Between-family Variation Research Articles

Parenting and disruptive child behavior: A daily diary study during the COVID-19 pandemic.

We examined how mothers' daily parenting cognitions and behaviors implicated by different theoretical perspectives (i.e., relational, learning theory, and cognitive perspectives) associated in linear or nonlinear ways with disruptive child behavior during the COVID-19 pandemic. We examined levels of heterogeneity between families in these patterns and whether this heterogeneity could be explained by mother and child characteristics. Mothers of 150 children, 3-8 years; 48% girls; 68% (sub)clinical conduct problems, completed 14 daily assessments (Nassessments = 1,993). Multilevel models indicate significant associations with daily disruptive child behavior for each of the parenting indicators, except for lax discipline. Positive involvement-implicated by relational perspectives-had a consistent, negative cubic association across families. Other associations were quadratic (for parental self-efficacy) or linear (for positive reinforcement, harsh discipline, and nonviolent discipline) and differed between families. Parenting behaviors indicative of learning theory and cognitive perspectives appeared more important in families with more maternal and child mental health problems; learning theory perspectives appeared more important also in families with older children. Our findings indicate the importance of considering nonlinear patterns of parent-child interactions in the context of disruptive behavior, at least in times where families are under pandemic-related stress. The identified between-family variation could potentially provide guidance as to what parenting support is most likely to benefit different families. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Exposure to 15 phthalates and two substitutes (DEHTP and DINCH) assessed in trios of infants and their parents as well as longitudinally in infants exclusively breastfed and after the introduction of a mixed diet.

Several phthalates have been restricted/banned due to their adverse endocrine disrupting properties. The use of other phthalates and substitutes has increased. Here we examine the current exposure to phthalates in family trios comprised of infants and their parents and in infants exclusive breastfed and following introduction to a mixed diet. Metabolites of 15 phthalates and two substitutes, di(2-ethylhexyl)-teraphthalate (DEHTP) and diisononyl-cyclohexane-1,2-dicarboxylate (DINCH), were measured in urine samples collected from >100 infants and their parents and in paired urine samples collected from 67 infants, while they were exclusively breastfed and when they got mixed diet. Among infants and their parents, metabolites of nine out of 15 phthalates and both substitutes were detected in >74% of all samples. Estimated daily intake (DI) calculated as µg/kg/day, showed similar exposure levels among infants and their parents for several of the substances, and infants were more exposed to DEHTP than their mothers. Significantly higher estimated DIs were observed for some low-molecular phthalates in infants exclusively breastfed. In contrast, comparable estimated DIs were observed for many other phthalates and DEHTP regardless of feeding status. For most of the substances, the within-family variation, was lower than the between-family variation. Likewise, the within-infant variation on exclusively breast vs. mixed diet was lower than the between-infant variation. Independent of food status, some infants were concurrently exposed to almost all the measured phthalates and substitutes in higher amounts than others. Surprisingly, irrespective of diet status infants were exposed to several phthalates and substitutes some of which have been regulated for years. Exposure patterns and levels were similar in infants and their parents. Importantly, risk assessment based on new refined reference doses (RfD-AA) exceeded the safety level for anti-androgenic effects in a number of infants and parents, which is of concern.

Genetic×environment variation in sheep lines bred for divergent resistance to strongyle infection.

Drug‐resistant parasites threaten livestock production. Breeding more resistant hosts could be a sustainable control strategy. Environmental variation linked to animal management practices or to parasite species turnover across farms may however alter the expression of genetic potential. We created sheep lines with high or low resistance to Haemonchus contortus and achieved significant divergence on both phenotypic and genetic scales. We exposed both lines to chronic stress or to the infection by another parasite Trichostrongylus colubriformis, to test for genotype‐by‐environment and genotype‐by‐parasite species interactions respectively. Between‐line divergence remained significant following chronic stress exposure although between‐family variation was found. Significant genotype‐by‐parasite interaction was found although H. contortus‐resistant lambs remained more resistant against T. colubriformis. Growth curves were not altered by the selection process although resistant lambs were lighter after the second round of divergence, before any infection took place. Breeding for resistance is a sustainable strategy but allowance needs to be made for environmental perturbations and worm species.

