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PubMed1987

Control theory predictions of reproductive allocation in female dusky salamanders.

A model of the reproductive ecology of female dusky salamanders was used to investigate the allocation scheme that a female might use to maximize her reproductive success. Analysis of the model with techniques of optimal control theory suggests that fecundity is maximized either by allocating food resources to reproduction for the entire time period prior to egg laying, or by growing first, then switching to reproduction later in the year. The analysis also indicates that egg mortality will be minimized if the female provides maternal care at the maximum level throughout egg brooding. These results are not specific to dusky salamanders, but can be extended to other organisms with similar reproductive characteristics.

Animals↗

PubMed1990

A cross-sectional study of bluetongue virus and Mycoplasma bovis infections in dairy cattle: II. The association between a positive antibody response and reproduction performance.

In a cross-sectional study to determine the possible relationship between a positive antibody test to bluetongue virus (BTV) or Mycoplasma bovis infections and reproductive performance of dairy cows, data were collected on 572 California dairy cows during December 1986 for analysis. Serum samples were tested using an enzyme-linked immunosorbent assay (ELISA). Data on reproduction variables were extracted from the individual cow sheets of the California Dairy Herd Improvement Association records and interfaced with the serological results for analysis. Similar data analyses for both BTV and M. bovis were performed to identify and quantitatively assess the association of the reproduction variables and each agent. These associations were evaluated unconditionally using the chi 2 for categorical variables and Student's t-test for continuous variables. Logistic regression analysis was used to determine if reproduction variables with significant unconditional associations remained significant when adjusted for the effects of possible confounding factors. Both the BTV and M. bovis ELISA antibody titres indicated exposure to the agents. The results of the multiple logistic regression analyses indicated that cows seropositive for BTV were significantly older at first calving (p less than 0.03). For M. bovis, seropositive cows were more likely to have longer intervals from calving to last service and longer intervals from calving to pregnancy diagnosis than seronegative cows (p less than 0.05). The other reproduction variables examined were not significantly associated with ELISA seropositivity.

Age Factors↗

PubMedDate not supplied

Oocyte atresia and reproductive success in fathead minnows (Pimephales promelas) exposed to acidified hardwater environments.

The ovarian histology of fathead minnows (Pimephales promelas) chronically exposed to three levels of environmental pH was examined for evidence of reproductive impairment. Exposures occurred in three experimental running-water channels receiving Mississippi River water. One of these channels was not acidified and two were dosed with H2SO4. The pH was approximately 8 in untreated river water and 6 and 5 in the two channels receiving H2SO4. Fish for ovarian examination were taken from these channels at four stages of the reproductive season: initiation of spawning (June 19), mid-spawning (July 12), end of spawning (August 14-15), and approximately 1 mo. post-spawning (September 19). The fish exhibited ovarian histological changes and depression of reproductive success which were directly associated with the level of environmental stress experienced. The association between these three factors was most consistent and pronounced if the fish were sampled near the end of the spawning season. When sampled at this time, reproductive impairment in a population was found when the ratio of the volume of atretic (resorbing) oocytes present in the ovary to the total ovarian volume exceeded 20% in all fish sampled. This was the case in the pH 5 channel fish sampled in August. At this same time, not all of the fish in the pH 6 channel exhibited such an accumulation of atretic oocytes, and egg deposition in that population was not reduced. None of the fish from the pH 8 channel were so affected nor was their reproduction.

Acid Rain↗

PubMed1993

Evolution of delayed reproductive senescence in male fruit flies: sperm competition.

Populations of Drosophila melanogaster that had been subjected to long-term selection favoring either delayed or rapid senescence were compared with respect to age-specific components of male reproductive success involving sperm competition. These components of reproductive success were divided into those related to sperm 'defense' (protection of sperm from other males), and into those related to sperm 'offense' (ability to mate with previously mated females and to displace the sperm of other males). Males were tested at four ages ranging from 1-2 d to 5-6 wk after eclosion. Several aspects of sperm defense capability showed clear evidence of senescent decline. Furthermore, males from populations selected for delayed senescence were superior to males from control (rapid senescence) populations with regard to components of sperm defense. The superiority of males from populations with delayed senescence either increased as a function of male age, or was present at all ages tested. These results indicate that the rate of reproductive senescence in male D. melanogaster can be altered in predictable directions by artificial selection. There were no differences between selection regimes with regard to sperm offense, and most components of sperm offense did not show clear evidence of senescence. The improved late-age reproductive success of males from populations selected for delayed senescence did not appear to entail any cost or trade-off at early ages with respect to the reproductive traits examined in these experiments.

