Individual Differences In Growth Research Articles

Awareness and analysis: concurrent and predictive roles of two morphological processes in early reading comprehension

IntroductionWe examine how awareness and analysis of morphemes contribute to children's reading comprehension and its development. A multidimensional perspective on reading comprehension posits morphological awareness and morphological analysis play distinct roles in reading comprehension. Assuming individual differences in growth in these aspects of morphological processing, their concurrent influences can vary depending on children's reading comprehension abilities, and predictive influences can change as children's reading comprehension abilities improve.MethodThe current longitudinal study examined the concurrent and predictive influences of awareness and analysis on children's reading comprehension from Grades 1 to 3. Data from 171 public school children, with diverse reading comprehension abilities, were collected across five waves and were analyzed using cross-lagged panel structural equation modeling.ResultsResults showed concurrent relationships among morphological awareness, analysis, and reading comprehension in Grades 1 and 2, and morphological analysis having a concurrent relationship with reading comprehension at the end of Grade 3. Morphological awareness in all waves but Wave 3, at the end of Grade 2, predicted subsequent reading comprehension. Morphological analysis did not predict subsequent reading comprehension.DiscussionFindings support the multidimensional conceptualization of awareness and analysis as distinct morphological processes that play early-wave concurrent and across-wave predictive roles in children's reading comprehension development.

Alcohol consumption and dependence risk among male and female Veterans: Trajectories and predictors

BackgroundWith few exceptions, previously conducted research on hazardous drinking among Veterans has employed samples in which the majority of participants identify as male. In addition, past studies have solely focused on alcohol consumption, rather than associated risk for dependence. In this study, we expanded upon the extant literature by investigating sex differences in trajectories and predictors of change in alcohol consumption and dependence risk among post-9/11 Veterans. MethodsA national sample of 1649 Veterans (50.0% female) were recruited in a five-wave longitudinal study that followed Veterans for up to 16 years after deployment. We used growth curve modeling to investigate trajectories of change in alcohol consumption and dependence risk among men and women Veterans. We examined predictors of growth, including demographics, support and resources, psychiatric symptoms, and trauma exposure. ResultsAmong male Veterans, alcohol consumption and dependence risk remained stagnant, which is in contrast to past work using non-Veteran samples. For female Veterans, consumption exhibited initial reductions that decelerated, and dependence risk reduced at a continuous rate. PTSD diagnosis was a significant predictor of individual differences in growth for men. Psychiatric symptoms (i.e., PTSD diagnosis, probable depression diagnosis, suicidal ideation) and psychosocial functioning were significant predictors of decreasing alcohol use for women. ConclusionsResults highlight important sex differences in patterns and predictors of change in alcohol consumption and dependence risk among post-9/11 Veterans. Findings are discussed in relation to screening for hazardous alcohol use and intervention strategies in this at-risk population.

Individual Differences in Growth and in Accumulation of Secondary Metabolites in Rhodiola rosea Cultivated in Western Siberia.

In this study, growth parameters of underground parts and concentrations of phenylpropanoids, phenylethanoids, flavonoids, hydroxybenzoic acids, and catechins in aqueous-ethanol extracts of 6-year-old cultivated plants of Rhodiola rosea (propagated in vitro) of Altai Mountain origin were analyzed, and differences in chemical composition among plant specimens and between plant parts (rhizome and root) were evaluated. High-performance liquid chromatography detected 13 phenolic compounds. Roots contained 1.28 times higher phenylethanoids levels (1273.72 mg/100 g) than rhizomes did. Overall, the concentration of phenylethanoids in underground organs was not high and ranged from 21.36 to 103.00 mg/100 g. High variation among R. rosea individual plants was noted both in growth characteristics and in levels of secondary metabolites under our cultivation conditions. It was found that concentrations of phenylpropanoids, phenylethanoids, and catechins significantly depend on the plant part analyzed (p ≤ 0.05). Specimen No. 4 is characterized by the highest concentration of rosavins (1230.99 mg/plant) and the lowest concentration of cinnamyl alcohol (62.87 mg/plant). Despite the wide range of values, all 10 tested specimens (underground part) met the minimum requirements of the United States Pharmacopeia (2015) for rosavins (0.3%) and of the Russia State Pharmacopoeia (2015) for the average level of rosavins (roots): (1%).

