Gametic Contributions Research Articles

Evolution of obligate asexuality in termites with mixed‐sex societies

AbstractMales are a ubiquitous feature of animals and play crucial roles beyond the contribution of gametes in some species (e.g., paternal care for offspring and nuptial gifts for females). In termites, colonies commonly consist of both male and female reproductives, workers, and soldiers (i.e., mixed‐sex societies), where males and females both play critical roles beyond reproduction (e.g., brood care, foraging, nest construction and maintenance, and colony defense). Male‐specific roles may also exist in termite colonies. While obligate asexuality had not been observed in any termite population until recently, all‐female asexual populations of the termite Glyptotermes nakajimai were reported in 2018. This was the first and only known case of evolutionary transition from mixed‐sex to all‐female asexual societies in animals. Here, asexual reproduction in termites is first reviewed, followed by a discussion of how and why G. nakajimai evolved obligate asexuality. The study of the evolution of obligate asexuality in termites with mixed‐sex societies is important because it may enhance our understanding of the significance of males in animal societies and populations.

Divergent Aspergillus flavus corn population is composed of prolific conidium producers: Implications for saprophytic disease cycle

ABSTRACT The ascomycete fungus Aspergillus flavus infects and contaminates corn, peanuts, cottonseed, and tree nuts with toxic and carcinogenic aflatoxins. Subdivision between soil and host plant populations suggests that certain A. flavus strains are specialized to infect peanut, cotton, and corn despite having a broad host range. In this study, the ability of strains isolated from corn and/or soil in 11 Louisiana fields to produce conidia (field inoculum and male gamete) and sclerotia (resting bodies and female gamete) was assessed and compared with genotypic single-nucleotide polymorphism (SNP) differences between whole genomes. Corn strains produced upward of 47× more conidia than strains restricted to soil. Conversely, corn strains produced as much as 3000× fewer sclerotia than soil strains. Aspergillus flavus strains, typified by sclerotium diameter (small S-strains, <400 μm; large L-strains, >400 μm), belonged to separate clades. Several strains produced a mixture (M) of S and L sclerotia, and an intermediate number of conidia and sclerotia, compared with typical S-strains (minimal conidia, copious sclerotia) and L-strains (copious conidia, minimal sclerotia). They also belonged to a unique phylogenetic mixed (M) clade. Migration from soil to corn positively correlated with conidium production and negatively correlated with sclerotium production. Genetic differences correlated with differences in conidium and sclerotium production. Opposite skews in female (sclerotia) or male (conidia) gametic production by soil or corn strains, respectively, resulted in reduced effective breeding population sizes when comparing male:female gamete ratio with mating type distribution. Combining both soil and corn populations increased the effective breeding population, presumably due to contribution of male gametes from corn, which fertilize sclerotia on the soil surface. Incongruencies between aflatoxin clusters, strain morphotype designation, and whole genome phylogenies suggest a history of sexual reproduction within this Louisiana population, demonstrating the importance of conidium production, as infectious propagules and as fertilizers of the A. flavus soil population.

Visualizing and Inferring Chromosome Segregation in the Pedigree of an Improved Banana Cultivar (Gold Finger) with Genome Ancestry Mosaic Painting

Banana breeding faces numerous challenges, such as sterility and low seed viability. Enhancing our understanding of banana genetics, notably through next-generation sequencing, can help mitigate these challenges. The genotyping datasets currently available from genebanks were used to decipher cultivated bananas’ genetic makeup of natural cultivars using genome ancestry mosaic painting. This article presents the application of this method to breeding materials by analyzing the chromosome segregation at the origin of ‘Gold Finger’ (FHIA-01), a successful improved tetraploid variety that was developed in the 1980s. First, the method enabled us to clarify the variety’s intricate genetic composition from ancestral wild species. Second, it enabled us to infer the parental gametes responsible for the formation of this hybrid. It thus revealed 16 recombinations in the haploid male gamete and 10 in the unreduced triploid female gamete. Finally, we could deduce the meiotic mechanism lying behind the transmission of unreduced gametes (i.e., FDR). While we show that the method is a powerful tool for the visualization and inference of gametic contribution in hybrids, we also discuss its advantages and limitations to advance our comprehension of banana genetics in a breeding context.

