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PubMed1999

Change in sexual size dimorphism as a correlated response to selection on fecundity.

Fecundity selection is often suggested as the main causal factor underlying the prevalence of female-biased sexual size dimorphism (SSD), but this assumption has not been empirically tested. We selected female Drosophila melanogaster for increased or decreased fecundity (eggs laid over a single 18-h period, between days 5 and 7 posteclosion) for 20 generations, to see what effect this would have on SSD in three morphological traits (thorax width, abdomen width and thorax length). A direct response to fecundity selection was found in the downward direction (16.6%), whereas the response to upward selection (5.7%) was not statistically significant. Significant sex by selection interaction terms in the ANOVAs for thorax width and abdomen width indicate that the two sexes responded differently. Females usually showed a greater correlated response than males. In lines selected for increased fecundity, the correlated response in females for thorax and abdomen width was greater than the direct response in standard deviation units. SSD generally increased with selection for increased fecundity, but showed no consistent trend with selection for decreased fecundity. These results support the general hypothesis that SSD can evolve rapidly in response to fecundity selection. Selection on fecundity also produced correlated responses in life history traits. Downward selection resulted in flies that had lower viability and longevity, and both directions of selection were associated with an increase in development time.

Animals↗
PubMed2000

Comorbid fibromyalgia accounts for reduced fecundity in women with myofascial face pain.

OBJECTIVE: This study examined factors related to reduced fecundity among women with myofascial face pain (MFP) arising from hypotheses concerning the role of neurohormonal factors in MFP and associated conditions. DESIGN: Fecundity rates among 162 MFP cases and 173 demographically equivalent acquaintance female controls were compared. OUTCOME MEASURES: Fecundity indicators and factors underlying differential fecundity rates were investigated. RESULTS: It was determined that female cases with MFP had significantly fewer children and were more likely to have never been pregnant. Although women with MFP were more likely than controls to indicate that volitional factors related to their health discouraged them from any or additional pregnancies, these factors did not account for lower rates of fecundity. MFP cases also did not differ from controls on self-reported indicators of infertility. Moreover, we show that reduced fecundity was restricted to the subgroup of MFP cases who reported a history of fibromyalgia. CONCLUSIONS: Reduced fecundity in women with MFP is restricted to those who self-report a history of fibromyalgia. Possible mechanisms for reduced fecundity in fibromyalgia are discussed. These findings highlight the need to screen for widespread pain among women with regional myofascial pain syndromes.

Adolescent↗
PubMed2002

Fecundity of the freshwater fish Channa punctatus (Bloch) from three aquatic bodies.

The fecundity studies on Channa punctatus revealed that there is a relationship between length of the fish with fecundity, weight of the fish and ovary with fecundity. The length and fecundity exhibit curvilinear relationship and a straight line relationship is observed between fecundity and body weight. Fecundity and ovary weight also exhibited linear relationship. The comparative degree of fecundity of the fish is Jagat tank > Kadaganchi tank > Kagina river. Although fish collected from Jagat tank exhibits higher fecundity, all the other three aquatic bodies provide proper environmental conditions for the growth and reproductive activity of the fish.

Animals↗
PubMed2004

Reduction in size and fecundity of the autumnal moth, Epirrita autumnata, in the increase phase of a population cycle.

Increasing fecundity with increasing density has been observed for many cyclic herbivore populations, including some forest Lepidoptera. We monitored population density, body size and reproductive capacity of the cyclic lepidopteran, the autumnal moth (Epirrita autumnata, Geometridae), from the early increase phase to the devastating outbreak density in northernmost Norway. Larval density of the species increased exponentially from 1998 to 2002 and remained at the outbreak level also in 2003. Within the same period, the body size and fecundity of individuals reduced as analysed from several parallel datasets on larvae, pupae and adults. In another study area in northernmost Finland, the density increase of the autumnal moth was moderate only, and true outbreak density was not attained during the study. Despite that, a reduction was again detected in the size and fecundity of individuals. Possible factors responsible for the reduced size and fecundity of individuals in the Norwegian population were quantitative shortage of foliage, rapid and delayed inducible resistances of the host, mountain birch (Betula pubescens ssp. czerepanovii), as well as crowding-induced responses of larvae. These factors likely acted in concert, although non-delayed responses to the density were emphasized. Our findings did not support the hypotheses of climatic release, inducible susceptibility of the host tree and mast depression (i.e. lowered chemical defence of the host tree after its mast seeding) as promoters of the fecundity-based density increase of the autumnal moth, since the reduced fecundity in relation to increased density was strongly against the predictions of these hypotheses. Therefore, we suggest that the density increase of autumnal moth populations is promoted by high survival rather than exceptionally high fecundity.

