Maternal Body Size Research Articles

The Long-Term Associations of Perinatal Obesogenic Environment with Offspring Biological Aging.

Biological age (BA), reflecting aging-related health decline beyond chronological age, varies among individuals. While previous research explored associations of maternal pregnancy-related body size with offspring health outcomes, its implications for BA in young adults remain unclear. Utilizing longitudinal data of 1,148 mother-offspring pairs from the Jerusalem Perinatal Study, we analyzed associations of maternal pre-pregnancy BMI and gestational weight gain (GWG) with offspring Klemera-Doubal method (KDM)-based BA at age 32, and potential familial life-course underlying mechanisms. Maternal pregnancy-related body size, adjusted for sociodemographic/lifestyle factors was associated with offspring BA (βmaternal pre-pregnancy BMI=0.183,95%CI:0.098,0.267;βGWG=0.093,95%CI:0.021,0.165). Association of GWG with BA was largely direct (90%,95%CI,44%,100%), while association with maternal pre-pregnancy BMI was partially mediated through adolescent BMI (36%,95%CI=18%,75%), with both associations eliminated after adjustment for offspring adult BMI. Associations persisted after adjusting for offspring polygenic risk score for BMI (βmaternal pre-pregnancy BMI=0.128;95%CI=0.023,0.234; βGWG=0.102;95%CI=0.006,0.198), and somewhat altered after adjustment for maternal cardiometabolic conditions (βmaternal pre-pregnancy BMI=0.144,95%CI=0.059, 0.230). Impact on GWG associations was negligible. Thus, perinatal obesogenic environment contributes to offspring BA beyond sociodemographic factors and maternal cardiometabolic history, yet intergenerational transmission of obesity seems to underlie these associations. Nonetheless, the period between adolescence and young adulthood could be targeted for weight-reducing interventions, ultimately promoting healthy aging.

Photoperiod-dependent effects of zinc oxide nanoparticles on the growth and reproduction of Daphnia pulex

The discharge of metal nanoparticles into the water inevitably poses a threat to aquatic organisms and the balance of the aquatic ecosystem. Photoperiod is one of the most important ecological factors for the development of cladocerans. In addition, different light conditions can also affect the toxicity of metal nanoparticles. In this study, we studied the effects of four photoperiods (8L/16D, 10L/14D, 14L/10D, and 16L/8D) combined with three concentrations of ZnO NPs (0 mg L−1, 0.05 mg L−1, and 0.10 mg L−1) on the growth and reproduction of Daphnia pulex. With the increase of photoperiod, the maternal body size and growth rate increased first and then decreased; the first time to reproduction was advanced, and broods and the total offspring also increased. Under the influence of ZnO NPs, growth rate and reproductive capacity were inhibited. The photoperiod 8L/16D and 16L/8D interacted with ZnO NPs on the growth of D. pulex, which significantly decreased the growth rate. Besides, the interaction between photoperiod 8L/16D and ZnO NPs decreased the reproduction ability of D. pulex. These results suggest that the effects of zinc oxide nanoparticles on the growth and reproduction of D. pulex is photoperiod dependent, which is useful for assessing the risk of pollutants to cladoceras under different light conditions.

Association of maternal blood and umbilical cord blood plasma fatty acid levels with the body size at birth of Japanese infants

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), mainly obtained from fish, have been implicated in fetal development. Because few studies have examined maternal and umbilical cord blood fatty acid levels and infant body size in Japan with a fish-eating culture, we examined differences in plasma fatty acid levels in pregnant women and infant size at birth. This study is a large birth cohort study of 1476 pairs of Japanese pregnant women and their infants. Maternal blood DHA levels and infant birth weight showed a positive relationship. However, analysis adjusted for gestational age did not reveal correlations. Negative relationships were found between cord blood DHA levels and infant body size, and between the difference in mother-to-child DHA levels and infant body size. Thus, the smaller the birth size, the higher the differences in umbilical cord blood DHA levels and mother-to-child DHA levels when considering gestational age.

Cardiac Structure and Function in 8- to 12-Year-Old Children Following In-Utero Exposure to Preeclampsia (FINNCARE Study).

