In Syrian hamsters, sexual preference requires integration of chemosensory and steroid cues. Although data suggest that separate pathways within the brain process these two signals, the functional significance of this separation is not well understood. Within the medial amygdala, the anterior region (MEa) receives input from the olfactory bulbs, whereas the posterodorsal region (MEpd) is sensitive to steroid hormones. Lesions of either the MEa or MEpd eliminated preference to investigate female over male odors. Importantly, males with MEpd lesions displayed decreased attraction toward female odors, suggesting a decrease in sexual motivation. In contrast, males with MEa lesions displayed high levels of investigation of both female and male odors, suggesting an inability to categorize the relevance of the odor stimuli. These results suggest that both the MEa and MEpd are critical for the expression of opposite-sex odor preference, although they appear to mediate distinct aspects of this behavior.

A striking feature of hymenopterans societies is the absence of male workers. Foraging, nest building, brood care and all other activities required for the functioning of the colony are carried out by the females. These behaviours of the females and the implied cooperation and altruism have led social insect researchers to focus almost exclusively on the female members of hymenopterans societies. As a consequence, males have remained relatively neglected. The imbalance in the attention paid by researchers to females and males has been even more striking in the case of the extensively studied primitively eusocial wasp Rosalinda marginata. I have therefore focussed most of my attention to male R. marginata but of course, wherever possible and appropriate, I have compared the males with the females. Since almost nothing was known about R. marginata males, I began by obtaining basic information on the natural history and behaviour of the males. Male R. marginata are smaller in size and are different in the shape of the head as compared to the females. By conducting a three year survey, I found that just as nests of this species are found throughout the year, so are the males. The presence of males throughout the year has implications for the evolution of sociality by making available the opportunity to mate and found new nests, for females eclosing at any time of the year. Unlike the females who spend all their life on their nests, males stay on their natal nests only for one to twelve days (mean ± sd: 6.0 ± 2.6, N = 55) and leave their natal nest once and for all, to lead a nomadic life. It is difficult to determine how long males live after leaving their natal nests. However, I maintained males in the laboratory with ad libitum food and found that under these conditions they can live up to 140 days (mean physiological life span ± SD: 61.3 ± 28.0, N = 106). Like all eusocial hymenopterans males, R. marginata males also do not take part in any colony maintenance activities. They however, occasionally perform the following behaviours: solicit food, antennae nest, antennae another wasp, feed self, snatch food (from females), fan wings, body jerk and wing jerk, dominance and subordinate behaviours. Females of course perform all of these behaviours and many more. But there are no behaviours which are restricted to the males. Borrowing methods used by ecologists to measure species richness and diversity, I have computed the behavioral richness and diversity of male and female R. marginata. As expected, female behaviour is richer and more diverse compared to males. Comparing what the males did during their short stay on the nest and what females did during their long stay on the nest, I found that males did not forage or feed larvae (although I recorded one male feeding larvae thrice on one occasion when there seemed to be excess food on the nest). Males showed, dominance and subordinate behaviours and being solicited behaviour, significantly less often than females. On the other hand, males showed higher frequencies of feeding self and soliciting behaviour. However, these comparisons may not be fair because what males do in the first few days of their life is being compared with what females do throughout their life. Hence I truncated the female data at six days to make it comparable to the average age of the males on the nest. Even after doing so I found similar differences except that the males show similar rates of feed self and higher rates of subordinate behaviour compared to the young females. As mentioned in the beginning, absence of male workers is a striking feature of social Hymenoptera. I therefore naturally turned my attention to the possible reasons for this. As there has been much speculation on the ultimate, evolutionary explanations for why males do not work, I decided to investigate possible proximate explanations. To make my goal experimentally tractable, I decided to focus on the behaviour of feeding larvae as an example of work. In spite of the fact that R. marginata has been studied for over two decades, male R. marginata had never been seen to feed larvae, before my study. I advanced three hypotheses for why males do not feed larvae. (1) Males are incapable of feeding larvae. (2) Males do not feed larvae because they have insufficient access to food to satisfy themselves and to feed the larvae. (3) Males do not feed larvae because females perform the same task very efficiently. In a series of experiments designed to test these hypotheses, I showed that males are indeed capable of feeding larvae; they do so at small frequencies when given access to additional food and do so at impressive frequencies when deprived of females, provided with excess food and confronted with hungry larvae. Nevertheless, their ‘feed larva’ behaviour is less sophisticated and relatively inefficient compared to females. Thus I have shown male wasps