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Growth Trajectories (growth + trajectory)
Selected AbstractsFunctional Mapping of Quantitative Trait Loci Underlying Growth Trajectories Using a Transform-Both-Sides Logistic ModelBIOMETRICS, Issue 3 2004Rongling Wu Summary The incorporation of developmental control mechanisms of growth has proven to be a powerful tool in mapping quantitative trait loci (QTL) underlying growth trajectories. A theoretical framework for implementing a QTL mapping strategy with growth laws has been established. This framework can be generalized to an arbitrary number of time points, where growth is measured, and becomes computationally more tractable, when the assumption of variance stationarity is made. In practice, however, this assumption is likely to be violated for age-specific growth traits due to a scale effect. In this article, we present a new statistical model for mapping growth QTL, which also addresses the problem of variance stationarity, by using a transform-both-sides (TBS) model advocated by Carroll and Ruppert (1984, Journal of the American Statistical Association79, 321,328). The TBS-based model for mapping growth QTL cannot only maintain the original biological properties of a growth model, but also can increase the accuracy and precision of parameter estimation and the power to detect a QTL responsible for growth differentiation. Using the TBS-based model, we successfully map a QTL governing growth trajectories to a linkage group in an example of forest trees. The statistical and biological properties of the estimates of this growth QTL position and effect are investigated using Monte Carlo simulation studies. The implications of our model for understanding the genetic architecture of growth are discussed. [source] Effects of reduced salinities on growth, food conversion efficiency and osmoregulatory status in the spotted wolffishJOURNAL OF FISH BIOLOGY, Issue 2 2001A. Foss No significant differences in mean mass between groups were found at any time in spotted wolffish Anarhichas minor, mean (±S.D.) initial mass 76 (±21) g, reared at salinities of 12, 17, 25 and 34, for 12 weeks at 8° C. Salinity did not have a significant effect on daily feeding rates, total food consumption, food conversion efficiency and protein efficiency ratio. Growth trajectories varied between groups, but no overall difference in growth was found. Plasma osmolality and plasma chloride levels decreased with salinity in a 48 h abrupt exposure trial, and in the growth experiment the low salinity groups (12 and 17,) exhibited significantly lower values compared with 25 and 34,. The decrease was moderate and concentrations were well within the range described for other marine species. The results indicate that the spotted wolffish is a strong osmoregulator which could be reared at various salinity levels. [source] Cross-sectional analysis of the association between age and corpus callosum size in chimpanzees (Pan troglodytes)DEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2010William D. Hopkins Abstract The CC is the major white matter tract connecting the cerebral hemispheres and provides for interhemispheric integration of sensory, motor and higher-order cognitive information. The midsagittal area of the CC has been frequently used as a marker of brain development in humans. We report the first investigation into the development of the corpus callosum and its regional subdivisions in chimpanzees (Pan troglodytes). Magnetic resonance images were collected from 104 chimpanzees (female n,=,63, male n,=,41) ranging in age from 6 years (pre-pubescent period) to 54 years (old age). Sustained linear growth was observed in the area of the CC subdivision of the genu; areas of the posterior midbody and anterior midbody displayed nonlinear growth during development. After adjusting for total brain size, we observed linear growth trajectories of the total CC and CC subdivisions of the genu, posterior midbody, isthmus and splenium, and nonlinear growth trajectories of the rostral body and anterior midbody. These developmental patterns are similar to the development of the CC in humans. As the growth curves of the CC mirrors growth seen in the percentage of white matter in humans, our results suggest chimpanzees show continued white matter development in regions related to cognitive development. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52:133,141, 2010 [source] The effect of host developmental stage at parasitism on sex-related size differentiation in a larval endoparasitoidECOLOGICAL ENTOMOLOGY, Issue 6 2009RIETA GOLS Abstract. 1For their larval development, parasitoids depend on the quality and quantity of resources provided by a single host. Therefore, a close relationship is predicted between the size of the host at parasitism and the size of the emerging adult wasp. This relationship is less clear for koinobiont than for idiobiont parasitoids. 2As size differentiation in host species exhibiting sexual size dimorphism (SSD) is likely to occur already during larval development, in koinobiont larval endoparasitoids the size of the emerging adult may also be constrained based on the sex of the host caterpillar. 3Sex-specific growth trajectories were compared in unparasitised Plutella xylostella caterpillars and in second and fourth instar hosts that were parasitised by the solitary larval koinobiont endoparasitoid Diadegma semiclausum. Both species exhibit SSD, where females are significantly larger than males. 4Healthy female P. xylostella caterpillars developed significantly faster than their male conspecifics. Host regulation induced by D. semiclausum parasitism depended on the instar attacked. Parasitism in second-instar caterpillars reduced growth compared to healthy unparasitised caterpillars, whereas parasitism in fourth-instar caterpillars arrested development. The reduction in growth was most pronounced in hosts producing male D. semiclausum. 