Effective Number Of Parents Research Articles

Fertility Variation and Effective Population Size across Varying Acorn Yields in Turkey Oak (Quercus cerris L.): Implications for Seed Source Management

This research examines the impact of varied acorn yields on the effective population size of Turkey oak (Quercus cerris L.) as assessed through the fertility averages of zygotic parents. We selected two distinct populations from the species’ natural habitats based on their good and poor acorn production rates to investigate acorn production, growth attributes, and their interrelationships over three years of production and two years of growth data. Results showed that the population with good acorn production exhibited greater growth attributes and acorn yields compared to the poor acorn production population. Acorn production had lower coefficients of variation compared to growth attributes. Fertility variation in both populations was moderate, with a decrease in the effective number of parents from the population with abundant acorn production to the one with limited acorn production. The presence of mixed seeds from diverse populations had a detrimental impact on fertility variation and related metrics. Nonetheless, this study suggests that regions with limited acorn production still have the potential for natural regeneration due to their larger effective population size when coupled with appropriate forestry practices such as selective acorn harvesting to enhance genetic diversity. These findings emphasize the importance of accounting for fertility variation in the selection and management of seed sources, even within the context of a limited area and three years of data. Further research should be conducted in larger populations and over longer periods to draw more comprehensive conclusions.

Impact of Crown Closure on Cone Production and Effective Number of Parents in Natural Stands of Taurus Cedar (Cedrus libani A. Rich.)

This study was carried out to estimate the effect of crown closure classes (degraded forest, low crown coverage, medium crown coverage, and full crown coverage) and growth characteristics (three heights, diameter at base, diameter at breast height, and crown diameter) on cone production and to estimate fertility variation and its allied parameters in 130-year-old natural populations of Taurus cedar, also called cedar of Lebanon (Cedrus libani A. Rich.). The effect of biotic (e.g., growth characteristics, crown closure) and abiotic (e.g., light penetration, temperature, humidity, and soil characteristics) factors on cone production, fertility variation, and gene diversity was evaluated in two consecutive years of Taurus cedar. The factors, viz., altitude, temperature, aspect, and rainfall, varied, while some of them could be managed by cultural operations such as management of the crown and stand density. The impact of crown closure on cone production, fertility variation, and related parameters were observed in Taurus cedar’s natural populations sampled from southern Turkey. Maximum cone productions of 29 and 40/tree were recorded with full crown closure in two consecutive years, due to significant differences among individuals within crown closure class. For instance, cone productions were between 10 and 67 in the full crown closure of the first year. The sibling coefficient, which is a measure of the fertility variation in a stand, was the highest (1.16) for the full crown closure in the first (meaning 86% fertile trees) and the second years (1.55, 65%), while it was the lowest for the medium crown closure (1.09, 92%) in both years. Gene diversity decreased from a degraded patch (0.987) to that with full crown closure (0.984). Results of variance analysis showed a significant (p ≤ 0.05) difference between crown closure classes for cone production within the second year and between years. Significant positive (p ≤ 0.05) correlations were noted between years for cone production (r = 0.22) and between cone production and crown closure in the first and second years (r = 0.29). However, growth characteristics had no effect on cone productions in individual crown closure classes, while there were significant (p ≤ 0.05) correlations between the diameter at breast height and cone production for both years (r = 0.15 and 0.17) in pooled populations.

Fertility variation, seed collection and gene diversity in natural stands of Taurus cedar (Cedrus libani)

Seed stand is a natural forest population that is one of the essential seed sources for global seed supply. Individual fertility is an ability to produce progeny to next generation. Prediction of fertility variation is useful for seed quality, ecosystem management and gene conservation. Fertility variation and gene diversity in seed stands of Taurus cedar were estimated based on the difference in strobilus production between female and male parents. A total of 50 trees were randomly chosen from each stand, and female and male strobili were counted for three consecutive years. The mean of female strobili ranged from 31 to 150, and that of male ranged between 77 and 828. The variation in strobilus production was subjected to estimation of female and male fertility variation. The total fertility variation (\(\Psi\)) was estimated from the female and male fertility variation. The \(\Psi\) in a good crop year was smaller than in a poor year. The effective number of parents (Np) was calculated based on the \(\Psi\), which varied from 34.7 to 44.2. When strobilus productions were pooled across 3 years or populations, the Np increased. Equal cone harvest could mitigate the fertility variation among individuals but caused loss of seed production. Mixing seeds from different years could also decrease the fertility variation and increase the gene diversity of seeds. However, a balance between the size of Np and the number of pooling years should be carefully considered for maintaining the gene diversity in the natural stands.

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

BackgroundGender 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.ResultsEffective 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.ConclusionsWe 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.

Aspectual Fertility Variation and Its Effect on Gene Diversity of Seeds in Natural Stands of Taurus Cedar (Cedrus libani A. Rich.).