We evaluated how elevated blood pressure in children exposed to preeclampsia (PE) impacted on their cardiac structure and function, as well as relations with maternal, gestational, and perinatal factors and child body size and composition. A total of 182 PE (46 early-onset preeclampsia) and 85 unexposed (non-PE) children were examined in the FINNCARE study 8 to 12 years after the index pregnancy with echocardiography; office, central, and 24-hour ambulatory blood pressures; and body anthropometrics and composition. PE children had lower right ventricular basal sphericity index (mean difference, -0.26 95% CI, -0.39 to -0.12) and lower mitral lateral E'-wave peak velocity (-1.4 cm/s [95% CI, -2.1 to -0.6]), as well as higher E to E' ratio (0.40 [95% CI, 0.15-0.65]) and indexed tricuspid annular plane systolic excursion (0.03 [95% CI, 0.01-0.05]) compared with non-PE children. These differences were accentuated in early-onset PE children. Left ventricular mass (LVM) or left atrial volume were not different between PE and non-PE children. Lean body mass, body fat percentage, and 24-hour systolic blood pressure were independent predictors of LVM. Lean body mass and body fat percentage were independent predictors of left atrial volume. No significant associations between LVM or left atrial volume and maternal, gestational, or perinatal parameters were found. Preadolescent PE children display a more globular-shaped right ventricle with higher longitudinal systolic displacement as well as mildly altered diastolic indices, with the alterations being pronounced in early-onset preeclampsia. Lean body mass and adiposity are independently related with LVM and left atrial volume, and systolic blood pressure with LVM in both PE and non-PE children. These unfavorable associations indicate remodeling of cardiac structure in young children also reflected in mild functional changes in PE children. URL: https://www.clinicaltrials.gov; unique identifier: NCT04676295.

Sexual dimorphism and reproductive biology of commercially harvested oriental rat snakes (Ptyas mucosa: Colubridae) from West Java

Large (>3 m) slender-bodied rat snakes are abundant in agroecosystems of southern Asia and are heavily exploited for their skins and meat. We examined 216 specimens killed at commercial facilities in Cirebon, West Java, to quantify morphological and reproductive traits and evaluate harvest sustainability by comparing this sample to one taken 25 years previously. The snakes we examined were mostly adults, and mostly male. Females were less heavy-bodied than males of the same body length, matured at a larger size than males, but attained smaller maximum sizes. Reproduction and energy (fatbody) storage was seasonal in both sexes, with females containing oviductal eggs primarily during the annual wet season. Clutch size averaged 12.6 eggs and increased with maternal body size. Comparison of the two samples taken 25 years apart revealed strong similarity in sex ratio, the numerical preponderance of adults, body sizes at sexual maturation and mean adult body sizes, sexual dimorphism in body length and mass, reproductive seasonality in females, mean fecundity, and the relationship between fecundity and maternal body size. That consistency suggests that commercial harvesting over the intervening period has not affected the biological traits of rat snake populations, consistent with a sustainable level of offtake.

Species-Specific Seasonal Shifts in Reproductive Allocation in the Southern Grass Lizard, Takydromus sexlineatus (Lacertidae).

We designed a common garden design to collect data on female reproductive traits from three populations of the southern grass lizard Takydromus sexlineatus, testing the hypothesis that a species-specific pattern of seasonal shifts in reproductive allocation should be shared by geographically separated populations. Of the seven examined traits, six differed among populations, with four of the six also differing among successive clutches. Females grew longer during the breeding season and produced more eggs in the first clutch than in the subsequent clutches; egg size was unchanged throughout the breeding season. After removing the influence of female size or postpartum body mass we found the following. First, postpartum body mass, clutch mass, and relative clutch mass were greater in the Wuzhishan population than in the Shaoguan and Zhaoqing populations. Second, egg size was greatest in the Wuzhishan population and smallest in the Zhaoqing population. Third, clutch size was greatest in the Wuzhishan population and smallest in the Shaoguan population. Females did not trade-off egg size against number within each population × clutch combination. Our study validates the hypothesis tested, supports the conventional view that reproductive output is highly linked to maternal body size in lizards, and follows the classic prediction that females with different amounts of resources to invest in reproduction should give priority to adjusting the total number rather than size of their offspring.