Aging↗

PubMed1977

Current status of PCB toxicity to mink, and effect on their reproduction.

Experiments were conducted from 1968 to 1974 to investigate reproductive complications and mortality in mink fed Great Lakes coho salmon and to ascertain the effects of polychlorinated biphenyls (PCB's) on this fur bearer. The results of mink feeding trials indicated that coho salmon, as such, were not responsible for the loss of reproduction in the adult, or the kit mortality. Mink diets that contained other species of Great Lakes fish caused similar reproductive complications, but to a lesser degree. Rancidity, mercury poisoning and chlorinated hydrocarbon pesticide contamination of the fish were all discounted as being responsible for the problem. The clinical signs and lesions noted in mink that died while receiving diets that contained Lake Michigan coho salmon were very similar to those observed in mink fed on rations that contained supplemental PCB's. These included anorexia, blood stools, fatty liver, kidney degeneration, and hemorrhagic gastric ulcers. Analyses of tissues from mink that died when fed 30% Lake Michigan coho salmon or 30 ppm supplemental PCB diets showed similar PCB residues. PCB toxicity experiments revealed that mink are very sensitive to these compounds and that the lethal dose varied inversely with the chlorine content of the PCB's although only Aroclor 1254 exerted a detrimental effect on reproduction when fed at a low level (2 ppm) for 8 months. The reproductive failure encountered in feeding mink Lake Michigan coho salmon and Aroclor 1254 was shown to be of a non-permanent nature.

Animal Feed↗

PubMedDate not supplied

Prolonged ingestion of commercial DDT and PCB; effects on progesterone levels and reproduction in the mature female rat.

A report linking human polycystic ovary with increased exposure to environmental DDT (Heinrichs et al. 1971) prompted the present study comparing effects of PCB and DDT or their combination on reproduction in female rats under more realistic conditions with respect to level (75 and 150 ppm), route of administration (dietary contaminant), and period of exposure (8 and 36 weeks). Evaluation of estrous cycle length, mating frequency, number and size of litters; as well as plasma levels of DDT, PCB, progesterone (P), and 17 alpha=hydroxyprogesterone (17 alpha=OH-P), permitted comparison of short and long term reproductive changes from ingestion of two levels of DDT and/or PCB. PCB reduced plasma progesterone (p less than .01) while plasma 17alpha OH-P was unchanged by PCB or DDT. High DDT and PCB abolished reproduction. Histologically, distinct ovarian stromal changes accompanied 150 ppm of PCB, while increased numbers of more prominent follicular cysts were evident with 150 ppm of DDT. Although DDT and PCB generally reduced or abolished litter production, no treatment tested significantly altered litter size. Long term chronic ingestion of more realistic levels of technical DDT (85% p,p', 15% o,p'-DDT) in these studies did not lead to polycystic ovaries in adult rats comparable to those reported following i.v. administration of pure o,p'-DDT to immature rats. Plasma DDT levels above 800 ppb are clearly detrimental to reproduction, while levels below 500 ppb had lettle effect. Finally, we present the first evidence reported to our knowledge demonstrating that prolonged ingestion of PCB (150 ppm) markedly reduces reproduction (p less than .05) accompanied by significantly reduced progesterone in plasma (p less than .01) as well as by histologically characteristic ovarian stromal changes not seen with DDT alone.

Animals↗

PubMed2005

Reproductive health education intervention trial.