Development of a feeding simulation to evaluate how feeding distribution in aquaculture affects individual differences in growth based on the fish schooling behavioral model.

In this study, we developed a feeding simulation using the fish schooling behavior model to evaluate growth differences from the feeding spatial distribution. In the proposed simulation, feeding behavior was modeled using the fish schooling model to simulate the amount of feed consumed by each individual. Next, body mass growth was calculated based on the amount of feed consumed. A 3.0-m diameter aquaculture tank was used for the simulation. We used three feeding methods to evaluate how feeding distribution affected growth: Feeding A, B, and C. The feed was distributed in a square pattern with one side length of 1.5, 1.0, or 0.5 m for Feeding A, B, and C groups, respectively. The results revealed that individual differences in body mass resulting from each feeding method differed greatly. The individual difference was largest in the Feeding C group. Here, maximum swimming speed was assumed to be proportional to total length. The feeding area of Feeding C was narrow; therefore, the first individual to arrive in the feeding area dominated the feed. Large individuals accessed the feed more easily than did small individuals. Consequently, the growth of large individuals became more rapid, and the individual differences became large in Feeding C. A rearing test can be conducted in a short time, and the optimal aquaculture operation was easily determined using the proposed simulation method. We concluded that the proposed simulation is useful as a decision-making tool for aquaculture management.

Study on the Dynamics of Stem Sap Flow in Minqin Wind and Sand Control Haloxylon ammodendron Forest, China

In this study, we obtained real-time data on the stem fluid flow of Haloxylon ammodendron in the growing season in Minqin, China, based on thermal diffusion (TDP) monitoring technology, and analyzed the dynamic changes of stem fluid flow in it to provide important supporting evidence for understanding the water consumption of H. ammodendron during its growth. The results indicate that the fluid flow in the stem of the H. ammodendron increases with increasing growth age and also decreases as the H. ammodendron grows older and declines. The average daily sap flow rates of H. ammodendron stems were 0.956, 1.059, 1.460 and 0.570 cm3·(cm2·h)−1 at 5, 10, 15 and 20 years, respectively, and the cumulative sap flow masses during the growing season from May to October were 610.173, 423.386, 1041.186 and 430.212 kg, respectively. H. ammodendron stem sap flow increases with the thickening of H. ammodendron’s ground diameter. The average daily sap flow rate of H. ammodendron stems at different stem levels ranged from 0.276 to 2.132 cm3·(cm2·h)−1, and the cumulative sap flow mass during the growing season ranged from 121.656 to 1722.810 kg. The larger the diameter of the H. ammodendron at different forest ages, the earlier the sap flow initiation time and the higher the peak. The stem flow initiation time was 7:00–8:00, and the average daily maximum fluid flow rate was 2.493–5.536 cm3·(cm2·h)−1, with the peak occurrence time advancing with age. The sap flow variation of H. ammodendron at different stand ages reflects the water-consuming process of H. ammodendron growth and its response to a drought environment, while the sap flow variation of H. ammodendron at different diameter classes shows that the individual growth differences of H. ammodendron also yield obvious competitive advantages. The results of the analysis can provide theoretical support for the estimation of ecological water use in desert H. ammodendron sand-fixing forests.