Life-history of masked water snakes (Homalopsis buccata) in Java: implications for the sustainability of harvesting

Context Masked water snakes (Homalopsis buccata, Homalopsidae) thrive in the muddy edges of agricultural ponds and canals in densely populated areas of West Java, Indonesia, and are harvested by local farmers to protect fish stocks and to provide meat, skins, and medicines for commercial use. Aims Here, we aimed to quantify sexual dimorphism and reproductive biology of H. buccata, so as to deepen our knowledge of the species’ inherent ability to withstand commercial harvests. Methods We examined carcasses of 4286 snakes at six processing sites to quantify biological attributes (e.g. sexual dimorphism in body size and shape, seasonality of reproduction, fecundity, reproductive frequency), with emphasis on traits that affect the ability of snake populations to withstand this intensive harvesting. Key results The snakes we examined were primarily adults (<1% juvenile), with approximately equal numbers of males and females except in January (when females comprised >90% of specimens). Females grow larger than males, and they are more heavy-bodied but shorter-tailed than are males of the same snout–vent length. Reproduction is seasonal in both sexes, with testis volumes decreasing to a minimum over the period August to November (late dry season) when most adult-size females were gravid. Litter sizes ranged from 1 to 37 (mean 12), increasing with maternal body size, with ~75% of females reproducing each year. Conclusions On the basis of these results, we infer that the life history of H. buccata (viviparity, high fecundity, frequent reproduction, rapid maturation) renders it inherently resilient to harvesting, especially because that offtake is based on males as well as females. Because a lack of sustainability is evident only in hindsight, regular monitoring of the trade could assure that any problems are detected rapidly. Implications To further buffer these populations from the impact of harvest, hunting could be restricted during January (a time when gravid females are disproportionately vulnerable) and the largest snakes (females, with high fecundity and reproductive frequency) could be excluded from harvests.

Maternal diet influences fecundity in a freshwater turtle undergoing population decline.

Food availability determines the amount of energy animals can acquire and allocate to reproduction and other necessary functions. Female animals that are food limited thus experience reduced energy available for reproduction. When this occurs, females may reduce frequency of reproductive events or the number or size of offspring per reproductive bout. We assessed how maternal diet affects reproductive output in adult female Murray River short-necked turtles, Emydura macquarii, from four wetlands in Victoria. We previously found that turtle diets differ in the composition of plants and animals between our study wetlands. In this study, we tested whether differences in turtle diet composition (i.e. plants and animals) at these wetlands were associated with differences in clutch mass, individual egg mass, bulk egg composition and hatching success. We found total clutch mass increased with maternal body size at each site. At sites where filamentous green algae were scarce and E. macquarii were carnivorous, females produced smaller clutches relative to body size compared to females from sites where algae were abundant, and turtles were more herbivorous. Individual egg mass, bulk egg composition and hatching success did not differ across wetlands. Isotopic analysis revealed significant positive relationships between the carbon and nitrogen isotopes (δ13C, δ15N) of the eggs and those of the mothers, indicating that mothers allocated ratios of carbon and nitrogen isotopes to their eggs similar to those present in their tissues. Our study suggests that at sites where females are more carnivorous due to a relative absence of algae, females produce smaller clutches, but other aspects of their reproduction are not significantly impacted. The reduction in clutch size associated with differences in the availability of dietary plants and animals may have long-term consequences for E. macquarii and other freshwater turtle species that are experiencing population declines.

Perinatal exposures and adolescence overweight: The role of shared maternal-offspring pathways

Background and aimsEarly life exposures affect offspring health across the life-course. We aimed to examine whether prevalent perinatal exposures and obstetric complications are independently associated with offspring overweight in adolescence. We then assessed whether shared maternal-offspring pathways drive the association of perinatal exposures with offspring overweight. MethodsUsing data from the Jerusalem Perinatal Study birth cohort, two perinatal scores were constructed: obstetric complications (OC) and prevalent perinatal exposures (PPE) scores. PPE score, generated by principal component analysis, included three primary components. Logistic regressions were used to assess associations of scores with offspring overweight, with and without adjustment for maternal life-course survival. ResultsOC and PPE scores were independently associated with offspring overweight (OROC = 1.15, 95%CI:1.07,1.25; ORPPE1- SEP and lifestyle = 0.85, 95%CI:0.79,0.91; ORPPE2- Maternal body size = 1.20, 95%CI: 1.13,1.28; ORPPE3-Fetal growth = 1.18, 95%CI:1.11,1.26). Maternal survival was associated with offspring overweight (OR = 1.38, 95%CI:1.08,1.76), yet introducing PPE score to the same model attenuated this association (OR = 1.16, 95%CI:0.90, 1.49). When OC score and maternal survival were included in the same model, their associations with offspring overweight remained unchanged. ConclusionsMother-offspring shared factors, captured by maternal life-course survival, underlie the effect of prevalent perinatal exposures on offspring overweight. However, the effect of obstetric complications was independent, highlighting the contribution of additional pathways.

