Variation in Platycladus orientalis (Cupressaceae) Reproductive Output and Its Effect on Seed Orchard Crops’ Genetic Diversity

The genetic efficiency of seed orchards is crucial for determining seed crops’ genetic gain and diversity. Platycladus orientalis is a conifer tree of important ecological value in China. Here, we assessed the reproductive output (fertility) variation for 166 clones in a first-generation P. orientalis seed orchard over five years and across three years for each gender (female: 2017, 2018, and 2020 and male: 2017, 2019, and 2021). Fertility variation and genetic diversity parameters were estimated for each gender-year combination. The reproductive output (fertility) variation differed among years, provinces, clones nested within provinces, and ramets within clones. We observed asymmetry in the gender reproductive output and parental imbalance and determined their profound effects on the genetic diversity of these seed crops. The maleness index revealed the existence of female-biased or male-biased clones. When seeds from multiple individuals and years were blended, we found an increase in the effective number of parents (Np) and in genetic diversity (GD), and a reduced fertility variation (Ψ) in the seed orchard. When we set the effective number of parents (Np) to 30, the GD of the seed orchard could be maintained at more than 95%. Thus, achieving genetic diversity balance in seed production can be accomplished through monitoring the fertility variation of orchards and through the utilization of the thereby generated information for the advanced generation of seed orchards.

Application of Two Level Count Regression Modeling on the Determinants of Fertility among Married Women in Ethiopia

Background: Fertility is the element of population dynamics that has a vital contribution towards changing population size and structure over time. The global population showed a major increment from time to time because of these dynamics, particularly in south Asia and sub-Saharan Africa including Ethiopia. So this study targeted on the factors affecting fertility among married women in Ethiopia through the framework of multilevel count regression analysis using EDHS 2016 data.Methods: The sampling design for EDHS 2016 was a two-stage stratified cluster sampling design, where stratification was achieved by separating every region into urban and rural areas except the Addis Ababa region. Results: Among the random sample of 6141 women in the country, 27150 births were recorded based on EDHS 2016 report. The histograms showed that the data has a positively skewed distribution extremely picked at the beginning. Two- level negative binomial regression model was fitted to spot out the determinants of fertility among married women in Ethiopia because it has the smallest value for the fit statistics and the variance of the data was higher than its mean.Conclusion: Findings from the study revealed that contraception method used, residence, educational level of women, women’s age at first birth, and proceeding birth interval were the major predictors of fertility among married women in Ethiopia. Moreover, the estimates from the random effect result revealed that there is more fertility variation between the enumeration areas than within the enumeration areas. Application of standard models by ignoring this variation ought to embrace spurious results, then multilevel modeling is recommended for such types of hierarchical data.

Natural variation in fertility is correlated with species-wide levels of divergence inCaenorhabditis elegans

ABSTRACTLife history traits underlie the fitness of organisms and are under strong natural selection in the face of environmental challenges. A new mutation that positively impacts a life history trait will likely increase in frequency and become fixed in a population (e.g.selective sweep). The identification of the beneficial alleles that underlie selective sweeps provides insights into the mechanisms that occurred during the evolution of species. In the global population ofCaenorhabditis elegans,we previously identified selective sweeps that have drastically reduced chromosomal-scale genetic diversity in the species. Here, we measured the fertility (viable offspring) of a collection of wildC. elegansstrains, including many recently isolated divergent strains from the Hawaiian islands and found that strains with larger swept genomic regions on multiple chromosomes have significantly higher fertility than strains that do not have evidence of the recent selective sweeps. We used genome-wide association (GWA) mapping to identify three quantitative trait loci (QTL) underlying the fertility variation. Additionally, we mapped previous fertility data of wildC. elegansstrains andC. elegansrecombinant inbred advanced intercross lines (RIAILs) that were grown in various conditions and detected eight QTL across the genome using GWA and linkage mappings. These QTL show the genetic complexity of life history traits such as fertility across this species. Moreover, the haplotype structure in each GWA QTL region revealed correlations with recent selective sweeps in theC. eleganspopulation. North American and European strains had significantly higher fertility than most strains from Hawaii, a hypothesized origin of theC. elegansspecies, suggesting that beneficial alleles that cause increased fertility could underlie the selective sweeps during the worldwide expansion ofC. elegans.

