Les interactions entre individus sont un socle vital pour l’organisation des colonies d’abeilles, en particulier lors du recrutement pour le butinage. Outre la communication de la localisation d’une source de nourriture par la fameuse danse, les abeilles recrutées apprennent les caractéristiques de l’odeur des fleurs butinées au cours de transferts de nectar (trophallaxie). Les mécanismes de cet apprentissage ne sont pas encore éclaircis car il est parfois effectif sans aucun transfert de nectar, suggérant que d’autres mécanismes, comme par exemple d’apprentissage social, sont impliqués. Nous avons reproduit cette interaction en laboratoire, suivant un protocole basé sur le conditionnement olfactif appétitif de la réponse d’extension du proboscis (REP). Ici, un composé odorant initialement neutre (Stimulus conditionnel) était associé à un contact avec une congénère (Stimulus Inconditionnel social), sans récompense sucrée. Nos expériences montrent que ce simple contact social entre congénères peut constituer un renforcement pour les abeilles. A la suite de cette association, celles-ci montrent donc des REP à l’odeur préalablement associée au contact social. Nos expériences montrent de plus que des contacts antennaires entre les abeilles sont indispensables à l’efficacité de cet apprentissage social, représentant un indice social tactile. Nous avons alors développé un dispositif permettant d’enregistrer les mouvements des antennes de manière précise et à haute vitesse (90 hz) et étudié les différents facteurs modulant les mouvements antennaires des abeilles. Les abeilles montrent des réponses contrastées et reproductibles à des odeurs de valeurs biologiques différentes. De plus, le couplage de ces enregistrements à des expériences de conditionnement associatif montre que ces réponses antennaires sont plastiques et modifiées par l’expérience des individus. Ce travail a permis de mettre en lumière un nouveau type d’apprentissage social chez les insectes et d’approfondir l’étude des mouvements antennaires comme indicateurs de l’état motivationnel, attentionnel et physiologique des abeilles ainsi que de la valence des stimuli perçus. / In honeybees, interactions between individuals are cornerstones for the organization of the colony, especially during recruitment for foraging. Besides learning the location of a food source thanks to the well-known dance, the recruited bees learn the characteristics of odors of foraged flowers through nectar transfer (trophallaxis). The underlying mechanisms are still unclear because this learning can occur without any nectar transfer, suggesting that other, probably social, learning mechanisms are involved. We reproduced this interaction in the lab, using a protocol based on the appetitive olfactory conditioning of the proboscis extension response (PER). Here, an initially neutral odorant (conditioned stimulus) was associated with a contact with a nestmate (social unconditioned stimulus), without any sugar reward. Our experiments show that this simple social contact between workers can act as a reinforcement for bees. As a result, they show PER to the odor previously associated with a social contact. We further demonstrate that antenna contacts are essential for the effectiveness of this social learning, representing a tactile social cue. We thus developed a system allowing to record bees’ antennal movements accurately and at high frequency (90 hz). We then determined the factors modulating bees’ antennal movements. First, we show that bees display contrasted and reproducible responses to odors of different biological values. Second, the coupling of these recordings with associative conditioning experiments shows that these antennal responses are plastic and modified by individual experience. This work has shed light on a new type of social learning in insects and has furthered our understanding of antennal movements as indicators of the motivational, attentional and physiological state of bees and of the valence of perceived stimuli.

This research project is an ongoing project in collaboration with colleagues in the Department of Biology at the University of the Pacific. The main purpose of this project was to separate and identify the female-attracting substance secreted by male frog by developing chromatography methods for the male and female aqueous extracts. Three methods were used to concentrate the samples: sample lyophilization,..solid phase extraction (SPE), and direct sample loading. Different parameters such as the type and concentration of the phase modifier, wavelength for UV-detection, composition of the mobile phase, flow rate, and gradient elution were studied to achieve the required separation. The optimal method was determined as: direct sample loading, 0.01% (v v) formic acid in in mobile phase A (water) and mobile phase B (acctonitrile), 200 nm, 0.60 mL/min, and gradient method. The chromatograms of male and female skin gland water samples were compared and the fractions specific to male frog were collected and lyophilized for bio-activity testing and mass spectrometry analysis. Three different mass spectrometer systems, JEOL LCMate (ES+), Micromass Q-Tof Ultima™ Global (ES-). Voyager-DE™ STR Biospectromelry™ Workstation (MALDI-TOF), and Varian Mercury 300 MHz FT-NMR were utilized to investigate the structure of the fractions collected through HPLC. Only Micromass Q-Tof Ultima™ Global (ES+) gave some potential results. After analysis, the proposed protonated molecular ion peak was determined to be at m/z 779 by analyzing the abundance and relationship among the peaks at higher m/z values. The detail structure was inconclusive. vi

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No description available.

