Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size

Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females) and annual growth increments of individuals of unknown age (1,152 males, 730 females). We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631–820 mm snout-vent length in males and from 835–1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further investigation.     

Growth rate and age at migration of Anguilla anguilla

The length, age and growth rate were investigated for downstream migrating male and female eels in the unexploited Burrishoole system, western Ireland. Significant differences were found in the age and length at migration with the larger, older female eels also showing faster annual growth as early as the first year in fresh water. Female eels normally migrated at lengths from 40.5 cm, exceptionally to 92.9 cm, and male eels at lengths between 28.9 and 46'0 cm. Back-calculation showed an irregular pattern of fast and slow annual growth. Mean annual growth increments were almost always greater for females than for males.     

Growth of dark chub, Zacco temmincki (Cyprinidae), with a discussion of sexual size differences

I examined the annual and seasonal growth of dark chub, Zacco temmincki, in a Japanese river. Investigation of opercular rings showed that the fish reached a maximum age of 8 years. There was no significant sexual size difference at younger ages (3–5 years), but males were larger than females at older ages (6–7 years). Annual increments of length and weight for males that were recaptured were also larger than those for females. The fish spawn from June to August. Females grew for a short period from April to May, but males on average grew for a longer period from April to August. There was no sexual difference in growth rate except during the spawning period. Annual growth rate was negatively correlated with fish length in each sex. The sexual size differences at older ages of the fish might be due to the polygynous mating system in which most mature males could not obtain females and invested for somatic growth in the spawning period, and a short growing season that was overlapped considerably with the spawning period.     

Grades of undernutrition and socioeconomic status influence cognitive development in school children of Kolkata

Cognitive development of children is influenced by different environmental factors like nutritional and socio‐economic status. The objectives of the present study were to determine the influence of grades of undernutrition and socio‐economic status (SES) on the cognitive development of school children of Kolkata. Five hundred sixty six (566) school children having 5–12 years of age were selected from different schools of Kolkata. The cognitive development was measured by the scores of Raven's colored progressive matrices (RCPM). The chronic and acute nutritional statuses were measured from height‐for‐age (HAZ) and weight‐for‐age (WAZ) Z scores respectively with reference to the values of WHO. SES was determined by updated Kuppuswamy scale. The prevalences of undernutrition in the observed children were 57.95% (according to HAZ) and 52.82% (according to WAZ). The age dependent growth curve of RCPM scores of the observed children remains in between the 10th and 25th centile of British children. The children belonging to superior and intellectual deficit IQ classes were 21.55 and 36.40%, respectively of the total subjects. Most of the subjects belong to lower middle (39.93%) and upper middle (36.40%) class of SES. RCPM scores of school children were gradually decreased with the grades of undernutrition and SES. RCPM scores were significantly correlated with HAZ, WAZ, SES, age, and sex (P < 0.001) and strongly associated with HAZ, SES, age, and sex (P < 0.001, P < 0.05). Present study indicates that cognitive development of school children of Kolkata is influenced by the grade of undernutrition and SES. Am J Phys Anthropol 156:274–285, 2015. © 2014 Wiley Periodicals, Inc.     

Age and growth of threaded sculpin <Emphasis Type="Italic">Gymnocanthus pistilliger</Emphasis> (Cottidae) in the southern Primorye (Sea of Japan)

The features are discussed of the growth of threaded sculpin Gymnocanthus pistilliger in the southern part of its range, in the Sea of Japan. Several methods were tested to determine the age of this species. The improved approach is suggested for determinating the age of threaded sculpin by annual increments on sagitta using thin cross-sections, characteristics of optical density in different zones of otolith growth, and their positions relative to otolith center. It was demonstrated that the growth rate of threaded sculpin in the waters of southern Primorye was significantly higher than in the northern part of its range: the males reached a length of about 20 cm and the females about 22 cm at the age 5+. The maximum length of individuals, 26 cm in the males and 31 cm in the females, significantly exceed those known from literature. The longevity of threaded sculpin calculated for maximum size is 12–13 yr for the waters of Primorye.     

