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PubMed2003

Lack of nonadditive genetic effects on early fecundity in Drosophila melanogaster.

Fecundity is usually considered as a trait closely connected to fitness and is expected to exhibit substantial nonadditive genetic variation and inbreeding depression. However, two independent experiments, using populations of different geographical origin, indicate that early fecundity in Drosophila melanogaster behaves as a typical additive trait of low heritability. The first experiment involved artificial selection in inbred and non-inbred lines, all of them started from a common base population previously maintained in the laboratory for about 35 generations. The realized heritability estimate was 0.151 +/- 0.075 and the inbreeding depression was very small and nonsignificant (0.09 +/- 0.09% of the non-inbred mean per 1% increase in inbreeding coefficient). With inbreeding, the observed decrease in the within-line additive genetic variance and the corresponding increase of the between-line variance were very close to their expected values for pure additive gene action. This result is at odds with previous studies showing inbreeding depression and, therefore, directional dominance for the same trait and species. All experiments, however, used laboratory populations, and it is possible that the original genetic architecture of the trait in nature was subsequently altered by the joint action of random drift and adaptation to captivity. Thus, we carried out a second experiment, involving inbreeding without artificial selection in a population recently collected from the wild. In this case we obtained, again, a maximum-likelihood heritability estimate of 0.210 +/- 0.027 and very little nonsignificant inbreeding depression (0.06 +/- 0.12%). The results suggest that, for fitness-component traits, low levels of additive genetic variance are not necessarily associated with large inbreeding depression or high levels of nonadditive genetic variance.

Animals↗
PubMed2004

Competition between vectors of Chagas disease, Triatoma infestans and T. sordida: effects on fecundity and mortality.

Interspecific competition between two species of triatomine bugs (Hemiptera: Reduviidae), vectors of Chagas disease, was assessed for 16 months through comparative fecundity and mortality of experimental populations in chicken nests, maintained indoors with ambient conditions. Triatoma sordida (Stål), the secondary vector in north-eastern Argentina, was compared with Triatoma infestans (Klug) the more widespread domestic vector in the southern cone of South America. Both species populations originated from females collected in 1995 from the community of Empedrado, Corrientes, Argentina. Three population units were monitored: T. infestans alone, T. sordida alone and both species together in equal proportions. Each population started with six male and six female adults, 116 eggs, and nymphal instars I to V numbering 82, 48, 16, 11 and 19, respectively. Numbers and weight of individual bugs were recorded monthly (August 1995 to December 1996). The pure populations of T. infestans and T. sordida showed temporal changes in abundance, rising in summer and falling in winter, similar to the typical trends under normal field conditions. In the mixed population, however, T. sordida fell to extinction after 6 months, whereas T. infestans reached similar abundance to the pure (control) population. For each nymphal instar of T. sordida, the mean body weight was significantly less and mortality rate was higher in the mixed population compared to the pure population, but there were no significant differences of adult longevity or fecundity between the pure and mixed populations of T. sordida. The apparent competitive displacement of T. sordida by T. infestans was attributed to the latter species having better ability to obtain bloodmeals. This might explain the rarity of mixed populations where these two species occur in sympatry.

Adaptation, Physiological↗
PubMed1993

Fecundity of Anopheles tessellatus reduced by the ingestion of murine anti-mosquito antibodies.

High titres of antibodies to antigens derived from head/thorax, midgut or abdomen of Anopheles tessellatus were produced in inbred mice. These antibodies, when ingested in a bloodmeal, reduced the fecundity of An. tessellatus by up to 29% in different experiments. It is postulated that antibodies directed against antigens shared between the head/thorax, abdomen and midgut tissues are involved in the reduction of fecundity.

Animals↗
PubMed1993

Effects of adult body size on fecundity and the pre-gravid rate of Anopheles gambiae females in Tanzania.