The effects of fertility and synchronization variation on seed production in two Chinese fir clonal seed orchards

Variations in fertility and synchronization information is fundamental to seed orchard management. Our objective was to determine clonal variation and stability in strobili production, phenology, synchronization, and seed production in two generation clonal seed orchards (CSO) of Chinese fir. The number of female and male strobili and the phenology of 42 clones in both the 2.0- and 2.5-generation clonal seed orchards were investigated and recorded to calculate the variation and stability of fertility and synchronization. In both seed orchards, an obvious variation in gamete contribution was found among clones, indicating deviation from random mating. Female receptivity was in the pollen shedding stage, which is favorable to pollination. However, low synchronization (mean POij = 0.283) between clones indicated low overlap between female receptivity and pollen shedding. A higher POij value within clones than within outcrossing combinations indicated a high risk of selfing in two seed orchards, particularly for early- and late-flowering clones. The number of female strobili and POij (as female) significantly influence seed production. Overall, fertility and synchronization variation had notable consequences for seed production. Scientific genetic management is indispensable for promoting fertility uniformity and synchronization to obtain maximal genetic gain.

Variation of Fertility and Phenological Synchronization in Cunninghamia lanceolata Seed Orchard: Implications for Seed Production

Reproductive synchronicity between parents influences the seed production and quality in seed orchards. Our objective was to determine clonal variation in fertility and phenological synchronization, as well as their effect on seed production, in a Chinese fir (Cunninghamia lanceolata) open-pollinated seed orchard. Significant variation of female fertility and male phenological synchronization occurred in the clones. The flowering of the male was 2 days earlier than the female. The gamete contribution of female and male were unbalanced between clones (the phenological synchronization indexes (POij) were 0.000–0.585 (as female) vs. 0.000–0.385 (as male)). In general, the average POij value of as a male was lower than as a female, but the number of male flowers were significantly higher than female, indicating that the management of female flowers should be enhanced. The average POij of self-pollination was 0.298, higher than cross-pollination (0.236), indicating that there was a larger probability to selfing in the orchard. The middle phenological type possessed higher phenological synchronization indexes than early and late phenological type. Genetic control was stronger for number of female flowers (H2 = 0.277) than for male and female initial stages and flower duration (H2 = 0.193–0.239). We found a positive correlation between POij and TSW (r = 0.756), SOsc (r = 0.612), and Cp (r = 0.337), suggesting the phenological synchronization determined the seed quality and yield. Comprehensively, this study provided fertility and phenology information for management of a Chinese fir seed orchard, as well as a reference for the establishment of advanced seed orchards of conifer trees.

P-270 Assisted gamete treatment to pinpoint acquired meiotic maturity and overcome oocyte activation deficiency contributed by both gametes