Social development of bonnet macaques from six months to three years of age: A longitudinal study

Observations of age-sex class associations of three young female and five young male bonnet macaques born in the spring, 1975, were taken semiannually over three years beginning in the fall, 1975. Analysis reveals several patterns: (1) both males and females show continuous decline in association with age mates; (2) solitary time of females peaks at 1.5 years after which they begin to associate with adult females; (3) solitary time of males peaks at 2.5 years after which they associate predominantly with sub-adult males; (4) both males and females showed higher association with juveniles of the same sex than of opposite sex; and (5) both males and females showed annual cycles of association with some age-sex classes. These results are best understood with reference to the natural breeding cycle of the animals and the different life histories of male and female macaques in the wild.     

Knemometry in the assessment of short-term linear growth in a population of healthy school children.

Short-term lower leg length increments were monitored with weekly knemometry measurements during 3 months in 27 healthy school children aged 8-12 years. One year after the first visit the children were measured once again. The mean short term velocity of lower leg growth was 0.40 mm/week (SD 0.12 mm/week). The mean short-term and annual ratios between height velocity and lower leg growth velocity were identical (2.8). The relative variation between two observers was 0.08%. Knemometry is a suitable method for monitoring short-term linear growth in populations of children. Two trained observers may substitute for each other in group studies.     

Growth standards for the tibia and radius in children aged one month through eighteen years

Standards for the growth of the tibia and the radius are presented for normal males and females ages one month through 18 years. Using radiographs of subjects from the Fels Research Institute for the Study of Human Development longitudinal program, means and standard deviations for bone length, interval increments and annual increments were determined. Males and females show little difference in growth of the tibia until adolescence while statistically significant differences are found at nearly all ages in the radius. The adolescent growth spurt occurs in the male from 12–15 years and in the female from 9–12 years.     

Red howler monkey birth data II: Interannual,habitat, and sex comparisons

Data presented in this paper are derived from the births and subsequent histories of red howler infants born in two habitats. Overall the sex ratio of infants at birth was about 1:1. Infant survivorship (at 1 yr) was about 80%, and 44% of infant mortality was attributed to infanticide by males. Survivorship curves indicated a dramatic sex difference, with far fewer females than males known to be alive at age 7 yr. However, this sex difference may be inflated because emigrant males are more easily identified than emigrant females, and females may be dispersing beyond the boundaries of the study area at a higher rate. Annual birthrate varied somewhat from year to year and was positively related to rainfall. Annual birthrate tended to be higher in the habitat with lower density and higher growth rate. Consistent with the trends, in annual birthrate, variation in interbirth interval length (TBR after births of surviving infants was related primarily to habitat differences and annual variation in rainfall. Season of birth and maternal age class had no effect on IBI. Infant sex had mostly nonsignificant effects on IBI. A small sample indicated that IBI's were significantly longer after the births of females who eventually became natal breeders than after the births of females who eventually emigrated. This difference might reflect differential parental (maternal) investment of some sort.     

Inbreeding effects on the growth in stature among Telaga boys and girls of Kharagpur, West Bengal, India

The present study is an attempt to understand the genetical effects of inbreeding on the process of growth. The inbred and non-inbred subjects were selected on the basis of extensive pedigrees of five generations in the Telaga, an endogamous population of Kharagpur, India. Preference was given to cousins belonging to the same kindreds while selecting control sample so that environmental variation was minimized. Altogether 633 boys and 614 girls of different inbreeding levels aged five to twenty years were measured for stature. Analysis has been done in different levels of inbreeding in each age and sex on mean annual increments and variances of increments. The results revealed that comparison of annual increment for each age between boys and girls with different degrees of inbreeding and application of the one-tailed t-test of significance does not provide any evidence of inbreeding effect on mean increment for stature studied in either sex. This might indicate the absence of marked dominant/recessive effects of genes determining annual increments in body size rather than the absence of genetical control of increments due to growth. Moreover, it is noteworthy that the variance of annual increment due to growth (which is estimated indirectly) consistently increases with increase of inbreeding level with only a few exceptions. The exceptions occur more often in girls than in boys, which can be explained by greater environmental stress and selection pressure and variation in X-linked inbreeding among girls. This would be worthwhile to verify in longitudinal growth data in future. Increased variances of annual increment with inbreeding, in the absence of change of mean increment on inbreeding, would indicate the influence of additive autosomal genes for the process of physical growth in children in either sex. A close scrutiny of the annual increments for the measurements in all the four levels of inbreeding in either sex fails to bring out any consistent trend of change in the age of adolescent spurt with inbreeding. This might suggest an underlying homozygosity of several genes with inbreeding in the population.     