The influence of adult body size on the pre-gravid state and fecundity was studied in Anopheles gambiae Giles females hand-caught inside houses and virgin females collected as pupae in Tanzania. Blood-fed mosquitoes were kept for 2-3 days before dissection and examination for insemination and ovarian condition. Those females which did not develop eggs were classified as pre-gravid. The number of mature eggs in those mosquitoes which became gravid was counted. Virgin females were fed and kept for egg maturation in the laboratory. Wing-length of females was measured as an index of mosquito size. The overall pre-gravid rate in the resting An.gambiae population was found to be 21% and, of these, 66% had been inseminated. In the virgin females the pre-gravid rate was 92.6%. The mean wing-length of wild females which became gravid was significantly larger than those which remained pre-gravid. There was a positive correlation between fecundity and wing-length. Smaller females tended to require two or three bloodmeals to facilitate completion of the first gonotrophic cycle. The critical size permitting oviposition from the first blood-meal was a wing-length of 3 mm.

Animals↗
PubMed1995

Malaria-induced reduction of fecundity during the first gonotrophic cycle of Anopheles stephensi mosquitoes.

Anopheles stephensi mosquitoes which had fed upon mice infected with Plasmodium yoelii nigeriensis malaria parasites produced significantly fewer eggs than mosquitoes fed on an uninfected mouse. Fecundity reduction was more pronounced when the bloodmeal contained malaria gametocytes and the mosquitoes developed oocysts. Egg production and haematin excretion were correlated for uninfected bloodfed mosquitoes; the presence of P.y.nigeriensis in the blood affected this relationship. Reduced fecundity was associated with a significant reduction of bloodmeal size (measured by haematin excretion) in mosquitoes which ingested gametocytaemic blood. The bloodmeal size in mosquitoes fed on parasitaemic blood without gametocytes was not significantly reduced. The use of haematin assays for determination of bloodmeal size in mosquitoes is discussed.

Animals↗
PubMed1996

Comparative fecundity and associated factors for two sibling species of the Anopheles gambiae complex occurring sympatrically in The Gambia.

For two sibling species of mosquitoes belonging to the Anopheles gambiae complex of malaria vectors, the effects of body size (wing length) and bloodmeal size (haematin excretion) on fecundity of wild females were investigated in The Gambia, West Africa. Freshly blood-fed individuals from sympatric populations of An.arabiensis and An.gambiae sensu stricto were sampled by collection at 07.00-09.00 hours from within bednets during July/August 1993, at the beginning of the rainy season. The possible confounding effect of infection with Plasmodium parasites was removed by eliminating infected mosquitoes from the study samples. An.arabiensis females comprised 75% of the An.gambiae sensu lato population and were significantly larger (greater mean wing length) than those of An.gambiae s.s. mosquitoes. Mean egg production per female (for the subsequent gonotrophic cycle, excluding pre-gravids) for the two species was not significantly different, though the relationship between wing length and egg production showed An.gambiae s.s. to be more fecund than the An.arabiensis of the same size. Pre-gravid An.gambiae s.s had consumed significantly smaller bloodmeals than gravid females but the mean wing length of these two gonotrophic categories was not significantly different. In contrast, An.arabiensis pre-gravids were smaller and had consumed smaller bloodmeals than the gravids.

Animals↗
PubMed1995

Anti-fecundity immunity induced in pigs vaccinated with recombinant Schistosoma japonicum 26kDa glutathione-S-transferase.

We have recently reported (Liu et al. 1995) that immunization of mice with recombinant 26kDa GST (reSjc26GST) induces a pronounced anti-fecundity effect after experimental infection with Chinese Schistosoma japonicum. A similar vaccination trial was thus carried out on pigs, important reservoirs for schistosomiasis japonica, using purified, reSjc26GST and reSjp26GST from Schistosoma japonicum with alum as adjuvant; in general, similar results were obtained with the two sources of recombinant 26kDa GST. Some protection in terms of worm reduction, significant with males, against challenge infection was observed in vaccinated pigs. Moreover, prior to challenge, levels of specific anti-re26GST antibodies in the vaccinated pigs were significantly higher than in non-vaccinated pigs as determined by GST-ELISA. The most striking feature of the vaccine trial was the significant reduction in the number of eggs, especially mature eggs, in the livers of vaccinated animals. The results indicate that immunization with recombinant Sj26GST can provide some reduction in worm burden following exposure of pigs to reinfection with S. japonicum. In addition, reSj26GST can induce an anti-fecundity effect, thereby reducing pathology, coupled with a delay or interruption of the development of immature to mature eggs in the liver. As a consequence, vaccination with Sj26GST would also prove useful in affecting the transmission of schistosomiasis japonica.

