927 resultados para Reproductive Tactics


Relevância:

20.00% 20.00%

Publicador:

Resumo:

We show that a new, simple, and robust general mechanism for the social suppression of within-group selfishness follows from Hamilton's rule applied in a multilevel selection approach to asymmetrical, two-person groups: If it pays a group member to behave selfishly (i.e., increase its share of the group's reproduction, at the expense of group productivity), then its partner will virtually always be favored to provide a reproductive "bribe" sufficient to remove the incentive for the selfish behavior. The magnitude of the bribe will vary directly with the number of offspring (or other close kin) potentially gained by the selfish individual and inversely with both the relatedness r between the interactants and the loss in group productivity because of selfishness. This bribe principle greatly extends the scope for cooperation within groups. Reproductive bribing is more likely to be favored over social policing for dominants rather than subordinates and as intragroup relatedness increases. Finally, analysis of the difference between the group optimum for an individual's behavior and the individual's inclusive fitness optimum reveals a paradoxical feedback loop by which bribing and policing, while nullifying particular selfish acts, automatically widen the separation of individual and group optima for other behaviors (i.e., resolution of one conflict intensifies others).

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Selostus: Tarhatun soopelin luonne ja lisääntymiskyky

Relevância:

20.00% 20.00%

Publicador:

Resumo:

1. The gene Pgm-3 (or a closely linked gene) influences the phenotype and reproductive success of queens in multiple-queen (polygynous) colonies but not single-queen (monogynous) colonies of the Fire Ant Solenopsis invicta. 2. We investigated the mechanisms of differential phenotypic expression of Pgm-3 in these alternate social forms. Mature winged queens with the homozygous genotype Pgm-3(a/a) averaged 26% heavier than queens with the genotypes Pgm-3(a/b) and Pgm 3(b/b) in the polygynous form. Heterozygotes were slightly heavier (2%) than Pgm-3(b/b) queens in this form, demonstrating that the allele Pgm-3(a) is not completely recessive in its effects on weight. 3. There was no significant difference in weight among queens of the three Pgm-3 genotypes in the monogynous form, with the mean weight of monogynous queens slightly greater than that of polygynous Pgm-3(a/a) queens. Differences in weight between queens of the two social forms and among queens of the three genotypes in the polygynous form are not evident at the pupal stage and thus appear to develop during sexual maturation of the adults. This suggests that some component of the social environment of polygynous colonies inhibits weight gains during queen maturation and that Pgm-(3a/a) queens are relatively less sensitive to this factor. 4. To test whether the high cumulative queen pheromone level characteristic of polygynous colonies is the factor responsible for the differential queen maturation, we compared phenotypes of winged queens reared in split colonies in which pheromone levels were manipulated by adjusting queen number. Queens produced in colony fragments made monogynous were heavier than those produced in polygynous fragments, a finding consistent with the hypothesis that pheromone level affects the reproductive development of queens. However, genotype-specific differences in weights of queens were similar between the two treatments, suggesting that pheromone level was not the key factor of the social environment responsible for the gene-environment interaction. 5. To test whether limited food availability to winged queens associated with the high brood/worker ratios in polygynous colonies is the factor responsible for this interaction, similar split-colony experiments were performed. Elevated brood/worker ratios decreased the weight of winged queens but there was no evidence that this treatment intensified differential weight gains among queens with different Pgm-3 genotypes. Manipulation of the amount of food provided to colonies had no effect on queen weight. 6. The combined data indicate that cumulative pheromone level and brood/worker ratio are two of the factors responsible for the differences in reproductive phenotypes between monogynous and polygynous winged queens but that these factors are not directly responsible for inducing the phenotypic effects of Pgm-3 in polygynous colonies.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Abstract