Growth of specific muscle strength between 6 and 18 years in contrasting socioeconomic conditions

The influence of sex, age, and socioeconomic conditions on specific grip strength of 6-18-year-old individuals was studied among 1,704 males and 1,956 females belonging to the so-called "Cape Coloured" community in the western part of South Africa. Half of the participants of both sexes came from communities in the Greater Cape Town area where living conditions are comparable to those of middle-class First World communities (high SES). The other half came from the poorest rural communities of Klein Karoo (low SES). Arm circumferences, triceps skinfold thickness, and grip strength of the right and of the left hand were greater in individuals from high SES at all ages. Females within each SES group had skinfolds thicker than males, especially at older ages, and were weaker. Specific grip strength (SS), estimated as grip strength per unit area of cross section of the fat-free arm, increased with age in each group, was greater in males, and was significantly lower in low SES groups, than in the high SES ones, especially during and after puberty. It seems that SES difference in SS will persist into adulthood. Sexual differences in SS can be attributed to hormonal differences; while the SS increase with age and the difference between SES groups find no clear explanation in current theories of muscle growth and development. Since the speed of neuromuscular reaction observed in our participants is slower among low SES individuals, it seems that the difference in neuromuscular control of strength may be responsible for our findings. Differences in muscle metabolism and hormonal regulation must also be considered.     

The Relationship of Ethnicity,Socioeconomic Factors,and Overweight in U.S. Adolescents

Objective: To examine the extent to which race/ethnic differences in income and education account for sex‐specific disparities in overweight prevalence in white, African American, Hispanic, and Asian U.S. teens. Research Methods and Procedures: We used nationally representative data collected from 13,113 U.S. adolescents enrolled in the National Longitudinal Study of Adolescent Health. Logistic regression models were used to examine the relationship of family income and parental education to overweight prevalence (body mass index ≥ 85th percentile of age and sex‐specific cutoff points from the 2000 Centers for Disease Control and Prevention/National Center for Health Statistics growth charts). In addition, we used coefficients from our logistic regression models to project the effects on overweight prevalence of equalizing the socioeconomic status (SES) differences between race/ethnic groups. Results: Keeping adolescents in their same environments and changing only family income and parental education had a limited effect on the disparities in overweight prevalence. Ethnicity‐SES‐overweight differences were greater among females than males. Given that overweight prevalence decreased with increasing SES among white females and remained elevated and even increased among higher SES African‐American females, African‐American/white disparity in overweight prevalence increased at the highest SES. Conversely, disparity was lessened at the highest SES for white, Hispanic, and Asian females. Among males, disparity was lowest at the average SES level. Discussion: One cannot automatically assume that the benefits of increased SES found among white adults will transfer to other gender‐age‐ethnic groups. Our findings suggest that efforts to reduce overweight disparities between ethnic groups must look beyond income and education and focus on other factors, such as environmental, contextual, biological, and sociocultural factors.     

Long‐term patterns in growth of Oneida Lake walleye: a multivariate and stage‐explicit approach for applying the von Bertalanffy growth function

Total length ( L _T) and its inter annual variation of walleye Sander vitreus from Oneida Lake, New York, based on 51 years (1950–2000) of data for ages 1 to 7 years were analysed. Growth increased over time at young ages, did not change at intermediate ages and decreased at old ages. Total length at age increased over time to age 4 or 5 years, but was stable at older ages. Principle component analysis was used to study the pattern of variations in annual L _T increments among years. More than 92 and 91% of inter annual variability in growth was described by the first three principal components for males and females, respectively. The first principal component was a general indicator of annual growth at all ages, but was dominated by annual growth at intermediate ages. The second and third principal components represented contrasts among yearling L _T, yearling growth and growth at older ages. Therefore, changes in the three stage‐specific parameters, yearling L _T, yearling growth and asymptotic L _T, explained most of the variance in observed growth. Using these three stage‐specific parameters for the von Bertalanffy growth function facilitated interpretations of growth comparisons.     