Historic, pre-stock enhancement, demographic conditions of exploited populations of dusky flathead, Platycephalus fuscus, in eastern Australia

Responsible stock enhancement initiatives require baseline data of wild population demographic conditions that can be used in testing management outcomes. This study provides the first fishery-independent assessment of length- and age-based biological characteristics of exploited populations of Platycephalus fuscus in eastern Australia prior to stock enhancement. Sampling was conducted over seven estuaries spanning seven degrees of latitude and the geographical range of proposed stock enhancements. Populations in all estuaries showed evidence of length and age truncation, especially those subject to commercial fisheries where young individuals of both sexes dominated populations. Maximum longevities were 12 and 11 years for females and males respectively, but few females >5 years and males >3 years were generally sampled. Females dominated populations, and on average, the mean lengths and ages of females were greater than males within each estuary and across all age classes. Sexually dimorphic variation in growth was evident across all estuaries, with females attaining greater maximum lengths than males. Estuary-specific differences in individual growth were not identified. On average, over 50% of females sampled in each estuary were > the minimum legal length (MLL), but the opposite was evident for males. In contrast, over 25% of males in each estuary were > the mean length at maturity (L50), whereas in all but one estuary <13% of the females were > the L50. Stocked male and female P. fuscus should recruit to the fishery in 2 and 3 years, and contribute to the spawning stock in 1.5 and 4.5 years, respectively. This study provides important historical baseline data that can contribute to testing stock enhancement outcomes on populations.

Stable individual differences in the frequency of chin‐marking behavior across development in the domestic rabbit

AbstractIndividual differences in behavior (“personality”) are of considerable interest to behavioral biologists. Important questions include how early in life such differences emerge, what factors influence their emergence, and whether they remain stable across development and into adult life. Given the demanding nature of longitudinal studies, there is a lack of information regarding these questions in mammals. Our aim in this study was to investigate the development of individual differences in chin‐marking behavior (chinning) in the domestic rabbit, a notable part of this species’ system of chemical communication, and to relate this to individual differences in growth and behavior among littermates during the early postnatal period. We tested repeatedly the frequency of chinning movements from weaning to sexual maturity in 63 chinchilla‐strain rabbits (35 females, 28 males) from 14 litters. Within litters, we found significant consistencies over time in this behavior, that is, in both sexes inter‐individual differences among litter siblings in the frequency of chinning movements remained stable across the postweaning period until sexual maturity. Unexpectedly, however, we found no significant associations with the morphological, physiological, or behavioral variables known to form a well‐correlated early developmental complex in this species. We tentatively conclude that in the rabbit, individual differences in the frequency of chinning have little relation to other previously studied aspects of individual developmental trajectories. The origin and functional significance of individual differences in chinning frequency, whether in reproductive or other social contexts is largely unknown and requires further investigation.

Comparative analysis of intestinal microbiota of discus fish (Symphysodon haraldi) with different growth rates

Discus fish (Symphysodon haraldi) is an important ornamental species. There are significant individual growth differences in the same batch of fry under the same feeding conditions. Such differences can greatly influence the efficiency and profitability of discus farming. Gut microbiota plays an important role in fish nutrition metabolism and growth. Studies on the relationship between intestinal microbiota and growth rates are scarce to the present. Here, we investigated the community diversity and function of intestinal microbiota of juvenile and adult discus from the same parents but with different growth speeds under the same conditions. The results showed that, for juvenile (40 days post-hatch (DPH)) and adult (270 DPH) discus, the OTUs (856 vs. 657 and 1408 vs. 1222, respectively) of bacterial community of the slow-growing discus were both higher than those of the fast-growing ones. No significant differences in microbial community diversity between fast- and slow-growing juveniles or adults were observed. However, for 40 DPH discus, relatively higher content of Plesiomonas (2.53% vs. 0.6%) was observed in the intestines of slow-growing juveniles while relatively higher levels of Bacillus (2.95% vs. 1.83%) and Lactococcus (0.86% vs. 0%) were found in those of fast-growing ones. For 270 DPH discus, relatively higher content of Enterococcus (5.62% vs. 0%) was observed in the intestines of slow-growing adults but relatively higher level of Lactococcus (7.06% vs. 1.27%) was found in those of fast-growing ones. Although no significant divergences in bacterial communities and in functional profiles between fast- and slow-growing juveniles or adults were observed, the bacterial species (e.g., Bacillus and Lactococcus) mentioned above might account for discus distinct growth performance.