<p>Sex steroids are critical for the post-natal development of the female reproductive system, and are involved in ovulatory cycling and pregnancy. In mice, <em>Mus musculus</em>, female development, cycling, and pregnancy can be affected by the urine of conspecifics, which is known to contain active steroids. Specifically, puberty can be accelerated (the Vandenbergh effect), estrous cycling can be prolonged (the Lee-Boot effect) or synchronized (the Whitten effect), and blastocyst implantation can be disrupted (the Bruce effect). Since steroids alone can affect females in ways that are indistinguishable from these social reproductive effects, I hypothesized that urinary steroids of conspecifics may be absorbed by females, arrive in the reproductive system, and thereby affect females through known mechanisms. First I showed that tritium-labelled 17β-estradiol (³H-E₂) injected into males is excreted in their urine, and that application of urine from these males to the nose of an inseminated female results in detectable levels in her uterus. When I paired inseminated females with non-sire males injected with ³H-E₂, radioactivity was detected in the brain and reproductive tissues of the females. This was the first demonstration of steroids from one animal directly entering the body of another. Similar results were found when I exposed juvenile females to adult males injected with ³H-E₂, and when I exposed nulliparous adult females to same-strain ³H‑E₂- or ³H-progesterone- (³H-P₄) treated adult males or females. Taken with the existing literature, these results suggest that steroid transfer may underlie various social reproductive phenomena in mice, with potential implications for many other species.</p> / Doctor of Philosophy (PhD)

The formation and persistence of species are the subject of much debate among biologists. Many species of Drosophila are behaviourally isolated, meaning that heterospecific individuals are not attracted to one another and do not interbreed. Often, this behavioural isolation is at least in part due to differences in pheromonal preference. Drosophila pheromones are long-chain cuticular hydrocarbons (CHCs). Desaturases are enzymes that are important for the production of CHCs. This thesis investigates the evolution of the gene family across 12 species of Drosophila. Desaturase genes were located in all species. Some genes, those that have previously been shown to have important roles in pheromonal communication, have experienced duplication and loss in several species. Two previously undiscovered duplicates were identified. Generally the desaturase gene family is governed by purifying selection, although following duplication these constraints are relaxed and in some cases duplicated genes show compelling evidence of positive selection. One of the loci under positive selection, the novel duplicate desat1b of the obscura group, was found to have a sex-biased expression pattern and alternative splicing in its 5′ UTR. In RNAi knock-down experiments of desaturase gene function in D. melanogaster, several desaturases were shown to affect CHC profiles of males and females, including some that were previously unlinked to CHC production.

