Pairing in captive brown-headed cowbirds (Molothrus ater)

1978 ◽  
Vol 56 (11) ◽  
pp. 2249-2252 ◽  
Author(s):  
James A. Darley
Keyword(s):  
Molothrus Ater ◽  
Field Studies ◽  
Adult Males ◽  
Breeding Condition ◽  
Males And Females ◽  
Effect Of Age

Twenty-five male and 15 female brown-headed cowbirds were captured in the fall of 1966. In mid-December of 1966 they were subjected to extended photoperiod to bring them into breeding condition. Various combinations of yearling and adult males and females were observed in eight trials to determine the effect of age and dominance of males on pairing with females. Both yearling and adult males paired with females. Only dominant males paired with females. Subordinate males remained unpaired if sufficient females were unavailable. These observations confirm impressions formed in field studies on the role of dominance and age in pairing in cowbirds.

Cimetidine-induced prolactin release in rats The effect of sex and gonadal steroids

1987 ◽  
Vol 114 (2) ◽  
pp. 178-184 ◽  
Author(s):  
Hajime Watanobe ◽  
Kazuo Takebe
Keyword(s):  
Anterior Pituitary ◽  
Male Rats ◽  
Minor Role ◽  
Adult Males ◽  
Adult Age ◽  
Significant Difference ◽  
Males And Females ◽  
Plasma Prl ◽  
A Minor

Abstract. The cimetidine-induced plasma Prl response was examined in rats of both sexes. First, 10 week old intact adult males and females (dioestrous) were compared. There was no significant difference in the Prl response to cimetidine between the two groups, despite the fact that in adult females the anterior pituitary Prl content was 4 times greater than in males. Second, the effect of gonadal state in adult age on the Prl response to cimetidine was examined in both sexes. In male rats, gonadectomy at the age of 6 weeks significantly reduced the plasma Prl response as well as the pituitary Prl content, both of which were sufficiently restored by testosterone replacement. However, in females, neither gonadectomy at the age of 6 weeks nor subsequent oestradiol replacement affected the Prl response to cimetidine, despite the fact that gonadectomy significantly reduced and oestradiol treatment significantly enhanced the pituitary Prl content. Third, possible permanent effects of the postnatal gonadal milieu on the cimetidine-induced Prl response and the pituitary Prl content were examined in both sexes by castration at varying postnatal ages. The ratio of plasma Prl response to pituitary Prl content was similar in all castrated males. In females, however, the ratio decreased with increasing castration age. In conclusion, the mechanism of cimetidine-induced Prl release is less sex-dependent than are the mechanisms of Prl release by other Prl secretagogues. First, this may be due to a minor role of oestrogen in females in determining the Prl response to cimetidine. Second, the postnatal ovarian secretions may exert a permanent inhibition of the development of the cimetidine-mobilized anterior pituitary Prl pool.

Impact of age and sex on response to ischemic preconditioning in the rat heart: differential role of the PI3K–AKT pathway

2013 ◽  
Vol 91 (8) ◽  
pp. 640-647 ◽  
Author(s):  
Veronika Ledvenyiova ◽  
Dezider Pancza ◽  
Jana Matejiková ◽  
Miroslav Ferko ◽  
Iveta Bernatova ◽  
...  
Keyword(s):  
Ischemic Preconditioning ◽  
Ischemia Reperfusion ◽  
Akt Pathway ◽  
Female Rat ◽  
Adult Males ◽  
Male And Female ◽  
Males And Females ◽  
The Impact ◽  
Old Females

Sex and aging represent important factors that determine morbidity and mortality due to cardiovascular diseases in the human population. This study aimed to investigate the impact of aging on the response to ischemia–reperfusion in male and female rat hearts, and to explore a potential role of the PI3K–Akt pathway in the cardioprotective effects of ischemic preconditioning (IPC) in the myocardium of younger and older adult males and females. Langendorff-perfused nonpreconditioned and preconditioned hearts of 12- and 18-week-old male and female Wistar rats were subjected to regional ischemia and reperfusion with or without prior perfusion with the PI3K inhibitor wortmannin for the evaluation of ischemia-induced arrhythmias and the size of myocardial infarction (infarct size; IS). Aging did not modify IS in both sexes; however, it markedly increased susceptibility to arrhythmias. Although IPC effectively reduced IS in males and females of both ages, only the hearts of males and 18-week-old females benefited from its antiarrhythmic effect. In the preconditioned 12-week-old females, but not the 18-week-old females, and in males of both ages, wortmannin blunted the anti-infarct effect of IPC. In conclusion, activation of the PI3K–Akt pathway plays an important role in protection against lethal injury conferred by IPC in males irrespective of age. The IS-limiting effect of IPC appears to be PI3K–Akt-dependent only in the 12-week-old females.