Childhood Cognitive Flexibility and Externalizing and Internalizing Behavior Problems: Examination of Prospective Bidirectional Associations.

The goal of this study was to examine reciprocal associations between cognitive flexibility and externalizing and internalizing behavior problems longitudinally using data on four occasions from kindergarten through first grade and test for potential gender differences in these associations. The Dimensional Change Card Sort task was used to assess children's cognitive flexibility as a measure of executive function. Participants were 12,462 kindergarteners (49% female) from the Early Childhood Longitudinal Study (ECLS-K: 2011). Results from multivariate latent curve models with structured residuals revealed that children's cognitive flexibility at the beginning of kindergarten was not associated with their growth in either externalizing (r = -0.01, p = .174), or internalizing (r = -0.03, p = .403) problems between kindergarten and the end of first grade. However, after controlling for individual differences in growth, cognitive flexibility at each assessment directly contributed to subsequent lower levels of internalizing (but not externalizing) behavior problems at the next assessment (b = -0.004, p = 0.013; β = -0.03), suggesting that children who are more flexible in switching from one activity to another may be less prone to developing internalizing problems. At kindergarten entry boys had lower levels of cognitive flexibility (b = -0.31, p < .001, β = -.12) and higher levels of externalizing (b = 0.25, p < .001, β = .23), and internalizing problems(b = 0.04, p = 001, β = .05) compared to girls, but did not differ from girls in their rates of change in cognitive flexibility and externalizing or internalizing behavior problems.

Timing of oviposition influences the effects of a non-native grass on amphibian development.

Land-use change can alter the energy dynamics in aquatic systems by changing the subsidies that form the nutrient base within them. However, experimental evaluations of subsidy change often fail to consider how effects, such as differences in individual growth and survival, may differ under varying ecological contexts experienced in the field. We used a mesocosm approach to investigate how litter (Native Prairie or Non-Native Tall-Fescue Grass) surrounding wetlands and timing of oviposition affected larval amphibian development. We found that survival differed between litter types in the Early-Oviposition treatment, with nearly 100% mortality in Fescue treatments. Conversely, survival was similar across litter types in the Late Oviposition treatment (~ 43%), and larvae in Late-Fescue treatments metamorphosed more quickly and were larger post-metamorphosis than larvae in Prairie treatments. Follow-up experiments confirmed that low dissolved oxygen (DO) was responsible for high mortality in Early-Fescue treatments; high quantities of Fescue resulted in a microbial bloom that reduced DO to < 2mg/L for several days, resulting in low hatching success. This effect was eliminated in treatments with supplemental aeration. Finally, we confirmed that experimentally observed DO patterns also occurred in the field. Context (i.e., timing of inundation relative to amphibian breeding) is critical to understanding the effects of subsidies on amphibian populations; early and explosively breeding species may experience catastrophic mortality due to DO depletion; whereas, species that breed later may experience enhanced fitness of recruits. Considering the effects of non-native species across different ecological contexts is necessary for elucidating the extent of their impacts.

Regional and stock-specific differences in contemporary growth of Baltic cod revealed through tag-recapture data

Abstract The use of growth estimation methods that depend on unreliable age data has previously hindered the quantification of perceived differences in growth rates between the two cod stocks inhabiting the Baltic Sea. Data from cod tagged in different regions of the Baltic Sea during 2007–2019 were combined, and general linear models were fit to investigate inter-regional (defined as area of release) and inter-stock (assigned to a subset of recaptures using genetic and otolith shape analyses) differences in individual growth. An average-sized cod (364 mm) caught in the western Baltic Sea and assigned to the western Baltic cod stock grew at more than double the rate (145 mm year−1) on average than a cod of the same size caught in the eastern Baltic Sea and assigned to the eastern Baltic cod stock (58 mm year−1), highlighting the current poor conditions for the growth of cod in the eastern Baltic Sea. The regional differences in growth rate were more than twice as large (63 mm year−1) as the stock differences (24 mm year−1). Although the relative importance of environmental and genetic factors cannot be fully resolved through this study, these results suggest that environmental experience may contribute to growth differences between Baltic cod stocks.