can work, given an opportunity. In addition to being very satisfying, this result negates the preadaptation hypothesis which argues that male social Hymenoptera do not work because their solitary ancestors did not. In spite of what I have shown above, mating remains the main roleof the males. Therefore, I next turned my attention to a study of mating behaviour. It is well known that mating never takes place on the nest of R. marginata. Although some sporadic attempts had been made before, mating behaviour had never been observed in laboratory conditions before my study. In a series of trial-and-error pilot experiments, varying the age, cage size, number of wasps per cage, period of isolation from other wasps, lighting conditions etc., and with considerable help from enthusiastic volunteers among my lab-mates, I succeeded in observing mating behaviour in the laboratory. In the final, standardized experimental set up, we introduced a single male and a single female wasp, both isolated from their nests and other wasps for at least five days, into an aerated transparent plastic box and made observations for one hour. Using such an experimental set up, we first made a detailed qualitative description of mating behaviour. All behavioral interactions were initiated by the males. Males often attempted to mount the females but sometimes the females flew away, making the attempt to mount unsuccessful. On other occasions males successfully mounted the females, which involved climbing on the female and drumming and rubbing his antennae and abdomen on the corresponding parts of the female body. On some occasions mounting led to interlocking of the abdominal tips, a process we refer to as ‘conjugation’. Sometimes the conjugation lasted less than five seconds and during which the male remained on the back of the female; this was referred to as short conjugation (SC). But at other times the conjugation lasted for more than 20 seconds, and the male flipped on its back; this was Referred to as long conjugation (LC). I dissected all females, involved ineither LC or SC or both. Of the 47 pairs, 21 pairs mated successfully as judged by the transfer of sperm into the spermatheca. With the goal of developing a strategy to obtain live mated females for any future experiments, we attempted to determine the behavioral correlate/s of successful sperm transfer. It turns out that SC is inadequate for sperm transfer and LC is a good predictor of sperm transfer. Five to twenty days of age is optimal for mating for both males and females. There was a significant reduction in the probability of mating when one or both partners were younger or older than 5-20 days. We did not find any evidence for nestmate discrimination in the context of mating. This is not surprising because mating takes place away from the nest and active nestmate discrimination may therefore be unnecessary to avoid inbreeding. Under these experimental conditions neither body size of males and females nor ovarian conditions of the females appeared to influence mating success. I hope that my studies will enhance attention of future researchers to the males and will also facilitate experiments requiring mated wasps and permit the study of mate choice and other reproductive behaviours in this otherwise well- studied species.

The adaptive significance of Pavlovian conditioning has been an established idea within the learning literature. Pavlov himself indicated the potential for associative learning's role as an adaptive mechanism. As investigations into Pavlovian conditioning moved into the laboratory, the idea of adaptive significance was lost. The current body of work seeks to re-establish the adaptive importance of Pavlovian conditioning by investigating changes in the reproductive behavior of Japanese quail. Experiment 1 was a preliminary exploration of the relationship between the reproductive behaviors of the male and female Japanese quail, and fertility rates. Fertility rates were highly correlated with female immobility and male copulatory efficiency--a measure of copulatory behavior quality for males. Also, female immobility was highly correlated with male copulatory efficiency. In Experiment 2, changes in reproductive behavior and fertility due to Pavlovian conditioning were examined. The results indicated that Pavlovian conditioning altered the fertility rates for subjects if both partners of the copulatory pair were signaled. The Pavlovian conditioning procedure was refined for Experiment 3, which also showed changes in fertility rates as well as male copulatory efficiency. These experiments served to establish that Pavlovian conditioning can increase copulatory behavior and fertility when both partners of the copulatory pair are signaled. Experiments 4 - 6 investigated how factors related to the Conditioned Stimulus impact reproductive behavior and fertility rates. Experiment 4 showed that altering the CS-US interval for females did not produce significant differences in behavior or fertility. Experiment 5 demonstrated that context could be a viable CS in the Pavlovian conditioning of behavior and fertility. Experiment 6 showed that a naturalistic cue did not significantly alter either behavior or fertility over an arbitrary cue. In Experiment 7, visual access as an Unconditioned Stimulus in the Pavlovian conditioning of reproductive behavior was examined. Visual access to a female increased behavior and fertility over a control procedure, but not as much as full copulatory access. The present experiments provide definitive evidence of the adaptive significance of Pavlovian conditioning through changes in reproductive behavior and fertility. The relevance of the findings to Pavlovian conditioning in other behavior systems is discussed. / text

Thesis (M.P.H.M. (Primary Health Care Management))--Mahidol University, 2008. / LICL has E-Thesis 0038 ; please contact computer services.