OBJECTIVE: To measure the effectiveness of a reproductive health education package in improving the knowledge of adolescent girls aged 15-19 years in Chandigarh (India). METHODS: A reproductive health education package, developed in consultation with parents, teachers and adolescents, was delivered to randomly sampled classes of two senior secondary schools and one school was selected as control. In one school, a nurse conducted 15 sessions for 94 students in three batches using conventional education approach. In another school she conducted sessions for a selected group of 20 adolescents who later disseminated the messages informally to their 84 classmates (peer education). Using a 70-item structured questionnaire the knowledge of 95 adolescents from conventional, 84 from peer, and 94 from control school were assessed before and one month after the last session. Change in the score in intervention and control groups was tested by ANOVA taking age and socio-economic status as covariates. RESULTS: Teachers, parents and students overwhelmingly (88%, 95.5% and 93% respectively) favoured reproductive health education program. Five percent of the respondents reported that someone in their class is having sexual relations, and 13% of the girls approved of pre-marital sexual relations. Reproductive health knowledge scores improved significantly after intervention in conventional education (27.28) and peer education group (20.77) in comparison to the controls (3.64). Post-test scores were not significantly different between peer education group and conventional education group (43.65 and 40.52 respectively) though the time consumed in delivering the peer education intervention was almost one third of the time taken to implement conventional education. CONCLUSION: Peer education and conventional education strategies were effective in improving the reproductive health knowledge of adolescent girls but peer strategy was less time consuming.

Adolescent↗

PubMed2004

Reproductive health awareness of school-going, unmarried, rural adolescents.

OBJECTIVE: In 1996, India included Adolescent Health in Reproductive and Child Heatlh Programme. This Task-Force Study was planned to test the awareness level of adolescents regarding various reproductive health issues and to identify lacunae in knowledge, particularly in legal minimum age of marriage, number of children, male preference, contraceptive practices, about STIs /AIDS etc. METHODS: It was a multicentre study, done in rural co-education/higher secondary schools of 22 districts located in 14 states through Human Reproductive Research Centre (HRRC's) of the Indian Council of Medical Research (ICMR). A sample of 8453 school going adolescents (aged 10-19 years) was surveyed by means of open ended, self-administered questionnaires maintaining confidentiality. RESULTS: Mean age of adolescents was 14.3 +/- 3.4 years. Awareness of legal minimum age of marriage was present in more than half of adolescents. Attitude towards marriage beyond 21 years in boys and 18 years in girls was favorable. Mean number of children desired was 2.2 +/- 1.4. However, number of children desired by boys (2.2+/-1.6) was significantly more (p< 0.000) than those desired by girls (2.0+/-1.1). More boys (23.7%) than girls (9.4%) wanted three or more children with male preference. Only 19.8% of adolescents were aware of at least one method of contraception. Only two-fifth (39.5%) were aware of AIDS and less than one-fifth (18%) were aware of STDs and most of them thought it is same as AIDS. Awareness of at least one method of immunization was present in three-fifth (60.1%) of students. It was least for DPT (13.5%) and most (55%) were aware of polio only. Awareness of all Reproductive Health matters was more in boys than girls and more in late teens (15-19) than earlier teens (10-14). CONCLUSION: The study showed tremendous lacunae in awareness of all Reproductive Health (RH) matters. There is a need for evolving information, education, and communication strategies to focus on raising awareness on RH and gender related issues. A sociocultural research is needed to find the right kind of sexual health services for young girls and boys.

Adolescent↗

PubMed2006

Winged queens replaced by reproductives smaller than workers in Mystrium ants.

In ants, winged queens that are specialized for independent colony foundation can be replaced by wingless reproductives better adapted for colony fission. We studied this shift in reproductive strategy by comparing two Mystrium species from Madagascar using morphometry, allometry and dissections. Mystrium rogeri has a single dealate queen in each colony with a larger thorax than workers and similar mandibles that allow these queens to hunt during non-claustral foundation. In contrast, Mystrium 'red' lacks winged queens and half of the female adults belong to a wingless 'intermorph' caste smaller and allometrically distinct from the workers. Intermorphs have functional ovaries and spermatheca while those of workers are degenerate. Intermorphs care for brood and a few mate and reproduce making them an all-purpose caste that takes charge of both work and reproduction. However, their mandibles are reduced and inappropriate for hunting centipedes, unlike the workers' mandibles. This together with their small thorax disallow them to perform independent colony foundation, and colonies reproduce by fission. M. rogeri workers have mandibles polymorphic in size and shape, which allow for all tasks from brood care to hunting. In M. 'red', colonial investment in reproduction has shifted from producing expensive winged queens to more numerous helpers. M. 'red' intermorphs are the first case of reproductives smaller than workers in ants and illustrate their potential to diversify their caste system for better colonial economy.

