and nitrate. Characteristics of the autotropic denitrifier were investigated through the cumulative gas production volume and rate, measured using an anaerobic respirometer, and through the nitrate, nitrite, and sulfate concentrations within the media. The bio-kinetic parameters were obtained based upon the Monod equation using mixed cultures in the MCR. Nonlinear regression analysis was employed using nitrate depletion and biomass production curves. Although this analysis did not yield exact biokinetic parameter estimates, the following ranges for the parameter values were obtained: μmax =0.12-0.2 hr-1; k=0.3-0.4 hr-1; Ks=3-10mg/L; YNO3=0.4-0.5mg Biomass/mg NO3--N. Inhibition of denitrification occurred when the concentrations of NO3--N, and SO42- reached about 660mg/L and 2,000mg/L, respectively. The autotrophic denitrifying sulfur bacteria were observed to be very sensitive to nitrite but relatively tolerant of nitrate, sulfate, and thiosulfate. Under mixotrophic conditions, denitrification by these bacteria occurred autotrophically; even with as high as 2 g COD, autotrophic denitrification was not significantly affected. The optimal pH and temperature for autotrophic denitrification was about 6.5–7.5 and 33–35 °C, respectively.

scholarly journals Calibrating a global three-dimensional biogeochemical ocean model (MOPS-1.0)

2017 ◽  
Vol 10 (1) ◽  
pp. 127-154 ◽  
Author(s):  
Iris Kriest ◽  
Volkmar Sauerland ◽  
Samar Khatiwala ◽  
Anand Srivastav ◽  
Andreas Oschlies
Keyword(s):  
Large Scale ◽  
Environmental Changes ◽  
Single Species ◽  
Ocean Model ◽  
Biogeochemical Model ◽  
Parameter Estimates ◽  
Spatial And Temporal Scales ◽  
Ocean Models ◽  
Biogeochemical Tracers ◽  
Parameter Values

Abstract. Global biogeochemical ocean models contain a variety of different biogeochemical components and often much simplified representations of complex dynamical interactions, which are described by many ( ≈ 10 to  ≈ 100) parameters. The values of many of these parameters are empirically difficult to constrain, due to the fact that in the models they represent processes for a range of different groups of organisms at the same time, while even for single species parameter values are often difficult to determine in situ. Therefore, these models are subject to a high level of parametric uncertainty. This may be of consequence for their skill with respect to accurately describing the relevant features of the present ocean, as well as their sensitivity to possible environmental changes. We here present a framework for the calibration of global biogeochemical ocean models on short and long timescales. The framework combines an offline approach for transport of biogeochemical tracers with an estimation of distribution algorithm (Covariance Matrix Adaption Evolution Strategy, CMA-ES). We explore the performance and capability of this framework by five different optimizations of six biogeochemical parameters of a global biogeochemical model, simulated over 3000 years. First, a twin experiment explores the feasibility of this approach. Four optimizations against a climatology of observations of annual mean dissolved nutrients and oxygen determine the extent to which different setups of the optimization influence model fit and parameter estimates. Because the misfit function applied focuses on the large-scale distribution of inorganic biogeochemical tracers, parameters that act on large spatial and temporal scales are determined earliest, and with the least spread. Parameters more closely tied to surface biology, which act on shorter timescales, are more difficult to determine. In particular, the search for optimum zooplankton parameters can benefit from a sound knowledge of maximum and minimum parameter values, leading to a more efficient optimization. It is encouraging that, although the misfit function does not contain any direct information about biogeochemical turnover, the optimized models nevertheless provide a better fit to observed global biogeochemical fluxes.

scholarly journals Stable Isotope Evidence Links Breeding Geography and Migration Timing in Wood Warblers (Parulidae)

The Auk ◽  
2006 ◽  
Vol 123 (2) ◽  
pp. 431-437 ◽  
Author(s):  
Jeffrey F. Kelly
Keyword(s):  
Hydrogen Isotope ◽  
Life Histories ◽  
Isotope Ratios ◽  
Interspecific Variation ◽  
Autumn Migration ◽  
Breeding Sites ◽  
Migration Timing ◽  
Wood Warblers ◽  
Stable Hydrogen Isotope ◽  
Hydrogen Isotope Ratios