Bias in genomic predictions by mating practices for linear type traits in a large-scale genomic evaluation

The objective of this study was to clarify how bias in genomic predictions is created by investigating a relationship among selection intensity, a change in heritability (Δh2), and assortative mating (ASM). A change in heritability, resulting from selection, reflects the impact that the Bulmer effect has on the reduction in between-family variation, whereas assortative mating impacts the within-family variance or Mendelian sampling variation. A partial data set up to 2014, including 841K genotyped animals, was used to calculate genomic predictions with a single-step genomic model for 18 linear type traits in US Holsteins. A full data set up to 2018, including 2.3 million genotyped animals, was used to calculate benchmark genomic predictions. Inbreeding and unknown parent groups for missing parents of animals were included in the model. Genomic evaluation was performed using 2 different genetic parameters: those estimated 14 yr ago, which have been used in the national genetic evaluation for linear type traits in the United States, and those newly estimated with recent records from 2015 to 2018 and those corresponding pedigrees. Genetic trends for 18 type traits were estimated for bulls with daughters and cows with phenotypes in 2018. Based on selection intensity and mating decisions, these traits can be categorized into 3 groups: (a) high directional selection, (b) moderate selection, and (c) intermediate optimum selection. The first 2 categories can be explained by positive assortative mating, and the last can be explained by negative assortative or disassortative mating. Genetic progress was defined by genetic gain per year based on average standardized genomic predictions for cows from 2000 to 2014. Traits with more genetic progress tended to have more "inflated" genomic predictions (i.e., "inflation" means here that genomic predictions are larger in absolute values than expected, whereas "deflation" means smaller than expected). Heritability estimates for 14 out of 18 traits declined in the last 16 yr, and Δh2 ranged from -0.09 to 0.04. Traits with a greater decline in heritability tended to have more deflated genomic predictions. Biases (inflation or deflation) in genomic predictions were not improved by using the latest genetic parameters, implying that bias in genomic predictions due to preselection was not substantial for a large-scale genomic evaluation. Moreover, the strong selection intensity was not fully responsible for bias in genomic predictions. The directional selection can decrease heritability; however, positive assortative mating, which was strongly associated with large genetic gains, could minimize the decline in heritability for a trait under strong selection and could affect bias in genomic predictions.

Host genetic variation explains reduced protection of commercial vaccines against Piscirickettsia salmonis in Atlantic salmon

Vaccination is a widely used control strategy to prevent Piscirickettsia salmonis causing disease in salmon farming. However, it is not known why all the currently available commercial vaccines generally fail to protect against this pathogenic bacteria. Here, we report, from two different populations, that between-family variation is a strong intrinsic factor that determines vaccine protection for this disease. While in some full-sib families, the protection added by vaccination increased the survival time in 13 days in comparison with their unvaccinated siblings; in other families, there was no added protection by vaccination or even it was slightly negative. Resistance to P. salmonis, measured as days to death, was higher in vaccinated than unvaccinated fish, but only a moderate positive genetic correlation was obtained between these traits. This disputes a previous hypothesis, that stated that both traits were fully controlled by the same genes, and challenges the use of unvaccinated fish as gold standard for evaluating and selecting fish resistant to P. salmonis, particularly if the offspring will be vaccinated. More studies are necessary to evaluate if variation in the host immune response to vaccination could explain the between-family differences in resistance observed in vaccinated fish.

Parasites under pressure: salmon lice have the capacity to adapt to depth-based preventions in aquaculture