Animals↗
PubMed2006

Do mothers producing large offspring have to sacrifice fecundity?

We artificially selected on egg size in a butterfly to study the consequences for fecundity, reproductive effort and offspring fitness. Correlated responses in either pupal mass, larval or pupal development time were virtually absent. Offspring size was positively related to fitness, but only partly traded off against fecundity. Rather, total reproductive effort (measured as fresh mass), egg water content and the decline of egg size with female age increased in the large-egg selected lines compared to either small-egg or control lines. Accounting for these effects showed that reproductive investment (in dry mass) was in fact similar across lines. Such mechanisms may enable increased investment in (early) offspring without a reduction in their number, revealing a much more complex picture than a simple trade-off between offspring size and number. Substantial variation among replicates suggests that there are different underlying mechanisms for change, rather than any single, unitary pathway.

Animals↗
PubMed2006

Weed evolution after crop gene introgression: greater survival and fecundity of hybrids in a new environment.

Crop-wild hybridization may produce offspring with lower fitness than their wild parents due to deleterious crop traits and outbreeding depression. Over time, however, selection for improved fitness could lead to greater invasiveness of hybrid taxa. To examine evolutionary change in crop-wild hybrids, we established four wild (Raphanus raphanistrum) and four hybrid radish populations (R. raphanistrum x Raphanus sativus) in Michigan (MI), USA. Hybrid and wild populations had similar growth rates over four generations, and pollen fertility of hybrids improved. We then measured hybrid and wild fitness components in two common garden sites within the geographical range of wild radish [MI and California (CA)]. Advanced generation hybrids had slightly lower lifetime fecundity than wild plants in MI but exhibited c. 270% greater lifetime fecundity and c. 22% greater survival than wild plants in CA. Our results support the hypothesis that crop-wild hybridization may create genotypes with the potential to displace parental taxa in new environments.

Biological Evolution↗
PubMed1999

The fertility and fecundity of patients with psychoses.

OBJECTIVE: Previous research has suggested that patients with schizophrenia have fewer offspring compared to the general population. Reduced fertility in a disorder with a strong genetic component and an apparently stable incidence has implications for models of genetic transmission. There is also a need to obtain contemporary estimates of the prevalence of parenthood among subjects with psychotic disorders in order to inform service planning. The aim of this study was to determine the fertility and fecundity of a representative sample of individuals with psychoses who were in contact with mental health services, and to explore the interactions between age at first diagnosis and fertility. METHOD: All clients of two community mental health clinics and an extended-care psychiatric hospital were surveyed. Data on diagnosis, age at first diagnosis, and the number and age of offspring were collected. Based on interviews with the proband and chart review, a genogram of the probands' family was drawn that identified sex, age, affected status and the number of offspring for each patient and their siblings. RESULTS: In total, 36% of all patients were parents. Most women with psychoses (59%) were mothers. Patients with psychoses had fewer offspring compared to their unaffected same-sex siblings. This was especially the case for men with non-affective psychoses. Higher levels of fertility were associated with a later age at first diagnosis. CONCLUSION: The consistent finding of reduced 'reproductive fitness' in those with non-affective psychoses needs to be incorporated in the genetic epidemiology of these disorders. Despite this reduction in fertility and fecundity, many patients with psychoses are parents. Services need to remain mindful of the special needs of these patients.

Australia↗
PubMed2004

Anti-thyroid antibodies and antiphospholipid syndrome: evidence of reduced fecundity and of poor pregnancy outcome in recurrent spontaneous aborters.