Animals↗
PubMed1989

The relationship of sperm parameters to cycle fecundity in superovulated women undergoing intrauterine insemination.

Semen parameters of raw and prepared (post-swim-up) specimens from 451 cycles of intrauterine insemination (IUI) were analyzed in relation to cycle fecundity in 232 patients undergoing ovarian stimulation with sequential clomiphene citrate/menotropin therapy. Pregnancy occurred in 42 cycles, resulting in an overall pregnancy rate of 17.7%, and a cycle fecundity of 9.3%. Cycle fecundity was positively correlated with the parameters of post-swim-up log sperm density (r = 0.994), and with log total motile sperm inseminated (r = 0.964; inseminates were limited to a maximum of 20 million total motile sperm). Post-swim-up motility did not correlate (r = 0.308) with cycle fecundity; however, most specimens had a motility of greater than 40% post-swim-up. Only one pregnancy occurred when less than 1 million motile sperm were inseminated (38 cycles), which resulted in a cycle fecundity of 2.6% for these cycles. This may represent the threshold of effectiveness for IUI in this setting. Highest cycle fecundity was obtained with an inseminate containing approximately 10 million or more motile sperm. Parameters of raw samples correlated less well with cycle fecundity than did prepared specimens. Analysis of post-swim-up semen parameters can provide useful prognostic information for women undergoing IUI with ovarian stimulation; this information is helpful in counseling patients regarding their chances of success with this therapy.

Adult↗
PubMed1998

Fecundity of infertile women with minimal or mild endometriosis and women with unexplained infertility. The Canadian Collaborative Group on Endometriosis.

OBJECTIVE: To assess whether infertile women with minimal or mild endometriosis have lower fecundity than women with unexplained infertility. DESIGN: Prospective cohort study. SETTING: Twenty-three infertility clinics across Canada. PATIENT(S): Three hundred thirty-one infertile women aged 20-39 years. INTERVENTION(S): Diagnostic laparoscopy for infertility. Infertile women with minimal or mild endometriosis (n = 168) were compared with women with unexplained infertility (n = 263). Both groups were managed expectantly. The women were followed up for 36 weeks after the laparoscopy or, for those who became pregnant, for up to 20 weeks of the pregnancy. MAIN OUTCOME MEASURE(S): Fecundity refers to the probability of becoming pregnant in the first 36 weeks after laparoscopy and carrying the pregnancy for > or = 20 weeks. The fecundity rate is the number of pregnancies per 100 person-months. RESULT(S): Fecundity was 18.2% in infertile women with minimal or mild endometriosis and 23.7% in women without endometriosis (log-rank test). The fecundity rate was 2.52 per 100 person-months in women with endometriosis and 3.48 per 100 person-months in women with unexplained infertility. The crude and adjusted fecundity rate ratios were 0.72 and 0.83 (95% confidence interval = 0.53-1.32), respectively. CONCLUSION(S): The fecundity of infertile women with minimal or mild endometriosis is not significantly lower than that of women with unexplained infertility.

Adult↗
PubMed2002

Fecundity and life-history strategies in marine invertebrates.

