41 resultados para female offspring
em Brock University, Canada
Resumo:
High fat diet (HFD) consumption in rodents alters body composition and weakens bones. Whether female offspring of mothers consuming a HFD are similarly affected at weaning and early adulthood is unclear. This research determined whether maternal HFD contributes to long-lasting alterations in body composition and bone health of female offspring. Rats were fed control or HFD for 10 weeks prior to and throughout pregnancy and lactation. Female offspring were studied at weaning or 3 months of age (consumed control diet). Main findings in female offspring: maternal HFD decreased lean mass, increased fat mass and femoral BMD at weaning, but not at 3 months; weanling femoral lipid composition reflected maternal diet, persisting to 3 months of age (decreased total and n6 polyunsaturates, increased saturates); and no differences in femoral strength at 3 months. In summary, 3 month old female offspring have similar body composition and bone health regardless of maternal diet.
Resumo:
Research into the evolutionary origins of sociality in insect colonies is changing emphasis from understanding how eusociality is maintained to how insects transition from solitary to social lifestyles. The pygmy carpenter bees (Ceratina spp.) offer an excellent model for investigating such factors as they have been historically thought of as solitary but have recently been shown to be socially polymorphic, which may indicate that they are currently in a transitive phase. By utilizing behavioural observation and experimental removal protocols, I show that extended parental care, as well as sibling care in Ceratina calcarata plays an important role in offspring development. I found, upon removal of the mother, that specifically produced ‘dwarf’ female offspring take over parental care roles in the nest. The existence of alloparental care and generational overlap suggests that although they are classified as solitary bees, C. calcarata possess the prerequisite behavioural repertoire for sociality.
Resumo:
The heritability of multiple mating in female Gryllus integer crickets was studied. Two preliminary experiments were conducted to determine when females first mate following the post-imaginal moult and to ascertain whether constant exposure to males affects female mating rate. Female Q. integer first mated at an average age of 3.6 days (S.D. = 2.3, Range = 0-8 days) . Exposing female crickets to courting males 24 hr daily did not significantly alter mating rates from those females in contact with males for only 5 hr per day. A heritability value of 0.690 ± 0.283 was calculated for multiple mating behavior in female Q. integer using a parent-offspring regression approach. Parental females mated between land 30 times (x 9.8, S . D. = 6. 6 ) and offspring matings ranged from 0 to 26 times (x 7 .3, S.D. = 3.4). Multiple mating is probably a sexually selected trait which functions as a mechanism of female choice and increases reproductive success through increased offspring production. Classical theory suggests that traits intimately related with fitness should exhibit negligible heritable variation. However, this study has shown that multiple mating, a trait closely linked with reproductive fitness, exhibits substantial heritability. These results are in concordance with a growing body of empirical evidence suggesting many fitness traits in natural populations demonstrate heritabilities far removed from zero. Various mechanisms which may maintain heritable variation for female multiple mating in wild, outbred Q. integer populations are discussed.
Resumo:
The objective of this investigation was to clarify the adaptive significance of female sexual behaviours in the house cricket, Acheta domesticus, and the Texas field cricket, Gryllus integer. Experiments were focussed primarily on: nutritional factors affecting female reproductive success; the ontogeny of female sexual behaviours; female mating frequency and progeny production; and the pattern of sperm competition. Reproduction of singly mated female A. domesticus assigned to 3 nutritional regimes was compared . Females fed a vitamin and protein-enriched mouse chow, cannibalistic females, and starved females produced on the average, 513 , 200 and 68 offspring, respectively. Cannibals probably could not obtain the same amounts of essential nutrients as females fed mouse chow. Reabsorption of oocytes was likely the major factor contributing to the decreased reproduction of starved females. In addition, female !. domesticus fed mouse chow, but allowed constant access to males produced 11 times as many offspring than did females fed corn meal. Females fed corn meal probably could not absorb or synthesize enough dietary lipids, thus resulting in poor ovariole growth. Female !. domesticus first mate at an average adult age of 7 days, closely corresponding to when they first exhibit positive phonotaxis. Females mate repeatedly and often consume the externally attached spermatophore. In ~. domesticus, females allowed constant access to males produced significantly more offspring than did single maters. Similarly, doubly mated G. integer females produced more offspring than did single maters. This difference resulted largely from the failure of many single maters to reproduce. Remating by female crickets partly functions in offsetting the possibility of a failed initial mating. Nymph production increased significantly with the time the spermatophore was attached in singly mated ~. domesticus. Spermatophore consumption by the female was not affected by male guarding behaviour, and the interval between mating and eating of the spermatophore may often be shorter than the time required for maximum insemination. Some degree of sperm depletion in singly mated !. domesticus and G. integer may have occurred. The patterns of daily offspring production of singly and multiplymated females suggests that a factor provided by a male during mating stimulates female oviposition and/or egg production. Female crickets also might acquire nutrition from spermatophore consumption, a benefit that is augmented by female multiple mating. The electrophoretic examination of various allozymes in ~. integer did not permit determination of a pattern of sperm competition. However, the possibility of last male sperm predominance is related to male guarding behaviour.
