Variation In Female Fertility Research Articles

Natural genetic variation in a dopamine receptor is associated with variation in female fertility in Drosophila melanogaster.

Fertility is a major component of fitness but its genetic architecture remains poorly understood. Using a full diallel cross of 50 Drosophila Genetic Reference Panel inbred lines with whole genome sequences, we found substantial genetic variation in fertility largely attributable to females. We mapped genes associated with variation in female fertility by genome-wide association analysis of common variants in the fly genome. Validation of candidate genes by RNAi knockdown confirmed the role of the dopamine 2-like receptor (Dop2R) in promoting egg laying. We replicated the Dop2R effect in an independently collected productivity dataset and showed that the effect of the Dop2R variant was mediated in part by regulatory gene expression variation. This study demonstrates the strong potential of genome-wide association analysis in this diverse panel of inbred strains and subsequent functional analyses for understanding the genetic architecture of fitness traits.

Physiological factors influencing female fertility in birds.

Fertility is fundamental to reproductive success, but not all copulation attempts result in a fertilized embryo. Fertilization failure is especially costly for females, but we still lack a clear understanding of the causes of variation in female fertility across taxa. Birds make a useful model system for fertility research, partly because their large eggs are easily studied outside of the female's body, but also because of the wealth of data available on the reproductive productivity of commercial birds. Here, we review the factors contributing to female infertility in birds, providing evidence that female fertility traits are understudied relative to male fertility traits, and that avian fertility research has been dominated by studies focused on Galliformes and captive (relative to wild) populations. We then discuss the key stages of the female reproductive cycle where fertility may be compromised, and make recommendations for future research. We particularly emphasize that studies must differentiate between infertility and embryo mortality as causes of hatching failure, and that non-breeding individuals should be monitored more routinely where possible. This review lays the groundwork for developing a clearer understanding of the causes of female infertility, with important consequences for multiple fields including reproductive science, conservation and commercial breeding.

Combining genetic and physiological data to identify predictors of lifetime reproductive success and the effect of selection on these predictors on underlying fertility traits

Fertility of the dairy cow relies on complex interactions between genetics, physiology, and management. Mathematical modeling can combine a range of information sources to facilitate informed predictions of cow fertility in scenarios that are difficult to evaluate empirically. We have developed a stochastic model that incorporates genetic and physiological data from more than 70 published reports on a wide range of fertility-related traits in dairy cattle. The model simulates pedigree, random mating, genetically correlated traits (in the form of breeding values for traits such as hours in estrus, estrous cycle length, age at puberty, milk yield, and so on), and interacting environmental variables. This model was used to generate a large simulated data set (200,000 cows replicated 100 times) of herd records within a seasonal dairy production system (based on an average New Zealand system). Using these simulated data, we investigated the genetic component of lifetime reproductive success (LRS), which, in reality, would be impractical to assess empirically. We defined LRS as the total number of times, during her lifetime, a cow calved within the first 42 d of the calving season. Sire estimated breeding values for LRS and other traits were calculated using simulated daughter records. Daughter pregnancy rate in the first lactation (PD_1) was the strongest single predictor of a sire's genetic merit for LRS (R2 = 0.81). A simple predictive model containing PD_1, calving date for the second season and calving rate in the first season provided a good estimate of sire LRS (R2 = 0.97). Daughters from sires with extremely high (n = 99,995 daughters, sire LRS = +0.70) or low (n = 99,635 daughters, sire LRS = -0.73) LRS estimated breeding values were compared over a single generation. Of the 14 underlying component traits of fertility, 12 were divergent between the 2 lines. This suggests that genetic variation in female fertility has a complex and multifactorial genetic basis. When simulated phenotypes were compared, daughters of the high LRS sires (HiFERT) reached puberty 44.5 d younger and calved ∼14 d younger at each parity than daughters from low LRS sires (LoFERT). Despite having a much lower genetic potential for milk production (-400 L/lactation) than LoFERT cows, HiFERT cows produced 33% more milk over their lifetime due to additional lactations before culling. In summary, this simulation model suggests that LRS contributes substantially to cow productivity, and novel selection criteria would facilitate a more accurate prediction at a younger age.