Age estimation,growth and maturity of the Argentine hake (Merluccius hubbsi Marini, 1933) along the northernmost limit of its distribution in the south-western Atlantic

Age, growth and length-at-maturity of the Argentine hake (Merluccius hubbsi) were studied in the northernmost limit of the species distribution in the south-western Atlantic. A total of 351 otoliths and information from 1610 specimens sampled from the industrial double-rig trawl landings between May 2013 and April 2014 were used. Age and growth were estimated by counting and measuring increments in sectioned sagittae otoliths, and length at maturity was estimated based on macroscopic gonadal analysis. For both sexes, hepatosomatic index and condition index increased mainly during spring, reaching a maximum at the end of summer before the subsequent spawning season began. Gonadosomatic index was highest in April, believed to correspond with peak spawning. The annual periodicity of alternate opaque and translucent zones was validated by marginal increment analysis. Growth curves were fitted to back-calculated size at age by fitting the three-parameters von Bertalanffy growth function. The maximum age was 5 years in fish of either sex. Females attained larger sizes than males. The parameters of the von Bertalanffy growth equations were: L∞?=?533?mm, k?=?0.231 year^?1 and t₀?=??0.935 year for females; L∞?=?394?mm, k?=?0.405 year^?1 and t₀?=??0.463 year for males. The mean length and age at first maturity was 273?mm at 1.9 years for males and 274?mm at 2.0 years for females.     

Age structure, growth and reproduction of Leuciscus pyrenaicus in an intermittent stream in the Guadalquivir river basin, southern Spain

The age, growth and reproduction of Leuciscus pyrenaicus (Günther, 1868), an endemic cyprinid from the Iberian Peninsula, was studied from November 1987 to September 1989 in a small seasonal tributary of the Guadalquivir river basin. Maximum fork lengths observed were a 160 mm male with six scale annuli and a 171 mm female aged 7 +. Maximum ages observed were 7 + in males and 8 + in females. There were no significant differences in the annual growth increments between sexes. Seasonal growth period started in March and continued for 5 to 6 months. Mean lengths of 1 + specimens onwards diminished during summer and/or autumn. Males and females matured in their third and fourth year of life respectively. The overall sex ratio (272 males: 310 females) differed significantly from equality. Spawning began in May and ended in July. L. pyrenaicus is a multiple spawner that releases a minimum of two batches of eggs per female each year. Eggs in each batch were similar in both size (egg diameter) and number released. The relationship between fecundity (Fee) and fork length (mm) was represented by the formula: Fec=1.96 10⁻³ L^2.50.     

The effect of school performance upon marriage and long-term reproductive success in 10,000 Swedish males and females born 1915–1929

Humans are an exceptionally intelligent species, and the selective pressures which may have shaped these advanced cognitive powers are therefore of interest. This study investigates the fitness consequences of pre-reproductive school performance in a Swedish population-based cohort of 5244 males and 4863 females born 1915-1929. School performance was measured at around age 10 using three variables: mean school marks, being promoted/held back in school, and recognised learning difficulties. Our primary outcomes were probability of ever marrying, total number of children and total number of grandchildren. In males (but not females), poorer school performance predicted fewer children and grandchildren. This was primarily mediated via probability of marriage; mortality and fertility within marriage were not important mediating pathways. The effect of school performance upon marriage in males was independent of early-life social and biological characteristics, including birth weight for gestational age, preterm birth, family composition, and family socioeconomic position. The effect of school performance upon the probability of marriage in males was, however, largely mediated by adult socioeconomic position. This suggests that in general sexual selection for cognitive abilities per se did not play a major role in either males or females in this cohort. Adult socioeconomic position did not, however, fully explain the marriage disadvantage in males or (at marginal significance) females with particularly poor school performance. We conclude that school performance can affect long-term reproductive success. In this population, however, the effect is confined to males and is largely mediated by the increased probability of marriage which comes with their greater socioeconomic success.     