Animals↗

PubMed2004

QTL mapping of chromosomal regions conferring reproductive frost tolerance in barley ( Hordeum vulgare L.).

Spring radiation frost is a major abiotic stress in southern Australia, reducing yield potential and grain quality of barley by damaging sensitive reproductive organs in the latter stages of development. Field-based screening methods were developed, and genetic variation for reproductive frost tolerance was identified. Mapping populations that were segregating for reproductive frost tolerance were screened and significant QTL identified. QTL on chromosome 2HL were identified for frost-induced floret sterility in two different populations at the same genomic location. This QTL was not associated with previously reported developmental or stress-response loci. QTL on chromosome 5HL were identified for frost-induced floret sterility and frost-induced grain damage in all three of the populations studied. The locations of QTL were coincident with previously reported vegetative frost tolerance loci close to the vrn- H1 locus. This locus on chromosome 5HL has now been associated with response to cold stress at both vegetative and reproductive developmental stages in barley. This study will allow reproductive frost tolerance to be seriously pursued as a breeding objective by facilitating a change from difficult phenotypic selection to high-throughput genotypic selection.

Acclimatization↗

PubMedDate not supplied

Sexual and reproductive health in young people with congenital heart disease: a systematic review of the literature.

BACKGROUND: Improved survival in young people with congenital heart disease (CHD) alters the significance of a range of developmentally important subjects, such as sexual and reproductive health. The aim of this study was to determine the level of knowledge about sexual and reproductive health issue in young people with CHD. METHODS: We undertook a systematic review of the literature from 1966 to March 2004, searching Medline, Psych Info, and Em base using a broad range of search terms. Additionally, we searched the literature for published guidelines on standards of care for young people with CHD. RESULTS: We identified ten articles that examined patients,' understanding of their heart disease. Seven of them specifically investigated knowledge of sexual and reproductive health as it related to cardiac disease. CONCLUSIONS: In general, young people have a poor understanding of their heart disease. They appear to have a particularly poor grasp of sexual and reproductive health issues, yet they are interested in these issues. Therefore, health care programs for young people with CHD should incorporate sexual and reproductive health information and include anticipatory counseling and health risk screening.

Adolescent↗

PubMed2004

Associations between fish reproductive cycle and the dynamics of metazoan parasite infection.

The parasite fauna of the stone loach (Barbatula barbatula) was investigated monthly from May to December 2001. Four parasite species were recorded: Gyrodactylus spp. (Monogenea), Tylodelphys clavata (Digenea), Proteocephalus sagittus (Cestoda), and Raphidascaris acus (Nematoda). The changes in the seasonal dynamics of parasite infection were investigated throughout the 8 months. The potential effect of the reproductive investment of the host, measured by gonad mass and gonado-somatic index (GSI), on the parasite infection was tested against the prediction that, during periods of high reproductive investment (beginning of the breeding period or forming gonads after breeding), the fish are more susceptible to parasite infection. Differences between parasite loads between genders were also hypothesized. Seasonal differences in infection were observed for all parasite species studied. The values of GSI showed a pattern of energy accumulation in the pre-reproductive period and at the beginning of breeding, a decrease during breeding, and an increase in the post-breeding period. A similar pattern was observed for parasite abundance, a strong or weak increase in spring and/or autumn and a decrease during summer (July and August). Positive correlations between the abundance of Gyrodactylus spp. and R. acus and both gonad mass and GSI were found in females after eliminating the effect of fish weight. Our results suggest that stone loach females are more susceptible to parasite infection in periods of higher reproductive investment. The main factor determining the infection of T. clavata was fish size. The abundance of P. sagittus was positively correlated with GSI in the total fish sample with no detectable effect of sex or fish weight. The increase in cestode infection in spring supports the hypothesis that the parasite life cycle could by synchronized with the beginning of host reproduction, probably induced by increasing fish hormone levels in the spring.

Animals↗

PubMed2003

Floral density, pollen limitation, and reproductive success in Trillium grandiflorum.