The evolution of pesticide resistance has driven renewed interest in non-chemical pest controls in agriculture. Spatial manipulations (physical barriers and fallowing, for example) can be an effective method of prevention, but these too might impose selection and cause rapid adaptation in pests. In salmon aquaculture, various non-chemical approaches have emerged to combat parasitic salmon lice (Lepeophtheirus salmonis) – a major pest with clear signs of evolved chemical resistance. ‘Depth-based’ preventions, now widely implemented, reduce infestation rates by physically segregating salmon from lice in their infective copepodid stage occurring in surface waters. Copepodids distributed deeper in the water column, however, can bypass these barriers and infest farms. If swimming depth is a heritable trait, we may see rapid evolutionary shifts in response to widespread depth-based prevention. We collected lice from Norwegian salmon farms and assayed more than 11,250 of their laboratory-reared offspring across 37 families. The vertical distributions of copepodids were measured using experimental water columns pressurised to simulate conditions at 0, 5 and 10 m depths. We demonstrated that lice respond strongly to hydrostatic pressure: an increase in pressure doubled the number of lice that migrated to the top of columns. There was also a large effect of family on this response, with the percentage of lice ascending to the top of pressurised columns ranging from 17 to 79% across families. Families with a weak swimming response to pressure are expected to occur deeper in the water column and so be more likely to infest farms employing depth-based preventions. If this between-family variation reflects genetic variation, then the parasite population may have the capacity to adapt to preventative measures. Such adaptation would have important commercial and ecological implications.

Family Functioning and Adolescent Internalizing and Externalizing Problems: Disentangling between-, and Within-Family Associations

Adolescence is often a period of onset for internalizing and externalizing problems. At the same time, adolescent maturation and increasing autonomy from parents push for changes in family functioning. Even though theoretically expected links among the changes in family functioning and adolescent internalizing and externalizing problems exist, studies examining this link on the within-family level are lacking. This longitudinal, pre-registered, and open-science study, examined the within-family dynamic longitudinal associations among family functioning, and internalizing and externalizing problems. Greek adolescents (N = 480, Mage = 15.73, 47.9% girls, at Wave 1) completed self-report questionnaires, three times in 12 months. Random-Intercept Cross-Lagged Panel Models (RI-CLPM) were applied; such models explicitly disentangle between-family differences from within-family processes, thereby offering a more stringent examination of within-family hypotheses. Results showed that family functioning was not significantly associated with internalizing or externalizing problems, on the within-family level. Also, alternative standard Cross-Lagged Panel Models (CLPM) were applied; such models have been recently criticized for failing to explicitly disentangle between-family variance from within-family variance, but they have been the standard approach to investigating questions of temporal ordering. Results from these analyses offered evidence that adolescents with higher internalizing and externalizing problems compared to their peers, tended to be those who later experienced worse family functioning, but not vice versa. Implications for theory and practice are discussed.

Assessing within- and between-family variations in an expanded measure of childhood adversity.

Previous measures of childhood adversity have enabled the identification of powerful links with later-life wellbeing. The challenge for the next generation of childhood adversity assessment is to better characterize those links through comprehensive, fine-grained measurement strategies. The expanded, retrospective measure of childhood adversity presented here leveraged analytic and theoretical advances to examine multiple domains of childhood adversity at both the microlevel of siblings and the macrolevel of families. Despite the fact that childhood adversity most often occurs in the context of families, there is a dearth of studies that have validated childhood adversity measures on multiple members of the same families. Multilevel psychometric analyses of this childhood adversity measure administered to 1,194 siblings in 500 families indicated that the additional categories of childhood adversity were widely endorsed, and increased understanding of the sources and sequalae of childhood adversity when partitioned into within- and between-family levels. For example, multilevel confirmatory factor analyses (MCFAs) indicated that financial stress, unsafe neighborhood, and parental unemployment were often experienced similarly by siblings in the same families and stemmed primarily from family wide (between-family) sources. On the other hand, being bullied and school stressors were often experienced differently by siblings and derived primarily from individual (within-family) processes. Multilevel structural equation modeling (MSEM) further illuminated differential criterion validity correlations between these categories of childhood adversity with midlife psychological, social, and physical health. Expanded, multidomain, and multilevel measures of childhood adversity appear to hold promise for identifying layered causes and consequences of adverse childhood experiences. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Statistics of Mendelian segregation-A mixture model.

