Individual Differences In Growth Rates Research Articles

Developmental trajectories for literacy and math skills from primary to secondary school

BackgroundResearch on academic development has mainly focused on early time periods with less attention on individual differences in development in the later school years.MethodsTo improve our knowledge of how students develop academically during later school years, this study used a multivariate growth model to investigate the developmental trajectories of literacy and math skills in a sample of Australian students in fifth through ninth grades (n = 114).ResultsStudents progressed at greater average rates in math from primary to secondary school than in literacy. Both literacy and math skills showed significant individual differences in growth rate at Grade 9. There was no evidence of an association between change in math and change in literacy. Primary school socioeconomic status was not a statistically significant predictor of inter‐individual differences in the development of either literacy or math.ConclusionsThese results, taken together, suggest that both domain‐general and domain‐specific influences act on the development of these academic skills.HighlightsWhat is already known about this topic We know that developmental trajectories for literacy and math skills demonstrate considerable inter‐individual variation in the early school years. The Integrated Intelligent Architecture model, a cognitive model that incorporates procedural knowledge and planning behaviour with the construction–integration process, suggests that these inter‐individual differences will persist into later school years. The developmental trajectories of literacy and math skills are inter‐related and are likely influenced by both domain‐general and, to a lesser degree, domain‐specific factors. There is substantial evidence that socioeconomic status acts as a domain‐general predictor of individual differences in school achievement over time. What this paper adds Much of the research to date has focused on early developmental time periods with less attention devoted to individual differences in development in the later school years. Less is known about developmental trajectories of writing. This study helps to fill these gaps by using a multivariate framework focused on the core academic outcomes of literacy and math to examine individual differences in development during the later school grades. By examining whether development in literacy is associated with development in math, or whether developmental trajectories unfold independently of each other, we can provide evidence for domain‐specific or domain‐general influences on academic development. SES was included as a potential domain‐general predictor in the model. Implications for theory, policy or practice Our results suggested that continued knowledge‐integration processes may underlie literacy and math ability in ninth grade. Additionally, this study provided evidence for domain‐general and domain‐specific influences on the development of academic skills from primary to secondary school. SES was not a significant domain‐general predictor, suggesting that other domain‐general predictors should be considered.

Defining and evaluating stability in early years assessment

ABSTRACT Stability is an important underlying assumption in any form of assessment-supported decision-making. Since early years development is frequently described as unstable, the concept plays a central role in the discussion surrounding early years assessment. This paper describes stability as a set of assumptions about the way individual scores change over time. Here, an analytical framework developed by Tisak and Meredith, which can be used to evaluate these assumptions, is extended and applied to evaluate the stability of mathematics scores of 1402 children between kindergarten and third grade. Multilevel models are used to evaluate the assumption that each child has a unique individual growth rate, as well as the assumption that the ranking of children’s test scores is consistent over time. The results show that for a large proportion of the children, assuming unique individual growth rates leads to similar predictions as assuming that children develop at an equal pace. While individual differences in growth rate may provide relevant information, these differences only become apparent after several test administrations. As such, decisions should not be based on perceived stagnated or accelerated growth over a short period.

Individual variability in the settlement of juvenile green turtles in the western South Atlantic Ocean: relevance of currents and somatic growth rate