Neonatal adiposity is associated with microRNAs in adipocyte-derived extracellular vesicles in maternal and cord blood, a discovery analysis.

Maternal body size, nutrition, and hyperglycemia contribute to neonatal body size and composition. There is little information on maternal-fetal transmission of messages which influence fetal growth. We analyzed adipocyte-derived small extracellular vesicular (ADsEV) microRNAs in maternal and cord blood to explore their adipogenic potential. There were 279 mother-neonate pairs with all phenotypic data (normal glucose tolerant NGT = 148, gestational diabetes mellitus GDM = 131). Neonates with adiposity were those in the highest tertile (T3) of sex-specific sum of skinfolds and those without adiposity (lean) in the lowest tertile T1 of NGT pregnancies. We studied ADsEV miRNAs in 76 and 51 neonates with and without adiposity respectively and their mothers based on power calculations (68 NGT and 59 GDM pregnancies). ADsEV miRNAs from maternal and cord blood plasma samples were profiled on Agilent 8*60 K microarray. Differential expression (DE) of ADsEV miRNAs in adipose vs. lean groups was studied before and after adjustment for maternal GDM, adiposity, and vitamin B12-folate status. Multiple miRNAs were common in maternal and cord blood and positively correlated. We identified 24 maternal and 5 cord blood miRNAs differentially expressed (discovery p ≤ 0.1) in the adipose group in unadjusted, and 19 and 26, respectively, in the adjusted analyses. Even though DE miRNAs were different in maternal and cord blood, they targeted similar adipogenic pathways (e.g., the forkhead box O (FOXO) family of transcription factors, mitogen‑activated protein kinase (MAPK) pathway, transforming growth factor beta (TGF-β) pathway). Maternal GDM and adiposity were associated with many DE ADsEV miRNAs. Our results suggest that the ADsEV miRNAs in mothers are potential regulators of fetal adiposity. The expression and functionality of miRNAs appear to be influenced by maternal adiposity, hyperglycemia, and micronutrient status during pregnancy.

Urban landscapes affect wild bee maternal investment and body size

Urban landscapes affect wild bee maternal investment and body size

Size distribution and reproductive phenology of the invasive Burmese python (Python molurus bivittatus) in the Greater Everglades Ecosystem, Florida, USA

The design of successful invasive species control programs is often hindered by the absence of basic demographic data on the targeted population. Establishment of invasive Burmese pythons (Python molurus bivittatus) in the Greater Everglades Ecosystem, Florida USA has led to local precipitous declines (> 90%) of mesomammal populations and is also a major threat to native populations of reptiles and birds. Efforts to control this species are ongoing but are hampered by the lack of access to and information on the expected biological patterns of pythons in southern Florida. We present data from more than 4,000 wild Burmese pythons that were removed in southern Florida over 26 years (1995–2021), the most robust dataset representing this invasive population to date. We used these data to characterize Burmese python size distribution, size at maturity, clutch size, and seasonal demographic and reproductive trends. We broadened the previously described size ranges by sex and, based on our newly defined size-stage classes, showed that males are smaller than females at sexual maturity, confirmed a positive correlation between maternal body size and potential clutch size, and developed predictive equations to facilitate demographic predictions. We also refined the annual breeding season (approx.100 days December into March), oviposition timing (May), and hatchling emergence and dispersal period (July through October) using correlations of capture morphometrics with observations of seasonal gonadal recrudescence (resurgence) and regression. Determination of reproductive output and timing can inform population models and help managers arrest population growth by targeting key aspects of python life history. These results define characteristics of the species in Florida and provide an enhanced understanding of the ecology and reproductive biology of Burmese pythons in their invasive Everglades range.