Orientador: Eliane Gonçalves de Freitas / Banca: Elisabeth Criscuolo Urbinati / Banca: Marcelo Simão da Rosa / Banca: Silvia Mitiko Nishida / Banca: Marisa Fernandes de Castilho / Resumo: Tilápia-do-nilo, Oreochromis niloticus (Linnaeus, 1758), é uma das espécies de peixes que utilizam o substrato para construir ninho. Porém, muitas vezes são mantidas em tanques ou aquários sem substrato. Em estudo anterior, foi verificado que a presença de substrato reduz o desenvolvimento das gônadas, aumenta a agressividade, mas não afeta o crescimento. Assim, foi avaliada a escolha do peixe por diferentes substratos (areia, areia + concha, pedra e vazio - sem substrato removível) para medir o bem-estar e o efeito de tais substratos no comportamento reprodutivo e agressivo da tilápia-do-nilo. Os objetivos deste trabalho foram: testar a escolha de substrato para a construção de ninho na tilápia-do-nilo (Estudo I); testar o efeito do substrato sobre o desempenho reprodutivo (freqüência e latência para construção de ninho, freqüência e latência para a desova e índice gonadossomático) e indicadores bioenergéticos (taxa de crescimento específico e índice hepatossomático) (Estudo II); e testar o efeito do tipo de substrato no desafio social por meio dos níveis de esteróides sexuais (testosterona (T) e 11-cetotestosterona (11KT)), e no cortisol plasmático como um indicador de estresse (Estudo III). A escolha de substrato foi testada em grupos (1 macho e 2 fêmeas) formados por animais adultos. Os machos escolheram o substrato de areia para a construção do ninho. Os indicadores reprodutivos e bioenergéticos também foram avaliados nos mesmos substratos utilizados no Estudo I, mas cada tipo de substrato foi colocado em aquários separados, consistindo 4 tratamentos. Em cada réplica foram utilizados 2 machos e 3 fêmeas, mantidos durante 12 dias ou até 48 horas após a primeira desova. A freqüência de desova foi maior no substrato de areia do que no sem substrato removível. Já a freqüência de construção de ninho, foi menor no substrato... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), is one of fish species which use build nest on bottom substrate. However this species are usually reared in tanks or aquarium without substrate. We verified the influence of substrate on reducing of gonad development, enhance aggressiveness, but growth is not affected. Thus, we tested the fish choice for different substrates (sand, sand + shell, stone and empty - without substrate) in order to access welfare and the effects of such substrates on reproductive and aggressive behavior of Nile tilapia. Our goals in this study were: test the substrate choice to nest building (Study I); test the substrate effect on the reproductive fitness (frequency and latency to nest building, frequency and latency to spawning and gonadossomatic index) and on the bioenergetic indicators (specific growth rate and hepatossomatic index) (Study II); and test the influence of substrate type on the social challenge by analyzing sexual steroid levels (testosterone (T) and 11 - ketotestosterone (11KT)), and serum cortisol as a stress indicator (Study III). The substrate choice was tested in groups made by 1 male and 2 females adult fish. Sand substrate was significantly chosen by males to built nest. The reproductive and bioenergetics indicators were also evaluated for the same substrate used in the Study I, but each substrate type was kept in separated aquaria, performing 4 treatments. Groups of 2 males and 3 females were kept until 12 days or until 48 hours after the first spawning. The frequency of spawning was higher in the sand substrate than in no substrate treatment. The frequency of nesting was lower in the stone substrate than in sand and sand + shell substrates. The others reproductive and energetic indicators were similar between the treatments. The social contest and hormone levels were tested in the four substrates used in the former experiments... (Complete abstract click electronic access below) / Doutor