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 614:173-182 (2019) - DOI: https://doi.org/10.3354/meps12909 Individual variability in the settlement of juvenile green turtles in the western South Atlantic Ocean: relevance of currents and somatic growth rate Patricia Campos, Luis Cardona* IRBio and Department of Evolutionary Biology, Ecology and Environmental Science, Faculty of Biology, University of Barcelona, Avenida Diagonal 643, 08028 Barcelona, Spain *Corresponding author: luis.cardona@ub.edu ABSTRACT: The settlement of demersal animals is influenced both by physical processes ruling the distribution of pelagic juveniles in the open ocean and by their active selection of suitable benthic habitats. Green turtles Chelonia mydas inhabiting the coastal areas of the western South Atlantic Ocean derive primarily from the rookery at Ascension Island and settle over a huge area spanning from northern Brazil to Uruguay. Here, we analysed the stable C and N isotope ratios in 30 µm of carapace layers from juvenile green turtles collected from 2 distinct areas of Brazil (Praia do Forte, 12°38’S, 38°05’W, and Ubatuba, 23°26’S, 45°05’W), with the goal of reconstructing their individual diets and habitat use patterns. Juvenile neritic green turtles from Praia do Forte usually had herbivorous diets, with limited individual variability and few temporal changes in diet or habitat. Conversely, most juvenile green turtles from Ubatuba had omnivorous diets, although they exhibited high levels of individual and temporal variability. These contrasting patterns could be linked to less abundant and predictable food availability in subtropical Ubatuba compared to tropical Praia do Forte. It is unknown why large numbers of juvenile green turtles bypass foraging grounds in north-eastern Brazil to settle in subtropical or warm temperate areas, although it may be related to individual differences in growth rate and their size being too small when reaching Brazil from Ascension Island. KEY WORDS: Juvenile turtles · Chelonia mydas · Settlement · Developmental habitat · Stable isotopes Full text in pdf format PreviousNextCite this article as: Campos P, Cardona L (2019) Individual variability in the settlement of juvenile green turtles in the western South Atlantic Ocean: relevance of currents and somatic growth rate. Mar Ecol Prog Ser 614:173-182. https://doi.org/10.3354/meps12909 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 614. Online publication date: April 04, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Stable isotope profiling for large-scale evaluation of feed efficiency in Atlantic salmon (Salmo salar )

In growing animals, individual variation in feed efficiency may arise from individual differences in growth rate and protein metabolism. Over a period of time, these factors will affect the ratio between ‘new’ vs. ‘old’ protein, which can be quantified using isotope profiling. The aim of this study was to investigate the relationship between relative weight gain and atom percentage excess 15N in the muscle, liver and mid-intestine. A 50-day experiment was conducted with a total of 375 fish initially fed a standard diet, subsequently replaced by one out of five experimental diets, enriched with 15N. In general, fast-growing fish are expected to have a better feed efficiency, and the results show that this is captured by isotope profiling in liver and muscle tissues. Furthermore, individual variation in isotope content, that is relative fraction of ‘new’ protein, among fish with comparable growth rates was observed, most expressed around ~50% isotope saturation, indicating differences in protein degradation and replacement not attributed to growth. The results suggest that isotope profiles can be used as individual indicator traits for feed efficiency and that inclusion levels of stable isotopes of 1%–2% gave the most reliable results.

Evaluation of growth-dependent survival during early stages of Pacific bluefin tuna using otolith microstructure analysis

The present study used otolith analysis-based body size back-calculation to: (1) evaluate the hypothesis of growth-dependent survival in young Pacific bluefin tuna (PBF; Thunnus orientalis) from the north-western Pacific Ocean; (2) identify critical developmental stages for survival; and (3) compare interannual differences in early growth. To this end, we compared the daily growth trajectories of a large number of larvae (standard length (SL) <15mm), juveniles (15≤SL≤150mm), and young-of-year (YOY; SL >150mm) collected between 2011 and 2015. Otolith radius and SL were highly correlated and yielded a single relationship applicable for the five year-classes. Body size back-calculation showed that only larvae with fast, steady growth successfully transitioned to the juvenile stage. The ontogenetic analysis of daily growth rates revealed interannual differences only in larvae, and not in the larval stage of juveniles and YOY. Neither sudden decreases nor increases in growth rates were observed during the larval stage of any of the stages, suggesting that the observed variability in larval body size may be the result of individual differences in growth rates rather than of drastic, one-time events. Overall, the results of the present study indicate that growth-dependent survival of larvae may be the most critical for PBF recruitment.