THE EFFECT OF PREDATOR AGE ON THE FUNCTIONAL RESPONSE OF PODISUS MACULIVENTRIS TO THE PREY SIZE OF GALLERIA MELLONELLA

1969 ◽  
Vol 101 (3) ◽  
pp. 314-327 ◽  
Author(s):  
M. K. Mukerji ◽  
E. J. LeRoux
Keyword(s):  
Functional Response ◽  
Galleria Mellonella ◽  
Prey Size ◽  
Podisus Maculiventris ◽  
Adult Males ◽  
Predator Satiation ◽  
Attack Model ◽  
Males And Females ◽  
The Relationship ◽  
Effect Of Age

AbstractExperiments were carried out to determine the effect of age on the functional response of the pentatomid predator Podisus maculiventris (Say), reared in a simple glass jar universe on different prey sizes of Galleria mellonella (L.). Holling’s (1959) ’disc’ equation accurately described the predator’s response at all prey sizes up to 50 days of life. For nymphs, the calculated ’rate of discovery’, a, increased as the predator age increased, but the time of handling prey, b, decreased; for both adult males and females, these calculated values increased gradually up to the 50th day. The relationship between predator age and numbers of prey killed, and predator age and amount of prey body contents consumed (food consumption), was linear at all prey sizes, but mainly negatively so. Prey size was an important component of the predation process for all stages of the predator.It is concluded that ’hunger’ is an important parameter of the attack model since the degree of predator satiation bears directly on b-type activities which in turn affects a-type activities. These findings indicate that under field conditions P. maculiventris will kill more small-sized lepidopterous prey larvae than large-sized ones, and that, because of the greater prey defense of the latter, their survival from predator attacks will increase. These actions may be of considerable importance in the survival of lepidopterous host species.

scholarly journals Vocal Development is Correlated with an Indicator of Hatching Date in Brown-Headed Cowbirds

The Condor ◽  
2002 ◽  
Vol 104 (4) ◽  
pp. 761-771 ◽  
Author(s):  
Adrian L. O'Loghlen ◽  
Stephen I. Rothstein
Keyword(s):  
New York ◽  
Molothrus Ater ◽  
New York State ◽  
Field Studies ◽  
Hatching Date ◽  
Adult Males ◽  
Vocal Development ◽  
Song Acquisition ◽  
Song Types ◽  
Song Repertoires

Abstract The timing and ecological circumstances under which individual songbirds acquire memorized copies of their species-typical songs can vary significantly within a population. Males that hatch later in the breeding season are likely to hear less conspecific song as juveniles than earlier-hatched individuals. In addition, late-hatched males will experience shorter days and decreasing photoperiods during their song acquisition phase, factors known to affect vocal development. We tested the prediction that yearling Brown-headed Cowbirds (Molothrus ater) that hatched earlier the previous season are more advanced in their development of repertoires of local songs than those hatched later. We recorded perched songs from 17 yearling and 20 adult males trapped at two adjacent sites in New York state and found that yearling perched song repertoires were smaller and contained few of the perched song types common to the repertoires of local adults (adult-shared types). As found in previous field studies of cowbirds, yearlings did not alter the content or size of their repertoires during the season. We used underwing juvenal-feather retention as a measure of relative hatching date in a subset of 15 yearlings and found that perched song repertoires of earlier-hatched yearlings contained more local adult-shared types than repertoires of younger, later-hatched birds. We also investigated flight whistles of males from one site and found that only 4 of 10 yearlings produced the flight whistle type typically given by local adults. Evidence linking flight whistle development and the plumage character we used as an indicator of hatching date was inconclusive. Correlación Entre el Desarrollo Vocal y un Indicador de Tiempo de Eclosión en Molothrus ater Resumen. El tiempo y las circunstancias ecológicas bajo las cuales las aves canoras adquieren copias memorizadas de los cantos típicos de su especie pueden variar entre poblaciones. Los machos juveniles que eclosionan tarde en la temporada tienen (1) menor probabilidad de escuchar cantos coespecíficos que los individuos que eclosionan antes y (2) experimentarán días más cortos y una disminución del fotoperiodo durante la fase de adquisición del canto, factores que afectan el desarrollo vocal. Probamos que juveniles de Molothrus ater que eclosionaron tempranamente durante la temporada anterior presentan un mayor avance en el desarrollo de repertorio de cantos locales que aquellos que eclosionaron más tarde. Registramos los cantos de percheo de 17 machos juveniles y de 20 machos adultos capturados en dos sitios adyacentes en el estado de Nueva York. Los repertorios de canto de juveniles fueron menores y contenían sólo unos pocos tipos de canto de percheo típicos de adultos locales (tipos compartidos entre adultos). Los juveniles no cambiaron el contenido ni el tamaño del repertorio durante la temporada. Utilizamos la retención de plumas juveniles bajo el ala como una medida relativa del tiempo de eclosión en un subconjunto de 15 juveniles. Los repertorios de canto de percheo de los juveniles que eclosionaron tempranamente contenían más tipos adultos que los de aves más jóvenes. En machos de uno de los sitios encontramos que sólo 4 de 10 juveniles produjeron el silbido al vuelo típicamente emitido por los adultos locales. La evidencia que conecta el desarrollo del silbido al vuelo y el indicador del plumaje que utilizamos como indicador del tiempo de eclosión no fue conclusiva.