Investigating down-shore migration effects on individual growth and reproduction of the ecosystem engineer Arenicola marina

Abstract Arenicola marina (Annelida Polychaeta) is a harvested ecosystem engineer inhabiting galleries within soft-sediment foreshores from the Mediterranean to the Arctic. It displays a typical distribution pattern on most foreshores, with the juveniles inhabiting the mediolittoral shore and migrating to the infralittoral shore while growing. In this study, we have characterized the shore migrations of a temperate population of A. marina and estimated its potential individual growth and reproduction under different migration scenarios using a Dynamic Energy Budget model. A sand temperature model was developed in order to predict the temperature experienced by lugworms according to the depth of their galleries and their bathymetric level. The food availability and the associated scaled functional response were estimated from in situ growth data and associated nitrogen content and chlorophyll-a concentration (Chla) data. The metabolic response of lugworms to temperature (temperature tolerance range, related Arrhenius temperatures) was assessed from literature data. The sand temperature model outputs did not explain alone spatial differences in individual growth and reproduction. However, an increase of food availability with bathymetry, with Chla as a proxy, well explained growth and reproduction. For now, the temperature hypothesis is discarded but other factors (desiccation or hypoxia) should be considered in future studies.

The effect of nutritional condition by two nucleic acid derived indices on the growth to post-flexion of Atlantic bluefin tuna and Atlantic bonito larvae

Notochord flexion increases the swimming capacity of fish larvae, aids in the capture of mobile prey, and coincides with the timing of when the physiological capacities of larvae begin to develop significantly, allowing an early shift to piscivory. Therefore, reaching the flexion stage as soon as possible can be considered beneficial for the growth and survival of the larvae. Individual growth differences of larvae from the same cohort are very common before reaching flexion and the potential explanation is still unknown. In this study, we examined if the nutritional status of the larvae, measured by the RNA:DNA and DNA:DW ratios, explains the differences in the development of notochord flexion in laboratory-reared Atlantic bluefin tuna (ABFT; Thunnus thynnus) and Atlantic bonito (AB; Sarda sarda) larvae. Moreover, we described the ontogeny of the different stages and condition indices. The daily average condition of ABFT estimated by the RNA:DNA and DNA:DW ratios increased with larval age and developmental stage, whereas in AB it was not. In both species, bigger larvae at a specific age had higher nutritional condition than smaller larvae regardless of developmental stage. However, in ABFT the DNA:DW ratio indicated lower condition for the biggest larvae within developmental stages F0 (pre-flexion) and F3 (post-flexion). After removing the size effect, larger individuals of ABFT within flexion stages F1 and F2 had higher condition than any other larval stages, whereas in AB an indistinct trend within stages was found. Our results confirm that in ABFT the RNA:DNA ratio is correlated with faster development while the DNA:DW ratio is negatively correlated with the time to flexion. The trends found in the DNA:DW ratio points at cell growth mechanisms being a better indicator of larval condition that the RNA:DNA ratio. Our findings suggest that under culture, ad libitum conditions, larval nutritional conditions measured by nucleic acid ratios, might not be enough to explain developmental differences in fast growing species.

Early performance of two tropical dry forest species after assisted migration to pine–oak forests at different altitudes: strategic response to climate change