Europe-wide consistency in density-dependence of red deer (Cervus elaphus) fertility

Population dynamics of large herbivores are affected by density dependent and density independent processes. Changing population size causes variation in age- and sex-specific demographic parameters such as reproduction, survival and dispersal. With our study, based on meta-analyses of literature data, we aimed at (1) describing age-specific fertility rates of red deer (Cervus elaphus) throughout Europe, and (2) tracking negative density feedback in reproduction of female red deer. Across the species range, in most European populations (84%) females began breeding as yearlings. We observed age-specific variation in female fertility, which was the lowest and most diverse in yearling females. Increasing population density had a negative effect on female fertility in all age groups. There was no difference in the strength of the relationship between different age classes of females. In 1.5-year old females, at low and moderate densities, fertility exhibited a high variation, which could indicate strong susceptibility of youngest females to detrimental external factors. Our study showed that meta-analysis of Europe-wide data was able to detect biologically relevant relationships which may be difficult to observe when applying locally-based and time-scale approach.

Fertility variation among individuals in natural stands of Acacia leucophloea

Abstract Growth characteristics and fertility variations were evaluated at four natural stands of tropical arid zone species, A. leucophloea in southern India. Three stands (TNL 1, TNL 2 and PDM) were situated in dry upland regions while one stand (RKP) was at waterlogged site. The tree height and girth at breast height did not vary between stands in two years. Fertility variation (sibling coefficient, ψ) was estimated based on flowering abundance and fruit set collected for two consecutive years. Fruit production per tree was generally lower in the RKP stand than the other three stands. No year-to-year variation was observed on fruit set in all stands. Growth and flower production showed a weak-positive correlation in both years (R2 = 0.39 to 0.1). The correlation to check if the larger inflorescence size, the higher number of fruit production was also failed. Male fertility variation did not vary much among stands (ψm = 1.28 ~ 1.62). Female fertility variation was low (ψf = 1.71 ~ 2.02) in the three stands situated in dry upland regions than the RKP stand (ψf = 4.09 ~ 4.16). The cumulative contribution of trees to the overall fertility was deviated from the ideal situation (equal contribution) in all stands, especially the RKP stand showed a skewed distribution (R2 ≤ 6.5). The effective population size was low in the RKP predicting a high genetic drift when compared with other sites. Similarly high group coancestry and low gene diversity were observed in the stand RKP. The implications of fertility variation on gene diversity of the species and future management of the natural stands were also discussed.

Fertility Variation and its Impact on Effective Population Size in Seed Stands of Tamarindus indica and Azadirachta indica

Abstract Growth and reproductive traits were assessed in seed stands of two native Indian tree species Tamarindus indica and Azadirachta indica. Positive correlation between growth (height and GBH) and reproductive traits (male and female contribution) were found in both species. Fertility was estimated from the flower and fruit production of individuals. Based on the fertility variation among individuals, parental balance, femaleness index and status number (Ns) were determined. The option of equal seed collection among individuals was also considered for estimating Ns. The percentage of fertile trees was higher in the high flowering year in both species. The best male contributing individuals also showed high female contribution (fruit production). The parental contribution in seed stands showed high deviation from expectation; 20% individuals contributed about 70% of male and female gametes in both species. Femaleness index showed that female and male contribution of individual tree was more balanced in the good flowering year, compared to the poor year. Coefficient of variation in male and female fertility was higher in the low flowering year resulting in high fertility variation among individuals and low status number. In T. indica, the female contribution was less variable compared to that of male fertility whereas in A. indica the female fertility variation was higher than that of male fertility. The relative status number (Nr = Ns/N) of the stands was lower for male and female fertility compared to the combined (male and female) fertility of individual trees.