The reproductive strategies of an organism play a major role in the dynamics of the population and the biogeography and continuity of the species. Numerous processes are involved in reproduction leading to the production of offspring. Although diverse processes are involved in oogenesis (the production of eggs) and spermatogenesis (the production of sperm), the basic patterns of gametogenesis are similar amongst invertebrates, with the proliferation and differentiation of germ cells leading to the final production of mature gametes. The production of gametes, especially eggs, is energetically expensive, and therefore strongly sensitive to selective pressures. An organism can ingest and assimilate a limited amount of energy from the environment. The different ways by which energy is allocated to growth and reproduction in order to maximize fitness forms the basis of the differing life-history strategies that have developed in marine invertebrates. Fecundity is defined as the number of offspring produced by a female in a determined time period. The term fecundity needs to be explicitly defined in each study in order to obtain the maximum information from the data analysed. Because of the variety of egg production patterns found among marine invertebrates, a wide range of methodologies has been developed to quantify fecundity. These include direct egg counts in brooding species, spawning induction in live individuals and histological studies of preserved material. Specific considerations need to be taken into account for colonial organisms, because of their modular organization. The production of eggs requires an optimal allocation of energy into growth and reproduction for the maximization of parental fitness. Fecundity is central in studies of life-history theory and in the development of life-history models because it is directly related to energy allocation and partitioning. There are important relationships and trade-offs between fecundity and other life-history traits, such as egg size, female size and age, age at first reproduction, reproductive effort and residual reproductive value. These trade-offs, together with morpho-functional constraints and genetic variation determine the evolution of life histories through natural selection. Fecundity is a highly plastic character within the limits defined by the bioenergetics and life-history strategy of the organism. Egg production is affected mainly by environmental factors such as food quantity and quality, temperature or presence of toxic elements in the habitat. The differences in fecundity found among closely related species from different biogeographical locations reflect, at least in part, the differing environmental conditions of their habitat.

Adaptation, Physiological↗
PubMed2002

Ulcerative colitis: female fecundity before diagnosis, during disease, and after surgery compared with a population sample.

BACKGROUND & AIMS: Women with ulcerative colitis generally have normal fertility. The aim of this study was to compare patients' fecundability before and after restorative proctocolectomy with ileal pouch-anal anastomosis with the fecundability of the general population. METHODS: Historical follow-up was performed on 343 consecutive female patients aged 10.6-40.5 years at surgery and a reference population of 1200 women aged 25-40 years. A total of 290 (85%) patients and 661 (55%) women in the reference population agreed to participate in a structured telephone interview concerning reproductive behavior and waiting times to pregnancy. Cox regression and Kaplan-Meier plots were used for analysis. RESULTS: Surgery significantly reduced the ratio of patient to reference population fecundability, which decreased to 0.20 (P < 0.0001). Before diagnosis and from diagnosis until colectomy, the fecundability of the patients was similar to that of the reference population. CONCLUSIONS: Female patients with ulcerative colitis have normal fecundity before surgical treatment. Surgery severely reduces female fecundity. Information about this reduction in fecundity should be given before surgery, and if a woman has an unfulfilled wish for pregnancy after surgery, early referral to a gynecologist is recommended.

Adult↗
PubMedDate not supplied

The age pattern of fecundability: an analysis of French Canadian and Hutterite birth histories.

This paper analyzes the age pattern of effective fecundability from populations with no evidence of deliberate fertility control using a new convolution model of fecundability. The analysis is based on a sample of Hutterite birth histories from the mid-20th century, and birth histories of French Canadians from the 17th and 18th centuries. The main findings are as follows: 1) the level of effective fecundability is higher among the French Canadians compared to the Hutterites; 2) effective fecundability peaks at age 20 for the Hutterites, and in the early to mid-20s for the French Canadians; 3) Hutterite effective fecundability declines almost linearly from age 20 to 45, and French Canadian effective fecundability declines slowly from its peak to the early 30s, and more rapidly at older ages; and 4) the duration of postpartum amenorrhea is longer for the French Canadians than for the Hutterites. Because of the shorter periods of postpartum amenorrhea the Hutterites have about the same average number of children as the French Canadians, even though the French Canadians have higher effective fecundability.

Adolescent↗
PubMed2006

Fecundity in Drosophila following desiccation is dependent on nutrition and selection regime.

