Reproductive Success and Sexual Selection in Drosophila melanogaster (Diptera: Drosophilidae)

Sexual selection is a branch of natural selection which acts upon variation in reproductive success. Sexual selection is a complex field of study in biology as each species has their own mating system and strategies. Models of sexual selection theory are not mutually exclusive, and often times there are multiple layers of selection within a given mating system. For instance, both direct and indirect benefits of sexual selection can occur simultaneously, and selection can act both before and after mating occurs. Postcopulatory sexual selection, which is not as well understood, can be comprised of both the male-male interaction of sperm competition and the male-female interaction of cryptic female choice. Although there are many studies which show the existence of postcopulatory sexual selection, there is limited knowledge of its underlying mechanisms or genetic basis. Although we know of the physical male traits that females prefer, the relationships among male trait, female preference, and postcopulatory sexual selection are often unknown. Here I use Drosophila melanogaster to show accurate alternative measurements for female lifetime reproductive success (Chapter 2) and the genetic architecture underlying lifetime reproductive success (Chapter 3). I found that the short term reproductive success measure of 5 days can accurately predict the lifetime reproductive success of females, and that lifetime reproductive success is a result of additive genetic variation. In Chapter 4, I compared lifetime reproductive success to mating success in a multi-generational study and found that males who were more successful at mating produced sons with lower fitness. I then examined mechanisms of sperm competition, specifically the role of Acps (accessory gland proteins) in sperm competition. I discovered that Acps from the first male to mate are beneficial to the second mated male, contributing to second male advantage (Chapter 5). Lastly, in Chapter 6, I assessed male quality based on five fitness measures and determined male performance in both pre- and postcopulatory sexual selection. I concluded that a combined fitness measure most accurately predicted male offspring production. This thesis characterizes the various factors that contribute to variation in lifetime reproductive success, specifically from a sexual selection perspective

Description of Geocenamus vietnamensis sp. n. (Nematoda : Merliniidae) from Vietnam

A new species of the genus Geocenamus was isolated from soil and root samples from the rhizosphere of Casuarina equisetifolia (Casuarinaceae) in Quang Nam province, Vietnam. This species is characterized by a round-to-hexagonal labial disc, the presence of a labial region, which is continuous or slightly offset from the body with six sectors, lateral sectors of first labial annulus being smaller than the submedian sectors, the presence of six to seven labial annules; the absence of deirids; stylet length 24 to 28 mu m long, body length 776 to 979 mu m long; lateral field with six to eight lateral lines, without areolation at mid-body and with areolation in outer bands at the tail region and a pointed tail terminus. Geocenamus vietnamensis n. sp. most closely resembles G. boghiae in having a non-sclerotized head framework and lacking a bursa in the males. It can be clearly distinguished from all other species of the genus Geocenamus by these characteristics. The combination of morphology, morphometric features, and phylogenetic trees, based on D2-D3 of 28S and ITS rDNA sequences, showed that this new species can be clearly separated from all other sequenced species. This record is the first for Geocenamus in Vietnam

Morphological and molecular characteristics of Pratylenchus haiduongensis sp. n., a new species of root-lesion nematodes associated with carrot in Vietnam

Pratylenchus haiduongensis sp. n. is described as associated with carrot (Daucus carota subsp. sativus (Hoffm.) Schubl. & G. Martens) in Hai Duong Province, Vietnam. P. haiduongensis sp. n. is characterized by the lip region with three annuli and slightly separated from the body. Stylet knobs are rounded (never indented anteriorly). The lateral field includes four incisures, bearing areolation at the pharynx region and tail region and occasionally appears in the vulval region. Sometimes the appearances of oblique broken striaes divide the lateral field into five or six incisures. The ovary is distinct with one row of oocytes. Spermatheca is oval in shape with round central cavity, without sperm or reduced in some specimens. The postvuval uterine sac is long surpassing the vulva body diameter by 2 to 2.5 times (PUS = 31 to 65 mm). High vulva position with V = 66 to 75%. The tail shape can be subhemispherical with a smooth, slightly indented, broadly smooth, or cleft terminus observed in some specimens. The matrix code of P. haiduongensis sp. n. is: A2, B1, C4, D(1,3), E1, F(5,6), G(1,2), H(1,4); I(1,2,3,4), J1, K(1,2) according to Castillo and Vovlas (2007). The LSU-D2D3 segment and the ITS-rDNA region of this species were amplified and sequenced. The morphological characters and molecular phylogenetic analyses confirmed that this is a new species of the genus Pratylenchus in Vietnam

First report of Longidorus mindanaoensis Coomans, De Ley, Jimenez and De Ley, 2012 (Nematoda: Longidoridae) from a mangrove forest in Vietnam

Longidorus mindanaoensis was recovered from a mangrove forest in Vietnam. The recovered population is in general morphological agreement with the type population, and the characters of pharyngeal bulb, i.e. the same unique pattern of pharyngeal glands nuclei as well as the lip region morphology, amphidial fovea shape and size and position of vulva corroborated its identity. Molecular studies of the recovered population using D2-D3 expansion segments of large subunit ribosomal DNA (LSU rDNA D2-D3) revealed the D2-D3 sequence of the recovered population is 99.6% similar to the sequence of the type population. A new morphometric range for body size was recorded for the species based upon present Vietnamese population, and the present study emphasized that the diversity of Longidorus spp. in Vietnam could be higher than previously assumed