Fertility Variation and Status Number in Clonal Seed Orchards of Pinus sylvestris

The present study was carried out to evaluate fertility variation, status number and gene diversity based on strobili productions in two clonal seed orchards of Scots pine (Pinus sylvestris L.). There were large differences among clones for the female and male strobili productions in the orchards. Positive and significant (p< or =0.05) correlations were found between female and male strobili production (r = 0.76, 0.55). Female fertility variation (1.03, 1.07) was larger than male fertility variation (1.02, 1.03) in the orchards. The status numbers estimated based on the total fertility were very high (97 and 98% of census numbers). The large fertility variation could be balanced by different treatments such as mixing seed equally from clones or genetinc thinning.

Clone Fertility and Genetic Diversity in a Black Pine Seed Orchard

Abstract Clonal variation in the number of female and male strobili was studied for three consecutive years (2002-2004) in a clonal black pine seed orchard in Turkey. The data showed large differences in female and male fertility among clones in the three years. The correlation between female and male strobilus production was negative and statistically significant in 2004, a good-flowering year. Clonal fertility and fertility variation, expressed by the sibling coefficient and coefficient of variation in strobilus production among 30 clones, were reported. Fertility varied among clones and among years, producing three-year averages of 99.3 and 801.6 for female and male strobili per ramet, respectively. Male fertility variation was higher than was female fertility variation in the three years. The status number, a measure of genetic diversity, was calculated as 26.4 (2002), 23.9 (2003), and 24.0 (2004). On average, the relative status number, estimated based on total fertility, was 86% of the census number. Sexual asymmetry calculations showed that clonal contributions would be balanced between genders. Some management activities such as adjusting ramet number to balance clone contributions and mixing of seeds from consecutive years are suggested for the black pine seed orchard.

Female Reproductive Success Variation in a Pseudotsuga menziesii Seed Orchard as Revealed by Pedigree Reconstruction from a Bulk Seed Collection

The impact of female reproductive success on the mating system, gene flow, and genetic diversity of the filial generation was studied using a random sample of 801 bulk seed from a 49-clone Pseudotsuga menziesii seed orchard. We used microsatellite DNA fingerprinting and pedigree reconstruction to assign each seed's maternal and paternal parents and directly estimated clonal reproductive success, selfing rate, and the proportion of seed sired by outside pollen sources. Unlike most family array mating system and gene flow studies conducted on natural and experimental populations, which used an equal number of seeds per maternal genotype and thus generating unbiased inferences only on male reproductive success, the random sample we used was a representative of the entire seed crop; therefore, provided a unique opportunity to draw unbiased inferences on both female and male reproductive success variation. Selfing rate and the number of seed sired by outside pollen sources were found to be a function of female fertility variation. This variation also substantially and negatively affected female effective population size. Additionally, the results provided convincing evidence that the use of clone size as a proxy to fertility is questionable and requires further consideration.

Oral health and the postcontact adaptive transition: A contextual reconstruction of diet in Mórrope, Peru

This work explores the effects of European contact on Andean foodways in the Lambayeque Valley Complex, north coast Peru. We test the hypothesis that Spanish colonization negatively impacted indigenous diet. Diachronic relationships of oral health were examined from the dentitions of 203 late-pre-Hispanic and 175 colonial-period Mochica individuals from Mórrope, Lambayeque, to include observations of dental caries, antemortem tooth loss, alveolar inflammation, dental calculus, periodontitis, and dental wear. G-tests and odds ratio analyses across six age classes indicate a range of statistically significant postcontact increases in dental caries, antemortem tooth loss, and dental calculus prevalence. These findings are associated with ethnohistoric contexts that point to colonial-era economic reorganization which restricted access to multiple traditional food sources. We infer that oral health changes reflect creative Mochica cultural adjustments to dietary shortfalls through the consumption of a greater proportion of dietary carbohydrates. Simultaneously, independent skeletal indicators of biological stress suggest that these adjustments bore a cost in increased nutritional stress. Oral health appears to have been systematically worse among colonial women. We rule out an underlying biological cause (female fertility variation) and suggest that the establishment of European gender ideologies and divisions of labor possibly exposed colonial Mochica women to a more cariogenic diet. Overall, dietary change in Mórrope appears shaped by local responses to a convergence of colonial Spanish economic agendas, landscape transformation, and social changes during the postcontact transition in northern Peru. These findings also further the understandings of dietary and biocultural histories of the Western Hemisphere.