Linking Neighbors’ Fertility: Third Births in Norwegian Neighborhoods

Geographical variations in fertility and the diffusion of fertility across space and social networks are central topics in demographic research. Less is known, however, about the role of neighborhoods and neighbors with regard to geographical variations in fertility. This paper investigates spatial variations in family size by analyzing third births in a neighborhood context. Using unique geo-data on neighbors and neighborhoods, this paper introduces a new geographical dimension of fertility variation and contributes to our understanding of geographical variations in fertility. Flexible, ego-centered neighborhoods are constructed using longitudinal geo-data taken from administrative registers (2000-2014). Data on inhabitants’ residential address, their housing, family situation and fixed effects for statistical tracts are used to account for sorting into housing and urban versus rural districts. The analysis shows that the likelihood of two-child couples having another child increases with the share of families in the neighborhood that have three or more children. This relationship remains unchanged, even after controlling for the sociodemographic characteristics of couples, the educational level attained by neighboring women as well as time-constant characteristics of neighborhoods. Results are consistent across various neighborhood definitions ranging from the 12 to the 500 nearest neighbors. However, the association between neighbors’ fertility becomes stronger as the number of neighbors increases, suggesting that selective residential sorting is an important driver. Consequently, this study indicates that transitions to third birth may be linked to social interaction effects among neighbors, in addition to well-known processes of selective residential sorting.

Gender, reproductive output covariation and their role on gene diversity of Pinus koraiensis seed orchard crops

Background Gender and fertility variation have an impact on mating dynamics in a population because they affect the gene exchange among parental members and the genetic composition of the resultant seed crops. Fertility is the proportional gametic contribution of parents to their progeny. An effective number of parents, derivative of effective population size, is the probability that two alleles randomly chosen from the gamete gene pool originated from the same parent. The effective number of parents is directly related to the fertility variation among parents, which should be monitored for manipulating gene diversity of seed crops. We formulated a fundamental equation of estimating the effective number of parents and applied it to a seed production population. Results Effective number of parents (Np) was derived from fertility variation (Ψ) considering covariance (correlation coefficient, r) between maternal and paternal fertility. The Ψ was calculated from the coefficient of variation in reproductive outputs and divided into female (ψf) and male (ψm) fertility variation in the population under study. The Np was estimated from the parental Ψ estimated by the fertility variation of maternal (ψf) and paternal (ψm) parents. The gene diversity of seed crops was monitored by Ψ and Np. in a 1.5 generation Pinus koraiensis seed orchard as a case of monoecious species. A large variation of female and male strobili production was observed among the studied 52 parents over four consecutive years, showing statistically significant differences across all studied years. Parental balance curve showed greater distortion in paternal than maternal parents. The Ψ ranged from 1.879 to 4.035 with greater ψm than ψf, and the Np varied from 14.8 to 36.8. When pooled, the relative effective number of parents was improved as 80.0% of the census number. Conclusions We recommend the use of fertility variation (i.e., CV, Ψ), Person’s product-moment correlation (r), and effective number of parents (Np) as tools for gauging gene diversity of seed crops in production populations. For increasing Np and gene diversity, additional management options such as mixing seed-lots, equal cone harvest and application of supplemental-mass-pollination are recommended.

Gender, reproductive output covariation and their role on gene diversity of Pinus koraiensis seed orchard crops

Background: Gender and fertility variation have an impact on mating dynamics in a population because they affect the gene exchange among parental members and the genetic composition of the resultant seed crops. Fertility is the proportional gametic contribution of parents to their progeny. An effective number of parents, derivative of effective population size, is the probability that two alleles randomly chosen from the gamete gene pool originated from the same parent. The effective number of parents is directly related to the fertility variation among parents, which should be monitored for manipulating gene diversity of seed crops. We formulated a fundamental equation of estimating the effective number of parents and applied it to a seed production population.Results: Effective number of parents (Np) was derived from fertility variation (Y) considering covariance (correlation coefficient, r) between maternal and paternal fertility. The Y was calculated from the coefficient of variation in reproductive outputs and divided into female (yf) and male (ym) fertility variation in the population under study. The Np was estimated from the parental Y estimated by the fertility variation of maternal (yf) and paternal (ym) parents. The gene diversity of seed crops was monitored by Y and Np. in a 1.5 generation Pinus koraiensis seed orchard as a case of monoecious species. A large variation of female and male strobili production was observed among the studied 52 parents over four consecutive years, showing statistically significant differences across all studied years. Parental balance curve showed greater distortion in paternal than maternal parents. The Y ranged from 1.879 to 4.035 with greater ym than yf, and the Np varied from 14.8 to 36.8. When pooled, the relative effective number of parents was improved as 80.0% of the census number.Conclusions: We recommend the use of fertility variation (i.e., CV, Y), Person’s product-moment correlation (r), and effective number of parents (Np) as tools for gauging gene diversity of seed crops in production populations. For increasing Np and gene diversity, additional management options such as mixing seed-lots, equal cone harvest and application of supplemental-mass-pollination are recommended.