5Parasitism itself had the largest impact on host growth. SSD in the parasitoid is mainly the result of differences in growth rate of the parasitoid,host complex producing male and female wasps and differences in exploitation of the host resources. Female wasps converted host biomass more efficiently into adult biomass than males. [source] Total population density during the first year of life as a major determinant of lifetime body-length trajectory in marble troutECOLOGY OF FRESHWATER FISH, Issue 4 2008S. Vincenzi Abstract,,, The conditions experienced early in life can strongly influence life-history trajectories in a variety of animal species. Here, we use data from four isolated populations of the endangered stream-dwelling salmonid marble trout (Salmo marmoratus Cuvier 1817) living in the Soca and Idrijca river basins (Slovenia) to explore the influence of the total density experienced during and after the first year of life by marble trout year-classes on body length of marble trout through the lifetime. Analyses were performed by pooling together the stream-specific datasets to cover a wider range of densities. Mean body length of marble trout year-classes through the lifetime (from age 1+ to 5+) was negatively related to total density of marble trout during the first year of life. The relationship between density during the first growth period and body length through the lifetime was well described by negative power curves. Total population density after the first year of life was not correlated with body length, thus suggesting that body growth trajectories are heavily determined early in life. Given size-dependent sexual maturity and egg production in marble trout, the relationship between density early in life and lifetime individual growth may have strong implications in terms of population dynamics and regulation of population size. [source] Global crisis and beyond: Sustainable growth trajectories for the developing worldINTERNATIONAL LABOUR REVIEW, Issue 2 2010Jayati GHOSH Abstract. Despite recent signs of output recovery, casual resumption of the growth model that crashed in 2008,09 will exacerbate the domestic and global imbalances that caused the crisis in the first place , to the detriment of the real economy, equitable development, and employment recovery. The model's environmental unsustainability is also evident. The author therefore argues for a broad policy agenda including reform of the international financial system, development strategies re-focused on wage-driven domestic demand and viable agriculture, fiscal promotion of greener technologies and demand patterns, and redistributive social policies to reduce inequalities and act as macroeconomic stabilizers in downturns. [source] The pattern of endocranial ontogenetic shape changes in humansJOURNAL OF ANATOMY, Issue 3 2009Simon Neubauer Abstract Humans show a unique pattern of brain growth that differentiates us from all other primates. In this study, we use virtual endocasts to provide a detailed description of shape changes during human postnatal ontogeny with geometric morphometric methods. Using CT scans of 108 dried human crania ranging in age from newborns to adults and several hundred landmarks and semi-landmarks, we find that the endocranial ontogenetic trajectory is curvilinear with two bends, separating three distinct phases of shape change. We test to what extent endocranial shape change is driven by size increase and whether the curved ontogenetic trajectory can be explained by a simple model of modular development of the endocranial base and the endocranial vault. The hypothesis that endocranial shape change is driven exclusively by brain growth is not supported; we find changes in endocranial shape after adult size has been attained and that the transition from high rates to low rates of size increase does not correspond to one of the shape trajectory bends. The ontogenetic trajectory of the endocranial vault analyzed separately is nearly linear; the trajectory of the endocranial base, in contrast, is curved. The endocranial vault therefore acts as one developmental module during human postnatal ontogeny. Our data suggest that the cranial base comprises several submodules that follow their own temporally and/or spatially disjunct growth trajectories. [source] Allometric studies on growth and development of the human placenta: growth of tissue compartments and diffusive conductances in relation to placental volume and fetal massJOURNAL OF ANATOMY, Issue 6 2006Terry M. Mayhew Abstract Correlations between placental size and fetal mass during gestation fail to account for changes in composition that accompany placental growth and maturation. This study uses stereological data on the sizes of different tissue compartments in human placentas from 10 weeks of gestation to term and relates them to placental volume and to fetal mass by means of allometric analysis. In addition, tissue dimensions are used to calculate a physiological transport measure (diffusive conductance) for the villous membrane. Histological sections randomly sampled from placentas and analysed stereologically provided estimates of structural quantities (volumes, exchange surface areas, lengths, numbers of nuclei, diffusion distances). These data were combined with a physicochemical quantity (Krogh's diffusion coefficient) in order to estimate oxygen diffusive conductances for the villous membrane and its two components (trophoblast and stroma). Allometric relationships between these quantities and placental volume or fetal mass were obtained by linear regression analyses after log-transformation. Placental tissues had different growth trajectories: most grew more rapidly than placental volume and all grew more slowly than fetal mass. Diffusion distances were inversely related to placental and fetal size. Differential growth impacted on diffusive conductances, which, again, did not improve commensurately with placental volume but did match exactly growth of the fetus. Findings show that successful integration between supply and demand can be achieved by differential tissue growth. Allometric analysis of results from recent studies on the murine placenta suggest further that diffusive conductances may also be matched to fetal mass during gestation and to fetal mass at term across species. [source] Seasonal growth patterns of wild juvenile fish: partitioning variation among explanatory variables, based on individual growth trajectories of Atlantic salmon (Salmo salar) parrJOURNAL OF ANIMAL ECOLOGY, Issue 1 2005P. J. BACON Summary 1We present an empirical, analytical model that estimates both temperature and seasonal response functions for the growth of wild juvenile fish without the need for costly tank experiments in less realistic conditions. 