Abstract Study question How can we treat couples with complete and persistent fertilization failure with ICSI linked to a combination of oocyte- and sperm-related oocyte activation deficiency (OAD)? Summary answer By targeting spindle presence, we optimized oocyte response to chemical activation and enhanced fertilization. Genomic assessment confirmed gamete contribution. What is known already Total fertilization failure occurs in 1-3% of all intracytoplasmic sperm injection (ICSI) cases. In sperm-factor OAD, the lack of phospholipase C zeta (PLCζ) prevents the spermatozoon from initiating downstream calcium oscillation in the oocyte. In these cases, assisted gamete treatment (AGT), which exposes gametes to calcium ionophore, has been adopted to artificially trigger the influx of calcium ions and has been shown to effectively improve fertilization. However, AGT is limited to triggering an intracytoplasmic calcium influx and still requires optimal ooplasmic maturity. Study design, size, duration Over the past 17 months, we identified couples with compromised PLCζ and reported persistent fertilization failure with ICSI despite AGT treatment. We then devised a treatment plan comprising an extended in vitro culture (IVC) to pinpoint meiotic oocyte maturity confirmed by the presence of a meiotic II spindle and followed by AGT post-ICSI. Genomic assessment was also carried out. Participants/materials, setting, methods Two couples with recurrent and total fertilization failure even after AGT were included. PLCζ expression was assessed using immunofluorescence on ≥ 200 cells/specimen with a 30% threshold. In the follow-up cycles, IVC was extended for at least 8 hours between retrieval and ICSI. Metaphase II spindles were visualized by Oosight®. AGT was performed by exposing both spermatozoa and oocytes to calcium ionophore. NGS was performed on spermatozoa to identify gene mutations involved in fertilization. Main results and the role of chance We identified 2 couples (couple A: 37-year-old female, 39-year-old male; couple B: 32-year-old female, 33-year-old male) with the following semen parameters: average volume of 2.6 ml, concentration of 82.0x106/ml, 44% motility, and normal morphology of 3%. The oocyte maturation rate was 76.3% (45/59) but resulted in zero fertilized out of a total of 45 MII oocytes injected. In-house PLCζ assessment revealed a deficiency of oocyte activation factor at 12.9%. AGT treatment alone failed to enhance fertilization on a subsequent cycle, resulting in 0% (0/8) and 5.6% (1/18) fertilization rates for couples A and B, respectively. Couple A then underwent 3 ICSI cycles with extended IVC and AGT; upon examination of nuclear maturity, 91.4% (32/35) of oocytes displayed normal metaphase II spindle and achieved an overall fertilization rate of 43.8% (14/32). To date, 12 blastocysts were cryopreserved. In couple B, 27 oocytes out of 34 retrieved presented normal metaphase II spindles after extended IVC; ICSI with AGT yielded a fertilization rate of 63.0% (17/27). All 17 zygotes were cryopreserved. Overall, our treatment improved fertilization to an overall rate of 52.5% (31/59, P &amp;lt;0.00001). Genomic assessment of spermatozoa identified gene mutations involved in fertilization (ADAM15, ADAM30) and calcium channel activity (CATSPER1). Limitations, reasons for caution Assisted gamete treatment can enhance fertilization in cases of deficiency in PLCζ. However, chemical activation requires a responsive ooplasm that has reached meiotic maturity. These rare cases require precise diagnoses and tailored treatment techniques to address each aspect of sperm- and/or oocyte-factor OAD. Wider implications of the findings Our study has demonstrated the usefulness of extended IVC by targeting spindle presence to enhance chemical responses to AGT. Our findings show that although calcium ionophore can trigger the release of intracellular calcium and allow fertilization, a fully mature ooplasm is required. Trial registration number N/A

Enhanced heterozygosity from male meiotic chromosome chains is superseded by hybrid female asexuality in termites

Although males are a ubiquitous feature of animals, they have been lost repeatedly in diverse lineages. The tendency for obligate asexuality to evolve is thought to be reduced in animals whose males play a critical role beyond the contribution of gametes, for example, via care of offspring or provision of nuptial gifts. To our knowledge, the evolution of obligate asexuality in such species is unknown. In some species that undergo frequent inbreeding, males are hypothesized to play a key role in maintaining genetic heterozygosity through the possession of neo-sex chromosomes, although empirical evidence for this is lacking. Because inbreeding is a key feature of the life cycle of termites, we investigated the potential role of males in promoting heterozygosity within populations through karyotyping and genome-wide single-nucleotide polymorphism analyses of the drywood termite Glyptotermes nakajimai We showed that males possess up to 15 out of 17 of their chromosomes as sex-linked (sex and neo-sex) chromosomes and that they maintain significantly higher levels of heterozygosity than do females. Furthermore, we showed that two obligately asexual lineages of this species-representing the only known all-female termite populations-arose independently via intraspecific hybridization between sexual lineages with differing diploid chromosome numbers. Importantly, these asexual females have markedly higher heterozygosity than their conspecific males and appear to have replaced the sexual lineages in some populations. Our results indicate that asexuality has enabled females to supplant a key role of males.

Forest cover at landscape scales increases male and female gametic diversity of palm seedlings.

Genetic diversity shapes the evolutionary potential of plant populations. For outcrossing plants, genetic diversity is influenced by effective population size and by dispersal, first of paternal gametes through pollen, and then of paternal and maternal gametes through seeds. Forest loss often reduces genetic diversity, but the degree to which it differentially impacts the paternal and maternal contributions to genetic diversity and the spatial scale at which these impacts are most pronounced are poorly understood. To address these questions, we genotyped 504seedlings of the animal-dispersed palm Oenocarpus bataua collected from 29 widely distributed sites across Ecuador and decomposed the contribution of paternal and maternal gametes to overall genetic diversity. The amount of forest cover at a landscape scale (>10km radius) had an equally significant positive association with both male and female gametic diversity. In addition, there was a significant positive association between forest cover and effective population size. Stronger fine-scale spatial genetic structure for female versus male gametes was observed at sites with low forest cover, but this did not scale up to differences in male versus female gametic diversity. These findings show that reductions in forest cover at spatial scales much larger than those typically evaluated in ecological studies lead to significant, and equivalent, decreases of diversity in both male and female gametes, and that this association between landscape level forest loss and genetic diversity may be driven directly by reductions in effective population size of O. bataua, rather than by indirect disruptions to local dispersal processes.