Resumo:
Existing research on attraction to body features has suggested that men show general preferences for women with lower waist-to-hip ratios (WHR), larger breasts, and slender body weights. The present study intended to expand on this research by investigating several individual difference factors and their potential contribution to variation in what men find attractive in female body features. Two hundred and seventy-three men were assessed for sex-role identity, 2D:4D digit ratios (a possible marker of prenatal exposure to androgens, and thus masculinization), physical attractiveness, early sexual experiences (as indices of early sexual conditioning), and early family attitudes toward body features, as well as their current preferences for WHR, breast size, weight, and height in women. For WHR, as predicted, physical attractiveness, early sexual experiences, and lower (more masculine) right-hand 2D:4D ratios significantly predicted current preferences for more feminine (lower) WHR. Early sexual experiences significantly predicted later preferences for breast size; in addition, more masculine occupational preferences and lower (more masculine) left-hand 2D:4D ratios predicted preferences for larger breasts. Participants' height, education level, Unmitigated Agency (masculinity) scores, and early sexual experiences significantly predicted current preferences for height. Finally, early sexual experiences significantly predicted current preferences for weight. The results suggest that variation in preferences for women's bodily features can be uniquely accounted for by a number of individual difference factors. Strengths and weaknesses of the study, along with implications for future research, are discussed.
Resumo:
This r\.~et.lrch examined ho\\' ~ight \\'omen artists \\'ho t~ach at the uni versity and college level, balance thcir artistic practic~ and their institu tional responsibilities as tcachers. This thesis reprt.~ents the culmination of \\'ork for my second graduate degree. For my first degrCt! on th~ grad uat~ level, I concentratoo on d~veloping my artistic practice. This ~Iaster's Degree in Education is no k~ important to m~. In pursuing studies in the field of education I \\'anted to understand my rol~ as both an educator and an artist and in the process I uncovered the interplay of race, class, and gender at \\'ork in th~ classroom. Coming from a \\'orking-class, immigrant background \\'here higher education \vas vie\\'cd as a stepping stone that \"ould enable my siblings and me a greater spectrum of opportunities, I \\'as at last able to understand my o\\'n educational experiences, more clearly. I discovered ho\\' d\.~ply I internalized the racism, sexism and class discrimination, I submitted to in my history as a student. Becoming a\\'are about the social forc\.~ at "'ork \\'ithin my day to day life has provided me \\'ith instruments \\'hich I can usc to examine and respond to these inequities as I confront them in th~ future. This \,'ork exists as a serk'S of responses and further av~nues for investigation on some themes I first began to explor~, albeit very tentati\'~ly, during my first incarnation as a graduate student and so though the h\'o bound volum~s rna-\' one da.v sit si.d~ b\' s id~ on the bookshelf, th~\-' exist in the context of my life as a set of brackets surrounding a series of qUl'Stions about being a \\'Onlan, a teachcr and an artist.
Resumo:
In the literature on voluntary childlessness there is a lack of research on the types of occupations held by women who choose not to mother and how their fertility choice influences their occupational experiences. At the same time, the experience ofwomen with regard to the childfree choice has not been adequately addressed in contemporary feminist literature. In the field of education, much has been written about the association between mothering and teaching. Thus, childfree teachers become particularly interesting since they made seemingly paradoxical choices in that they chose not to bear and rear children yet they chose an occupation in which they are surrounded by and responsible for the daily care of many children. To gain an understanding of the work-related experiences of childfree women, in-depth interviews were conducted with 7 voluntarily childless female elementary school teachers from Southern Ontario. In addition, a focus group interview in which 3 of the 7 childfree teachers participated was conducted. Findings revealed that these women's "choice" to be childless was the result of complex circumstances and multiple motivations. Also, despite their decision to forgo the traditional female role of mother, these women held surprisingly conventional beliefs with regard to family and gender roles. In addition, these childfree women at times identified themselves as mother-like when teaching, yet at other times distanced themselves as teachers from mothers. Finally, results showed that these women experienced both direct and indirect pronatalist pressures outside as well as inside the workplace as a result of their childfree status.