Life-history trade-offs of populations of Drosophila melanogaster selected for enhanced desiccation resistance (D populations) include increased pupal mortality, retarded development, increased longevity, and decreased fecundity. We tested the effects of acute desiccation on fecundity and the effects of various nutritional regimes on fecundity following a bout of desiccation in the D populations and their control populations (C populations). Female flies were desiccated for 8 h (C populations) or 24 h (D populations) and then recovered on one of four treatments: distilled water, a saline solution, a saline and sucrose solution, or food. Each treatment was tested in the presence and absence of a yeast supplement. Fecundity was then measured on an oviposition medium over a 12-h period. Fecundity was also measured in flies that did not undergo a desiccation stress. Yeast increased fecundity under all conditions examined in the C populations but not in the D populations. There was an overall effect of recovery treatment on fecundity but no effect of desiccation stress.

Animal Nutritional Physiological Phenomena↗
PubMed2001

The evolution of trade-offs: effects of inbreeding on fecundity relationships in the cricket Gryllus firmus.

The evolution of traits is modulated by their interrelationships with each other, particularly when those relationships result in a fitness trade-off. In this paper we explore the consequences of genetic architecture on functional relationships between traits. Specifically, we address the consequences of inbreeding on these relationships. We show that the linear regression between two traits will not be affected if there is no dominance genetic variance in either trait, whereas the intercept but not the slope of the regression will change if there is dominance genetic variance in one trait only. We test the latter hypothesis using fecundity relationships in the cricket Gryllus firmus. Data from pedigree analysis and an inbreeding experiment show that there is significant dominance genetic variance in fecundity, but not head width (an index of body size) or dorsal longitudinal muscle (DLM) mass. Fecundity increases with head width, but decreases with DLM mass. As predicted, the intercepts of the regressions of fecundity on these two morphological traits decrease with inbreeding, but there is little or no change in slope. Gryllus firmus is wing dimorphic, with the macropterous (LW) morph having a lower fecundity than the micropterous (SW) morph. We hypothesize that the difference in fecundity arises primarily because of a competition for resources in the LW females between DLM maintenance (i.e., mass) and egg production. As a consequence, we predict that the fecundity within each morph should decline linearly with the inbreeding coefficient at the same rate in both morphs. The result of this will be a change in the relative fitness of the two morphs, that of the SW morph increasing with inbreeding. This prediction is supported. These results indicate that trade-offs will evolve and such changes will affect evolutionary trajectories by altering the pattern of relationships among fitness components.

Animals↗
PubMed2000

The effects of population size limitation on fecundity in mosaic populations of the clonal macrophyte Scirpus maritimus (Cyperaceae).

The clonal macrophyte Scirpus maritimus (Cyperaceae) propagates locally by rhizomes and reproduces sexually by achenes. The purpose of this paper was to examine whether in size-limited habitats in patchy and discrete marshes in two Mediterranean wetlands in southern France natural populations may suffer from a reduced maternal fecundity due to a deficit in outcross pollen. We first verified that S. maritimus suffers from a reduced fecundity when self-pollinated. At a site in the Camargue, mean fecundity (mean number of achenes per centimetre of spikelet) measured in 1995 and 1996 in seven and nine populations, respectively (surface area from 50 to 4500 m) increased significantly with population surface area in 1995 but not in 1996. In the second wetland at Roquehaute, which is composed of small ponds, fecundity was very low in all 12 local populations studied in 1996 (1.1 achenes per spikelet, SD = 1.2) and was not correlated with the population surface area (from 10 to 400 m). We performed a pollen supplementation experiment in five local populations at Roquehaute to determine whether this low fecundity may be due to a pollen limitation. A significant increase in fecundity after among-pond pollinations compared to within-pond pollinations indicated that local populations suffer from a deficit in outcross pollen, since each pond appears to contain one or a few number of clones (or incompatibility types). In S. maritimus, clonal spread may have a cost in terms of reduced fecundity in small habitats because each habitat is colonized by very few clones.

Journal Article↗
PubMed1986

The determinants of effective fecundability based on the first birth interval.