Mendel's law of segregation explains why genetic variation can be maintained over time. In diploid organisms, an offspring receives one allele from each parent, not just half of the blended genetic material of the parents. Which of the two alleles is received is purely random. This stochastic process generates genetic variation among members of the same family, called Mendelian segregation variance or within-family variance. In statistics, the genetic value of a quantitative trait for an offspring follows a mixture distribution consisting of the four alleles of the two parents, guided by a Mendelian variable from each parent. The mixture model allows us to partition the total genetic variance into between-family and within-family variances. In the absence of inbreeding, the genetic variance splits half to the between-family variance and half to the within-family variance. With inbreeding, however, the between-family variance is increased at the cost of the within-family variance, leading to a net increase of the total genetic variance. This study defines multiple Mendelian variables and develops a mixture model of quantitative genetics. The phenomenon that allelic variance is maintained over time is guided by "the law of conservation of allelic variance" in biology, which is comparable to "the law of conservation of mass" in physics.

Supplemental Material for Assessing Within- and Between-Family Variations in an Expanded Measure of Childhood Adversity

Supplemental Material for Assessing Within- and Between-Family Variations in an Expanded Measure of Childhood Adversity

Adult Siblings Who Have a Brother or Sister with Autism: Between-Family and Within-Family Variations in Sibling Relationships.

Prior research on the sibling relationship in the context of autism spectrum disorder (ASD) has included only one sibling per family. We used multi-level modeling to examine aspects of the sibling relationship in 207 adults who have a brother or sister with ASD from 125 families, investigating variability in sibling relationship quality and pessimism within and between families. We found that there was greater variability in aspects of the sibling relationship with the brother or sister with ASD within families than between families. Sibling individual-level factors were associated with positive affect in the sibling relationship, while family-level factors were associated with the sibling's pessimism about their brother or sister's future. The findings illustrate the unique experiences of siblings within families.

The Mother-Child Relationship and Children’s Behaviours: A Multilevel Analysis in Two Countries

We examined the influences of culture, maternal malaise, household chaos, and both family-wide and child-specific aspects of parenting on children’s adjustment in a socioeconomically diverse sample of 118 English and 100 Turkish families. Each family included two children aged 4-8 years, enabling the separation of within- and between-family factors by modelling the multilevel structure of the data. Mothers reported about the parent-child relationship, contextual factors, child behaviours (internalising, externalising and prosocial). Maternal differential treatment, age, and gender were tested as sources of within-family variance, and culture, household chaos, maternal malaise, and family-wide parenting were tested as sources of between-family variance. The current study adds to the literature by showing the effects of maternal treatment were different for Turkish and English children. Conversely, similar effects across cultures were revealed for age, gender, household chaos and maternal malaise.

Gene coexpression network analysis for family studies based on a meta-analytic approach.

For a better understanding of the biological mechanisms involved in complex traits or diseases, networks are often useful tools in genetic studies: coexpression networks based on pairwise correlations between genes are commonly used. In case of a family-based design, it can be problematic when there is a large between-family variation in expression levels. We propose here a gene coexpression network analysis for family studies. We build a coexpression network for each family and then combine the results. We applied our approach to data provided for analysis in the Genetic Analysis Workshop 19 and compared it to 2 naïve approaches—ignoring correlations among the expressions and decorrelating the gene expression by using the residuals of a mixed model—and a single-probe analysis. Our approach seemed to better deal with heterogeneity with regard to the naïve approaches. The naïve approaches did not provide any significant results, while our approach detected genes via indirect effects. It also detected more genes than the single-probe analysis.

Impact of genetic variation and long-term limited water availability on the ecophysiology of young Sitka spruce (Picea sitchensis (Bong.) Carr.).

Future limited water availability may reduce the potential of tree improvement to increase timber yields. We investigated ecophysiological variation between full-sibling families of Sitka spruce (Picea sitchensis (Bong.) Carr.) growing under contrasting water availability conditions: control (optimal) water availability and limited water availability. One-year-old seedlings of nine improved families plus an unimproved seed lot were grown in pots in a greenhouse and the two water availability treatments imposed via drip irrigation. Whole-plant water use varied between families. Stomatal conductance and the light-saturated quantum yield of photosystem II at times differed between families, but not consistently. Certain families showed considerably greater increases in electron transport rate with increasing photosynthetically active radiation. Limited water availability resulted in reduced branch water potential, leaf stomatal conductance and transpiration per unit leaf area, and increased whole-plant water-use efficiency, in all genetic material. The responses of plant water use and leaf carbon isotope composition to water limitation, were, however, initially influenced by variation in vigour between families-with conservative growth in some material slowing the decline in substrate moisture content. As the duration of water deficit extended, these variables showed a more uniform response across families. Between-family variation in physiological mechanisms of drought tolerance was not detected. Thus, for Sitka spruce, assessing juvenile material may not allow selection to prevent reductions in productivity associated with long-term sub-optimal growing conditions, but screening for conservative growth (within families as well as between families) may be beneficial where survival of relatively short-term water limitation is the primary concern.