Size-At-Age Variability and Sexual Dimorphism of Morphometric Characteristics in the Late Ontogenesis of the Marsh Frog, Pelophylax Ridibundus (Anura, Ranidae), from Terrytory of Crimea

2019 ◽  
Vol 53 (4) ◽  
pp. 325-334
Author(s):  
V. N. Peskov ◽  
N. A. Petrenko ◽  
V. Yu. Reminnyi
Keyword(s):  
Age Groups ◽  
The Body ◽  
Adult Males ◽  
Morphometric Characteristics ◽  
Morphometric Characters ◽  
Mean Values ◽  
Marsh Frog ◽  
Males And Females ◽  
Size At Age ◽  
Linear Body

Abstract We study size-at-age and sexual variability of morphometric characteristics of the marsh frog. According to the size of the body, males were divided into three size-age groups (juvenis, subadultus, adultus), females — into four groups (juvenis, subadultus, adultus, adultus-I). We found that the chronological age of frogs (skeletochronology) does not always correspond to their biological age (size and proportions of the body). We noted that the semi-adult males are reliably larger than females by mean values of 26 studied morphometric characters. Males and females of “adultus” group do not differ by linear body size, significant differences were found in body proportions (7 characters). For the females of “adultus-I” group, the mean values of 26 characters are significantly larger than for “adultus” males. The results of our study showed that with the age of the marsh frog, the level of exhibition, directionality and structure of morphometric sex differences changes.

Gender Diversity in Computing: An Environmental Perspective

10.28945/3248 ◽  
2008 ◽  
Author(s):  
Cecille Marsh
Keyword(s):  
Gender Diversity ◽  
Household Head ◽  
Female Students ◽  
Political Factors ◽  
Female Household Head ◽  
Dominant Female ◽  
Computer Confidence ◽  
Males And Females ◽  
Research Questions

Previous research conducted by the author investigated the socio-political backgrounds of two groups of female students studying computer-related university programmes. They came from distinctly different backgrounds and were enrolled at two institutions with very different legacies. The author found that socio-political factors, in particular the role of a dominant female household head and aggressive governmental affirmative action, had a significant effect on the girls’ levels of confidence and subsequently on their decision to study computer-related courses. Based on this insight, the researcher undertook to look further into gender diversity with respect to self-perceived general computer confidence and self-perceived ability to program a computer. A sample of both female and male Information T echnology students from very similar disadvantaged socio-economic backgrounds was surveyed. The sample of 204 students was drawn from all three years of the National Diploma in Information Technology. The author considered the following research questions: (i) Do males and females studying computer-related courses have differing computer selfefficacy levels? (ii) Do males and females studying computer programming have differing attitudes towards their ability to program? (iii) Do males and females differ in their attitudes towards the programming learning environment?

Selenium Role in Reproduction, Pregnant/Postpartum Women and Neonates: A Current Study

2020 ◽  
Vol 17 (1) ◽  
pp. 28-37
Author(s):  
Tabinda Sattar
Keyword(s):  
Infant Development ◽  
Selenium Deficiency ◽  
Human Reproduction ◽  
Postpartum Women ◽  
Female Reproduction ◽  
Pregnancy And Lactation ◽  
Males And Females ◽  
One Year ◽  
Selenium Supplements