This study is primarily concerned with assessing the influence of the sex determination genes, transformer (tra), doublesex (dsx) and fruitless (fru) on three sexually dimorphic traits within Drosophila; pheromone blend, courtship song and sex comb tooth number. The sex determination loci have all been implicated as possible candidate genes affecting these important traits that contribute to sexual isolation, which is a major cause of speciation. Quantitative Trait Loci (QTL) analysis is used to assess the effects of these known candidate genes on the naturally occurring variation of mean interpulse interval (IPI) of courtship song and the differing pheromone blend profiles between Drosophila simulans and D. sechellia. The QTL analysis for both song and pheromone blend variation incorporated Multiple Interval Mapping (MIM), which enables the detection for epistasis. The desaturase loci desat1, desat2 and desatF were also included in the assessment on pheromone blends (cuticular hydrocarbon compounds), since they facilitate ecological adaptation and are also candidate genes, which are likely to exert a large affect on this particular trait. The sex determination genes were not significantly influential on the interspecific variation of the cuticular hydrocarbon compounds between these two sibling species. However significant effects were detected from two of the desaturase loci. desat1 was associated with a strong effect on the interspecific variation of a saturated hydrocarbon chain compound (unbranched-23). Additionally the candidate gene desatF potentially exerts an influence on the variation of 7,11-heptacosadiene, through a large epistatic effect with unidentified loci, situated between the markers pros and Mtn. The candidate gene eloF is situated in this region, and is known to affect the elongation of unsaturated hydrocarbon chains. The QTL associated with the marker desatF influenced the variation of both diene compounds (7,11-heptacosadiene and 7,11-pentacosadiene). Intriguingly epistasis was only detected for the variation of these two diene compounds. The MIM analysis assessing the affects of the sex determination genes on interspecific variation of mean IPI detected the candidate gene fru as the closest marker associated with a significant QTL on the third chromosome. The MIM also found a significant QTL associated with the marker Dgα situated on the second chromosome. Moreover significant epistatic interactions were detected between a further QTL situated nearest the marker forked on the X-chromosome with both of the other significant QTL situated on the third and second chromosomes. The analysis of a number of Recombinant Inbred (RI) lines was also carried out to test for the affects of the sex determination genes on both mean IPI and sex comb tooth number. The fru locus was associated with a significant increase in mean IPI, whereas the opposite was true for the dsx locus. In the analysis of sex comb tooth variation, it appears that all RI lines homozygous for D. sechellia alleles at the sex determination loci had significantly higher numbers of sex comb teeth. The final data chapter involves the sequence analysis of the fruitless locus, including all 13 fru proteins between ten recently sequenced Drosophilid genomes. The PAML program was used to detect the possible influence of natural selection on sequence divergence. There was no significant positive selection detected at the BTB functional domain and the sequences encoding for this domain were extremely conserved. Positive selection was found to be acting on the exon encoding for the Zinc-finger C domain. This domain is present in two protein isoforms including the male sex-specific isoform FRUMC, and the common non-sex-specific isoform FRUComC. Interestingly positive selection was also found at the non sex-specific Zinc-finger D domain.

The trade-off between gametes and soma is central to life-history evolution. Oosorption has been proposed as a mechanism that can mediate this trade-off. When conditions are not conducive to successful reproduction, females are expected to be able to recoup nutrients from unfertilized oocytes and reinvest them into the somatic processes that promote survival and hence future reproduction. Although positive correlations between oocyte degradation and lifespan have been documented in oviparous insects, the adaptive significance of this process in species with more complex reproductive biology has not been explored. Oocyte degradation via apoptosis (programmed cell death) occurs in response to enforced virginity in females of the ovoviviparous cockroach, Nauphoeta cinerea. Observed apoptosis may represent oosorption, however, an alternative but not mutually exclusive argument is that oocyte apoptosis may represent oocyte ageing and clearance in order to maintain reproductive synchrony. The aim of this thesis was to test the hypothesis that the function of oocyte apoptosis is oosorption in N. cinerea. I found that in addition to enforced virginity, starvation induces oocyte apoptosis. However, the life history outcome following one form of stress is the opposite of the other. Hence, the functional role of oocyte apoptosis appears to be different depending on whether apoptosis is induced through starvation or age. Following a period of starvation-induced apoptosis females exhibit the increase in survival and future reproduction predicted by oosorption. Whereas, following a period of age-induced apoptosis females suffer fecundity and longevity cuts. However, age-induced apoptosis does not appear to simply be cellular ageing and clearance. In conjugation with age-induced apoptosis, ovariole number declines whilst the size of surviving oocytes increases. Hence, it appears that resources from sacrificed oocytes are being recycled into the survivors, and that this reinvestment in current reproduction trade-offs with future reproductive capacity. My thesis shows the importance of studying proximal mechanisms alongside more traditional measures of life history, as the relationship between isolated biological levels is not always clear.