The functional ecology of plant silicon: geoscience to genes

Podcast

Evaluation of Genome-Enabled Selection for Bacterial Cold Water Disease Resistance Using Progeny Performance Data in Rainbow Trout: Insights on Genotyping Methods and Genomic Prediction Models.

Bacterial cold water disease (BCWD) causes significant economic losses in salmonid aquaculture, and traditional family-based breeding programs aimed at improving BCWD resistance have been limited to exploiting only between-family variation. We used genomic selection (GS) models to predict genomic breeding values (GEBVs) for BCWD resistance in 10 families from the first generation of the NCCCWA BCWD resistance breeding line, compared the predictive ability (PA) of GEBVs to pedigree-based estimated breeding values (EBVs), and compared the impact of two SNP genotyping methods on the accuracy of GEBV predictions. The BCWD phenotypes survival days (DAYS) and survival status (STATUS) had been recorded in training fish (n = 583) subjected to experimental BCWD challenge. Training fish, and their full sibs without phenotypic data that were used as parents of the subsequent generation, were genotyped using two methods: restriction-site associated DNA (RAD) sequencing and the Rainbow Trout Axiom® 57 K SNP array (Chip). Animal-specific GEBVs were estimated using four GS models: BayesB, BayesC, single-step GBLUP (ssGBLUP), and weighted ssGBLUP (wssGBLUP). Family-specific EBVs were estimated using pedigree and phenotype data in the training fish only. The PA of EBVs and GEBVs was assessed by correlating mean progeny phenotype (MPP) with mid-parent EBV (family-specific) or GEBV (animal-specific). The best GEBV predictions were similar to EBV with PA values of 0.49 and 0.46 vs. 0.50 and 0.41 for DAYS and STATUS, respectively. Among the GEBV prediction methods, ssGBLUP consistently had the highest PA. The RAD genotyping platform had GEBVs with similar PA to those of GEBVs from the Chip platform. The PA of ssGBLUP and wssGBLUP methods was higher with the Chip, but for BayesB and BayesC methods it was higher with the RAD platform. The overall GEBV accuracy in this study was low to moderate, likely due to the small training sample used. This study explored the potential of GS for improving resistance to BCWD in rainbow trout using, for the first time, progeny testing data to assess the accuracy of GEBVs, and it provides the basis for further investigation on the implementation of GS in commercial rainbow trout populations.

Radial and between-family variations of the microfibril angle and the relationships with bending properties in Picea jezoensis families

ABSTRACTWith emphasis on tree breeding for wood quality in Picea jezoensis, we aimed to evaluate radial and between-family variations in the microfibril angle (MFA) of the S2 layer in the latewood tracheids in 10 open-pollinated families of 43-year-old P. jezoensis trees. In addition, the relationships between MFA/wood density with the modulus of elasticity (MOE) or modulus of rupture (MOR) were investigated. Significant differences in MFA between families were found from the pith toward the bark. MFA showed higher values around the pith area, although some families showed relatively lower values than others around this area. In addition, due to a larger coefficient of variations of MFA near the pith, the potential for juvenile wood MFA improvement may be greater compared with mature wood. MOE was correlated with MFA in juvenile wood and with wood density in mature wood, whereas MOR was mainly correlated with wood density at radial positions in both woods. Therefore, to improve the MOE and MOR of P. jezoensis wood, both MFA and wood density would be factors to consider in both juvenile and mature woods. On the other hand, there are indications that, only wood density would be an important criterion for improving mature wood properties.