Background: Selenium is a micronutrient, although required in low amounts, its importance in male and female reproduction is well known. Objectives: The core purpose of this study is to evaluate the role of selenium in human reproduction, during pregnancy/ lactation in women and newborns. The review explains side by side the sources of selenium, required amounts of selenium in humans and during pregnancy or lactation. Methods: Selenium deficiency is a major cause of male infertility. Similarly, selenium deficiency, both in pregnant and postpartum women, would greatly affect the health of the newborn baby in all respects. The effect of maternal selenium upon the fetus and the neonates even one year after birth has been explained with some recent examples. Results: The study elaborates the fact that the selenium deficiency in pregnancy and lactation is common due to fetal/infant development, so selenium supplements must be provided in order to overcome these deficiency symptoms. Conclusions: The better reproductive health in humans is possible due to the sufficient amounts of selenium present both in males and females as well.

scholarly journals Sex Difference in Self-Reported Sexual Functioning Among Frail Older Adults

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 313-313
Author(s):  
Brianne Olivieri-Mui ◽  
Sandra Shi ◽  
Ellen McCarthy ◽  
Dae Kim
Keyword(s):  
Older Adults ◽  
Logistic Regression ◽  
Sex Differences ◽  
Sexual Function ◽  
Older Adult ◽  
Sexual Functioning ◽  
Social Life ◽  
Well Being ◽  
Adult Males ◽  
Males And Females

Abstract Frailty may differentially impact how older adult males and females perceive sexual functioning, an important part of well-being. We assessed the level of frailty (robust, pre-frail, frail) for anyone with data on 11 sexual functioning questions asked in wave 2 of the National Social Life, Health, and Aging Project, 2010-2011 (n=2060). Questions covered five domains: overall sexual function (OSF), sexual function anxiety (SFA), changes in sexual function (CSF), erectile/vaginal dysfunction (EVD), and masturbation. Logistic regression identified sex differences in frailty and reporting worse sexual functioning. Linear regression predicted the number of domains reported as worse. Among males (n=1057), pre-frailty meant higher odds of reporting SFA (OR 1.8 95%CI 1.2-6.6), CSF (OR 1.7 95%CI 1.1-2.7), and EVD (OR 1.5 95%CI 1.0-2.2). Among females (n=1003), there was no difference in reporting by frailty. Females were more likely to report worse OSF (Robust: OR 7.4, 95%CI 4.8-11.4; Pre-frail: OR 6.2, 95%CI 3.9-9.9; Frail: OR 3.4 95%CI 1.7-6.6), but less likely to report SFA (Robust OR .3, 95%CI .2-.5; Pre-frail OR .2, 95%CI .1-.3; Frail OR .2 95%CI .1-.3). Pre-frail and frail females reported fewer domains as worse (Pre-frail coefficient -0.21 SE 0.09, Frail -0.43 SE 0.14). As frailty worsened, males reported more domains as worse (Pre-frail 0.24 SE 0.07, Frail 0.29 SE 0.08). Self-reported sexual functioning differs by sex at all levels of frailty, and reporting by males, but not females, changes with frailty. Providers should be aware that sexual functioning is of importance to both sexes despite varying degrees of frailty.

scholarly journals Genetic Studies of mei-P26 Reveal a Link Between the Processes That Control Germ Cell Proliferation in Both Sexes and Those That Control Meiotic Exchange in Drosophila

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 1757-1772 ◽  
Author(s):  
Scott L Page ◽  
Kim S McKim ◽  
Benjamin Deneen ◽  
Tajia L Van Hook ◽  
R Scott Hawley
Keyword(s):  
Meiotic Recombination ◽  
Double Mutant ◽  
P Element ◽  
Genetic Studies ◽  
Germline Differentiation ◽  
Males And Females ◽  
Bag Of Marbles ◽  
Differentiation And Proliferation

Abstract We present the cloning and characterization of mei-P26, a novel P-element-induced exchange-defective female meiotic mutant in Drosophila melanogaster. Meiotic exchange in females homozygous for mei-P261 is reduced in a polar fashion, such that distal chromosomal regions are the most severely affected. Additional alleles generated by duplication of the P element reveal that mei-P26 is also necessary for germline differentiation in both females and males. To further assess the role of mei-P26 in germline differentiation, we tested double mutant combinations of mei-P26 and bag-of-marbles (bam), a gene necessary for the control of germline differentiation and proliferation in both sexes. A null mutation at the bam locus was found to act as a dominant enhancer of mei-P26 in both males and females. Interestingly, meiotic exchange in mei-P261; bamΔ86/+ females is also severely decreased in comparison to mei-P261 homozygotes, indicating that bam affects the meiotic phenotype as well. These data suggest that the pathways controlling germline differentiation and meiotic exchange are related and that factors involved in the mitotic divisions of the germline may regulate meiotic recombination.

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