O processo reprodutivo é de extrema importância para os organismos vivos, é através dele que os indivíduos transmitem as informações contidas em seus genes para as próximas gerações. Para que qualquer indivíduo seja bem-sucedido nesse processo, o primeiro desafio a ser superado é encontrar um parceiro sexual. Para cumprir essa tarefa, machos e fêmeas comunicam sua presença utilizando uma variedade de canais sensoriais. Nas abelhas sociais,o encontro entre machos e fêmeas é um processo complexo e resultado de um refinado sistema de comunicação, mediado principalmente por sinais químicos. Embora Meliponini seja o maior e mais diverso grupo de abelhas sociais, existem poucas informações sobre a comunicação sexual desses insetos. Um fenômeno comum nesse grupo de abelhas é a formação de grandes agregados de machos nas proximidades de colônias que possuem uma rainha virgem. No entanto, os sinais envolvidos na atração dos machos e na formação desses agregados são pouco conhecidos. Desse modo, este trabalho objetivou investigar os fatores envolvidos na comunicação sexual de Meliponini. Para explorar esse problema, nós realizamos uma revisão sobre a biologia reprodutiva dessas abelhas (cap. 1), testamos o papel das forrageiras na atração de machos (cap.2), identificamos os compostos presentes nas marcas depositadas por machos nas agregações (cap.3) e investigamos os fatores relacionados à escolha dos machos por uma determinada colônia (cap. 4). Os resultados obtidos apontam que as forrageiras têm um papel central na atração dos machos e que os machos depositam ativamente seus hidrocarbonetos cuticulares nos locais de agregação. Além disso, foi possível identificar que a atratividade de uma colônia está relacionada com a sua biomassa. Assim, esses resultados contribuem para ampliar nosso conhecimento sobre o processo reprodutivo em abelhas sem ferrão e mostram que a comunicação sexual desse grupo de insetos é um processo tão complexo quanto fascinante que envolve machos, rainhas e operárias / Reproduction is the utmost important process for living organisms since it is through this process that individuals can transmit their genetic information to the next generation. To be successful in this process, the first challenge individuals need to overcome is finding a sexual partner. To accomplish this task, males and females communicate their presence using several sensorial modalities. In highly eusocial bees, this complex process is the outcome of a precise chemical communication system. Stingless bees (Meliponini) represents the most species-rich group of eusocial bees and although a lot of information related to the group can be found in the literature, very little is known about their mating communication. A common phenomenon in this group of social bees is the formation of large male aggregations in front of nests during reproductive events. However, the factors involved in the formation of such male aggregation are poorly understood. Therefore, the aim of this study was to investigate the mating communication of stingless bees. To explore this problem, we reviewed the mating biology of the bees (chapter 1), tested the role of foragers in the attraction of males (chapter 2), identified the compounds that drones deposit at the aggregation site (chapter 3) and investigated the factors related to the differential attraction of males to colonies (chapter 4). Our results suggest that foragers have a central role in the long-range attraction of males and that males actively deposit their cuticular hydrocarbons at the aggregation site. Furthermore, we observed that the number of attracted males increased with the weight of colonies, showing that the attractiveness of colonies is related to their biomass. Thus, these results contribute to improve our knowledge about the reproductive process of stingless bees and show that the sexual communication of these bees is as complex as fascinating and involves males, queens and workers

As abelhas sem ferrão (Hymenoptera: Meliponini) possuem um sistema sexual haplodiplóide com determinação sexual complementar em um único lócus. Tal sistema é uma grande carga genética para o grupo e, assim, a diversidade genética de machos que se agregam nas proximidades dos ninhos é essencial para minimizar as chances de endogamia. As interações entre os indivíduos da colônia nas abelhas sem ferrão são diversas e grande parte delas é mediada por compostos químicos. A comunicação química é maior entre as rainhas e suas operárias, mas compostos químicos também são importantes para o acasalamento das rainhas. Como muitos machos se agregam nos eventos reprodutivos, é possível coletar e obter uma boa representatividade local de indivíduos e assim analisar certos caracteres que estruturam essas populações. Desse modo, o