Demography and life history of Thomas langurs (Presbytis thomasi)

Life history data from wild primate populations are necessary to explain variation in primate social systems and explain differences between primates and other mammals. Here we report life history data from a 12.5-year study on wild Thomas langurs. Mean age at first reproduction was 5.4 years and the sex ratio at birth was even. The mean interbirth interval (IBI) after a surviving infant was 26.8 mo, after nonsurviving infants 17.7 mo, and combined 22.0 mo. Mean annual birth rate of adult females was 0.44, while reaching a peak at 6 years of age and showing no decrease with age. Mortality was highest during the first year of life (48.0% for males and 43.0% for females) and consistently higher for males than females. The oldest female observed during the study was estimated to be 20 years of age, whereas the oldest male disappeared at age 13 years, indicating that males die at a much earlier age than females. A Leslie matrix based on these estimates yielded a growth rate of 1.01, which is comparable to the nonsignificant increase in density indicated by our long-term field data. A comparison with life history data for sympatric frugivorous primates suggests that folivory might be associated with faster life history.     

Age and growth of ocellated icefish, Chionodraco rastrospinosus DeWitt and Hureau, 1979, from the South Shetland Islands

Age and growth of ocellated icefish, Chionodraco rastrospinosus, were investigated using counts of annual growth increments from sagittal otoliths. Samples were collected during research surveys by benthic trawl carried out around Elephant and South Shetland Islands in January–February 2002 and December 2006–January 2007. A total of 290 specimens were selected for the study, consisting of 120 females and 170 males. The age of fish was estimated by counting annuli on transverse sections obtained by grinding and polishing whole otoliths embedded in epoxy resin. The precision-of-age estimates within and between readers were tested applying both the average percent error (APE) and the coefficient of variation (CV). The estimated age-range was 1–12 for both sexes of C. rastrospinosus. Applying the von Bertalanffy growth function to the age–length data, a growth curve was obtained for each sex. The estimated values of VB growth parameters L _∞ and k were, respectively, 47.9 cm and 0.28 for females and 42.9 cm and 0.36 for males. Compared to other congeneric species, the growth performance of C. rastrospinosus was relatively high, being 2.82 and 2.81 in males and females, respectively. Age at sexual maturity was estimated to be about 4 years in both sexes. C. rastrospinosus captured in the studied area consisted mainly of adult specimens between 3 and 8 years, with few older fish.     

Validation of the periodicity of increment formation in the otoliths of a cichlid fish from Lake Tanganyika, East Africa

Tetracycline was used as a chemical tag in a mark‐recapture study to examine the pattern of increment formation in the otoliths of Tropheus moorii , a rock‐dwelling cichlid from Lake Tanganyika. A total of 256 fish were captured by divers and injected with tetracycline. Of these, nine were recaptured after either 1 or 2 years at liberty and eight retained tags within their otoliths. Comparison of the number of growth increments formed after the tag and the time at liberty demonstrated that increments were deposited on an annual basis in the otoliths of this species. Furthermore, there was a strong relationship between otolith mass and age suggesting that otoliths grew at a predictable rate throughout the life of the fish. Validation of an annual pattern of increment deposition allowed age and growth information to be derived from otoliths. This showed that T. moorii grew rapidly to attain adult size by 3 years of age. Males grew faster than females and also attained a larger size than females (8·74 v . 7·91 cm L _S respectively). The longevity of some of these small freshwater fish was surprising; the oldest individual had an age of 10 years, while the average age of adults was 4 years.     

Sex differences in age structure, growth rate and body size of common frogs Rana temporaria in the subarctic

The thermal environment and length of the activity season are important factors in shaping life-history trait variation in ectotherms. Many ectothermic vertebrates living at high latitudes or altitudes tend to be larger and older than their conspecifics living at lower latitudes or altitudes. However, detailed data on age, body size and growth variation—and how they may differ between males and females—are still scarce, especially from extreme high-latitude environments. We studied growth (body length increment), age and size structure of common frogs (Rana temporaria) in subarctic Finland (69°04′N) by applying skeletochronological methods to individually marked adults (n?=?169) captured and recaptured between 1999 and 2003. We found that breeding males were on average younger (mean?=?8.5?years) than females (11.9?years) and that males started reproducing earlier (≥3–4?years of age) than females (>4–5?years). The oldest encountered individual was an 18-year-old female, which to our knowledge is the oldest wild common frog ever reported. Females were on average larger (mean body length?=?76.6?mm) than males (70.7?mm), and this appeared to be mainly due to their older age as compared to males. While body length increased and growth rate decreased with age in both sexes, growth rate declined significantly faster with age in males than in females. The latter finding provides a proximate explanation for the observation that even after accounting for age differences among sexes (females?>?males), females were longer than males.