2Analysis of monthly recapture data on the lengths and weights of individual wild juvenile fish demonstrates that simple temperature-driven models of growth can be less informative than more realistic, empirical, models. 3A case study of wild Atlantic salmon parr (Salmo salar) showed that: most growth took place in a 10-week period in spring, at temperatures below those that previous published models report as necessary for rapid growth and at faster rates than the maximum that previous models predicted. 4Temperature and fish size allometry explained 45% of growth variation, but the effects of temperature were significantly and markedly different at different seasons. 5Seasonal effects explained an additional 18% of the variation and were strongly associated with the abundance of potential ,drift' food. 6The seasonal patterns for growth in length and weight were different, implying differential allocation of resources to structural and reserve tissues. 7The growth patterns of sexually maturing male parr and emigrants also differed in comparison to other parr. 8Condition factor, length at first capture and seasonal interactions with both early maturity and smolting explained another 7% of the variation. 9However, individual fish did not grow consistently better, or worse, than the ,average' fish. 10This study emphasizes the necessity to test the adequacy of laboratory-based physiological models with suitably detailed field data and to focus model refinement by identifying processes which otherwise confound interpretation. [source] The growth of the common two-banded seabream, Diplodus vulgaris (Teleostei, Sparidae), in Canarian waters, estimated by reading otoliths and by back-calculationJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2003J. G. Pajuelo Summary The yearly nature of increment formation in the otoliths of 1,9-year-old seabream, Diplodus vulgaris (E. Geoffrey Saint-Hilaire 1817), from the Canary Islands was validated. The marginal increment method showed that the opaque rings were formed in summer, and the translucent rings in winter. The Brody Proportional Hypothesis and the power length,radius relationship used to back-calculate the growth trajectories of D. vulgaris showed that this growth model could provide reasonable growth estimates in this species. Growth back-calculation and growth estimates obtained by direct otolith readings were similar. Data on age and size used to estimate the parameters of the von Bertalanffy growth model for D. vulagris from the Canary Islands showed that males and females had similar growth rates. [source] Phenotypic variation in growth trajectories in the Arctic charr Salvelinus alpinusJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2003M. Björklund Abstract Animals with determinate growth have shown little variation in individual growth patterns, but similar analyses for animals with indeterminate growth have been lacking. We analysed the amount of phenotypic variation in growth patterns across ages among individuals of a hatchery-based population of Arctic charr, Salvelinus alpinus, Salmonidae, using the infinite-dimensional model and including the effects of group size structure. There was little phenotypic variation in growth trajectories: individuals that were small (in relation to the mean) early in life were among the smallest 2.5 years later. If the genetic variation reflects phenotypic variation, not much evolutionary change can be expected. Our results show that there are ecological conditions that determine the strong covariation of size across ages, most likely size-related dominance behaviour, which can mask the true variation of growth patterns. Thus, social interactions can have strong evolutionary effects on traits not directly involved in the behavioural interactions. [source] Development of Mathematics Interest in Adolescence: Influences of Gender, Family, and School ContextJOURNAL OF RESEARCH ON ADOLESCENCE, Issue 2 2010Anne C. Frenzel This study investigated adolescents' developmental trajectories of mathematics interest and explored related effects of gender, family, and school context. Latent growth curve modeling was used to analyze longitudinal data of N=3,193 students (51% female) from grades 5 to 9 from all 3 ability tracks of the German state school system. Annual assessments involved student questionnaires on interest in mathematics, perceptions of classroom characteristics (classroom values for mathematics, mathematics teacher enthusiasm), as well as parent questionnaires regarding family values for mathematics. Results indicated a downward trend of students' mathematics interest that plateaued in later years, with high variability in mean levels, but little variability in the shape of the growth trajectories. Boys reported higher mathematics interest than girls, but similar downward growth trajectories. Students from the lowest ability track showed more favorable interest trajectories than students from the middle and highest tracks. Family values and classroom characteristics were positively related to within-person levels of interest over time and to average individual levels of interest, but not to growth parameters. Theoretical and practical implications are discussed. [source] A Latent Growth Curve Analysis of the Structure of Aggression, Drug Use, and Delinquent Behaviors and Their Interrelations Over Time in Urban and Rural AdolescentsJOURNAL OF RESEARCH ON ADOLESCENCE, Issue 2 2005Albert D. Farrell Latent growth curve analysis was used to examine the structure and interrelations among aggression, drug use, and delinquent behavior during early adolescence. Five waves of data were collected from 667 students at three urban middle schools serving a predominantly African American population, and from a more ethnically diverse sample of 950 students at four rural middle schools. One set of models focused on changes in individual behaviors; the