62 Investigating differences in gene expression between invitro-produced bovine embryos and parthenotes

Parthenogenic activation allows for the development of an oocyte without male gamete contribution and may serve as a suitable model for understanding maternal and paternal contributions during development. In the bovine, parthenotes lack the ability to survive to term once transferred into females. The goal of this study was to investigate the gene expression profile at the blastocyst stage in parthenotes and embryos by characterising expression of developmentally important genes, such as markers for pluripotency (OCT4, NANOG), hypoblast (GATA6), epiblast (SOX2), trophectoderm (CDX2), and maternal-embryo communication (IFNT2). To test this, IVM oocytes were either fertilized to a bull with known fertility invitro or activated. To activate, oocytes were denuded, and placed in ionomycin calcium salt for 5min. They were incubated for 3h in 6-(dimethylamino)purine (6-DMAP) and placed in synthetic oviductal fluid (SOF). Putative zygotes and activated oocytes were cultured in SOF for 8 days. Cleavage (at least one cellular division) was recorded on Day 3 and development to the blastocyst stage was recorded on Day 8 after insemination or activation. Cleavage rate was 85.9% and 83.2% for parthenotes and embryos, respectively. Both groups produced a similar blastocyst rate, 32.3% for parthenotes and 33.7% for embryos. On Day 8, blastocyst stage parthenotes and embryos were collected. Data were analysed by ANOVA (Tukey HSD post hoc test) using the GLM procedure of SAS version 9.4. Pools of 5 embryos or parthenotes (3 replicates) were flash frozen and stored until RNA isolation (PicoPure™ RNA Isolation Kit). Real-time PCR was used for quantification of gene expression. Genes were analysed relative to a housekeeping gene, GAPDH. There was no difference in gene expression detected for OCT4 (P=0.25), NANOG (P=0.11), GATA6 (P=0.32), SOX2 (P=0.25), or IFNT2 (P=0.52). Expression of CDX2 was lower in the parthenotes than the embryos (P=0.05). In a second experiment, the proteins GATA6, NANOG, and CDX2 were immunolocalized in 17 parthenotes and 15 embryos. Fixed embryos were permeabilized, blocked, and placed in primary antibodies overnight. After, they were placed into the secondary antibody for 1h, followed by nuclear stain. There was a decreased mean intensity of CDX2 in the parthenotes compared to embryos (P=0.005). No difference (P&amp;gt;0.05) in GATA6 or NANOG was observed between the 2 groups. The ratio of inner cell mass to trophectoderm was higher (P=0.04) in the parthenotes (2.5±0.23) than in the embryos (1.7±0.25). Here we analysed and confirmed the expression of developmentally important genes at the blastocyst stage in embryos and parthenotes. CDX2, a marker of the trophectoderm that will later give rise to the placenta, was downregulated in parthenotes. This highlights the importance of the contribution of the paternal genome to development. Further research is necessary to elucidate the ability of the parthenotes to establish and maintain pregnancy. This research was supported by the National Needs Fellowship funded by USDA NIFA Grant 2019-38420-28972.

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.