PROBLEM: To determine the presence of anti-thyroid antibodies in patients with primary antiphospholipid syndrome (APS) [antiphospholipid antibodies (aPL) + recurrent spontaneous abortion (RSA)], compare APS alone with APS and thyroid autoimmunity for fecundity and for pregnancy outcome. METHOD OF STUDY: A total of 203 non-pregnant women affected with primary APS were evaluated for anti-thyroid antibodies; 162 non-pregnant women affected with RSA and thyroid autoimmunity alone served as controls. RESULTS: Anti-thyroid antibodies were found in 27% of APS patients studied. Patients with aPL alone had higher percentages of spontaneous pregnancies (P < 0.0001) and live births (P = 0.0003), when compared with patients positive for anti-thyroid antibodies alone or with aPL. CONCLUSIONS: Thyroid autoimmunity is frequently present in APS recurrent aborters and is often associated with either reduced fecundity or with poor pregnancy outcome. Thyroid antibodies should always be evaluated in women with RSA including those with aPL.

Abortion, Spontaneous↗
PubMed1980

Does malnutrition affect fecundity? A summary of evidence.

Moderate chronic malnutrition has only a minor effect on fecundity (reproductive capacity), and the resulting effect on fertility (actural reproduction) is very small. Among the fecundity components examined here in noncontracepting populations, age at menarche and the duration of lactational amenorrhea appear to be the ones most affected by malnutrition. But from neither of those effects can a difference in fertility of more than a few percent be expected between poorly and well-nourished women in developing countries.

Abortion, Induced↗
PubMed1999

Egg laying is delayed but worm fecundity is normal in SCID mice infected with Schistosoma japonicum and S. mansoni with or without recombinant tumor necrosis factor alpha treatment.

Mice with severe combined immunodeficiency (SCID mice) lack functional B and T cells. Egg laying by Schistosoma mansoni and S. japonicum was delayed in SCID mice, but in a matter of weeks worm fecundity was equivalent to that in intact mice. SCID mice formed smaller hepatic granulomas and showed less fibrosis than did intact mice. The reduction in egg-associated pathology in SCID mice correlated with marked reductions in interleukin-4 (IL-4), IL-5, IL-13, and gamma interferon mRNA expression in the liver. S. mansoni infections were frequently lethal for SCID mice infected for more than 9 weeks, while S. japonicum-infected SCID mice died at the same rate as infected intact mice. We were unable to affect hepatic granuloma formation or egg laying by worms in SCID mice by administration of recombinant murine tumor necrosis factor alpha (TNF-alpha). In fact, SCID and BALB/c mice appeared to express nearly equivalent levels of TNF-alpha mRNA in their granulomatous tissues, suggesting that there is little or no deficit in TNF-alpha expression in infected SCID mice. The data indicate that TNF-alpha may be in large part derived from a non-T-cell source. Together, these findings provide little evidence that TNF-alpha alone can reconstitute early fecundity, granuloma formation, or hepatic fibrosis in schistosome-infected SCID mice.

Animals↗
PubMed2003

Removal of Wolbachia from Brugia pahangi is closely linked to worm death and fecundity but does not result in altered lymphatic lesion formation in Mongolian gerbils (Meriones unguiculatus).

Approximately 30 years ago, researchers reported intracellular bacteria in filarial nematodes. These bacteria are relatives of the arthropod symbiont Wolbachia and occur in many filarial nematodes, including Brugia pahangi and Brugia malayi. Wolbachia bacteria have been implicated in a variety of roles, including filaria development and fecundity and the pathogenesis of lymphatic lesions associated with filarial infections. However, the role of the bacteria in worm biology or filarial disease is still not clear. The present experiments support previous data showing that tetracycline eliminates or reduces Wolbachia bacteria in B. pahangi in vivo. The elimination of Wolbachia was closely linked to a reduction in female fecundity and the viability of both sexes, suggesting that the killing of Wolbachia is detrimental to B. pahangi. The gerbils treated with tetracycline showed reduced levels of interleukin-4 (IL-4) and IL-5 mRNA in renal lymph nodes and spleens compared with the levels in B. pahangi-infected gerbils not treated with tetracycline. However, similar findings were noted in B. pahangi-infected gerbils treated with ivermectin, suggesting that the loss of circulating microfilariae, not the reduction of Wolbachia bacteria, was associated with the altered cytokine profile. Despite the change in T-cell cytokines, there was no difference in the sizes of renal lymph nodes isolated from gerbils in each treatment group. Furthermore, the numbers, sizes, or cellular compositions of granulomas examined in the lymphatics or renal lymph nodes did not differ with treatment. These data suggest that Wolbachia may not play a primary role in the formation of lymphatic lesions in gerbils chronically infected with B. pahangi.