Resumo:
The effects of the female postmating odour on male sexual behaviour were examined in Heliconius erato and H. charithonia (Lepidoptera: Nymphalidae). Predictions from the antiaphrodisiac hypothesis were tested using the two reproductive strategies of these species. Within the pupal mating strategy, results from behavioural experiments quantified and statistically tested dispersal rates of pupal-perched males to the presence of stimuli with and without the postmating odour. Results do not support an antiaphrodisiac function to the postmating odour. Similarly, within the adult courtship strategy, behavioural test results indicate that males do not alter their expenditure of energy in terms of either the duration or frequency of courtship behaviours elicited by females with and without the postmating odour. The data from both experiments did not support the antiaphrodisiac hypothesis for the function of the female postmating odour. A novel hypothesis predicting that the postmating female odour acts as an oviposition-deterring pheromone is presented.
Resumo:
A looming attrition rate, a steady increase in the number of women in administration, and a lack of Canadian research all provided the rationale for this study. The problem in this study was to investigate the needs and challenges of new female administrators and to examine the role that mentors play in addressing these issues. This study also explored the perceived benefits of having a mentor. This study examined the inductive year of 33 female administrators from 3 Ontario school boards. It was a qualitative and quantitative design, using questionnaire and interview data. It was found that the majority felt that they struggled with biases and expectations that were gender specific. The challenges that were perceived to be most prevalent were categorized into 4 thematic areas: Maintaining Balance, Feeling Pressured, The Perceptions of Others, and Being Challenged by Others. Regarding the benefits of mentoring, the participants perceived mentoring to be most beneficial in terms of professional growth, followed by learning how to run a school, and then career advancement. The significance of this study was threefold: it had theoretical implications as well as implications for practice and future research. Suggestions included: facilitating longitudinal relationships, having the board become more actively involved in facilitating the relationship, and implementing an internship program. This study attempted to extend the current literature by theorizing that a mentorship is cyclical in nature. Future research could include program design and implementation, as well as providing consistent and accessible mentoring opportunities for all.
Resumo:
The sugar beet cyst nematode, Heterodera schachtii, is a major agricultural pest. The disruption of the mating behaviour of this plant parasite in the field may provide a means of biological control, and a subsequent increase in crop yield. The H. schachtii female sex pheromone, which attracts homospecific males, was collected in an aqueous medium and isolated using high performance liquid chromatography. Characterization of the male-attractive material revealed that it was heat stable and water soluble. The aqueous medium conditioned by female H. schachtii was found to be biologically active and stimulated male behaviour in a concentration dependent manner. The activity of the crude pheromone was specific to males of H. schachtii and did not attract second stage juveniles. Results indicated that vanillic acid, a putative nematode pheromone, is not an active component of the H. schachtii sex pheromone. Male H. schachtii exhibited stylet thrusting, a poorly understood behaviour of the male, upon exposure to the female sex pheromone. This behaviour appeared to be associated with mate-finding and was used as a novel indicator of biological activity in bioassays. Serotonin, thought to be involved in the neural control of copulatory behaviour in nematodes, stimulated stylet thrusting. However, the relationship between stylet thrusting induced by the sex pheromone and stylet thrusting induced by serotonin is not clear. Extracellular electrical activity was recorded fi-om the anterior region of H. schachtii males during stylet thrusting, and appeared to be associated with this behaviour. The isolation of the female sex pheromone of H. schachtii may, ultimately, lead to the structural identification and synthesis of the active substance for use in a novel biological control strategy.