presente estudo teve como objetivos: (1) analisar quimicamente rainhas virgens e fisogástricas de Tetragonisca angustula; (2) analisar o perfil químico de machos dentro e fora dos ninhos; (3) analisar a diversidade genética das agregações de machos, quantas colônias contribuem com machos para formar essas agregações e avaliar qual o parentesco entre agregações de machos e rainhas dos ninhos onde havia agregações; (4) avaliar o potencial de dispersão dos machos de seus ninhos de origem até as agregações; (5) analisar morfometricamente machos compondo agregações de diferentes localidades. Técnicas de criação in vitro de rainhas virgens e instalação de ninhos-armadilha foram utilizadas a fim de otimizar a coleta de indivíduos. Nossos resultados indicam que rainhas virgens e rainhas fisogástricas são quimicamente distintas. Embora ambas possuam compostos voláteis atrativos sexualmente para os machos, as rainhas virgens possuem exclusivamente octadecenoato de octadecila e nerol em suas glândulas de Dufour e extratos cefálicos, respectivamente. Os machos que vivem dentro e os que vivem fora dos ninhos são semelhantes quimicamente, possuindo diversos ácidos carboxílicos em seus extratos cefálicos. Cinco agregações, contando com 376 machos, foram analisadas geneticamente sendo os machos provenientes de 83 colônias. Em média, eles se deslocaram ± 612 metros de seus ninhos de origem até as agregações. Essas agregações são muito semelhantes geneticamente entre si, não formando unidades distintas. Somente 3.45% dos machos das agregações eram aparentados às rainhas, o que diminui a probabilidade de inbreeding. Por fim, populações de machos de três localidades distintas puderam ser separadas com boa acuidade de acordo os dados morfométricos. Concluímos que existe comunicação química mediando a interação macho-rainha. A quantidade de colônias em uma determinada área contribui para a grande quantidade de indivíduos e para a diversidade genética das agregações. Os indivíduos nessas agregações são pouco aparentados e podem vir de colônias geograficamente muito distantes. A morfometria é útil em agrupar os machos de diferentes localidades / The stingless bees (Hymenoptera: Meliponini)present a haplodiploid sex determination system with complementary sex determination in a single locus. Such a system is a large genetic load for the group and thus the genetic diversity of male\'s aggregations near the nests is essential to minimize the chances of inbreeding. The interactions among the stingless bees nestmates are diverse and chemical compounds mediate most. The chemical communication is higher among the queens and their workers, but chemicals are also important for mating of queens. As the amount of males that aggregate near the nests with gynes is very large, these events allow us to collect and evaluate a local representation of males and thus to analyze certain characters that structure these populations. Thus, this study aimed to: (1) chemically analyzing virgin and physogastric queens of Tetragonisca angustula, (2) analyze the chemical profile of males inside and outside their nests, (3) analyze the genetic diversity of the aggregations of males, how many colonies contribute with males to these aggregations and to assess the relatedness between queens and males, (4) evaluate the potential dispersion of males from their nests to aggregations, (5) analyze morphometrically males composing aggregates of different locations. Techniques for rearing virgin queens in vitro and installation of trap-nests were used to optimize the sampling of individuals. Our results indicate that virgin queens and physogastric queens are chemically distinct. Although both present volatile compounds sexually attractive to males, virgin queens have exclusively nerol and ethyl octadecenoate in their cephalic extracts and Dufour\'s glands, respectively. Males from both types(living inside and outside their nests) are chemically similar, possessing several carboxylic acids in their cephalic extracts. About 83 colonies contributed for five aggregations with 376 males. On average, they moved ± 612 meters from their nest of origin to aggregations. These aggregations are genetically very similar to each other, without forming discrete units. Only 3.45% of the males are related to queens. Finally, populations of males of three different locations could be morphometrically separated with good accuracy. We conclude that there is chemical communication mediating the interaction male-queen. The number of colonies in one area contributes to the large number of individuals and the genetic diversity of the aggregations. Individuals in these aggregations are not related and can originate from distant colonies. The morphometry is useful to group the males from different localities