Morphological diversity of Meloidogyne spp. from carrot (Daucus carota subsp. Sativus) in Vietnam

Carrot (Daucus carota subsp. Sativus) is known as one of the most widely cultivated and widely consumed vegetables in the world due to its nutritional and economic values. During a survey of nematodes parasites carrots from Vietnam, six populations of three species of root-knot nematodes, namely M. incognita, M. arenaria, and M. graminicola were found. The species specific primers were confirmed before morphological studies. By combining the morphology and morphometry of the females, males, and juveniles, this study provided useful references for classification of Meloidogyne on carrots in the future. Quantitative morphological studies reveal profound changes corresponding with the generation of morphological disparity at high taxonomic diversity. Especially, this study provided the first morphological and morphometric information of M. graminicola, that is known as aquatic root-knot nematodes, on carrots

First report of Mesocriconema sphaerocephalum (Taylor, 1936) Loof, 1989 associated with carrot (Daucus carota subsp. Stativus) in Vietnam

Our study recorded the presence of Mesocriconema sphaeroce phalum on carrot in Hanoi city and Hai Duong province in Vietnam. This species was identified by morphometric, morphological characterizations, and molecular characterization of D2D3 of 28S rDNA sequence. To our knowledge, this is the first report of M. sphaerocephalum on carrot in Vietnam

IMPACT OF COOPERATIVE LEARNING ON LEARNER MOTIVATION IN SPEAKING AT A VIETNAMESE HIGH SCHOOL

Cooperative learning has been increasingly recognized as an effective instructional strategy in English language teaching and learning. However, traditional lecturing still dominates in education in Vietnam, thereby hindering learners from participating in speaking activities or sharing responsibility for their learning. Also, research into cooperative learning in relation to learner motivation in speaking at high school is scant in the Mekong Delta. This paper therefore reports on a study examining the impact of cooperative learning on learner motivation to speak English and investigating their attitudes towards this type of interactive learning. Data collected for this study include a one-group pre-test and post-test design, questionnaires, and interviews with grade ten learners at a high school in Vinh Long province. The findings indicate that learners were motivated and improved in speaking through cooperative learning after the study. Implications for this interactive speaking practice are also presented.  Article visualizations

THE EFFECTS OF QUESTIONING AS PRE-READING ACTIVITY ON EFL GRADE 12 STUDENTS’ CRITICAL THINKING IN READING CLASSES IN KIEN GIANG, VIETNAM

Research has indicated that questioning is used as an interactive way to engage students in learning English as a foreign or second language. In particular, rooted in Socratic philosophy, this strategy involves students in thinking and communicating ideas and knowledge to others for effective learning. However, teacher questioning in English classroom context in higher education in Viet Nam has not received much attention. Moreover, classroom questioning and teachers’ perceptions of this instructional practice facilitating students’ critical thinking in English major classes remained scarce. Therefore, this study aims to investigate the effects of questioning as pre-reading activity on students’ critical thinking in EFL reading classes. The participants in this study were 80 grade 12 students of the two classes at a high school, in Kien Giang province. Data collection in this study includes pre-tests, post-tests, questionnaires, and interviews. The findings from this study indicate that the implementation of questioning as a pre-reading activity by students in the experimental group yielded positive effects on students’ critical thinking in reading classes. Pedagogical implications for teachers and school administrators are made.   Article visualizations

Desarrollo de la presión del sujetador: Sistema de medición con aire y sensor de presión

Introduction: This paper is the result of the research “Development of bra pressure measuring system using air pressure sensor” developed in the Ha Noi University of Science and Technology in 2019.  Proplem: The pressure of the bra on the human body affects the comfort of the wearer and the wearer's health. Therefore, bra pressure is one of the most important parameters taken into account when designing and manufacturing bras. Objective: To determine the pressure value of a bra, it is necessary to use a suitable pressure measuring device. Methodology: The device operates on the principle of resitive gas pressure sensor, with 8 measuring channels. The system is controlled by the computer via programming software in the Visual C language, measuring the pressure of the shirt on the position on the curved surface of the human body. Pressure values ​​and timed charts are displayed on the computer. The measuring device was tested with GE Druck DPI 610 pressure generator.  Results: Test results showed that the device has a sensitivity of 0.01 kPa, measuring range from 0.1to 10 kPa and an accuracy of 0.01 kPa. Conclusion: This measurement system is important for objectively assessing the pressure of the bra on the wearer.  Originality: This paper presents the results of research and design of the PB228 system when measuring the pressure of the bra on the wearer's body in static, dynamic and static-dynamic combined states.  Limitations: The accuracy of the device only applies in standard condition

YOUTH EDUCATION AND ORIENTATION TOWARD HO CHI MINH'S IDEOLOGY IN THE CONTEMPORARY CONTEXT

During his time, Former President Ho Chi Minh had consistently emphasized the central role, position, and competence of the young generation in realizing the Party and the people's revolutionary path. He believed, “The youth are the future owners of the home country. Indeed, the vitality of the home country, whether it is prosperous or wilting, depends largely on the youth.” Before passing, his words had become the guiding principle for leaders of the Communist Party of Vietnam, “Nurturing future revolutionary generations is of utmost importance and necessity.” Especially, given that the functioning of the current market economy has revealed its multiple drawbacks, it is salient to educate and orient the youth following Ho Chi Minh's ideology to produce a young generation that is moral in ethics and efficient in labour.  Article visualizations