other on changes in a global problem behavior factor. Models with separate growth trajectories for aggression, drug use, and delinquent behavior provided the best fit for both samples and revealed relations between initial levels of aggression and subsequent changes in the other behaviors. Boys and girls differed in their initial levels of these behaviors, but not their patterns of change. Differences in growth curve trajectories were found across samples. These findings have important implications for assessment and prevention of problem behaviors in adolescents. [source] Multiple growth-correlated life history traits estimated simultaneously in individualsOIKOS, Issue 1 2010Fabian M. Mollet We present a new methodology to estimate rates of energy acquisition, maintenance, reproductive investment and the onset of maturation (four-trait estimation) by fitting an energy allocation model to individual growth trajectories. The accuracy and precision of the method is evaluated on simulated growth trajectories. In the deterministic case, all life history parameters are well estimated with negligible bias over realistic parameter ranges. Adding environmental variability reduces precision, causes the maintenance and reproductive investment to be confounded with a negative error correlation, and tends, if strong, to result in an underestimation of the energy acquisition and maintenance and an overestimation of the age and size at the onset of maturation. Assuming a priori incorrect allometric scaling exponents also leads to a general but fairly predictable bias. To avoid confounding in applications we propose to assume a constant maintenance (three-trait estimation), which can be obtained by fitting reproductive investment simultaneously to size at age on population data. The results become qualitatively more robust but the improvement of the estimate of the onset of maturation is not significant. When applied to growth curves back-calculated from otoliths of female North Sea plaice Pleuronectes platessa, the four-trait and three-trait estimation produced estimates for the onset of maturation very similar to those obtained by direct observation. The correlations between life-history traits match expectations. We discuss the potential of the methodology in studies of the ecology and evolution of life history parameters in wild populations. [source] Lumbar ontogenetic growth and sexual dimorphism in modern humansAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2010Elías Valverde To detect and differentiate between possible heterochronic processes in the ontogenetic growth pattern of the human lumbar region, in relationship with sexual dimorphism. We measured the growth trajectories of average length and width, length/width ratio, posterior projected surface area, and bone mineral density using dual energy X-ray absorptiometry, in a sample group of 1718 modern humans. These growth patterns were analyzed using the Gompertz model. In adult lumbar region, only surface area and width were significantly higher in men. Regarding the ontogenetic growth pattern leading to the dimorphic states, all values obtained for women were significantly higher than those obtained for men. Maximum initial growth rates occurred for surface area and density in women. Width scaled faster than length in both sexes. The lumbar region followed patterns similar to those of other skeletal elements when compared with a previous classification of growth patterns in the human skeleton; however, in this study, the growth rate was slower. With regard to the effect of dimorphism, sexual differences in growth rate accounted for only a small proportion of the variation in lumbar length, mineral density, and surface area. Nevertheless, these sexual differences played an important role in the increase of the length/width ratio, which was reflected in the ages at which sexual dimorphism developed. The sexual dimorphism found in the lumbar region of human adults is not caused by any heterochronic process. The lower values of bone mineral density in adult women could explain the origin of some pathologies related. Am. J. Hum. Biol. 22:596,603, 2010. © 2010 Wiley-Liss, Inc. [source] Short but catching up: Statural growth among native Amazonian Bolivian childrenAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2010Ricardo Godoy The ubiquity and consequences of childhood growth stunting (<,2 SD in height-for-age Z score, HAZ) in rural areas of low-income nations has galvanized research into the reversibility of stunting, but the shortage of panel data has hindered progress. Using panel data from a native Amazonian society of foragers-farmers in Bolivia (Tsimane'), we estimate rates of catch-up growth for stunted children. One hundred forty-six girls and 158 boys 2 , age , 7 were measured annually during 2002,2006. Annual , height in cm and in HAZ were regressed separately against baseline stunting and control variables related to attributes of the child, mother, household, and village. Children stunted at baseline had catch-up growth rates 0.11 SD/year higher than their nonstunted age and sex peers, with a higher rate among children farther from towns. The rate of catch up did not differ by the child's sex. A 10% rise in household income and an additional younger sibling lowered by 0.16 SD/year and 0.53 SD/year the rate of growth. Results were weaker when measuring , height in cm rather than in HAZ. Possible reasons for catch-up growth include (a) omitted variable bias, (b) parental reallocation of resources to redress growth faltering, particularly if parents perceive the benefits of redressing growth faltering for child school achievement, and (c) developmental plasticity during this period when growth rates are most rapid and linear growth trajectories have not yet canalized. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source] Early rapid growth, early birth: Accelerated fetal growth and spontaneous late preterm birthAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 2 2009Michelle Lampl The past two decades in the United States have seen a 24% rise in spontaneous late preterm delivery (34,36 weeks) of unknown etiology. This study tested the hypothesis that fetal growth was identical prior to spontaneous preterm (n = 221, median gestational age at birth 35.6 weeks) and term (n = 3706) birth among pregnancies followed longitudinally in Santiago, Chile. The hypothesis was not supported: Preterm-delivered fetuses were significantly larger than their term-delivered peers by mid-second trimester in estimated fetal weight, head, limb, and abdominal dimensions, and they followed different growth trajectories. Piecewise regression assessed time-specific differences in growth rates at 4-week intervals from 16 weeks. Estimated fetal weight and abdominal circumference growth rates slowed at 20 weeks among the preterm-delivered, only to match and/or exceed their term-delivered peers at 24,28 weeks. After an abrupt growth rate decline at 28 weeks, fetuses delivered preterm did so at greater population-specific sex and age-adjusted birth weight percentiles than their peers from uncomplicated pregnancies (P < 0.01). Growth rates predicted birth timing: one standard score of estimated fetal weight increased the odds ratio for late preterm birth from 2.8 prior to 23 weeks, to 3.6 (95% confidence interval, 1.82,7.11, P < 0.05) between 23 and 27 weeks. After 27 weeks, increasing size was protective (OR: 0.56, 95% confidence interval, 0.38,0.82, P = 0.003). These data document, for the first time, a distinctive fetal growth pattern across gestation preceding spontaneous late preterm birth, identify the importance of mid-gestation for alterations in fetal growth, and add perspective on human fetal biological variability. Am. J. Hum. Biol., 2009. © 2008 Wiley-Liss, Inc. [source] Growth rates and life histories in twenty-two small-scale societies,AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2006Robert Walker This study investigates variation in body growth (cross-sectional height and weight velocity) among a sample of 22 small-scale societies. Considerable variation in growth exists among hunter-gatherers that overlaps heavily with growth trajectories present in groups focusing more on horticulture. Intergroup variation tends to track environmental conditions, with societies under more favorable conditions displaying faster growth and earlier puberty. In addition, faster/earlier development in females is correlated with higher mortality. For example, African "Pygmies," Philippine "Negritos," and the Hiwi of Venezuela are characterized by relatively fast child-juvenile growth for their adult body size (used as a proxy for energetic availability). In these societies, subadult survival is low, and puberty, menarche, and first reproduction are relatively early (given their adult body size), suggesting selective pressure for accelerated development in the face of higher mortality. In sum, the origin and maintenance of different human ontogenies may require explanations invoking both environmental constraints and selective pressures. Am. J. Hum. Biol. 18:295,311, 2006. © 2006 Wiley-Liss, Inc. [source] Growth in colony living anubis baboon infants and its relationship with maternal activity budgets and reproductive statusAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Cécile Garcia Abstract Early growth is of interest because it is susceptible to maternal effects and linked to fitness components for a range of species. Here we present anthropometric measurements on 23 infant olive baboons born into a captive colony in order to describe growth over the first 2 years of life, to explore maternal influences on growth, and to assess the impact of growth profiles on maternal reproduction. Six main findings emerged: 1) Infant growth rates in our colony were higher than those reported for wild populations but comparable to those observed for food-enhanced animals. 2) The ratio of infant mass to maternal mass was positively associated with reproductive parameters, such as duration of post-partum amenorrhea and interbirth interval. 3) Mothers resumed cycling and reconceived when their infants attained a relatively consistent threshold mass. 4) Infant mass-for-age was associated with maternal rank and, independently, with maternal mass such that females of high dominance rank and heavy females had relatively large infants at their resumption of cycling. 5) Low-ranking and lighter females had longer investment periods but smaller infants. They continued investment in infant through prolonged lactation until their infants reached a mass similar to that of infants of high-ranking/heavy mothers, suggesting that the lengthening of investment is essentially compensatory for slow early growth. 6) There was no relationship between infant growth and maternal activity budgets. Maternal physical and social factors, not energetics, contributed to differences among infants in growth trajectories, and infant growth temporally influenced successive reproductive events. Am J Phys Anthropol 2009. © 2008 Wiley-Liss, Inc. [source] Ontogeny and phyletic size change in living and fossil lemursAMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2010Matthew J. Ravosa Abstract Lemurs are notable for encompassing the range of body-size variation for all primates past and present,close to four orders of magnitude. Benefiting from the phylogenetic proximity of subfossil lemurs to smaller-bodied living forms, we employ allometric data from the skull to probe the ontogenetic bases of size differentiation and morphological diversity across these clades. Building upon prior pairwise comparisons between sister taxa, we performed the first clade-wide analyses of craniomandibular growth allometries in 359 specimens from 10 lemuroids and 176 specimens from 8 indrioids. Ontogenetic trajectories for extant forms were used as a criterion of subtraction to evaluate morphological variation, and putative adaptations among sister taxa. In other words, do species-level differences in skull form result from the differential extension of common patterns of relative growth? In lemuroids, a pervasive pattern of ontogenetic scaling is observed for facial dimensions in all genera, with three genera also sharing relative growth trajectories for jaw proportions (Lemur, Eulemur, Varecia). Differences in masticatory growth and form characterizing Hapalemur and