Modeling the reproductive impact of aquaculture-produced sexually fertile triploids on conspecific diploid populations

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 11:205-211 (2019) - DOI: https://doi.org/10.3354/aei00308 Modeling the reproductive impact of aquaculture-produced sexually fertile triploids on conspecific diploid populations Federico M. Winkler1,2,3,*, Miguel Concha4, Christopher Concha1 1Departamento de Biología Marina, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo 1780000, Chile 2Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Larrondo 1281, Coquimbo 1780000, Chile 3Centro de Innovación Acuícola AquaPacífico, Universidad Católica del Norte, Larrondo 1281, Coquimbo 1780000, Chile 4Departamento de Física, Liceo Bicentenario Alejandro Álvarez Jofre, Victoria 150, Ovalle 1840000, Chile *Corresponding author: fwinkler@ucn.cl ABSTRACT: The use of artificially produced triploid (3n) organisms has been proposed as a strategy to produce total or partial sterility in a number of species in order to prevent the potential negative effects of escapees on the genetic structure and integrity of wild conspecific populations or to avoid having alien species become feral in a new environment. When infertility is incomplete, triploid organisms are able to produce gametes that compete with those produced by wild diploid populations or crops that share the same habitat during reproductive periods, which may adversely affect the reproductive success of the wild population. In the present study, a model was developed in order to estimate the effects of the production of gametes by triploid organisms on the reproductive efficiency of a sympatric diploid population of the same species. The chance of the production of balanced gametes by triploids rapidly reduced with the increase of haploid number of the species. It was concluded that, in most aquatic species, this effect depends on the relative contribution of gametes derived from triploid individuals ( pet), which is determined by the proportion of triploids in the population and their relative fecundity relative to normal diploids. The variation of the reproductive efficiency in a mixed population of diploids and triploids will be directly proportional to pet if only one sex is fertile in triploids but will have a logarithmic relationship if both sexes are fertile. KEY WORDS: Triploids · Risk assessment · Reproductive success · Sterility · Chromosome manipulation · Fecundity Full text in pdf format PreviousNextCite this article as: Winkler FM, Concha M, Concha C (2019) Modeling the reproductive impact of aquaculture-produced sexually fertile triploids on conspecific diploid populations. Aquacult Environ Interact 11:205-211. https://doi.org/10.3354/aei00308 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 11. Online publication date: May 23, 2019 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2019 Inter-Research.

Genetic variability of an orange-shell line of the Pacific oyster Crassostrea gigas during artificial selection inferred from microsatellites and mitochondrial COI sequences

Rare breeds represent a valuable resource for current or future market demands, but their low census compromises the genetic variability and future utilization of these breeds. Whether genetic variability of rare breeds with low initial genetic variation can be maintained during an intense mass selection becomes the key to applying mass selection to the genetic improvement of these breeds. The genetic variability among three generations of successive mass selection of the orange-shell line of Crassostrea gigas (MS1–MS3) were evaluated by both 20 nuclear microsatellite loci and mitochondrial cytochrome oxidase I sequences (mtCOI) compared to four wild populations. In this study, the orange-shell line exhibited very low genetic variability. Only one mtCOI haplotype was detected in all individuals of MS1–MS3. Significant reductions in average number of alleles (Na: 69.55–76.92%), allelic richness (Ar: 68.17–74.91%) and expected heterozygosity (He: 34.21–39.24%) as well as increased mean pairwise genetic relatedness (R: 6.87–25.79 times) were observed in MS1–MS3 when compared to wild populations. However, the genetic variability of orange-shell line with very low initial variation successfully maintained during three generations of mass selection. No significant difference in Na (3.60–4.40), Ar (3.51–4.08) and He (0.48–0.50) occurred among MS1–MS3. Pedigree reconstructions (no full-sib group from MS1–MS3 was larger than 16% of the whole group) revealed artificial spawning used in this study has a better control over contribution of gametes than traditional mass spawning. In addition, effective population size of MS1–MS3 calculated by linkage disequilibrium methods increased from 29.3 to 67.0 indicating the linkage disequilibrium decays over time. This study provides important insights in the genetic consequences of a rare variant line of C. gigas with very low genetic variation over generations of mass selection. This will provide a reference for carrying out genetic improvement programs on rare breeds where small populations are inevitable.

Temporal quantification of mating system parameters in a coastal Douglas-fir seed orchard under manipulated pollination environment

Seed orchards main function is delivering breeding programs’ gains in the form of genetically improved seedlings. They are unique experimental populations, perfectly suited for studying various pollination environments (natural or otherwise), affecting their mating system parameters. Here, under different pollination environment (natural and intrusive (pollen augmentation and/or bloom-delay)), the mating system of a second generation, wind-pollinated, coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) seed orchard was evaluated over four years. Using DNA microsatellite markers and bulk seed samples, we conducted pedigree reconstruction to assign each seed’s male and female parents, followed by determining the extent of pollen contamination (external gene flow), selfing rate, and, parental gametic contribution for each year. Overall, external pollen contamination rates ranged between 10 and 28%, selfing rate varied between 12 and 17%, and 80% of the seed crops were produced by 37–64% of the orchard’s parents. Pollination environment and seed crop size substantially influenced the observed results, particularly for small crops as pollen contamination was high in natural (28%) vs. intrusive pollination (10%). Generally, irrespective of the crop size, seed produced under natural pollination had higher pollen contamination, confirming the role of pollination environment manipulation in improving seed crops’ genetic quality.