Altitudinal variation in life-history features of a Qinghai-Tibetan Plateau lizard.

Environmental changes along an altitudinal gradient can facilitate the differentiation of life-history features in ectothermic species, but little attention has been devoted to the reciprocal influence of altitude and alpine slope directionality on life-history variation. According to life-history theory, increased environmental stress causes a change in reproductive allocation from number to quality of offspring, as well as a stronger trade-off between size and number of offspring. To clarify the influence of environmental pressures on the life-history features of the Qinghai toad-headed lizard Phrynocephalus vlangalii along an altitudinal cline, we surveyed late pregnant females from 3 populations of low (2,600 m), middle (3,400 m), and high (3,600 m) elevations in the Dangjin Mountain of Gansu, China from July to October 2019, and compared their inter-population differences in maternal body size, reproductive characteristics, offspring growth, and locomotor performance. Because of lower temperatures, higher humidity, and lower light intensity caused by slope aspect and altitude, the middle-altitude region experienced stronger environmental stress than the high- and low-altitude regions. Our results showed that females were larger at middle- and high-altitude sites and smaller at the low-altitude site, following Bergmann's rule. We also found that females from low-altitude population gave birth earlier than those from the middle and high altitudes. Our results showed a shift in the offspring size-number trade-off of P. vlangalii in response to colder and harsher environments, with lizards from the alpine steppe (i.e. the middle- and high-altitude habitats) producing fewer but larger offspring than those from the warm steppe (i.e. the low-altitude habitat). Low-altitude juveniles grew faster than high-altitude ones, but at the same rates as middle-altitude juveniles. This result demonstrates that the growth of P. vlangalii was associated with temperature and light intensity. Our findings contribute to enhancing our understanding of the altitudinal variation in life-history features of plateau ectotherms and their phenotypic plasticity or local adaptation.

Neonatal head circumference by gestation reflects adaptation to maternal body size: comparison of different standards

Neonatal head circumference (HC) not only represents the brain size of Homo sapiens, but is also an important health risk indicator. Addressing a lack of comparative studies on head size and its variability in term and preterm neonates from different populations, we aimed to examine neonatal HC by gestation according to a regional reference and a global standard. Retrospective analysis of data on neonatal HC obtained from the Lithuanian Medical Birth Register from 2001 to 2015 (423 999 newborns of 24–42 gestational weeks). The varying distribution by gestation and sex was estimated using GAMLSS, and the results were compared with the INTERGROWTH-21st standard. Mean HC increased with gestation in both sexes, while its fractional variability fell. The 3rd percentile matched that for INTERGROWTH-21st at all gestations, while the 50th and 97th percentiles were similar up to 27 weeks, but a full channel width higher than INTERGROWTH-21st at term. INTERGROWTH-21st facilitates the evaluation of neonatal HC in early gestations, while in later gestations, the specific features of neonatal HC of a particular population tend to be more precisely represented by regional references.

Measuring Annual Variation in Reproductive Output Reveals a Key Role of Maternal Body Condition in Determining the Size of Eggs in Snakes.