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The main scope of this work was to detect (Panicum maximum Jacq.) genotype differences as to morphoagronomic and seed quality indices, and to establish character correlations useful for determining vegetative and reproductive trends. Besides the flowering cycle, eight phenological and two seed quality traits were scored in a greenhouse randomized complete block experiment, as follows: plant height (PH), reproductive tiller number/overall tiller number (RTN/OTN), panicle number/reproductive tillers (PN/RT), leaf length (LL), leaf width (LW), panicle length (PL), fresh weight (FW), dry weight (DW), number of seeds/g (NS/G) and seed sample physical purity (SPP). Very-early and early-flowering hybrids consistently showed the highest correlation values among flowering cycle and RTN/OTN (r = -0.59**), PN/RT (r = -0.48**), NS/G (r = -0.88**) and SPP (r = -0.80**) (reproductive parameters) while intermediate and late-flowering hybrids presented the highest values for LL (r = 0.53**), LW (r = 0.60**), PL (r = 0.77**), FW (r = 0.78**) and DW (r = 0.85**) (vegetative traits). The implications of these results for plant breeding and forage management purposes are discussed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The objective of this research was to evaluate the effect of the insect resistant soybean genotype IAC 17 on reproductive characteristics of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) females compared to the soybean insect susceptible genotype UFV 16. Treatments were: T1) females of P. nigrispinus fed on plants of the UFV 16 and Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) caterpillars reared on leaves of this variety; T2) females of P. nigrispinus fed on plants of the IAC 17 and A. gemmatalis caterpillars reared on leaves of this variety. Longevity of females, pre-oviposition, oviposition and pos-oviposition periods, number of eggs and egg masses/female, egg weight, interval between egg mass laying, number of eggs/egg mass, percentage of nymphs, number of nymphs/female and total number of prey killed/female of P. nigrispinus were evaluated. Most of the characteristics evaluated showed similar results between treatments, but the oviposition period was longer for females reared on the resistant genotype than on the susceptible one and the percentage of total females that laid eggs was lower on the IAC 17. Also, the resistant genotype caused higher mortality of P. nigrispinus females at the beginning of its adult stage and egg production by females of this predator was better spread along its adult stage with this resistant genotype. On the other hand, results suggest no effect of the resistant genotype on the offspring of this predator.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Phyllophaga cuyabana is a univoltine species and its development occurs completely underground. Its control by conventional methods, such as chemical and biological insecticides, is difficult, so it is important to understand its dispersion, reproduction, and population behavior in order to determine best pest management strategies. The objective of this work was to study the behavior of adults of P. cuyabana. This study was carried out in the laboratory, greenhouse and field sites in Paraná State, Brazil (24º25' S and 52º48' W), during four seasons. The results obtained demonstrate that: a) P. cuyabana adults have a synchronized short-flight period when mating and reproduction occurs; b) adults tend to aggregate in specific sites for mating; c) the majority of adults left the soil on alternate nights; d) the choice of mating and oviposition sites was made by females before copulation, since after copulation adults did not fly from or bury themselves at nearby locations; e) females that fed on leaves after mating, oviposited more eggs than females that had not fed;f) plant species such as sunflower (Helianthus annuus) and the Crotalaria juncea are important food sources for adults.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

