Reversed Sexual Size Dimorphism: Effect on Resource Defense and Foraging Behaviors of Nonbreeding Northern Harriers

The Auk ◽  
1986 ◽  
Vol 103 (1) ◽  
pp. 70-78 ◽  
Author(s):  
Ethan J. Temeles
Keyword(s):  
Sexual Size Dimorphism ◽  
Sexual Differences ◽  
Foraging Strategies ◽  
Resource Defense ◽  
Aggressive Interactions ◽  
Nonbreeding Season ◽  
Males And Females ◽  
Circus Cyaneus ◽  
Reversed Sexual Size Dimorphism

Abstract Sexual differences in resource defense and foraging behaviors during the nonbreeding season are detailed for Northern Harriers (Circus cyaneus) in California. Female harriers hunted more frequently in high (>0.5 m) vegetation than males. In addition, females hunted at slower speeds and used different hunting behaviors than males. Females in high vegetation showed a significantly greater response (i.e. attack) rate to approaching harriers than males, and females won nearly all (28/29) aggressive interactions with males. These results suggest that sexual differences in harrier foraging behavior during the nonbreeding season result from females excluding males from preferred foraging areas and males adopting alternative foraging strategies. Foraging strategies of harrier sexes are compared with foraging strategies of sexes of birds in which males are larger than females to examine the role of body size in determining sexual foraging strategies.

Reversed Sexual Size Dimorphism and Parental Care: Minimal Division of Labour in the Blue-Footed Booby

Behaviour ◽  
1995 ◽  
Vol 132 (7-8) ◽  
pp. 479-496 ◽  
Author(s):  
Hugh Drummond ◽  
Maria Guerra
Keyword(s):  
Parental Care ◽  
Sexual Size Dimorphism ◽  
Division Of Labour ◽  
Avian Species ◽  
Nest Defence ◽  
Adult Size ◽  
Size Dimorphism ◽  
Behavioural Observation ◽  
Males And Females ◽  
Reversed Sexual Size Dimorphism

AbstractReversed sexual size dimorphism in avian species (females larger than males) may be an adaptive consequence of different roles of males and females in parental care. We examined the alleged division of labour in two-chick broods of the blue-footed booby, using behavioural observation and frequent weighing of chicks. In the first week of parental care, males and females fed broods at similar frequencies and provided similar masses of food, but females brooded more than males when broods were 5-10 d old. Subsequently, females provided a greater mass of food and frequency of feeds than males until chicks were at least 35 d old (mass) and 60 d old (frequency), while attending the brood for just as much time as males until chicks were at least 35 d old. Males and females did not differ in the tendency to feed (frequency and mass) the first-hatched chick differentially. In nearly all components of parental care examined here, and in other studies, the female's contribution is equal to or greater than the male's. Only in clutch attendance and nest defence does the male contribute more than the female, but his small size seems unlikely to enhance performance in these activities. Overall, small size appears potentially to limit male provisioning of the brood, and is unlikely to be an adaptation for division oflabour in parental care. This result casts doubt on the relevance of the division-of-labour hypothesis for adult size dimorphism.

scholarly journals Microglial and Astrocytic Function in Physiological and Pathological Conditions: Estrogenic Modulation

2020 ◽  
Vol 21 (9) ◽  
pp. 3219 ◽  
Author(s):  
Andrea Crespo-Castrillo ◽  
Maria-Angeles Arevalo
Keyword(s):  
Neurological Diseases ◽  
Autism Spectrum ◽  
Sexual Differences ◽  
Main Role ◽  
Cell Functions ◽  
Physiological Processes ◽  
Males And Females ◽  
The Brain ◽  
Lateral Sclerosis