Resumo:
reports, the players did not show an anticipatory rise in either Cortisol or testosterone prior to competition. In addition to the effects of status outcome on hormonal levels, it was also found that these hormonal responses were specific to competition. The athletes in the current study did not demonstrate any hormonal responses to the practice sessions. Last, there were significant differences in pre-game testosterone as well as in selfconfidence, cognitive, and somatic anxiety levels depending on the location at which the status contest took place. Pre-game testosterone and self-confidence levels were significantly higher prior to games played in the home venue. In contrast, pre-game somatic and cognitive anxiety levels were significantly higher prior to games played in the away venue. The current findings add to the developing literature on the relationship between hormones and competition. This was the first study to detect a moderating effect of status outcome on testosterone responses in a team sport. Furthermore, this was also the first study in humans to demonstrate that post-contest Cortisol levels were significantly higher after a loss of status. Last, the current study also adds to the sport psychology literature by demonstrating that pre-game psychological variables differ depending on where the status contest is being held: higher self-confidence at home and higher somatic and cognitive anxiety away. Taken together, the results from the current thesis may have important practical relevance to coaches, trainers and sport psychologists who are always trying to find ways to maximize performance. the cycle. The sex-specific age differences in locomotor responses to amphetamine are not due to gonadal immaturity, as females are cycling at this stage of adolescence. However, age differences may reflect the ongoing maturation of the neural substrates that that are involved in locomotor sensitizing, but not rewarding effects of amphetamine.
Resumo:
This qualitative phenomenological investigation explored six female Master of Education students' critical understandings of their identity and role negotiations, and their perceptions of environmental conditions that facilitated or impeded their identity explorations and negotiations within the institution. The interweaving of Feminist and Women's Development theories enabled the data to be examined under different, yet complementary, lenses. The data collection strategies included: four to five in-depth semistructured interviews, three take-home activities (involving identity mapping, object and metaphor identification, and strategy development), and the compilation of extensive interview notes as well as researcher reflections. The combination of a constant comparative method and a voice-centered method were used in tandem to analyze the data. Together they uncovered five emergent themes: (a) intricate understandings of key terms; (b) life-long learning and transformative pathways; (c) gender issues; (d) challenges, tensions, and possibilities; as well as (e) personal, professional, and educational implications. The findings underscored the possibility for both a singular static identity and dynamic multifaceted identities to exist in tandem, and the emergence of natural or logical identity intersections, as well as disjointed or colliding identity intersections. Ultimately, it is the continuous negotiation of internal and external spheres that contributes to the complexity and multidimensionality of graduate students' identities.
Resumo:
This study detennined whether or not a high functioning autistic girl can develop game structure strategies that may allow her to become an active participant in a game or sport environment. This qualitative case study involved the in-depth observation and description of one high functioning autistic student whose experience in a game setting would be studied. The type of case study carried out was a combination of descriptive and evaluative. This experience was investigated through structured, individual programming. Through on-site observation, journal entries, and hands on instruction, I was able to describe what progress the autistic student made in tenns of skill development. The results of the study demonstrated that a high-functioning autistic female has the potential to develop the necessary motor skills to participate in the chosen sport of basketball. The observation results and field notes contributed to a movement profile which described her habits of body. Teaching strategies and frameworks utilized during the study were described and listed. Insights and commentary are further provided. A thorough examination of autism and games programming is provided in the literature review.
Resumo:
Recent Ontario legislation by the Ministry of Education has targeted a goal of 50 percent as the minimum objective for representation by women in positions of responsibility by the year 2000. As a result,those few women currently in the field of Educational Administration have become a focus for researchers. The intent of this research is to contribute to the current knowledge and understanding of women principals in the leadership role. In-depth interviews with four experienced female principals were conducted centering on their perceptions and experiences on a wide range of issues that included: gender characteristics and impact on role, perceived differences as a result of gender characteristics, decision making, curriculum leadership, communication, the perception of others, and the advantages and disadvantages of being a woman in the role. Narrative profiles were constructed for each participant and analyzed. A description for each woman emerged by an analysis of common patterns and themes in the participants' narratives. Results revealed that the participants were able to identify and to describe particular gender traits that they perceived had impact on their role. Moreover the participants regarded their gender characteristics as facilitating and enhancing the performance of their role. Common patterns for all the participants emerged from the data that conveyed a strong feminine imagery of mother and espoused the idea of school as home, and staff and students as family. Leadership ii styles demonstrated an emphasis on collaborative decision making, open communication, and apparent difficulty and ambiguity arising from the role of Curriculum leader. The results of this study also indicate that personal metaphors ascribed and embedded in the narratives are significant in conceptualizing and interpreting the administrative role.