OBJECTIVE: To define the dynamics of antimüllerian hormone (AMH) and inhibins during the physiologic menstrual cycle. DESIGN: Longitudinal study. SETTING: University hospital. PATIENT(S): 36 young, healthy, normal weight Caucasian women without medication. INTERVENTION(S): Normal ovulatory menstrual cycles were evaluated by regular blood sampling taken every other day and periovulatory every day. MAIN OUTCOME MEASURE(S): Serum concentrations of AMH, inhibin A and B, follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin, estradiol, progesterone, and free testosterone were measured in all blood samples. RESULT(S): Median AMH levels are statistically significantly higher in the late follicular compared with ovulation or the early luteal phase. There are statistically significant correlations between both AMH and FSH, and AMH and free testosterone in all cycle phases. Inhibin A increases strongly in the late follicular phase and peaks at day LH + 4. Inhibin B shows a broad midfollicular and a sharp early luteal peak, the difference being statistically significant between day LH + 4 and the earlier time points and between day LH + 2 and day LH. Although there is a negative association between inhibin A or B and the body mass index (BMI), there is no correlation between AMH and the BMI. CONCLUSION(S): Levels of AMH show a statistically significant change during the menstrual cycle and may influence the circulating gonadotropin and steroid hormone levels.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Reproductive morphology of the Mediterranean red alga Kallymenia patens is described for the first time, confirming its position in the genus. K. patens is characterized by a non-procarpic female reproductive apparatus, carpogonial branch systems consisting of supporting cells bearing both three-celled carpogonial branches and subsidiary cells that lack a hypogynous cell and carpogonium; fusion cells develop numerous connecting filaments, and tetrasporangia are scattered over the thallus and are probably cruciately divided. Old fertile spathulate specimens of K. patens are morphologically similar to K. spathulata, but they can be distinguished by the length of spathulated proliferations (up to 0.6 cm and 6 cm, respectively), the length of inner cortical cells (up to 70 and 30 μm, respectively), and the gonimoblast location (in proliferations from the perennial part of the blade and over all the thallus surface, respectively)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Recently considerable research has focused on the causes of evolution of multiple-queen (polygynous) colonies. In order to better understand the factors which may have led to these polygynous associations it is vital to compare the reproductive success of queens in monogynous (one queen per colony) and polygynous colonies as well as the relative fitness of queens in polygynous colonies. This paper addresses the difficulties arising from such comparisons and their implications with regard to the methods commonly used to assess reproductive success in queens. The relative reproductive success of queens in monogynous and polygynous colonies is commonly assessed by comparing the relative number of reproductives they produce during a single reproductive season. However, shift in queen number seems to be only one aspect of a profound shift in social structure and reproductive strategy that constitutes, in effect, a ''polygyny syndrome''. For example, female reproductives produced in polygynous colonies frequently use a different mode of colony founding, which in turn affects the probability of their survival. Furthermore, queens from monogynous and polygynous colonies frequently differ in their life-span and the number of sexual broods they produce. As a result, the reproductive success of queens in monogynous and polygynous colonies may not be directly related to the relative number of sexuals they produce during a single reproductive season.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background:There is no actual evidence that the ART are directly related to the occurrence of weight discordance. In some studies, ART-­‐conceived twin pregnancies are at greater risk than non-­‐ART-­‐conceived ones for pregnancy complications and adverse perinatal outcome: the incidences of pregnancy-­‐induced hypertension, uterine bleeding, premature contractions, IUGR, fetal death, discordance, and cesarean section were significantly higher. Discordance rate was elevated (25.3% vs.17.0%) among ART twins, which can increase perinatal risk (increased incidence of SGA and NICU admission). Other studies say that perinatal and neonatal morbidity, gestational age at delivery, and birth weight are not affected by ART. Regarding the first trimester ultrasound, some studies didn’t notice significant differences in CRL disparity or birth weight discordance between spontaneous and ART-­‐ conceived dichorionic twin pregnancies. In ART-­‐conceived dichorionic twin pregnancies, CRL disparity may be associated with birth weight discordance. In some studies, CRL discordance in twin pregnancies in the first trimester was a frequent finding. Objectives: To analyze the association of the ART in the occurrence of weight discordance in the pregnancies between 2010 and 2013 in the Hospital Universitari de Girona Doctor Josep Trueta, and to describe the proportion of diagnosis of growth discordance in the first trimester by the ultrasonography technology. Methods: A retrospective cohort study will be performed in those patients with twin pregnancies between 2010 and 2013, within the Hospital Universitari de Girona Doctor Josep Trueta (HUJT). A retrospective and descriptive study will be done in those cases with discordance weight in the moment of the birth, in which the CRL will be studied in the first trimester ultrasound, describing the percentage of discordance detected in that moment. The general characteristics of the sample are going to be analyzed by Logistic RegressionInfluenceof

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background:There is no actual evidence that the ART are directly related to the occurrence of weight discordance. In some studies, ART-­‐conceived twin pregnancies are at greater risk than non-­‐ART-­‐conceived ones for pregnancy complications and adverse perinatal outcome: the incidences of pregnancy-­‐induced hypertension, uterine bleeding, premature contractions, IUGR, fetal death, discordance, and cesarean section were significantly higher. Discordance rate was elevated (25.3% vs.17.0%) among ART twins, which can increase perinatal risk (increased incidence of SGA and NICU admission). Other studies say that perinatal and neonatal morbidity, gestational age at delivery, and birth weight are not affected by ART. Regarding the first trimester ultrasound, some studies didn’t notice significant differences in CRL disparity or birth weight discordance between spontaneous and ART-­‐ conceived dichorionic twin pregnancies. In ART-­‐conceived dichorionic twin pregnancies, CRL disparity may be associated with birth weight discordance. In some studies, CRL discordance in twin pregnancies in the first trimester was a frequent finding. Objectives: To analyze the association of the ART in the occurrence of weight discordance in the pregnancies between 2010 and 2013 in the Hospital Universitari de Girona Doctor Josep Trueta, and to describe the proportion of diagnosis of growth discordance in the first trimester by the ultrasonography technology. Methods: A retrospective cohort study will be performed in those patients with twin pregnancies between 2010 and 2013, within the Hospital Universitari de Girona Doctor Josep Trueta (HUJT). A retrospective and descriptive study will be done in those cases with discordance weight in the moment of the birth, in which the CRL will be studied in the first trimester ultrasound, describing the percentage of discordance detected in that moment. The general characteristics of the sample are going to be analyzed by Logistic RegressionInfluenceof