Whisker growth in wild Eurasian badgers Meles meles: implications for stable isotope and bait marking studies

The use of biomarkers such as stable isotopes to study the foraging ecology and movement of animals is a rapidly expanding area of research. With respect to mammals, the analysis of inert keratinous tissue such as whiskers (vibrissae) is particularly attractive as they can be sequentially sampled to provide a long-term time series of individual movement or diet. However, in order to interpret data from such tissues researchers require details of growth rates and patterns, and also how these vary within populations. In this study, we use the fluorescent biomarker Rhodamine B to measure vibrissa growth rate and patterns in a wild population of Eurasian badgers. In addition, we compare stable isotope ratio values of blood and vibrissae in order to test whether vibrissae are retained for long periods following growth. We found that badger vibrissae grow at an average rate of 0.43 mm day−1 (range 0.23–0.83) such that single vibrissae sampled for stable isotope analysis contain an average of 104 days of ecological data. Age, sex and body condition did not affect growth rate, and there was no evidence of consistent individual differences in growth rate or long-term retention of vibrissae following growth. However, variation in growth rate within the population suggest that the temporal scales reflected in vibrissae may vary both between and within individuals, such that results are not always directly, temporally comparable. This research provides useful information for any future research using vibrissae in combination with biomarkers to study mammalian ecology.

Does growth rate in oral reading fluency matter in predicting reading comprehension achievement?

In this study, we examined the relationship of growth trajectories of oral reading fluency, vocabulary, phonological awareness, letter-naming fluency, and nonsense word reading fluency from 1st grade to 3rd grade with reading comprehension in 1st, 2nd, and 3rd grades. Data from 12,536 children who were followed from kindergarten to 3rd grade longitudinally were used. These children were administered Dynamic Indicators of Basic Early Literacy Skills subtests, Peabody Picture Vocabulary Test-Third Edition, and reading comprehension (Stanford Achievement Test, 10th ed.) tasks multiple times in each year. Students' initial status and rate of growth in each predictor within each grade were estimated using individual growth modeling. These estimates were then used as predictors in dominance regression analyses to examine relative contributions that the predictors made to the outcome: reading comprehension. Among the 1st-grade predictors, individual differences in growth rate in oral reading fluency in 1st grade, followed by vocabulary skills and the autoregressive effect of reading comprehension, made the most contribution to reading comprehension in 3rd grade. Among the 2nd- and 3rd-grade predictors, children's initial status in oral reading fluency had the strongest relationships with their reading comprehension skills in 3rd grade.

A Time Varying Evaluation of Identity Theory and Father Involvement for Full Custody, Shared Custody, and No Custody Divorced Fathers

This study tested identity theory models of father involvement for 230 divorced fathers of young children aged 4 to 11 followed over 18 months. Research questions were (1) Do measures of identity salience and centrality of the fathering role predict fathering involvement over time? (2) Does father involvement predict fathering identity over time? (3) Does father custody moderate these relationships? Involvement was assessed as contact frequency, number of father-child activities, and positive involvement observed during father-child interaction. Comparisons showed that the quantity of involvement differed by custody but there were few differences in the quality of involvement. Fathers did not exhibit significant mean decreases in involvement and custodial groups did not differ in the growth rates for involvement nor identity measures. However, there were significant individual differences in growth rates, meaning there was variance in fathers increasing and decreasing in measures over time. Time 1 father identities, measured as salience and centrality, predicted days per month, overnights per month, and father child activities over time. Time-varying predictors suggested that identities were more predictive of growth in involvement than vice versa although father involvement predicted salience and primarily centrality. Implications for practice and future research are discussed.

The relationship between growth, brain asymmetry and behavioural lateralization in a cichlid fish

Cerebral lateralization, the partitioning of cognitive tasks to one cerebral hemisphere, is a widespread phenomenon among vertebrates. Despite this diversity, every species studied to date shows substantial individual variation in the strength of lateralization. The neural basis of this trait is unclear, although asymmetries in cerebral structures have been investigated for over a century. The habenular nuclei, for example, have been shown to present striking neuroanatomical and/or neurochemical asymmetries in species ranging from jawless fish to mammals. In teleost fish, these nuclei are relatively symmetrical in most species. Those teleosts that do have asymmetrical habenular nuclei, show varying patterns of asymmetry in different species. Here we investigate the relationship between individual variation of asymmetry in the habenula of a South American cichlid fish, Geophagus brasiliensis, and behaviour in a commonly used test for visual laterality in fish, the detour task. We show that the strength of asymmetry in the habenula is correlated with strength of behavioural lateralization in the detour task. Both the strength and direction of habenular asymmetry are correlated with individual differences in growth rate. We suggest that this relationship results from processes linking growth rate and sexual differentiation to frequency-dependent variation in life-history strategies. To our knowledge, this is the first study to demonstrate a relationship at the individual level between neural asymmetry and lateralized behaviour in a fish.