Assisted migration has been proposed as a strategy for adaptive management of forest species in response to expected effects of climate change, but it is controversial for several reasons. Tropical dry forests are among the most threatened ecosystems in the world. In Mexico, historically, land-use change and deforestation have been decreasing forest cover, and climate change is shifting the potential distribution of different forest types, exacerbating the risk of local extinctions. Assisted altitudinal migration could be a feasible strategy for reducing local extinctions in response to climate change and lack of landscape connectivity. Our objective was to evaluate survival and growth of Albizia plurijuga and Ceiba aesculifolia, two tropical deciduous forests species in Mexico. We transplanted 4-month-old seedlings to experimental raised beds at three altitudes (2100, 2400 and 2700 m a.s.l.), exceeding their upper regional limit of distribution (2000 m a.s.l.). We also tested seed germination at each altitude. We monitored the experiment for 10 months. For both species, as altitude increased and cold weather was more prevalent, plant performance declined. Within species, differences in individual growth were significant among altitudes. Overall survival was 18.5% for A. plurijuga and 24.5% for C. aesculifolia. Both species had higher survival and better growth at lower altitude, and no seedling emergence at any altitude. We conclude that assisted migration can be implemented for each species by an upward attitudinal shift within, and not exceeding, 400 m beyond their present upper altitudinal limit of distribution. Our results indicate that for many species that show altitudinal gradients at regional scales, unless current climate conditions change, the potential to establish outside their range is minimal.

STUDY ON EXTRACTION METHODOLOGY OF RICE GROWTH CHARACTERISTICS IN FIELD USING TERRESTRIAL LASER MEASUREMENT DATA

Abstract. Smart agriculture is recommended for labor-saving, refinement and high quality production of rice cultivation with safety and security. The Terrestrial laser measurement has the advantage of acquiring 3D point cloud information with high accuracy and high density, but there is a disadvantage that it becomes difficult to measure the base of rice plant when paddy rice grew. In this study, the 3D point cloud information obtained by terrestrial laser measurement was used to three-dimensionally measure the growth state in the field corresponding to the growing period in time series. The growth characteristics of the whole field as a community were extracted as a representative value of mean growth. Then we attempted extraction of individual differences in growth and growth unevenness, as the deviation from the mean value of the field in terms of the growth characteristics of each strain focused on the individual plants. it is difficult to observe the root of the rice during the growing period, it was used for analyzing the growth quantity as the growth difference height for each growing period by obtaining the difference of the elevation value of the rice at the early stage of growth and at each stage of growing. The spatial variation in the growth quantity of the whole field area and the local area was calculated, the range of the deviation for evaluating the mean variation and the growth abnormality was examined, and the setting of the threshold for evaluating the growth normal and abnormality was examined.

Oxytocin and the emergence of individual differences in the social regulation of stress

AbstractThe ability to use social support to regulate stress is critical to mental and physical health. Here, we posit that the oxytocin system contributes to the variability in individual responses to social support. We first review the evidence that oxytocin is related to both social functioning and stress regulation. We focus on results from molecular genetics suggesting that individual variations in both of these functions are associated with natural variations in the oxytocin receptor gene (OXTR). We then describe research that exploits this natural variation to directly and experimentally test relationships between the oxytocin system, social support, and stress regulation in both infants and adults. On the basis of our findings, we propose a novel theoretical model of how biological processes might interact with psychological beliefs about relationships—even in infants—to affect long‐term patterns of social regulation of stress.

Predicting academic achievement growth among low-income Mexican American learners using dynamic and static assessments

Dynamic assessment methods, initially developed by Feuerstein in the 1970s, have been recommended as being more equitable for identifying the academic abilities of students who may not perform well on traditional assessments due to these learners' cultural, linguistic, or economic differences from the population for whom the traditional measures were developed. In this exploratory study we examined seven years' follow-up performance on a state proficiency test to determine the extent to which dynamic and static measures administered in second grade predicted academic growth among a low-income population of students of Mexican American heritage. Based on a series of multilevel models, we concluded that neither the dynamic nor static test performance was a statistically significant predictor of individual differences in growth, though confidence intervals are suggestive that a larger sample with more power might identify such a relationship. We discuss findings in the context of identification for gifted education programming.