fossil Pachylemur likely reflect dietary factors. Pervasive ontogenetic scaling characterizes the facial skull in extant Indri, Avahi, and Propithecus, as well as their larger, extinct sister taxa Mesopropithecus and Babakotia. Significant interspecific differences are observed in the allometry of indrioid masticatory proportions, with variation in the mechanical advantage of the jaw adductors and stress-resisting elements correlated with diet. As the growth series and adult data are largely coincidental in each clade, interspecific variation in facial form may result from selection for body-size differentiation among sister taxa. Those cases where trajectories are discordant identify potential dietary adaptations linked to variation in masticatory forces during chewing and biting. Although such dissociations highlight selection to uncouple shared ancestral growth patterns, they occur largely via transpositions and retention of primitive size-shape covariation patterns or relative growth coefficients. Am. J. Primatol. 72:161,172, 2010. © 2009 Wiley-Liss, Inc. [source] The role of growth stop as a morphogenetic factor in Mastomys natalensis (Rodentia: Muridae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009CARLO FADDA The present study investigated growth patterns under three different environmental conditions in a single population of the rodent Mastomys natalensis (Rodentia, Muridae) in Morogoro, Tanzania. The study aimed to test whether and how post-weaning ontogenetic processes are affected by different environmental conditions. Morogoro is characterized by a bimodal rainfall pattern, with unreliable peaks occurring in November/December of some years and reliable ones in February to May. We recognized three different generation types. In the first one, the , generation, growth occurred during the dry second half of the year in years when the November/December rains were very poor. The second group (, generation) grew under conditions when these rains were abundant. Finally, the , generation, consisted of animals that were born in the middle of the rainy season in years when there was a continuity between both rainfall peaks. Analyses of size and shape following both Huxley,Jolicoeur and Gould,Mosimann approaches revealed that the three groups differ significantly both in size and shape. In both cases, the importance of the environment in assessing growth trajectories during post-natal ontogenetic processes is apparent. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 791,800. [source] Ecological correlates of body size in relation to cell size and cell number: patterns in flies, fish, fruits and foliageBIOLOGICAL REVIEWS, Issue 2 2007Jeff Arendt Abstract Body size is important to most aspects of biology and is also one of the most labile traits. Despite its importance we know remarkably little about the proximate (developmental) factors that determine body size under different circumstances. Here, I review what is known about how cell size and number contribute to phenetic and genetic variation in body size in Drosophila melanogaster, several fish, and fruits and leaves of some angiosperms. Variation in resources influences size primarily through changes in cell number while temperature acts through cell size. The difference in cellular mechanism may also explain the differences in growth trajectories resulting from food and temperature manipulations. There is, however, a poorly recognized interaction between food and temperature effects that needs further study. In addition, flies show a sexual dimorphism in temperature effects with the larger sex responding by changes in cell size and the smaller sex showing changes in both cell size and number. Leaf size is more variable than other organs, but there appears to be a consistent difference between how shade-tolerant and shade-intolerant species respond to light level. The former have larger leaves via cell size under shade, the latter via cell number in light conditions. Genetic differences, primarily from comparisons of D. melanogaster, show similar variation. Direct selection on body size alters cell number only, while temperature selection results in increased cell size and decreased cell number. Population comparisons along latitudinal clines show that larger flies have both larger cells and more cells. Use of these proximate patterns can give clues as to how selection acts in the wild. For example, the latitudinal pattern in D. melanogaster is usually assumed to be due to temperature, but the cellular pattern does not match that seen in laboratory selection at different temperatures. [source] Joint Spatial Modeling of Recurrent Infection and Growth with Processes under Intermittent ObservationBIOMETRICS, Issue 2 2010F. S. Nathoo Summary In this article, we present a new statistical methodology for longitudinal studies in forestry, where trees are subject to recurrent infection, and the hazard of infection depends on tree growth over time. Understanding the nature of this dependence has important implications for reforestation and breeding programs. Challenges arise for statistical analysis in this setting with sampling schemes leading to panel data, exhibiting dynamic spatial variability, and incomplete covariate histories for hazard regression. In addition, data are collected at a large number of locations, which poses computational difficulties for spatiotemporal modeling. A joint model for infection and growth is developed wherein a mixed nonhomogeneous Poisson process, governing recurring infection, is linked with a spatially dynamic nonlinear model representing the underlying height growth trajectories. These trajectories are based on the von Bertalanffy growth model and a spatially varying parameterization is employed. Spatial variability in growth parameters is modeled through a multivariate spatial process derived through kernel convolution. Inference is conducted in a Bayesian framework with implementation based on hybrid Monte Carlo. Our methodology is applied for analysis in an 11-year study of recurrent weevil infestation of white spruce in British Columbia. [source] Functional Mapping of Quantitative Trait Loci Underlying Growth Trajectories Using a