There are substantial differences in fecundability among nine developing countries in different parts of the world. In addition, within countries, later age at marriage has a clear, positive, nonlinear effect on fecundability. Women with higher education and those with more educated husbands have higher fecundability. Urban residents have higher fecundability than rural. The higher fecundability of more recent cohorts is the most consistent observation. Since those variables most frequently shown to have inverse relationships to fertility show direct relationships to fecundability within populations, the role of fecundability as a proximate variable in models of the determinants of fertility requires further specification.

Adult↗
PubMedDate not supplied

Impaired fecundity in the United States: 1982-1995.

CONTEXT: The 1995 National Survey of Family Growth (NSFG) provides new nationally representative data to test the accuracy of the commonly held assumption that impaired fecundity has been rising in the United States over the past decade. METHODS: Using data from the 1982, 1988 and 1995 rounds of the NSFG, trends in both the proportions and numbers of women with impaired fecundity and of those who received infertility services were examined. Multiple logistic regressions were carried out to estimate the effects of demographic characteristics on the likelihood of currently having impaired fecundity and of ever having received medical help for infertility. RESULTS: The proportion of U.S. women aged 15-44 who reported some form of fecundity impairment rose from 8% in 1982 and 1988 to 10% in 1995, an increase in absolute numbers from 4.6 million to 6.2 million women. Although the proportion of fecundity-impaired women who had ever sought medical help did not change between 1988 and 1995 (44%), the absolute numbers of such women grew by nearly 30%, from 2.1 million to 2.7 million. Women who had ever sought help for fertility problems were older and had a higher income than those who had not, and were more likely to be married. CONCLUSION: The dramatic increase in the numbers of U.S. women with impaired fecundity occurred because the large baby-boom cohort, many of whom delayed childbearing, had reached their later and less fecund reproductive years. This increase in both rates and numbers occurred across almost all age, parity, marital status, education, income, and race and ethnicity subgroups.

Adolescent↗
PubMedDate not supplied

Caffeine intake and fecundability: a follow-up study among 430 Danish couples planning their first pregnancy.

Fecundability has been defined as the ability to achieve a recognized pregnancy. Several studies on caffeine and fecundability have been conducted but have been inconclusive. This may be explained partly by lack of stratification by smoking. Furthermore, few researchers have tried to separate the effect of caffeine from different sources (coffee, tea, cola, and chocolate). Clearly, the relationship between caffeine and fecundability needs further research, given the high prevalence of caffeine intake among women of childbearing age. We examined the independent and combined effects of smoking and caffeine intake from different sources on the probability of conception. From 1992 to 1995, a total of 430 couples were recruited after a nationwide mailing of a personal letter to 52,255 trade union members who were 20 to 35 years old, lived with a partner, and had no previous reproductive experience. At enrollment and in six cycles of follow-up, both partners filled out a questionnaire on different factors including smoking habits and their intake of coffee, tea, chocolate, cola beverages, and chocolate bars. In all, 1596 cycles and 423 couples were included in the analyses. The cycle-specific association between caffeine intake and fecundability was analyzed in a logistic regression model with the outcome at each cycle (pregnant or not pregnant) in a Cox discrete model calculating the fecundability odds-ratio (FR). Compared to nonsmoking women with caffeine intake less than 300 mg/d, nonsmoking women who consumed 300 to 700 mg/d caffeine had a FR of 0.88 [95% confidence interval (CI) 0.60-1.31], whereas women with a higher caffeine intake had a FR = 0.63 (95% CI 0.25-1.60) after adjusting for female body mass index and alcohol intake, diseases of the female reproductive organs, semen quality, and duration of menstrual cycle. No dose-response relationship was found among smokers. Among males, the same decline in point estimates of the FR was present. Smoking women whose only source of caffeine was coffee (>300 mg/d) had a reduced fecundability odds-ratio (FR = 0.34; 95% CI 0.12-0.98). An interaction between caffeine and smoking is biologically plausible, and the lack of effect among smokers may be due to faster metabolism of caffeine. Our findings suggest that especially nonsmoking women who wish to achieve a pregnancy might benefit from a reduced caffeine intake.