Animals↗
PubMed1999

Salpingectomy for unilateral hydrosalpinx may improve in vivo fecundity.

The objective of this study was to determine whether unilateral salpingectomy for hydrosalpinx could improve fecundity in women with an apparently normal contralateral tube. Two women with unilateral hydrosalpinx and with an apparently normal contralateral tube, and a long history of infertility, including failure to conceive despite several cycles of in vitro fertilization (IVF), had unilateral salpingectomies prior to considering subsequent IVF cycles. Case 1 conceived after 1 month following surgery and case 2 after 8 months without the use of assisted reproductive technology. Though the ensuing pregnancies may have been fortuitous, the possibility exists that in cases of unilateral hydrosalpinx, the performance of salpingectomy may improve fecundity without the need for IVF. Hopefully the outcome of these 2 case reports may generate interest in a larger cooperative prospective study.

Adult↗
PubMed2006

Cervical mucus symptom and daily fecundability: first results from a new database.

With the collaboration of Italian centres providing services on natural family planning, a prospective study collected data on 2755 menstrual cycles of 193 women. A database was constructed using information on the daily characteristics of cervical mucus and episodes of intercourse. Taking the day of peak mucus as a conventional marker of ovulation, the database identified the length (12 days) and location of a 'window' of potential fertility, the highest level of conception probability being confined to the central five to six days. Univariate analysis provided evidence of the impact on fecundability of the woman's age and the basic infertile pattern of a cycle. Several analytical approaches highlighted the relationship between daily mucus characteristics and levels of fecundability

Adolescent↗
PubMed2000

Fecundability and parental exposure to ambient sulfur dioxide.

Recently it has been observed that birth rates in Teplice, a highly polluted district in Northern Bohemia, have been reduced during periods when sulfur dioxide levels were high. This study, which is based on data from 2,585 parental pairs in the same region, describes an analysis of the impact of SO(2) on fecundability in the first unprotected menstrual cycle (FUMC). We obtained detailed personal data, including time-to-pregnancy information, via maternal questionnaires at delivery. We estimated individual exposures to SO(2) in each of the 4 months before conception on the basis of continual central monitoring. Three concentration intervals were introduced: < 40 microg/m(3 )(reference level); 40-80 microg/m(3); and [greater than or equal to] 80 microg/m(3). We estimated adjusted odds ratios (AORs) of conception in the FUMC using logistic regression models. Many variables were screened for confounding. AORs for conception in the FUMC were consistently reduced only for couples exposed in the second month before conception to SO(2) levels as follows: 40-80 microg/m(3), AOR 0.57 [95% confidence interval (CI), 0.37-0.88; p < 0.011]; [greater than or equal to] 80 microg/m(3), AOR 0.49 (CI, 0.29-0.81; p < 0.006). The association was weaker in the second 2 years of the study, probably due to the gradual decrease of SO(2) levels in the region. The relationship between SO(2) and fecundability was greater in couples living close to the central monitoring station (within 3.5 km). The timing of these effects is consistent with the period of sperm maturation. This is in agreement with recent findings; sperm abnormalities originating during spermatid maturation were found in young men from Teplice region who were exposed to the increased levels of ambient SO(2). Alternative explanations of our results are also possible.

Adolescent↗
PubMed1986

Female rats in a laboratory display seasonal variation in fecundity.

Female laboratory rats housed in controlled environments of two separate laboratories displayed seasonal variation in fecundity. Fecundity peaked between May and August and reached a trough between December and February, as measured by oestrous cycle length, variability and regularity, as well as number of animals mating and the percentage of litters reared to weaning. The percentage of mated animals giving birth remained constant throughout the year. Seasonal variations in the laboratory coincided with the seasonal cycle reported for wild rats in natural conditions. Several environmental variables, e.g. food, water, humidity and airborne factors, were evaluated as putative cues for seasonal variation.

Animals↗