Growth‐mortality tradeoffs and ‘personality traits’ in animals

Consistent individual differences in boldness, reactivity, aggressiveness, and other 'personality traits' in animals are stable within individuals but vary across individuals, for reasons which are currently obscure. Here, I suggest that consistent individual differences in growth rates encourage consistent individual differences in behavior patterns that contribute to growth-mortality tradeoffs. This hypothesis predicts that behavior patterns that increase both growth and mortality rates (e.g. foraging under predation risk, aggressive defense of feeding territories) will be positively correlated with one another across individuals, that selection for high growth rates will increase mean levels of potentially risky behavior across populations, and that within populations, faster-growing individuals will take more risks in foraging contexts than slower-growing individuals. Tentative empirical support for these predictions suggests that a growth-mortality perspective may help explain some of the consistent individual differences in behavioral traits that have been reported in fish, amphibians, reptiles, and other animals with indeterminate growth.

Oxygen consumption of newly settled summer flounder, Paralichthys dentatus (Linnaeus, 1766)

The timing of larval metamorphosis in summer flounder, Paralichthys dentatus, from the same cohort (i.e., siblings with the same parents) and among cohorts (different parents) is variable due to large differences in individual growth rates. In an effort to understand the energetic basis for growth rate differences, rates of routine (RR) and specific dynamic action (RSDA) respiration (μg O2/fish/h) were measured in groups of newly metamorphosed summer flounder and compared among fish of different sizes (15, 20, 25 and 30 mm total length, TL) and between fast- and slow-growing fish from five cohorts each having a different set of parents. Although rates of RR significantly increased with increasing fish size (RR=3.02±1.04 DM0.88±0.12, they were not significantly different between the fastest and slowest growing fish within a cohort. Respiration rates rapidly increased during feeding and the mean±SD peak RSDA was 1.91±1.29·RR. The mean±SD energy loss due to RSDA was 15.6±11.5% of the ingested prey energy. Differences in RSDA were noted among fish of different sizes and between fast- and slow-growing fish. However, the results of this study suggest that the energetic basis for growth differences among summer flounder appears to result from processes related to energy intake (e.g., food consumption) rather than those related to routine or feeding energy loss.

Associations between first encounters and ensuing social relations within dyads of two species of lacertid lizards

Researchers often presume that dominant individuals, during an initial series of social interactions, ultimately gain possession of the territory, but detailed studies of the process of social relation establishment in animals are rare. We used an experimental approach on pairs of conspecific newborns of two lizard species (Podarcis sicula and P. melisellensis) to examine whether the outcomes of first encounters are consistent with the formation of social relations during the ensuing three weeks. A major objective was to determine whether social relations expressed during prolonged cohabitation induced divergence of individual growth rates within a dyad. Moreover, we explored to what extent individual differences in growth rate and behavior during social cohabitation paralleled differences expressed when the animals were housed in isolation. Differential expression of behavior within dyads was examined by calculating the difference between values for the two individual lizards. During brief first encounters, access to a localized basking site was determined by agonistic interactions between lizards. Cohabitation of two lizards during prolonged encounters resulted in differences in their thermal microhabitat usage, which in turn induced divergence of their growth rates. The direction and magnitude of the differences in thermal microhabitat use and the divergence in growth rates during prolonged encounters mirrored differences in the interactions exhibited during the first encounter. Moreover, differences between two lizards in initial social interactions, and in thermal microhabitat use and growth rate during prolonged encounters, paralleled differences in thermal microhabitat use exhibited when lizards were housed alone. Thus, it may be possible to predict the outcome of social interactions within dyads based on the differential expression of traits between two lizards housed in isolation.