Early development and the emergence of individual differences in behavior among littermates of wild rabbit pups

The ontogeny of associated individual differences in behavior and physiology during early postnatal life, and in particular the emergence of such differences among litter siblings, has been hardly explored in mammals under natural conditions. We studied such within-litter differences in behavior in European rabbit pups Oryctolagus cuniculus prior to weaning, and whether and how these differences co-varied with other individual characteristics such as postnatal body temperature and early growth. The study was conducted under semi-natural conditions in a colony of rabbits of wild origin, where the young were born and developed in nursery burrows. We equipped two siblings per litter with interscapular skin temperature loggers on postnatal day 2 and recorded temperature profiles for 48h. Individual body (skin) temperatures of pups within litters were repeatable across time, indicating the existence of consistent individual differences. Such differences within litters were associated with relative differences in pre-weaning growth, revealing that relatively warmer pups showed a greater increase in body mass during the nest period. Between postnatal days 12 and 17, after the pups had reached a developmental stage of greater mobility, we carried out different behavioral tests: a handling-restraint test, an open field test and a jump-down test from a platform. Individual responses in the former two tests were associated, as those pups showing a quicker struggling response to restraint during handling also exhibited greater exploratory activity in the open field. This correlation across contexts suggests the existence of personality types in wild rabbits at an early developmental stage. Furthermore, pups' behavioral responses were strongly associated with their relative within-litter body mass at testing. Animals with a lower body mass compared to their siblings showed a relatively quicker struggle response to handling restraint and covered a relatively larger distance in the open field, suggesting greater reactivity and responsiveness of relatively lighter pups in these tests. In contrast, relatively heavier pups jumped sooner from the platform, which may have been due to their greater physical maturation. In conclusion, our study shows that individual differences in behavior and associated differences in body temperature and growth are already present during early postnatal life, although such relationships can be easily overlooked, as they predominantly emerge as relative differences among littermates.

Growth, Maturation and Exercise During Youth-2016.

For The Year that Was-2016, I have selected three papers in the area of growth, maturation, and exercise during youth. The year of 2016 was a successful year and it was not an easy task to highlight the most significant publications in this specific area of pediatric exercise science. The first paper has been chosen because it provides, for the first time, the growth and maturational status of elite junior tennis players belonging to the top eight players in the National rankings in various ages and compares against population norms. It appeared that individual differences in growth and maturation contribute towards the selection of elite junior tennis players in both sexes, with a bias towards these athletes who are comparatively tall and heavy for their age already in younger ages. The second paper is a methodological paper and was selected because it provides a unique perspective on the use of different tracking coefficients to investigate short-term tracking of cardiorespiratory and performance-related physical fitness among adolescents during growth and maturation. Specifically, three distinct statistical approaches were applied in this paper: auto-correlations, mulitilevel modeling corrected tracking values for time-varying covariates and Cohen`s Kappa in order to identify group and individual tracking as well as individuals whose trajectories are unstable across time. This methodological paper demonstrated the importance of the selection of the statistical approach to monitor and describe short-term tracking of cardiorespiratory and performance-related physical fitness variables in adolescents during growth and maturation. The third selected paper provided some evidence that the consequence of physical activity during childhood can be far reaching as physical activity might not only promote health benefits but also have positive effects on adulthood earnings.

Variation in growth of Damaraland mole-rats is explained by competition rather than by functional specialization for different tasks.

In some eusocial insect societies, adaptation to the division of labour results in multimodal size variation among workers. It has been suggested that variation in size and growth among non-breeders in naked and Damaraland mole-rats may similarly reflect functional divergence associated with different cooperative tasks. However, it is unclear whether individual growth rates are multimodally distributed (as would be expected if variation in growth is associated with specialization for different tasks) or whether variation in growth is unimodally distributed, and is related to differences in the social and physical environment (as would be predicted if there are individual differences in growth but no discrete differences in developmental pathways). Here, we show that growth trajectories of non-breeding Damaraland mole-rats vary widely, and that their distribution is unimodal, contrary to the suggestion that variation in growth is the result of differentiation into discrete castes. Though there is no evidence of discrete variation in growth, social factors appear to exert important effects on growth rates and age-specific size, which are both reduced in large social groups.