Decomposing the Effect of Women Educational Status on Fertility Across the Six Geo-political Zones in Nigeria: 2003-2018

Background: High level of fertility has been consistently reported in Nigeria. Women education is often identified as one of the important factors that have contributed to reduction in fertility across countries. It is essential to identify the factors that explain the fertility variation in educational status and know the extent of association of these factors across the regions in Nigeria. Thus, this study aimed to examine the fertility differentials among uneducated and educated women in Nigeria.Methods: A cross-sectional population-based design which involved secondary data analyses of the weighted sample of 2003 (n1=7620), 2008 (n2=33385), 2013 (n3=38948) and 2018 (n4=41821) Nigeria Demographic and Health Survey data sets was used. Fertility was measured from information on the full births history of women aged 15-49 years. Oaxaca-Blinder decomposition was used to identify factors that explain fertility differentials among educated and not educate women (α=0.05).Result: Total fertility rate estimate was higher among uneducated women (6.7) than educated women (4.5) in 2018. The pattern was similar across the regions and survey periods. The mean children ever born among women aged 45-49 years was significantly higher among the uneducated than educated women in each of the survey year. Maternal age at first marriage, wealth index and age at first birth were contributory factors to the dissimilarities found in fertility between the educated and uneducated women. Risk difference (RD) of high fertility between uneducated-educated women was highest in South-East (RD=56.9; 95%CI=49.1-64.8) and least in North-East (RD=15.0; 95%CI=9.9-20.1).Conclusion: The fertility level in Nigeria was high but more prominent among the uneducated than educated. Improving the level of educational enrolment of women of reproductive age will facilitate reduction in the fertility rate in Nigeria.

Gender, reproductive output covariation and their role on gene diversity of Pinus koraiensis seed orchard crops

Background: Gender and fertility variation have an impact on mating dynamics in a population because they affect the gene exchange among parental members and the genetic composition of the resultant seed crops. Fertility is the proportional gametic contribution of parents to their progeny. An effective number of parents, derivative of effective population size, is the probability that two alleles randomly chosen from the gamete gene pool originated from the same parent. The effective number of parents is directly related to the fertility variation among parents, which should be monitored for manipulating gene diversity of seed crops. We formulated a fundamental equation of estimating the effective number of parents and applied it to a seed production population.Results: Effective number of parents (Np) was derived from fertility variation (Ψ) considering covariance (correlation coefficient, r) between maternal and paternal fertility. The Ψ was calculated from the coefficient of variation in reproductive outputs and divided into female (ψf ) and male (ψm) fertility variation in the population under study. The Np was estimated from the parental Ψ estimated by the fertility variation of maternal (ψf ) and paternal (ψm) parents. The gene diversity of seed crops was monitored by Ψ and Np in a 1.5 generation Pinus koraiensis seed orchard as a case of monoecious species. A large variation of female and male strobili production was observed among the studied 52 parents for four consecutive years, showing statistically significant across all studied years. Parental balance curve showed greater distortion in paternal than maternal parents. The Ψ ranged from 1.879 to 4.035 with greater ψm than ψf , and the Np varied from 14.8 to 36.8. When pooled, the relative effective number of parents was improved as 80.0% of the census number.Conclusions: We recommend the use of fertility variation (CV, Ψ), Person’s product-moment correlation (r) and effective number of parents (Np) as tools for gauging gene diversity of seed crops in production populations. For increasing Np and gene diversity, additional management options such as mixing seed-lots, equal cone harvest and application of supplemental-mass-pollination are recommended.