Variation in Clone Fertility and its Effect on the Gene Diversity of Seeds From a Seed Orchard of Chamaecyparis obtusa in Korea

Abstract Male and female strobilus production was assessed annually over a four-year period for a clonal seed orchard of hinoki (Chamaecyparis obtusa Endl.) in Korea. Clonal fertility and fertility variation, expressed by both sibling coefficient and coefficient of variation in strobilus production among 50 orchard clones, were reported. Fertility varied among clones and among years producing four-year averages per ramet of 510.2 and 1050.6 for female and male strobili, respectively. The correlation between female and male strobilus production was positive in each of the four years studied and, with the exception of one year, statistically significant. The clonal status number (Ns), a measure of gene diversity, was calculated based on the observed clonal fertility variation and varied from 28.0 (N = 50) in the poorest flowering year (2002) to 46.7 in the best year (2005). On average (pooled), the relative status number was 95% of the census number (N). Variation in female fertility was generally higher than that for male fertility, and this variation was reflected in the status numbers of female and male parents. The pooled Ns estimated from all four years was higher than that for any single year, implying that gene diversity would increase when seeds collected from different years are pooled. Sexual asymmetry calculations showed that clonal contributions would be balanced between genders.

Fertility variation and its impact on seed crops in seed production areas and a natural stand of teak in southern India

Reproductive output and fertility variation in teak were evaluated in five study sites in Western Ghats region of southern India. In four seed production areas (SPA1-4)) and a natural population (NAT) plots with 100 trees were investigated. The 40-year-old seed production areas are located in high rainfall (>2,500 mm) sites in Kerala state and the natural stand is at a drier location in Tamil Nadu. Fruit production per tree was rather high in the natural stand (1500) and quite variable in the seed production areas. SPA 4, located far south from the other sites, had the highest fruit production (almost twice that in the other study sites), high relative population size (Nr = 0.5) and predicted low genetic drift in two consecutive years. Fecundity was very low in SPAs 2 & 3 (200 fruits per tree). Reproductive output was similar in successive years except SPA 1, where the fruit production in the first year was almost five times that in the second year. Fertility variation (computed as sibling coefficient, Ψ) was in general higher in NAT and hence the relative population size was lower than in SPAs. The variation in female fertility in the natural stand was, somewhat surprisingly, similar to that in the seed production areas, while the male fertility variation was higher. In the seed production areas the male fertility variation was lower or similar to the female fertility variation. The fertility variation, Ψ was on average around 3 and correspondingly the relative effective population size, Nr = 0.36 and the variance effective number around 60. Selection for tree diameter would improve predicted diversity of the seed crop as it was positively correlated with reproductive output and negatively correlated with fertility variation among trees.

Female fertility variation in mature Pinus sylvestris clonal seed orchards

Female fertility is the basis for the output of seeds from clonal orchards and its variation is of major interest for the economics and biology of seed orchards, especially for the efficiency and diversity of seed orchard crops. Assessments of female fertility variation in 10 mature (>15 years old) seed orchards of Scots pine (Pinus sylvestris L.) were evaluated and compared. Depending on the individual orchard, fertility variation for each clone was assessed in slightly different ways, e.g. number of strobili, cones, seeds or litre of cones per ramet. Assessments in five of the orchards were made over consecutive years. The main result was that the clonal variation in mean female fertility per surviving ramet was lower than expected from the literature; the Kang–Lindgren sibling coefficient (Ψ) within individual years averaged 1.35. The variation between ramets within clones and years was of similar magnitude as that between clones. Clone by year interactions were noticeable, but were slightly lower than the variation between as well as that within clones in individual years. There was considerable variation in the variance components between years. The limited variation in female fertility indicated that it should not be a selection criterion when selecting clones for a seed orchard. Furthermore, it will not result in large differences between clones in seed set or large reductions in gene diversity in productive Scots pine seed orchards.