Transform-Both-Sides Logistic ModelBIOMETRICS, Issue 3 2004Rongling Wu Summary The incorporation of developmental control mechanisms of growth has proven to be a powerful tool in mapping quantitative trait loci (QTL) underlying growth trajectories. A theoretical framework for implementing a QTL mapping strategy with growth laws has been established. This framework can be generalized to an arbitrary number of time points, where growth is measured, and becomes computationally more tractable, when the assumption of variance stationarity is made. In practice, however, this assumption is likely to be violated for age-specific growth traits due to a scale effect. In this article, we present a new statistical model for mapping growth QTL, which also addresses the problem of variance stationarity, by using a transform-both-sides (TBS) model advocated by Carroll and Ruppert (1984, Journal of the American Statistical Association79, 321,328). The TBS-based model for mapping growth QTL cannot only maintain the original biological properties of a growth model, but also can increase the accuracy and precision of parameter estimation and the power to detect a QTL responsible for growth differentiation. Using the TBS-based model, we successfully map a QTL governing growth trajectories to a linkage group in an example of forest trees. The statistical and biological properties of the estimates of this growth QTL position and effect are investigated using Monte Carlo simulation studies. The implications of our model for understanding the genetic architecture of growth are discussed. [source] Elephants and water provision: what are the management links?DIVERSITY AND DISTRIBUTIONS, Issue 6 2007I. P. J. Smit ABSTRACT In a recent paper we demonstrated that elephant bull groups and mixed herds exhibited spatial and resource segregation across the Kruger National Park. It was found, inter alia, that both bull groups and mixed herds occurred more frequently closer to rivers than expected if they were randomly distributed, but that only bull groups occurred more frequently closer to the artificial waterholes. Although Chamaillé-Jammes et al. (2007) accepted these results, they disagreed with our interpretation regarding the potential effect that closure of artificial waterholes might have. Here we address some of the specific concerns expressed and provide a broader context regarding water provision and elephant management. Although water provision can influence elephant density and distribution, we argue that the effectiveness of surface-water manipulation as a management tool will depend on (1) natural surface-water availability, (2) forage quality, (3) elephant densities, (4) position of a population on its growth trajectory, and (5) management objectives. Even though elephants are water-dependent, the effectiveness of water provision as a management tool will therefore be area- and population-specific and will depend on management objectives. [source] Comparative growth in the postnatal skull of the extant North American turtle Pseudemys texana (Testudinoidea: Emydidae)ACTA ZOOLOGICA, Issue 2 2008Gabe S. Bever Abstract Bever, G.S. 2007. Comparative growth in the postnatal skull of the extant North American turtle Pseudemys texana (Testudinoidea: Emydidae). ,Acta Zoologica (Stockholm) 88: 000,000 Postnatal growth is one of the many aspects of developmental morphology that remains distinctly understudied in reptiles. Variation and ontogenetic scaling within the skull of the extant emydid turtle, Pseudemys texana is described based on 25 continuous characters. Results indicate that skull shape in this species changes little during postnatal growth relative to the only cryptodire taxa for which comparable datasets are available (Apalone ferox and Sternotherus odoratus). This relative lack of change results in the paedomorphic retention of a largely juvenile appearance in the adult form of P. texana. The skulls of males and females, despite the presence of distinct sexual dimorphism in size, grow with similar scaling patterns, and the few observed differences appear to reflect alteration of the male growth trajectory. Comparisons with A. ferox and S. odoratus reveal a number of similarities and differences that are here interpreted within a phylogenetic context. These preliminary hypotheses constitute predictive statements that phylogenetically bracket the majority of extant cryptodire species and provide baseline comparative data that are necessary for the future recognition of apomorphic transformations. Plasticity of ontogenetic scaling as a response to the homeostatic needs and behaviour of individuals commonly is evoked as a limitation of ontogenetic scaling as a means to inform phylogenetic studies. These evocations are largely unfounded considering that variability itself can evolve and thus be phylogenetically informative. [source] Are parametric models suitable for estimating avian growth rates?JOURNAL OF AVIAN BIOLOGY, Issue 4 2007William P. Brown For many bird species, growth is negative or equivocal during development. Traditional, parametric growth curves assume growth follows a sigmoidal form with prescribed inflection points and is positive until asymptotic size. Accordingly, these curves will not accurately capture the variable, sometimes considerable, fluctuations in avian growth over the course of the trajectory. We evaluated the fit of three traditional growth curves (logistic, Gompertz, and von Bertalanffy) and a nonparametric spline estimator to simulated growth data of six different specified forms over a range of sample sizes. For all sample sizes, the spline best fit the simulated model that exhibited negative growth during a portion of the trajectory. The Gompertz curve was the most flexible for fitting simulated models that were strictly sigmoidal in form, yet the fit of the spline was comparable to that of the Gompertz curve as sample size increased. Importantly, confidence intervals for all of the fitted, traditional growth curves were wholly inaccurate, negating the apparent robustness of the Gompertz curve, while confidence intervals of the spline were acceptable. We further evaluated the fit of traditional growth curves and the spline to a