There are sexual differences in the onset, prevalence, and outcome of numerous neurological diseases. Thus, in Alzheimer’s disease, multiple sclerosis, and major depression disorder, the incidence in women is higher than in men. In contrast, men are more likely to present other pathologies, such as amyotrophic lateral sclerosis, Parkinson’s disease, and autism spectrum. Although the neurological contribution to these diseases has classically always been studied, the truth is that neurons are not the only cells to be affected, and there are other cells, such as glial cells, that are also involved and could be key to understanding the development of these pathologies. Sexual differences exist not only in pathology but also in physiological processes, which shows how cells are differentially regulated in males and females. One of the reasons these sexual differences may occur could be due to the different action of sex hormones. Many studies have shown an increase in aromatase levels in the brain, which could indicate the main role of estrogens in modulating proinflammatory processes. This review will highlight data about sex differences in glial physiology and how estrogenic compounds, such as estradiol and tibolone, could be used as treatment in neurological diseases due to their anti-inflammatory effects and the ability to modulate glial cell functions.

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 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.

Variation in Weight, Size, and Sex Ratio of Coccinellid Adults (Coleoptera: Coccinellidae)

1966 ◽  
Vol 98 (6) ◽  
pp. 639-644 ◽  
Author(s):  
B. C. Smith
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Water Content ◽  
Food Supply ◽  
Sexual Differences ◽  
Intraspecies Variation ◽  
Food Scarcity ◽  
Food Requirement ◽  
Males And Females

AbstractThe weight and size of coccinellid adults varied with species, sex, and feeding. Intraspecies variation in weight was generally similar in the eight species studied. Females were more variable than males in body size. Females of some species were heavier and larger than males, and species can be classified on a basis of difference in the weight and size of the sexes.An increase in the food supply after a period of food scarcity affected the sex ratio, as the minimum food requirement of females was greater than males. Females increased in weight more rapidly than males after feeding. The availability of food in the field affected the weight and size of some species. Adult water content was influenced by feeding but not by sex or the quantity of food given to the larva.Males were more abundant in species with small sexual differences in weight and size. The degree of difference in weight and size between males and females may be used as a criterion to select species that are best adapted to survive when food is scarce.

scholarly journals Teacher Discrimination Reduces School Performance of African American Youth: Role of Gender

2018 ◽  
Vol 8 (10) ◽  
pp. 183 ◽  
Author(s):  
Shervin Assari ◽  
Cleopatra Howard Caldwell
Keyword(s):  
African American ◽  
School Performance ◽  
African American Youth ◽  
National Sample ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Grade Point ◽  
Significant Difference ◽  
Males And Females

Background: Gender may alter African Americans’ vulnerability to discrimination. The type of outcomes that follow exposure to discrimination may also be gender-specific. Although teacher discrimination is known to deteriorate school performance, it is yet unknown whether male and female African American youth differ in the effect of teacher discrimination on school performance. Objective: This cross-sectional study explored the moderating role of gender on the effect of teacher discrimination on school performance in a national sample of African American youth. Methods: The National Survey of American Life-Adolescent Supplement (NSAL-A) enrolled a nationally representative sample (n = 810) of 13–17-year-old African American youth. Demographic factors, socioeconomic status, teacher discrimination, and school performance (grade point average, GPA) were measured. Linear multivariable regression models were applied for data analysis. Results: Males and females reported similar levels of perceived teacher discrimination. In the pooled sample, higher teacher discrimination was associated with lower school performance among African American youth (b = −0.35; 95% confidence interval (CI) = −0.49 to −0.22). Gender interacted with perceived teacher discrimination (b = 12; 95% CI = 0.24–2.02), suggesting a significant difference between males and females in the magnitude of the association between perceived teacher discrimination and GPA. In stratified models, perceived teacher discrimination was associated with worse school performance of females (b = −12; 95% CI = −0.03 to −2.78) but not males (b = 0.01; 95% CI = −0.07 to 0.08). Conclusion: In line with previous studies, gender was found to alter the vulnerability of African American youth to perceived discrimination. African American boys and girls may differ in their sensitivity to the effects of teacher discrimination on school performance.