The interplay of pollination, costs of reproduction and plant size in maternal fertility limitation in perennial Paeonia officinalis

Although several factors can limit female fertility in perennial plants, rarely have they been jointly studied in a single species over several years. In this study we experimentally manipulate seed production and simultaneously analyse the potential contribution of pollen limitation, costs of reproduction and plant size to variation in seed output over a 3-year period in the perennial herb Paeonia officinalis, in southern France. Since this rare species is threatened by forest closure in many sites we also examine the causes of female fertility variation in relation to habitat closure (open habitat vs. woodland). P. officinalis has a partial self-incompatibility system and only very low ability for autonomous self pollination in the absence of pollinators. However, supplementary pollination of individual plants in three consecutive years did not significantly increase seed production above natural levels. Forest closure was associated with a decline in ovule and seed production, which again was not due to pollen limitation since supplementary pollination had no significant effect on seed set in the woodland habitat. Comparison of the maternal fertility of plants which were previously excluded from reproduction with those which were hand pollinated to maximise seed set in two previous years produced no evidence that seed production in year three is limited by costs associated with prior reproduction. Likewise, flowering probability was not related to prior seed production but was however positively related to plant size. The absence of any influence of pollen limitation or prior reproduction on seed production suggests that sub-maximal seed production in long-lived perennial herbs may be part of a size-dependent strategy that maximises life-time seed production and fitness without compromising survival.

Fertility Variation and Genetic Diversity in a Clonal Seed Orchard of Cryptomeria japonica

AbstractClonal differences in fertility (expressed as the number of female and male strobili) were determined for three consecutive years (2002-2004) in a clonal seed orchard of sugi (Cryptomeria japonica D. Don) in Korea. Fertility varied among clones and among years producing three-year averages of 196 and 652 for female and male strobili per ramet, respectively. Correlation between female and male strobilus production was positive over the three years and statistically significant in 2003, a good flowering year. Based on the observed fertility variation, the status numbers (Ns, measure of genetic diversity) were calculated and varied from 25.6 to 31.7 among the three studied years. On average (pooled), relative status number was 86% of the census number (N). Variation in female fertility was higher than that in male fertility, and this variation was reflected on female and male parents’ status numbers. Pooled Ns estimated from the three years was higher than that for any single year, implying that genetic diversity would increase when seeds collected from different years are pooled.

Spatial ecology of mating success in a sexually polymorphic plant

The spatial context of reproduction is of crucial importance to plants because of their sessile habit. Since pollen and seed dispersal is often restricted, mating success is likely to depend on the quantity and quality of mates in local neighbourhoods. Here we use neighbourhood models to investigate the spatial ecology of pollination and mating in Narcissus assoanus, a sexually polymorphic plant with two mating morphs that differ in style length. By mapping individuals in eight populations from southwestern France, we investigated the influence of the density and morph identity of plants at different spatial scales on variation in female fertility. By using inferences on the expected patterns of pollen transfer based on floral morphology, we were able to predict the quantitative relations between local morph ratios and variation in fertility. Our analyses revealed differences in the spatial clustering of morphs and in their response to plant density and morph identity within local neighbourhoods. Mating success in N. assoanus was characterized by both density- and frequency-dependent processes, a condition that may be a general feature of the spatial ecology of plant mating.