Adult↗
PubMed1994

Cigarette smoking, alcohol consumption, and caffeine intake and fecundability.

BACKGROUND: In a prospective study the effect of the behavioral risk factors of both partners on fecundability was studied. METHODS: Information was collected on smoking habits, alcohol consumption, and caffeine intake (e.g. coffee, tea, and cola consumption) by interviewing 259 female nonmedical hospital workers, i.e., clerical staff, cleaners, kitchen and restaurant workers, and their partners, who were planning a pregnancy. The occurrence of pregnancy was tested prospectively during the 12 months after enrollment. RESULTS: Among the participants as well as among their partners, smoking a moderate number of cigarettes (1-10/day) was associated with higher fecundability (i.e., the probability of becoming pregnant each month) than among those not smoking (participant: OR = 1.4 (95% CI, 0.9-2.2); partner: OR = 2.1 (95% CI, 1.2-3.5)). The level of alcohol consumption in the female partner was not related to fecundability. However, in the male partner, there was a positive influence for drinking more than 10 alcoholic drinks per week compared with that observed for those drinking less than 5 (OR = 1.6; 95% CI, 1.0-2.4). Participants with a moderate caffeine intake (400-700 mg/day) showed a higher fecundability than those with a lower intake level (ORadjusted = 2.1 (95% CI, 1.2-3.7)). Heavy caffeine intake (> 700 mg/day) among partners was negatively related to fecundability when compared with the lowest intake level (ORadjusted = 0.6 (95% CI, 0.3-0.97)). CONCLUSIONS: This study does not support the hypothesis that moderate cigarette smoking, caffeine intake, and alcohol consumption have an adverse influence on fecundability.

Adolescent↗
PubMed2006

An evolutionary heterogeneity model of late-life fecundity in Drosophila.

There is now a significant body of research that establishes the deceleration of mortality rates in late life and their ultimate leveling off on a late-life plateau. Natural selection has been offered as one mechanism responsible for these plateaus. The force of natural selection should also exert such effects on female fecundity. We have already developed a model of female fecundity in late life that incorporates the general predictions of the evolutionary model. The original evolutionary model predicts a decline in fecundity from a peak in early life, followed by a plateau with non-zero fecundity in late life. However, in Drosophila there is also a well-defined decline in fecundity among dying flies, here called the "death spiral". This effect produces heterogeneity between dying and non-dying flies. Here a hybrid evolutionary heterogeneity model is developed to accommodate both the evolutionary plateau prediction and the death spiral. It is shown that this evolutionary heterogeneity model gives a much better fit to late-life fecundity data.

Aging↗
PubMed2000

Mild winter temperatures reduce survival and potential fecundity of the goldenrod gall fly, Eurosta solidaginis (Diptera: Tephritidae).

We tested the hypothesis that mild winter temperatures are detrimental to the survival and reproductive potential of insects. We measured survival, body size, and potential fecundity of a freeze tolerant insect, the goldenrod gall fly (Eurosta solidaginis), after overwintering in the laboratory for ~3 mo. frozen at -22 degrees C, unfrozen at 0 degrees C, or unfrozen at 12 degrees C. Larvae held at 12 degrees C suffered high mortality (70%) and relatively low potential fecundity as adults (mean+/-SEM=199+/-11 eggs/female), while those held at 0 degrees C had both low mortality (11%) and high potential fecundity (256+/-15 eggs/female). Freezing (-22 degrees C) increased mortality (30% overall) but did not significantly reduce fecundity (245+/-13 eggs/female). Egg length and width were constant regardless of treatment group or female body size. Analysis of covariance indicated that reduced fecundity in the 12 degrees C group was related to reduced larval body weight following treatment. Patterns of larval weight loss in the experimental treatments were generally correlated with previous reports of latitudinal trends in weight loss through the winter. We conclude that mild winter temperatures may be detrimental to some overwintering insects, particularly species that do not feed following winter diapause. Low temperature and even freezing are beneficial, allowing conservation of energy reserves to maintain high survival and potential fecundity.

Journal Article↗