A longitudinal study of math achievement gains for initially low achieving students

Standardized testing has been implemented in most school districts as part of an effort to improve student achievement in mathematics, reading, science, and English. There have been heated debates as to the effects of these improvement efforts on student achievement. In studying these issues, it is important to examine longitudinal growth patterns for individuals. In most of the studies, however, there is a lack of empirical data at the individual student level or the studies are cross-sectional in nature. The current study attempts to examine growth patterns of student math achievement between 1997 and 2000 and individual differences in growth patterns. MDS exploratory growth modeling was used in the investigation based on data from 716 students in a single school district. Individual differences in growth rates were found. Disadvantaged (limited English proficiency and special education) students had lower initial achievement levels and did not seem to be catching up to other students because their average growth rates were similar to those of other students. These results are discussed in light of recent school reform efforts and the goal of closing achievement gaps.

Transition from a random to an ideal free to an ideal despotic distribution: the effect of individual difference in growth

Individual differences in growth can lead to a monopolistic form of food competition. We studied the long-term transition in the mode of competition and the distribution of individuals between food patches of the cloned salmonid fish, Oncorhynchus masou ishikawae, in the laboratory. This transition was accompanied by growth depensation, i.e., the increase over time in the variance of size between individuals resulting from the differences in individual growth rates. The 120-cm experimental tanks were divided into two compartments (patches) between which an opaque partition was placed. Fish were able to move freely between the patches and therefore were able to assess the patch quality using long-term memory, but they were not able to see the food input in the other patch directly. The distribution between the two food patches, the amount of food gained, and the growth and the agonistic behavior of four groups of six individuals were observed over 4 weeks. We found that (1) within-group variation in body weight increased with time; (2) on average, the better patch was used by more individuals than predicted by a random distribution but fewer individuals than predicted by an ideal free distribution, and (3) the distribution and pat- tern of resource use by the fish changed over the 4-week experimental period from a random distribution to an ideal free distribution and finally to an ideal despotic distribution. We suggest that growth depensation causes the long-term change in the spatial distribution and pattern of resource use by competitors.

Modeling Intraindividual Changes in Children's Social Skills at Home and at School: A Multivariate Latent Growth Approach to Understanding Between-Settings Differences in Children's Social Skill Development

Multivariate latent growth modeling was used to conceptualize and analyze intraindividual changes in children's social skills and interindividual differences in these changes in home and school settings. Parent and teacher ratings assessing children's social skills at home and school settings, respectively, were obtained for a sample of 378 children at 4 time points spaced at approximately 12-month intervals over a 4-year period from Kindergarten to Grade 3. Results showed that, in initial status at Kindergarten, there were significant individual differences in social skills in both home and school settings and a significant positive association between initial status in social skills in the two settings. Systematic between-settings differences in children's social skill development were found. Social skills development at home was best described with a nonlinear trajectory in which skills increased from Kindergarten to Grade 2 with a substantially larger increase from Grade 1 to Grade 2 than from Kindergarten to Grade 1, and then remained relatively constant from Grade 2 to Grade 3. In contrast, social skills development at school was best described with a negative linear trajectory in which skills decreased at a constant rate from Kindergarten to Grade 3. The differences in social skills development may derive form the fact that different teachers with different expectations regarding social skills provided ratings each year while the same parent was the source of at-home social skills ratings. There were significant individual differences in growth rates in the school as well as the home setting. Evidence of between-settings differences in social skills development were obtained from differential patterns of associations between growth parameters (initial status and growth rate) and individual predictors (family income, parent education, child verbal skills) across settings.