Fertility Variation and Status Number Between a Base Population and a Seed Orchard of Pinus brutia

Abstract Female, male and total fertility variations were estimated in a base population and a seed orchard derived from the base population in Pinus brutia. Relative status number for gametes (female and male contribution) and zygotes (average of female and male contribution) were estimated based on the fertility variation. Average female and male strobilus production were 229.1 and 1003.3 in the base population, and 98.9 and 244.9 in the seed orchard for combined years, respectively. Positive and significant correlations were found between female and male strobilus production in both base population and seed orchard. The male fertility variation was higher than female fertility variation in the seed orchard, while female fertility variation was higher than male fertility variation in the base population. Coefficients of variations in female and male strobilus production were 0.721 and 0.696 in the base population, and 0.403 and 1.110 in the seed orchard for combined years, respectively. Total fertility variation was 1.41 in the base population and 1.40 in the seed orchard for combined years. The relative status numbers estimated based on the total fertility were 70% of census number in the base population, and 71% in the seed orchard for combined years.

Predictors of fecundability and conception waits among the Dogon of Mali.

Surprisingly little is known about the mechanisms that underlie variation in female fertility in humans. Data on this topic are nonetheless vital to a number of pragmatic and theoretical enterprises, including population planning, infertility treatment and prevention, and evolutionary ecology. Here we study female fertility by focusing on one component of the interbirth interval: the waiting time to conception during menstrual cycling. Our study population is a Dogon village of 460 people in Mali, West Africa. This population is pronatalist and noncontracepting. In accordance with animist beliefs, the women spend five nights sleeping at a menstrual hut during menses. By censusing the women present at the menstrual huts in the study village on each of 736 consecutive nights, we were able to monitor women's conception waits prospectively. Hormonal profiles confirm the accuracy of the data on conception waits obtained from the menstrual hut census (Strassmann [1996], Behavioral Ecology 7:304-315). Using survival analysis, we identified significant predictors of the waiting time to conception: wife's age (years), husband's age (< 35, 35-49, > 49 years), marital duration (years), gravidity (number of prior pregnancies), and breast-feeding status. Additional variables were not significant, including duration of postpartum amenorrhea, sex of the last child, nutritional status, economic status, polygyny, and marital status (fiancée vs. married). We fit both continuous and discrete time survival models, but the former appeared to be a better choice for these data.

Variation among populations of the sailfin molly in the rate of concurrent multiple paternity and its implications for mating-system evolution

We examined patterns of concurrent multiple mating in a live-bearing poeciliid fish, the sailfin molly (Poecilia latipinna). We tested whether the probability of multiple paternity was related to female body size or fertility and whether the rate of multiple paternity varied among four populations that differed in their distributions of female body size and fertility. We analyzed data on mother and offspring genotypes for three polymorphic allozymes by three techniques, including a maximum-likelihood estimator that accounts for sampling error in both parental and offspring allele frequencies. The estimated rate of multiple paternity varied between 0.09 and 0.85, and the rate in one population varied seasonally between 0.33 (spring) and 0.85 (autumn). The variation in these rates was not associated with variation in body-size distributions among populations but was closely associated with variation in size-specific fertility: populations with greater variation in female fertility had higher multiple-paternity rates. Within two populations, logistic regression revealed that individual females of larger body size and greater size-specific fertility were more likely to carry multiply sired broods. This result is consistent with observations made in one of the populations 5 years earlier. In general, the results strongly suggest that the mating system varies markedly among conspecific populations of sailfin mollies and that larger, more fertile females are the objects of intermale competition.

Male and Female Fertility Variation in Wild Radish, a Hermaphrodite

We estimated male and female fertilities in a naturally occurring population of 41 hermaphroditic wild radish plants. Male fertilities were estimated by analyzing the paternity of 2,428 seeds (from 39 of the plants), coupled with a maximum-likelihood method to estimate fertility from the paternity data. Female fertilities were estimated as the fraction of the seed yield of the population produced by each individual. We detected a 15-fold range in mean male fertility, nearly a 200-fold range in female fertility, and a 25-fold range in total fertility. Male fertility was correlated with the distance among mates and with a number of phenotypic features of the plants: the total number of flowers produced, flower color, peak flowering time, whether the peak flowering times of the male and female parents overlapped, and some of the interactions of these variables. An additional portion of the variance of male fertility, however, was accounted for by a class variable denoting each male parent, suggesting that un...