Decreases in floral density can disrupt mutualistic interactions between plants and their pollinators, and decrease reproductive success. I addressed the relationship between floral density and plant reproductive success using two experimental approaches: a pollen supplementation experiment in 12 populations of Trillium grandiflorum that naturally varied in floral density, and a transplant experiment in which floral density was manipulated in plots at four experimental sites. In the pollen supplementation experiments, the degree of pollen limitation, in terms of fruit set and seed set, decreased with floral density. Further, in the experimental sites, plant reproductive success increased asymptotically with floral density. These results demonstrate the value of simultaneously conducting experiments in both experimental sites and natural populations to understand how population density influences plant reproductive success. Factors that reduce the density of this perennial herb, such as habitat fragmentation and herbivory by white-tailed deer ( Odocoileus virginianus), should be expected to limit its reproduction.

Flowers↗

PubMed2004

Characterizing the interaction between the bogus yucca moth and yuccas: do bogus yucca moths impact yucca reproductive success?

Yucca moths are most well known for their obligate pollination mutualism with yuccas, where pollinator moths provide yuccas with pollen and, in exchange, the moth larvae feed on a subset of the developing yucca seeds. The pollinators, however, comprise only two of the three genera of yucca moths. Members of the third genus, Prodoxus, are the "bogus yucca moths" and are sister to the pollinator moths. Adult Prodoxus lack the specialized mouthparts used for pollination and the larvae feed on plant tissues other than seeds. Prodoxus larvae feed within the same plants as pollinator larvae and have the potential to influence yucca reproductive success directly by drawing resources away from flowers and fruit, or indirectly by modifying the costs of the mutualism with pollinators. We examined the interaction between the scape-feeding bogus yucca moth, Prodoxus decipiens, and one of its yucca hosts, Yucca filamentosa, by comparing female reproductive success of plants with and without moth larvae. We determined reproductive success by measuring a set of common reproductive traits such as flowering characteristics, seed set, and seed germination. In addition, we also quantified the percent total nitrogen in the seeds to determine whether the presence of larvae could potentially reduce seed quality. Flowering characteristics, seed set, and seed germination were not significantly different between plants with and without bogus yucca moth larvae. In contrast, the percent total nitrogen content of seeds was significantly lower in plants with P. decipiens larvae, and nitrogen content was negatively correlated with the number of larvae feeding within the inflorescence scape. Surveys of percent total nitrogen at three time periods during the flowering and fruiting of Y. filamentosa also showed that larval feeding decreased the amount of nitrogen in fruit tissue. Taken together, the results suggest that although P. decipiens influences nitrogen distribution in Y. filamentosa, this physiological effect does not appear to impact the female components of reproductive success.

Analysis of Variance↗

PubMed2004

Ecotypic differentiation and phenotypic plasticity in reproductive traits of Armadillidium vulgare (Isopoda: Oniscidea).

Armadillidium vulgare differed in growth and survivorship on two field sites. Growth rates were higher at a site with consistently higher quality food than at the other site where less high-quality food was produced and which was less predictably accessible. Survivorship was higher at the second site where temperature fluctuations were consistently smaller. Individuals from the two populations were kept for 6 months under the same food and temperature conditions and patterns of resource allocation to reproductive traits analysed. Members of the population from the site with good growth conditions had significantly higher reproductive allocation, by 13.5%, and larger broods, by 9.1%, than those from the site with poor growth conditions. Contrary to theoretical predictions, they also had significantly larger offspring, by 7.5% dry mass. Larger offspring survived better than small ones. This differential survivorship, by 20% for a 3.4% difference in live mass, was much more pronounced under conditions of moisture stress and under fluctuating temperature regimes. Larger offspring would therefore be at a selective advantage on the site with more severe temperature fluctuations. Phenotypic plasticity in reproductive traits in response to experimental changes in food quality, temperature and crowding were monitored. Reproductive allocation was increased by 20.8% under conditions of higher food quality, by 14.7% at higher temperatures, and by 12.5% under less crowded conditions. Brood size, but not offspring dry mass, increased when food quality increased. When crowding increased by 25.0%, the size of broods remained the same but the dry mass of individual offspring decreased by 11.2%. Members of the population from the site with more variable access to high-quality food showed more plasticity in reproductive traits in response to changes in food supply than members of the population from the site with the more predictable food supply. Members of the population from the site with more stable temperatures showed less plasticity to temperature changes than members of the population from the site with greater temperature fluctuations. It is concluded that the observed microevolutionary processes and phenotypic plasticity have adaptative value as responses to spatial and temporal heterogeneity in environmental conditions.