Mating patterns and pollen dispersal in a Japanese larch (Larix kaempferi) clonal seed orchard: a case study.

Pollination dynamics highly determines the genetic quality of seed orchard crops. However, there is less research about the effect of mating patterns on seed productivity of orchard crops. So far, clonal seed orchards have been producing genetically improved seedlings used for most Japanese larch (Larix kaempferi (Lamb.) Carr.) plantations in China. In the present study, a total of 17 highly variable simple sequence repeat (SSR) markers were used for genotyping a progeny trial population consisting of 647 open-pollinated progenies germinated from seeds which were collected from 63 maternal clones with 140 potential paternal clones in a Japanese larch clonal seed orchard in China. Paternity analysis was used in the present case study in order to evaluate the level of paternal gametic contribution, estimate pollen contamination and selfing rates, and investigate pollination patterns, pollen dispersal patterns and the impact of mating patterns on seed productivity of orchard crops. We observed 93.7% of the success rate of the parental assignment, unequal paternal gametic contribution (0-12.4%) with 6.3% of the progenies derived from pollen contamination or unsampled pollen donors, and absence of evidence for selfing. We also found that pollination rate highly depended on the distance between pollen donors and maternal parents, the majority of the identified crossing (65.7%) occurred between clones within a 150-m radius, and large variations in growth performance existed among the paternal half-siblings. Progeny growth performance (diameter at breast (DBH) and height (HGT)) was measured at Age-20 in order to investigate the impact of mating patterns on timber production of orchard crops. As either the paternal or maternal, two clones (i. e., clones Z38 and Z62) were identified to have produced progenies with higher average stem volume breeding values than that of all of the progenies. Specifically, the genetic gains for volume were 3.53% for the two clones as paternal parents, and 8.26% as the maternal parents at Age-20. Thus, both elite clones were ideal candidates for the construction of next-generation clonal seed orchards due to their synchronous reproductive phenology with greater crossing rate and higher genetic gain. These results improved the pedigree information to provide solid evidence of mating patterns for future design and effective management of seed orchards and for the development of viable long-term breeding strategies for other coniferous species.

On the Consequences of Purging and Linkage on Fitness and Genetic Diversity

Using computer simulation we explore the consequences of linkage on the inbreeding load of an equilibrium population, and on the efficiency of purging and the loss of genetic diversity after a reduction in population size. We find that linkage tends to cause increased inbreeding load due to the build up of coupling groups of (partially) recessive deleterious alleles. It also induces associative overdominance at neutral sites but rarely causes increased neutral genetic diversity in equilibrium populations. After a reduction in population size, linkage can cause some delay both for the expression of the inbreeding load and the corresponding purging. However, reasonable predictions can be obtained for the evolution of fitness under inbreeding and purging by using empirical estimates of the inbreeding depression rate. Purging selection against homozygotes for deleterious alleles affects the population’s pedigree. Furthermore, it can slow the loss of genetic diversity compared to that expected from the variance of gametic contributions to the breeding group and even from pedigree inbreeding. Under some conditions, this can lead to a smaller loss of genetic diversity, even below that expected from population size in the absence of selection.