Post-emergent field activity and growth rates of hatchling spur-thighed tortoises,Testudo graeca

Activity, mobility, growth rates, and space use of 48 hatchling spur-thighed tortoises, Testudo graeca, were monitored over a period of 8 months, from emergence from the nest in September until May. Individuals were followed by means of thread trailing and radio tracking. Overall average distance moved was 4.42 m/day and average home-range size was 13.7 m2. Hatchlings were active from emergence until mid-December, exhibited discontinuous hibernation until mid-February, and reached highest activity and mobility values in April–May. Overall, mobility varied significantly with daily solar radiation values and maximum temperature, and was significantly dependent on body condition in winter. Body size and mass had no influence on individual performance, and a significant proportion of variance among individuals remained unexplained. Little growth occurred in autumn and body condition decreased steadily, increasing only from February onwards. Growth rates increased in March–April. No individual differences in growth rates were detected, initial body size being the main determinant of body size after 8 months.

Exuvium analysis: A nondestructive method of analyzing copepod growth and development

Quantitative measurements of individual growth and developmental rates are necessary to study copepod life‐history ecology, population dynamics, and secondary production, yet these measurements are difficult to obtain, particularly for naupliar instars. Copepods molt several times during their life cycle, and the resulting exuvium provides an accurate record of an individual’s size at molting. Newly hatched nauplii of two freshwater calanoid copepods (Boeckella triarticulata and Boeckella hamata) were reared in the laboratory under identical conditions and examined daily for the presence of exuviae, which were used to quantify individual growth and development. Both size and age at successive molts were variable among individuals of each species. Some individuals consistently developed more slowly or more rapidly than others, and individual differences in growth rates also were highly significant. Exuvium analysis provides accurate, quantitative data on individual patterns of growth and development throughout the life cycle.

Antisocial Behavior, Delinquent Peer Association, and Unsupervised Wandering for Boys: Growth and Change from Childhood to Early Adolescence.

Latent growth curve analysis was used to study individual differences in initial status and growth rates of antisocial behavior, delinquent peer association, and unsupervised wandering during the transition from childhood to early adolescence for a sample of 206, primarily working-class, European-American boys. All three constructs showed significant individual differences in initial status at Grade 4 and growth rates from Grade 4 to Grade 8. Wandering and delinquent peer association showed positive mean trends. Linear growth curves adequately described growth for delinquent peer association and antisocial behavior. Growth on wandering was linear up to Grade 7 and then showed positive acceleration from Grade 7 to Grade 8. All three constructs were highly related at the initial assessment point. Individual differences in growth rates were highly correlated on all three constructs. The findings were discussed in terms of the trait-confluence model for peer influence on antisocial behavior.

Growth in Reptiles

This paper reviews the literature on growth in reptiles. The current consensus is that growth data for small and medium-sized reptiles are best fitted by logistic-by-mass equations, data for larger reptiles by the von Bertalanffy equation. Experiments on the relationships between behavioural thermoregulation, food consumption and growth in both the laboratory and field are described, and an account is given of some recent work on individual differences in growth rates and their adaptive significance. In general, it may be said that in almost all areas of biology relating to growth, less is known about reptiles than about equivalent phenomena in fishes.

Winter injury to subalpine red spruce: influence of prior vigor and effects on subsequent growth

We assessed the relationship between prior vigor and severity of winter injury to trees and saplings of red spruce (Picearubens Sarg.) at Mount Moosilauke, New Hampshire. Severity of injury was quantified as percent foliar damage on current-year needles after severe injury in the winter of 1988–1989. There was no relationship between severity of injury and prior crown condition. There was only a weak tendency for trees with high live crown ratios to be less damaged than trees with proportionally smaller crowns. Severity of winter injury was not correlated with prior growth rates in the 1-, 2-, or 5-year periods preceding injury, for either trees (radial growth) or saplings (extension growth). However, crown condition of trees and saplings deteriorated significantly following injury. For both trees and saplings, prior growth and subsequent growth were positively correlated for the 1- and 2-year periods before and after the winter injury event. Effects of winter injury on growth in 1989 and 1990 were analyzed using growth ratios (subsequent growth relative to prior growth) to avoid ambiguity resulting from individual differences in growth rates. Severity of winter injury had no effect on growth ratios in the 1- or 2-year periods following winter injury. Although no effects on growth were detected following a single winter injury event, it remains plausible that successive, severe episodes of winter injury could reduce growth and increase mortality risk in red spruce.