Role of Screening Tests in the Detection and Management of Blood Pressure Abnormalities Among Young Population

Angiology ◽  
2016 ◽  
Vol 68 (5) ◽  
pp. 441-446 ◽  
Author(s):  
Mehmet Karaduman ◽  
Mustafa Aparci ◽  
Murat Unlu ◽  
Cengiz Ozturk ◽  
Sevket Balta ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiovascular Disease ◽  
Body Mass Index ◽  
Heart Rate ◽  
Medical Records ◽  
Screening Tests ◽  
Young Population ◽  
Males And Females ◽  
Apparently Healthy

The prevalence of hypertension is increasing among young population worldwide. So there is an interest in detecting prehypertension and hypertension in childhood. We determined blood pressure (BP) recorded at a screening test in a young population. We retrospectively evaluated the medical records including systolic blood pressure (SBP), diastolic blood pressure (DBP), weight, height, and body mass index (BMI) of 685 male and 130 female apparently healthy adolescents. We evaluated the prevalence of BP categories: normotension, prehypertension, and hypertension. The prevalence of normotension (n = 369), prehypertension (n = 333), and hypertension (n = 113) was 45.3%, 40.9% and 13.9%, respectively; prehypertension and hypertension were significantly higher among males. The prevalence of prehypertension and hypertension was significantly higher among overweight males and females. The BMI significantly correlated with SBP, DBP, and heart rate among both genders. The prevalence of prehypertension and hypertension is high among Turkish adolescents. Screening tests focused on BP and BMI measurement may help detect the young population at risk of hypertension and cardiovascular disease in the future.

Plasma testosterone surge and luteinizing hormone beta (LH-β) following parturition: lack of association in the male rat

1995 ◽  
Vol 133 (3) ◽  
pp. 366-374 ◽  
Author(s):  
Robert F McGivern ◽  
Ralph HM Hermans ◽  
Robert J Handa ◽  
Lawrence D Longo
Keyword(s):  
Luteinizing Hormone ◽  
Cesarean Section ◽  
Gnrh Antagonist ◽  
Male Rat ◽  
Plasma Testosterone ◽  
Treatment Groups ◽  
Natural Birth ◽  
Males And Females ◽  
Lh Secretion

McGivern RF, Hermans RHM, Handa RJ, Longo LD. Plasma testosterone surge and luteinizing hormone beta (LH-β) following parturition: lack of association in the male rat. Eur J Endocrinol 1995; 133:366–74. ISSN 0804–4643 Studies examining the role of luteinizing hormone (LH) in the initiation of the postnatal surge of testosterone in the male rat have produced ambiguous results. We examined the pattern of postnatal LH secretion in the newborn male rat, coincident with plasma testosterone levels, using a specific monoclonal antibody for LH-β. In some males, we attempted to block LH secretion and the postnatal testosterone surge by injecting males with a gonadotropin-releasing hormone (GnRH) antagonist, an LH antibody or progesterone immediately after delivery by cesarean section on day 22. Following injection, animals were immediately sacrificed (time 0) or housed in a humidified incubator maintained at 30°C until sacrifice at 60, 120, 240, 360 or 480 min after delivery. Plasma from individual animals was measured subsequently for LH-β and testosterone by radioimmunoassay. Results revealed a postnatal surge of testosterone which peaked at 2 h after delivery in males from all treatment groups. This testosterone surge was not accompanied by a postnatal rise in plasma LH-β in any group. Administration of the GnRH antagonist or the ethanol vehicle produced a transient drop of approximately 25% in LH-β levels at 60 min but did not decrease the postnatal testosterone surge in the same animals. Additional studies in untreated males and females born by cesarean section or natural birth also failed to reveal a postnatal rise in plasma LH-β during the first 3 h after birth. Plasma levels in both sexes were significantly lower in animals delivered by cesarean section compared to natural birth. Overall, these results indicate that the postnatal surge of testosterone occurs without a corresponding surge of detectable LH-β in the male rat. Robert F McGivern, 6363 Alvarado Ct, Suite 200H. San Diego, CA 92120, USA

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