Estimates of pollen contamination and selfing in a coastal Douglas-fir seed orchard

Seed orchards are the link from tree breeding to reforestation programs and are theoretically expected to function as closed, perfect populations, ensuring gain and diversity are consistently and predictively delivered as improved seed and seedlings. Seed orchard populations often deviate from panmixia due to fertility variation, reproductive asynchrony, and gene flow, leading to reduced seed crops genetic quality. Here, as a part of multiyear monitoring study, we used DNA fingerprinting (simple sequence repeat markers) to assess a Douglas-fir (Pseudotsuga menziesii) seed orchard's seed crop genetic quality (2009 seed crop). The studied seed crop was produced under ambient temperature (i.e. no reproductive phenology manipulation) and pollination was augmented by pollen from within orchard's pollen donors. DNA fingerprinting of the parental population (66 parents) along with 207 gametophyte (1n) – embryo (2n) pairs of random bulk sample of seed allowed parentage (maternal and paternal) assignment and the direct assessment of pollen contamination (0.18 ± 0.027) and selfing (0.17 ± 0.025) rates as well as parental (pollen, ovule and individual parent) gametic contribution was compared to a previous year's crop (2005). The extended reproductive phenology coupled with variable within-orchard pollen availability has created opportunities for both self and foreign pollen to be successful at various times resulting in the seemingly paradoxical scenario of high selfing and gene flow. These results (2005 and 2009) allowed comparison of seed orchard's crop management practices and are expected to provide scientific foundations to effective seed crops genetic quality improvement.

Determination of paternal and maternal parentage in lodgepole pine seed: full versus partial pedigree reconstruction

Estimating seed orchards’ maternal and paternal gametic contributions is of importance in assessing the genetic quality of seed crops. The advantage of full over partial pedigree reconstruction in investigating the mating dynamics in a lodgepole pine (Pinus contorta Dougl. ex. Loud. ssp. latifolia Engelm.) seed orchard population (N = 74) was demonstrated using nuclear and chloroplast microsatellite markers. We analyzed offspring of equivalent sample sizes representing full (bulk seed with unknown maternal and paternal parentage (n = 635)) and partial (11 maternal family arrays (n = 619)) pedigree reconstruction methods. Small differences in selfing rate, gene flow, and male reproductive success were observed between the two methods; however, the full pedigree reconstruction enabled simultaneous estimation of female-related fertility parameters (female reproductive success and effective number of maternal parents) that partial pedigree reconstruction could not provide. The use of bulk random sample of seed from orchards’ crops is recommended when male and female fertility parameters, as well as selfing and contamination rates, are needed for seed orchards’ seed crops genetic rating.

The possible effect of gamete cell quality on IVF outcome: experience on both fresh and frozen vitrified/warmed human oocytes in a donation programme

In failed IVF treatments, individual contribution of gametes on the outcome is mostly hampered by the multiparametric nature of observations. This study has been performed in order to evaluate the impact of gamete cell characteristics by using donated gamete cells that has been shared by at least two different gamete donors with different cell characteristics.

Experimental Effects of Temperature and Photoperiod on Synchrony of Gametogenesis and Sex Ratio in the European OysterOstrea edulis(Linnaeus)

Insufficient knowledge about physiological processes underpinning reproduction in the European flat oyster, Ostrea edulis (Linnaeus), presents a number of unique challenges when designing a large-scale selective breeding program for hatchery production. The European flat oyster is a larviparous, protandric hermaphrodite wherein asynchronous spawns and variable sex ratios can lead to loss of genetic diversity and inbreeding depression within hatchery populations as a result of disproportionate gametic contributions in mass matings. A better understanding of O. edulis physiology in relation to environmental factors has the potential to improve hatchery processes for synchronization of gametogenesis, thus increasing fertilization potential and maximizing breeding population size of broodstock. This study sought to determine whether specific conditioning procedures—notably, manipulation of temperature and photoperiod—could be used to improve synchrony of gametogenesis and predictability of sex ratios in O. edulis. Two trials of accelerated yearly variations of temperature and photoperiod were conducted to uncouple the specific role of these factors in the timing of gametogenesis and sex of gametes over several spawning cycles. Histological analysis and quantitative analysis of gonad using a gonad filling index allowed for determination of sex ratios and staging of gametogenesis. Temperature was a controlling factor, although experimental results suggested that the effects of photoperiod, uncoupled from temperature, had no effect on the timing or rate of gametogenesis, or on sex ratios during a breeding season. A better understanding of factors affecting sex ratio and synchrony in timing of gamete release will allow for improved conditioning and broodstock handling protocols in the selective breeding of O. edulis.

On the Moral Asymmetry of Gametic Contributions

An Ravelingien and Guido Pennings (2013) argue that donor-conceived children have a moral right to know the identity of their genetic fathers 1 in cases in which the genetic father is not the socia...