Simple SummaryWe measured female reproductive traits of a colubrid snake (Lycodon rufozonatus) from Zhejiang, East China in four years (1999, 2010, 2011, and 2014). After removing the influence of female size, postpartum body mass was greater in 2010 than in 2014, clutch mass was greater in 2010 than in 2011 and 2014, and egg size was greater in 2010 than in the other three years. Egg size was positively related to postpartum body condition in each year. Females laid larger eggs in 2010 than in other three years after removing the influence of maternal size and body condition. Our study does not follow the prediction that reproductive females with different amounts of resources to invest should give priority to adjusting the number rather than size of offspring.Long-term studies are especially suited for disentangling the effects of extrinsic and intrinsic factors on both total reproductive investment and reproductive allocation in offspring number versus offspring size. Female reproductive traits of the red-banded wolf snake (Lycodon rufozonatus) from Zhejiang, East China were studied in four years between 1999 and 2014. Egg-laying dates overall extended from late June to late July, and varied among years. Postpartum body mass, clutch size, clutch mass, and egg size were positively related to female size (snout vent length, SVL) in each year. Postpartum body mass, clutch mass, and egg size differed among years after accounting for female SVL, whereas clutch size did not. Setting female SVL at the same level, postpartum body mass was greater in 2010 than in 2014, clutch mass was greater in 2010 than in 2011 and 2014, and egg size was greater in 2010 than in the other three years. Females did not trade off egg size against number. Egg size was positively related to postpartum body condition in each year. Females laid larger eggs in 2010 than in other three years after removing the influence of maternal body condition. Our study provides evidence for the traditional view that reproductive output is highly linked to maternal body size in snakes, but not following Smith and Fretwell’s (1974) classic prediction that females with different amounts of resources to invest in reproduction should give priority to adjusting the number rather than size of their offspring. Maternal body size and condition both are important sources of variation in egg size, but factors other than these two variables may also affect the size of eggs produced by female L. rufozonatus.

Effects of stem rotifer body size on morphology, starvation resistance and population growth of offspring in Brachionus calyciflorus

The morphological plasticity of rotifers has been investigated for several decades, and the maternal effects as an important source of variation in life history traits of rotifers have been reported. However, little is known in relation to the effects of maternal body size on offspring. In the represent study, resting eggs were collected from three Brachionus calyciflorus strains (A, B and C). From the hatchlings of each strain, the biggest and smallest stem rotifers were collected and named as the large-sized and small-sized morphotypes, respectively. The differences in body size (at 20 °C, 25 °C and 30 °C), starvation resistance and population growth were compared between strains and morphotypes. The results showed that strain and morphotype of maternal rotifers showed more important effects on the body size of offspring than temperature. Large-sized stem rotifers revealed significantly bigger offspring than small-sized stem rotifers, indicating significant maternal effects of body size on the morphology of offspring. At 25 °C, compared with small-sized stem rotifers, the offspring of large-sized stem rotifers showed significantly longer starvation resistance time in strain C and significantly higher population growth rate in strain B. These results demonstrated that strain is an important factor affecting the maternal effects of stem rotifer body size on offspring. Overall, this study provides more information to understand the morphological diversity of rotifers in field environments.

Fetal growth, birth size and energetic cost of gestation in southern right whales.

The cost of reproduction greatly affects a species’ life history strategy. Baleen whales exhibit some of the fastest offspring growth rates in the animal kingdom. We quantified the energetic cost of gestation for southern right whales (Eubalaena australis) by combining whaling catch records of pregnant females with photogrammetry data on southern right whale mothers and calves from two breeding grounds in Argentina and Australia. The relationship between calf birth size and maternal length was determined from repeated measurements of individual females before and after giving birth. Fetal growth was determined from generalized linear models fitted to fetal length data from whaling operations between 1961 and 1967. Fetal length was converted to volume and mass, using the volume‐to‐length relationship of newborn southern right whales calves, and published tissue composition and energy content estimates. Fetal maintenance costs (heat of gestation) and the energy content of the placenta were predicted from published relationships and added to the fetal growth cost to calculate the total cost of gestation. Our findings showed that fetal growth rates and birth size increased linearly with maternal length, with calves being born at ∼35% maternal length. Fetal length increased curvilinearly through gestation, which resulted in an exponential increase in fetal volume and mass. Consequently, the cost of gestation was very low during the first (0.1% of total cost) and second trimester (4.9%), but increased rapidly during the last trimester (95.0%). The heat of gestation incurred the highest cost for pregnant females (73.8%), followed by fetal growth (21.2%) and the placental energy content (5.0%).Key points Baleen whales exhibit some of the fastest fetal growth rates in the animal kingdom. Despite this, the energetic cost of gestation is largely unknown, as well as the influence of maternal body size on fetal growth rates and calf birth sizes.We combined historical whaling records and drone photogrammetry data to determine fetal growth rates and birth sizes in southern right whales (Eubalaena australis), from which we estimated the cost of gestation.Calf birth size, and consequent fetal growth rates, increased positively with maternal body size.The cost of gestation was negligible for southern right whale females during the first two trimesters, but increased rapidly during the last trimester.These results show that late gestation incurs a significant cost for baleen whale females, and needs to be accounted for in bioenergetic models.