There are many environmental and biological factors on forestry practices as known. Aspect called as slope faces is one of the most important environmental factors in these practices because of its easy application for managers. Fertility variation defined as an individual ability to give progeny and gene diversity estimated based on effective number of parents were investigated as the proportion of numbers of cones counted from individuals in natural stands sampled aspectual of Taurus cedar (Cedrus libani A. Rich.) for three consecutive years. The averages of cone number were 19.4, 47.2, and 75.5 for the years. It was the highest in flat (23.5) for 2013, in south (92.1) for 2014, and in flat (95.7) for 2015, while it was lowest in south (16.3), in east (18.2), and in north (39.4) for the years, respectively. Significant correlations (p ≤ 0.01) were estimated among years for cone production in polled aspect. Estimated fertility variations changed for the years and stands. It could be generally acceptable level for typical natural stands except of west of 2014. Fertility variations were 1.55, 3.05, and 1.64 in polled stands for the years. Gene diversity was 0.99 for the years in polled stands. North aspect could be taken into consideration in establishment and selection of seed sources and gene conservation areas based on fertility variation and gene diversity.

Fertility variation in endemic populations of Ehrami black pine (Pinus nigra Arnold. subsp. pallasiana var. pyramidata)

Fertility variation and effective number of parents were estimated in the 100 individuals from each of three plantation populations (P1, P2 and P3) of the endangered Pinus nigra. subsp. pallasiana var. pyramidata established in the Isparta–Golcuk district in southern Turkey in 1990. Potential relations between cone yield and growth characters (height, diameter at breast height, diameter at base and crown diameter) were also investigated. Large differences were found among populations and within populations for cone production and growth characters. Mean cone production was eight (ranging from 6.5 in P2 to 9.1 in P1) for the three populations. The 10 most productive individuals for cones produced 32% of the total cones in P1, 39% in P2 and 34% in P3; 21, 16 and 6 individuals, respectively did not produce any cones in the populations. According to the correlation analyses, the relation between cone yield and growth characters changed for the populations, while height, diameter at breast height and crown diameter were positively significantly correlated (r = 0.182, 0.135 and 0.209; p ≤ 0.05) with cone production for the three populations. Fertility variation was 1.81 in total of three populations, ranging from 1.72 in P3 to 3.45 in P1). Effective number of parents was 142 (55.2 of number of parents censused; 29%, P1; 49.8%, P2; 58.3%, P3).

Long-term effective population size dynamics of an intensively monitored vertebrate population.

Long-term genetic data from intensively monitored natural populations are important for understanding how effective population sizes (Ne) can vary over time. We therefore genotyped 1622 common buzzard (Buteo buteo) chicks sampled over 12 consecutive years (2002-2013 inclusive) at 15 microsatellite loci. This data set allowed us to both compare single-sample with temporal approaches and explore temporal patterns in the effective number of parents that produced each cohort in relation to the observed population dynamics. We found reasonable consistency between linkage disequilibrium-based single-sample and temporal estimators, particularly during the latter half of the study, but no clear relationship between annual Ne estimates () and census sizes. We also documented a 14-fold increase in between 2008 and 2011, a period during which the census size doubled, probably reflecting a combination of higher adult survival and immigration from further afield. Our study thus reveals appreciable temporal heterogeneity in the effective population size of a natural vertebrate population, confirms the need for long-term studies and cautions against drawing conclusions from a single sample.

Clonal fertility variation and its effects on the effective population size in the seed orchard of dioecious species, Fraxinus rhynchophylla

Abstract The numbers of female and male flowers were assessed in a clonal seed orchard of Fraxinus rhynchophylla for four consecutive years from 2004 through 2007. The female and male flowers of the grafts from 48 clones were counted individually over the crown. Fertility variation was calculated by sibling coefficient that is related to the coefficient of variation in parental flower assessment. Estimated maternal and paternal fertilities were not constant but varied from year to year, and they were also found to be weakly correlated. The effective numbers of clones serving as male and female parents were calculated from the sibling coefficients of maternity and paternity. We applied two theoretical approaches to estimate the clonal effective population sizes based on 1) fertility variation (i.e., effective number of parents, N(c)) and 2) gender balance (effective population size, Ne e) among parental genotypes. The values of Ne (c) were higher in the years with abundant flowering and seed production, while sibling coefficients were lower. On average (pooled), the maternal, paternal and clonal values of Ne (c) were calculated to be 17.3, 21.0 and 38.1 respectively. The Ne (c) for maternal gamete gene pool was ranged from 9.8 to 16.7. The values of Ne for paternal gamete gene pool were generally higher (ranged from 14.9 to 21.9) than those for maternal. When pooled, the Ne was 47.2 and the values of Ne were higher when the gender ratio was more balanced. An option of equal seed harvest might be good to mitigate fertility variation and to improve gene diversity of seeds.