An Adaptive Weighted Sum Test for Family-Based Multi-Marker Association Studies

Backgrounds: Although many disease-associated common variants have been discovered through genome-wide association studies, much of the genetic effects of complex diseases have not been explained. Population-based association studies are vulnerable to population stratification. A possible solution is to use family-based tests. However, if tests only estimate the genetic effect from the within-family variation to avoid population stratification, they may ignore the useful genetic information from between-family variation and lose power. Methods: We have developed an adaptive weighted sum test for family-based association studies. The new test uses data driven weights to combine two test statistics, and the weights measure the strength of population stratification. When population stratification is strong, the proposed test will automatically put more weight on one statistic derived from within-family variation to maintain robustness against spurious positives. On the other hand, when the effect of population stratification is relatively weak, the proposed test will automatically put more weight on the other statistic derived from both within-family and between-family variation to make use of both sources of genetic variation; and at the same time, the degrees of freedom of the test will be reduced and power of the test will be increased. Results: In our study, the proposed method achieves a higher power in most scenarios of linkage disequilibrium structure as well as Hap Map data from different genes under different population structures while still keeping its robustness against population stratification.

Abstract 20310: Cardiovascular Risk Markers in a Large Cohort of Children With Genetically Verified FH Show No Inheritance-Related but LDL Receptor Mutation-Type and Family History of CVD-related Variance

Introduction: Familial hypercholesterolemia (FH) is an autosomal dominant disease caused primarily by mutations in the low density lipoprotein (LDL) receptor gene. FH patients have increased total- and LDL cholesterol leading to accelerated atherosclerosis and premature cardiovascular disease (CVD). In an FH pregnancy the absolute rise in lipid levels are often much higher than in healthy pregnancies, and this maternal hypercholesterolemia may thus contribute to an unfavorable in utero environment potentially increasing susceptibility of adult CVD. Few studies have investigated whether maternal FH is associated with an unfavorable phenotype in offspring compared with paternal FH inheritance. Hypothesis: The aim of the present study was to investigate the impact of maternal vs. paternal FH on pre-treated plasma lipids. In addition, the effect of LDL receptor mutation types and Family history of early CVD in FH children was evaluated Methods: We included 1063 children with FH (0-19 years) in the study. Five-hundred had inherited FH maternally and 563 paternally. Furthermore, 624 children with FH had an LDL receptor negative mutation and 332 of the FH children had an FH grandparent suffering from early CVD whereas the remaining children had an FH grandparent with late or no CVD. Differences were tested for using a random intercept mixed model taking account for between-family variation. Results: Children with maternal FH did not have different levels of total-, LDL- or HDL-cholesterol, triglycerides, apoA1, apoB, lipoprotein (a) compared with children With paternal FH. Moreover, children with LDL receptor negative mutations had higher levels of total- and LDL cholesterol in addition to apoB, and concomitantly lower levels of HDL-cholesterol and apoA-1 than children with other LDL receptor mutations. Finally, children with an FH grandparent with early CVD had significant higher LDL-cholesterol levels than children without. Conclusions: Maternal FH does not lead to a more unfavorable phenotype in untreated FH children. However, both FH children with LDL receptor negative mutation and FH children with early CVD in family had a more unfavorably phenotype. Hence statin treatment should potentially be initialized earlier in this group.

Multigenerational response to artificial selection for biased clutch sex ratios in Tigriopus californicus populations.

Polygenic sex determination (PSD) is relatively rare and theoretically evolutionary unstable, yet has been reported across a range of taxa. Evidence for multilocus PSD is provided by (i) large between-family variance in sex ratio, (ii) paternal and maternal effects on family sex ratio and (iii) response to selection for family sex ratio. This study tests the polygenic hypothesis of sex determination in the harpacticoid copepod Tigriopus californicus using the criterion of response to selection. We report the first multigenerational quantitative evidence that clutch sex ratio responds to artificial selection in both directions (selection for male- and female-biased families) and in multiple populations of T. californicus. In the five of six lines that showed a response to selection, realized heritability estimated by multigenerational analysis ranged from 0.24 to 0.58. Divergence of clutch sex ratio between selection lines is rapid, with response to selection detectable within the first four generations of selection.