AbstractTracking seasonal movements of songbirds is a key step in understanding the annual cycle of migrants. To better understand autumn migration of wood warblers, I analyzed stable-hydrogen isotope ratios of feathers collected from three species captured during stopover at the Bosque del Apache National Wildlife Refuge, New Mexico. To assess the form and strength of the relationship between timing of migration and breeding origins, I regressed stable-hydrogen isotope ratios of feathers against date of capture. These analyses indicated that Orange-crowned Warblers (Vermivora celata) and Common Yellowthroats (Geothlypis trichas) breeding in the southern portion of these species' ranges precede their northern conspecifics in autumn migration. By contrast, Yellow Warblers (Dendroica petechia) from northern breeding sites arrived before more southerly breeding conspecifics. This pattern is similar to that reported previously in Wilson's Warbler (Wilsonia pusilla). These findings suggest that, among wood warblers, (1) timing of autumn migration is often strongly related to breeding location and (2) interspecific variation in the direction of this relationship is large. The direction and strength of these patterns have implications for our understanding of inter- and intraspecific geographic variation in the life histories of migrants.Evidencia de Isótopos Estables Conecta la Geografía de Nidificación con el Momento de la Migración en Especies de Parulidae

Modeling of respiratory system impedances in dogs

1987 ◽  
Vol 62 (2) ◽  
pp. 414-420 ◽  
Author(s):  
A. C. Jackson ◽  
K. R. Lutchen
Keyword(s):  
Respiratory System ◽  
Element Model ◽  
Parameter Estimates ◽  
Frequency Range ◽  
Nonlinear Regression Analysis ◽  
Entire Frequency Range ◽  
Frequency Dependent ◽  
Impedance Data ◽  
Parameter Values ◽  
Gas Compressibility

Mechanical impedances between 4 and 64 Hz of the respiratory system in dogs have been reported (A.C. Jackson et al. J. Appl. Physiol. 57: 34–39, 1984) previously by this laboratory. It was observed that resistance (the real part of impedance) decreased slightly with frequency between 4 and 22 Hz then increased considerably with frequency above 22 Hz. In the current study, these impedance data were analyzed using nonlinear regression analysis incorporating several different lumped linear element models. The five-element model of Eyles and Pimmel (IEEE Trans. Biomed. Eng. 28: 313–317, 1981) could only fit data where resistance decreased with frequency. However, when the model was applied to these data the returned parameter estimates were not physiologically realistic. Over the entire frequency range, a significantly improved fit was obtained with the six-element model of DuBois et al. (J. Appl. Physiol. 8: 587–594, 1956), since it could follow the predominate frequency-dependent characteristic that was the increase in resistance. The resulting parameter estimates suggested that the shunt compliance represents alveolar gas compressibility, the central branch represents airways, and the peripheral branch represents lung and chest wall tissues. This six-element model could not fit, with the same set of parameter values, both the frequency-dependent decrease in Rrs and the frequency-dependent increase in resistance. A nine-element model recently proposed by Peslin et al. (J. Appl. Physiol. 39: 523–534, 1975) was capable of fitting both the frequency-dependent decrease and the frequency-dependent increase in resistance. However, the data only between 4 and 64 Hz was not sufficient to consistently determine unique values for all nine parameters.

scholarly journals Escherichia coli O157 infection on Scottish cattle farms: dynamics and control

2010 ◽  
Vol 8 (60) ◽  
pp. 1051-1058 ◽  
Author(s):  
Xu-Sheng Zhang ◽  
Mark E. J. Woolhouse
Keyword(s):  
Escherichia Coli ◽  
Herd Size ◽  
Parameter Estimates ◽  
Control Effort ◽  
Considerable Uncertainty ◽  
Targeted Interventions ◽  
Dynamics And Control ◽  
And Control ◽  
Parameter Values ◽  
Cattle Farms

In this study, we parametrize a stochastic individual-based model of the transmission dynamics of Escherichia coli O157 infection among Scottish cattle farms and use the model to predict the impacts of both targeted and non-targeted interventions. We first generate distributions of model parameter estimates using Markov chain Monte Carlo methods. Despite considerable uncertainty in parameter values, each set of parameter values within the 95th percentile range implies a fairly similar impact of interventions. Interventions that reduce the transmission coefficient and/or increase the recovery rate of infected farms (e.g. via vaccination and biosecurity) are much more effective in reducing the level of infection than reducing cattle movement rates, which improves effectiveness only when the overall control effort is small. Targeted interventions based on farm-level risk factors are more efficient than non-targeted interventions. Herd size is a major determinant of risk of infection, and our simulations confirmed that targeting interventions at farms with the largest herds is almost as effective as targeting based on overall risk. However, because of the striking characteristic that the infection force depends weakly on the number of infected farms, no interventions that are less than 100 per cent effective can eradicate E. coli O157 infection from Scottish cattle farms, implying that eliminating the disease is impractical.

Sign in / Sign up

Export Citation Format

Share Document