Adaptation, Physiological↗

PubMed2006

Combined food and predator effects on songbird nest survival and annual reproductive success: results from a bi-factorial experiment.

Food and predators have traditionally been viewed as mutually exclusive alternatives when considering factors affecting animal populations. This has led to long controversies such as whether annual reproductive success in songbirds is primarily a function of food-restricted production or predator-induced loss. Recent studies on both birds and mammals suggest many of these controversies may be resolved by considering the combined effects of food and predators. We conducted a 2x2 manipulative food addition plus natural predator reduction experiment on song sparrows (Melospiza melodia) over three consecutive breeding seasons. Food and predators together affected partial clutch or brood loss, nest survival (total clutch or brood loss) and annual reproductive success. When combined, our two treatments reduced partial losses by more than expected if the effects of food and predators were independent and additive. Food and predators also interacted in their effects on nest survival since food addition significantly reduced the rate of nest predation. While annual reproductive success was highly correlated with nest predation (r2=0.71) the strength of this relationship was reinforced by the indirect effects of food addition on nest predation. A stepwise multiple regression showed that the residual variation in annual reproductive success was explained by food effects on the total number of eggs laid over the season and the combined effects of food and predators on partial losses noted above. We conclude that annual reproductive success in song sparrows is a function of both food-restricted production and predator-induced loss and indirect food and predator effects on both clutch and brood loss. We highlight the parallels between our results and those from a comparable bi-factorial experiment on mammals because we suspect combined food and predator effects are likely the norm in both birds and mammals.

Animals↗

PubMed2006

Experimental investigation of the effect of spatial aggregation on reproductive success in a rewardless orchid.

Plant reproductive success within a patch may depend on plant aggregation through pollinator attraction. For rewardless plants that lack rewards for pollinators, reproductive success may rely strongly on the learning abilities of pollinators. These abilities depend on relative co-flowering rewarding and rewardless plant species spatial distributions. We investigated the effect of aggregation on the reproductive success of a rewardless orchid by setting up 16 arrays in a factorial design with two levels of intraspecific aggregation for both a rewardless orchid and a rewarding co-flowering species. Our results show that increasing aggregation of both species negatively influenced the reproductive success of the rewardless plants. To our knowledge, this is the first experimental study demonstrating negative effects of aggregation on reproductive success of a rewardless species due both to its own spatial aggregation and that of a co-flowering rewarding species. We argue that pollinator learning behaviour is the key driver behind this result.

Analysis of Variance↗

PubMed2006

Association of menstrual and reproductive factors with pancreatic cancer risk in women: findings of the Japan Collaborative Cohort Study for Evaluation of Cancer Risk.

BACKGROUND: The etiology of pancreatic cancer remains largely unknown. We examined the association of pancreatic cancer deaths with menstrual and reproductive factors in a cohort study involving Japanese women. METHODS: A total of 63,273 women were followed up for mortality from 1988 to 1999. Information on menstrual and reproductive factors was obtained by a questionnaire survey at baseline. Cox proportional-hazards models were used to estimate the relative risks (RRs) and 95% confidence intervals (CIs) for death from pancreatic cancer in relation to menstrual and reproductive factors. RESULTS: During 631,401 person-years of follow-up, 154 women died from pancreatic cancer. Parity was not significantly associated with the risk of death from pancreatic cancer; the RR was 0.80 (95% CI, 0.31-2.11) for women with six or more births compared with women with zero or one birth. We found no significant overall association with other reproductive factors, including pregnancy, age at first birth, and menopause. The risk appeared to increase with increasing age at menarche; the RR was 1.49 (95% CI, 0.95-2.34) for women who had menarche after 16 years of age compared to those who had menarche before they were 15 years old. CONCLUSIONS: Our prospective data indicate that menstrual and reproductive factors are not associated with the risk of death from pancreatic cancer among Japanese women.

Adult↗