Non-linear latitudinal cline of egg size and its consequence for larval survival in the rhinoceros beetle

Abstract The egg size of insects often exhibits latitudinal trends, which are attributed to local adaptations to temperature or temperature-related ecological factors. Although increased egg size improves offspring fitness, the relationship between size and fitness is influenced largely by environmental variables. Additionally, there is a trade-off between the size and number of eggs if the quantity of reproductive resources is constant. Despite the key associations among offspring size, number and performance, relatively few studies have jointly considered these traits when studying the genetic differentiation of egg size. Here, we examined the effects of latitude on egg size using 14 populations of the univoltine rhinoceros beetle Trypoxylus dichotomus (Coleoptera, Scarabaeidae, Dynastinae) along a 1200-km latitudinal gradient under common garden laboratory conditions. We found that egg size decreased with increasing latitude in a non-linear manner. Geographical variation in egg size was independent of maternal body size, and there was no difference in female lifetime fecundity between the low-latitude (large eggs) and high-latitude (small eggs) populations. Therefore, low-latitude females invest more resources in reproduction compared with high-latitude females. We further found that the larvae of the high-latitude population showed higher mortality than those of the low-latitude population under both nutrient-poor and nutrient-rich conditions. Although the ecological factors that shape the non-linear cline of egg size were not identified in our study, geographical variation in local environments or in female reproductive strategies could have caused the latitudinal trend.

Associations of maternal birth weight, childhood height, BMI, and change in height and BMI from childhood to pregnancy with risks of preterm delivery

It remains unknown whether maternal early life body size and changes in height and BMI from childhood to pregnancy are associated with risks of having a preterm delivery. We investigated whether a woman's birth weight, childhood height, BMI, and changes in height and BMI from childhood to pregnancy were associated with preterm delivery. We studied 47,947 nulliparous women born from 1940 to 1996 who were included in the Copenhagen School Health Records Register with information on birth weight and childhood heights and weights at ages 7 and/or 13 years. Gestational age was obtained from the Danish Birth Register, as was prepregnancy BMI, for 13,114 women. Deliveries were classified as very (22 to <32 weeks) or moderately (32 to <37 weeks) preterm. Risk ratios (RRs) and 95% CIs were estimated using binomial regression. A woman's birth weight and childhood height were inversely associated with having very and moderately preterm delivery. Childhood BMI had a U-shaped association with having a very preterm delivery; at age 7 years, compared to a BMI z score of 0, the RRs were 1.31 (95% CI, 1.11-1.54) for a z score of -1 and 1.18 (95% CI, 1.01-1.38) for a z score of +1. Short stature in childhood and adulthood was associated with higher risks of very and moderately preterm delivery. Changing from a BMI at the 85th percentile at 7 years (US CDC reference) to a prepregnancy BMI of 22.5kg/m2 was associated with RRs of 1.12 (95% CI, 0.91-1.37) and 0.88 (95% CI, 0.78-0.99) for very and moderately preterm delivery, respectively, compared to a reference woman at the 50th percentile at 7 years (22.5kg/m2 prepregnancy BMI). Maternal birth weight, childhood height, and BMI are associated with very and moderately preterm delivery, although in different patterns. Consistent short stature is associated with very and moderately preterm delivery, whereas normalizing BMI from childhood to pregnancy may reduce risks of having a very preterm delivery.

Differences between Northern and Southern Female Coyotes

The coyote (Canis latrans) has a wide distribution range, spanning boreal forests from the north of the continent to tropical environments in Central America, showing great adaptation and plasticity. Bergmann's rule states that individuals inhabiting colder climates are larger than those in warmer climates. It is suggested that in carnivore species, litter size is influenced by allometric constraints such as maternal body size. The aim of this study is to analyze the relations using correlation between female coyote mass, latitude, and litter size. Using data compiled from the literature, I carried out statistical analyses to correlate female body size, litter size, and latitude for coyotes across their distribution range. The results indicated a soft significant correlation between female body size and latitude, confirming Bergmann's rule. However, no significant correlation was found between litter size and latitude or between litter size and female body size; litter size in coyotes remains roughly uniform across their distribution range.