Inheritance pattern of microsatellite loci and their use for kinship analysis in the Japanese scallop Patinopecten yessoensis

The inheritance mode of seven microsatellite markers was investigated in Patinopecten yessoensis larvae from four controlled crosses, and the feasibility of using these markers for kinship estimation was also examined. All the seven microsatellite loci were compatible with Mendelian inheritance. Neither sex-linked barriers to transmission nor major barriers to fertilization between gametes from the parents were evident. Two of the seven loci showed the presence of null alleles in two families, suggesting the need to conduct comprehensive species-specific inheritance studies for microsatellite loci used in population genetic studies. However, even if the null allele heterozygotes were considered as homozygotes in the calculation of genetic distance, offspring from four families were all unambiguously discriminated in the neighbor-joining dendrogram. This result indicates that the microsatellite markers used may be capable of discriminating between related and unrelated scallop larvae in the absence of pedigree information, and of investigating the effective number of parents contributing to the hatchery population of the Japanese scallop.

Inheritance mode of microsatellite loci and their use for kinship analysis in the Pacific oyster (Crassostrea gigas)

Five full-sib families of the Pacific oyster (Crassostrea gigas) larvae were used to study the mode of inheritance at eight microsatellite loci, and the feasibility of these markers for kinship estimate was also examined. All eight microsatellite loci were compatible with Mendelian inheritance. Neither evidence of sex-linked barriers to transmission nor evidence of major barriers to fertilization between gametes from the parents was shown. Three of the eight loci showed the presence of null alleles in four families, demonstrating the need to conduct comprehensive species-specific inheritance studies for microsatellite loci used in population genetic studies. Although the null allele heterozygotes were considered as homozygotes in the calculation of genetic distance, offspring from five full-sib families were unambiguously discriminated in the neighbor-joining dendrogram. This result indicates that the microsatellite markers may be capable of discriminating between related and unrelated oyster larvae in the absence of pedigree information, and is applicable to the investigation of the effective number of parents contributing to the hatchery population of the Pacific oyster.

In-Breeding Effect on Performance of Rhode Island Chickens Selected for Part-Period Egg Production

Data from 4336 pullets progeny of 144 sires and 779 dams for strain A and 4843 pullets, progeny of 158 sires and 1108 dams for strain B belonging to 5 generations under selection for part-period egg production to 280 days of age were used for this study. The number of pullets housed at about 18weeks per population ranged from 326 and 1000 per generation for each of the population. The effective number of parents in each generation averaged 174 and 187 for male and female populations, respectively. The traits measured were egg number to 280 days (EGG280 D), age at sexual maturity (ASM), egg weight average (EWTAV) and body weight at 40 weeks of age (BWT40). The co-efficient of inbreeding per generation due to finite population size was 0.005 for both the male and the female lines respectively. For the control population the values obtained were 0.008 vs 0.007 for both the male and female lines respectively. The average performance of the birds over the study period for the male and female lines respectively ranged from 38.38 vs 50.94 and 37.03 vs 51.25 for EGG280 D, 194 vs 212 and 197 vs 214 for ASM, 48.29 vs 55.93 and 48.29 vs 55.11 for EWTAV, 1600 vs 1754 and 1440 vs 1908 for BWT40.The effective number of parent in each generation averaging about 175 probably caused an average inbreeding of about 0.5% per generation. Although the level of inbreeding in this population is not critical there is evidence of an increasing trend, which could lead to homozygosity in the flock. There is need to widen the genetic base to prevent selection depression too early in the flock.

MASS SELECTION FOR POST-WEANING GROWTH IN SWINE: I. THE VALUE OF A PEDIGREED CONTROL POPULATION

A pedigreed control population of Yorkshire swine has been described. The average size of the breeding population was 20 males and 40 females in each of the seven generations. The effective number of parents per generation was estimated at 87.5. There has been little or no evidence of any significant changes in the genetic value of the population over the seven generations as determined by estimates of additive genetic variance, selection differentials, and other related parameters. The performance of the control population was compared with that of a selected population and with crossbreds produced by mating select population males to control population females. Comparisons were made in the same environments. The comparisons of the effects of the selection program on several traits measured in the two populations have been made, based on the absolute trends in these populations over the seven generations and as a deviation from the performance of the control population.

Relative Contributions of Genetics and Environment to Turkey Improvement

PHENOTYPIC changes (improvements) which occur over a period of years may be subdivided into a genetic and an environmental component through the use of randombred control populations. Recently, randombred control populations have been used in an attempt to hold the genetics constant and measure environmental change over years (Kinney et al., 1968; Merritt, 1968; and Kinney and Lowe, 1968).Genetic changes in a control flock may result from random changes of gene frequency due to genetic sampling or “genetic drift” and directional changes due to natural selection (Gowe et al., 1959). With additive gene action, the expected drift variance of the mean is equal to 2F σg2 where F is the inbreeding coefficient and σg2 is the additive genetic variance in the character concerned. This is equal to σg2/Ne drift variance per generation. Ne is the effective number of parents (Gowe et al., 1959). Thus, from the above, the larger…