large data set of wood thrush Hylocichla mustelina mass and wing chord observations. The spline fit the wood thrush data better than the traditional growth curves, produced estimates that did not differ from known observations, and described negative growth rates at relevant life history stages that were not detected by the growth curves. The common rationale for using parametric growth curves, which compress growth information into a few parameters, is to predict an expected size or growth rate at some age or to compare estimated growth with other published estimates. The suitability of these traditional growth curves may be compromised by several factors, however, including variability in the true growth trajectory. Nonparametric methods, such as the spline, provide a precise description of empirical growth yet do not produce such parameter estimates. Selection of a growth descriptor is best determined by the question being asked but may be constrained by inherent patterns in the growth data. [source] Developmental plasticity in a passerine bird: an experiment with collared flycatchers Ficedula albicollisJOURNAL OF AVIAN BIOLOGY, Issue 3 2007Gergely Hegyi Young birds often face poor food supply, which reduces their growth and development. However, if the shortage of resources is only temporary, there is a possibility to adjust the growth trajectory of morphological traits after the end of the short-term limitation period. The two main ways of compensatory growth are delayed development (parallel growth) and growth acceleration (catch-up growth). Parallel growth has been widely demonstrated in birds, but the presence of catch-up growth in altricial species has been questioned. However, most experiments have been conducted in laboratory conditions. We manipulated the food supply of nestling collared flycatchers Ficedula albicollis in the wild by removing the male parent for three days at 4,7 days of chick age. We performed early partial swapping to control for origin effects on growth, and total swapping after the period of food limitation to ensure similar late growth environment for deprived and control chicks. Both body mass and tarsus length of deprived chicks was negatively affected by the food scarcity. Body mass showed efficient catch-up growth, but this compensation was absent in skeletal size. Body mass is an important determinant of postfledging survival in this long-distance migrant. Further studies are needed in a variety of species to examine developmental plasticity in relation to age at food scarcity and the allocation hierarchy of various morphological traits. [source] Effect of cycles of feed deprivation on growth and food consumption of immature three-spined sticklebacks and European minnowsJOURNAL OF FISH BIOLOGY, Issue 1 2003L. Wu Individual juvenile three-spined sticklebacks Gasterosteus aculeatus and European minnow Phoxinus phoxinus, from sympatric populations, were subjected to four cycles of 1 week of food deprivation and 2 weeks of ad libitum feeding. Mean specific growth rate during the weeks of deprivation was negative and did not differ between species. The three-spined stickleback showed sufficient growth compensation to recover to the growth trajectory shown by control fish daily fed ad libitum. The compensation was generated by hyperphagia during the re-feeding periods, and in the last two periods of re-feeding, the gross growth efficiencies of deprived three-spined sticklebacks were greater than in control fish. The expression of the compensatory changes in growth and food consumption became clearer over the successive periods of re-feeding. The European minnow developed only a weak compensatory growth response and the mass trajectory of the deprived fish deviated more and more from the control trajectory. During re-feeding periods, there were no significant differences in food consumption or gross growth efficiency between control and deprived European minnows. The differences between the two species are discussed in terms of the possible costs of compensatory growth, the control of growth and differences in feeding biology. [source] Maternal capital and the metabolic ghetto: An evolutionary perspective on the transgenerational basis of health inequalitiesAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2010Jonathan C.K. Wells There is particular interest in understanding socioeconomic and ethnic variability in health status. The developmental origins of disease hypothesis emphasize the importance of growth patterns across the life-course in relation to noncommunicable disease risk. The physiological components of cardiovascular risk, collectively termed the metabolic syndrome, derive in part from a disparity between the homeostatic "metabolic capacity" of vital organs and the "metabolic load" induced by large tissue masses, a rich diet and sedentary behavior. From an evolutionary perspective, the risk of such disparity is decreased by maternal physiology regulating offspring growth trajectory during gestation and lactation. Maternal capital, defined as phenotypic resources enabling investment in the offspring, allows effective buffering of the offspring from nutritional perturbations and represents the environmental niche initially occupied by the offspring. Offspring growth patterns are sensitive to the magnitude of maternal capital during early windows of plasticity. Offspring life-history strategy can then respond adaptively to further factors across the life-course, but only within the context of this initial maternal influence on growth. Maternal somatic capital is primarily gained or lost across generations, through variable rates of fetal and infant growth. I argue that the poor nutritional experience of populations subjected to colonialism resulted in a systematic loss of maternal capital, reflected in downward secular trends in stature. Accelerating the recovery of somatic capital within generations overloads metabolic capacity and exacerbates cardiovascular risk, reflected in increased disease rates in urbanizing and emigrant populations. Public health policies need to benefit metabolic capacity without exacerbating metabolic load. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||