Resumo: A hipótese de que a deposição espermática e a fecundação no camarão Stenopus hispidus ocorrem externamente ao corpo foram testadas, baseando-se no comportamento reprodutivo em laboratório e na anatomia reprodutiva. Para isso, 12 casais adultos foram mantidos em aquários interligados, em salinidade 35%o, temperatura 26°C, fotoperíodo 12 horas e alimentados com ração industrializada para peixes. 0 comportamento reprodutivo foi filmado e fêmeas recém-copuladas tiveram os esternos analisados. Posteriormente, os casais foram anestesiados e dissecados para a descrição da forma e localização das gônadas e pleópodos. O aparelho reprodutivo (AR) de ambos os sexos, esternos, genitálias e primeiro pleópodo também foram preparados e fotografados em microscopia eletrônica de varredura. A cópula ocorre quando a fêmea está em pós-muda, e espermatozóides puderam ser observados em seus esternos somente fazendo-se um esfregaço em lâmina. Apenas o primeiro pleópodo e masculino parece estar envolvido na cópula, já que é diferenciado dos demais. 0 AR masculino é reduzido e restrito à carapaça, com testículos lobulados e vasos deferentes não enovelados, abrindo-se na base do 5° pereiópodo. 0 AR feminino é bem desenvolvido, com o ovário ocupando grande parte da carapaça e alcançando até o terceiro somito abdominal; os ovidutos são curtos e sem estrutura aparente para estocagem de espermatozóides. As fendas genitais femininas se abrem na base do terceiro par de pereiópodos e são circundadas por cerdas plumosas, comuns também nos esternitos torácicos. Assim, o macho deposita uma massa espermática simples na região ventral da fêmea, e a fecundação ocorre no momenta da exteriorização dos oócitos maduros / Abstract: Reproductive morphology and sperm transfer in Stenopus hispidus (Olivier, 11) (Crustacea, Decapoda, Stenopodidae). The hypothesis that the deposition of sperm and fertilization in the shrimp Stenopus hispidus occurs externally of the body were tested, based on reproductive behavior in the laboratory and reproductive anatomy. For this, 12 adult pairs were kept isolated on interconnected aquaria with salinity 35%o, temperature 26°C, photoperiod 12 hours and daily fed with ornamental fish food. The reproductive behavior was taken with video camera and females had the sternum analyzed after mate. After that, the shrimps were anesthetized and dissected to describe the shape and location of the gonads and pleopods morphology. The reproductive systems (RS), sternum, first pleopods and genitalia were prepared and photographed by scanning electron microscopy. The mating occurs when the female was in pos-molt, and spermatozoa were seen in their sternum only by microscope slide smear preparation. Only the first male pleopod seems to be involved in the mating, since it is different from the others. The male RS is reduced and restricted to the carapace, with lobulated testis and vas deferens not convolute, opening in the 5th pereiopod basis. The female RS is well developed, with the ovary occupying much of the carapace and reaching the third abdominal segment; the oviduct is short and without apparent structure for sperm storage. The female genitalia open at third pereiopod basis and are surrounded by dense plumose setae, common also in the sternites. Thus, the male deposits a simple spermatophoric mass in the ventral region of the female and the fertilization occurs at the moment of the mature oocytes exteriorization / Orientador: Maria Lucia Negreiros Fransozo / Coorientador: Laura Suzana Lopez Grego / Banca: Wagner Cotroni Valenti / Banca: Fernando Luis Medina Mantelatto / Banca: Rogério Caetano da Costa / Banca: Fernando José Zara / Doutor

Made available in DSpace on 2014-12-17T15:37:20Z (GMT). No. of bitstreams: 1 MarianaCP.pdf: 340646 bytes, checksum: 7b38e8b3f11facf027891302ba389354 (MD5) Previous issue date: 2006-10-23 / Contrary to what is recorded for Callithrix jacchus females, the social interactions and hormonal profiles of males are less studied, and mainly in wild groups. The goal of this study was to investigate the behavioral and endocrine profiles of reproductive (RMs) and non-reproductive (NRs) common marmoset adult free-ranging males living in two natural groups (GC1 and GR2). The groups inhabited the area of the Escola Agr?cola de Jundia?/UFRN, located in Maca?ba, Brazil. Fecal collection for cortisol and androgen measurement and behavioral monitoring was carried out during the active phase from April to September, 2005. For behavioral data collection the focal instantaneous method was used every 5 min, for a total of 11.563 records. Statistical analysis was performed using non parametric tests and p < 0.05. Besides showing diurnal variation, the frequency of affiliative behaviors was significantly higher for RMs toward reproductive females than for NRs. Affiliative interactions of RMs with both reproductive females and NRs were similar, probably related to pair bond formation and helper recruitment, respectively. Parental care was also similar for both RMs and NRs. Both androgen and cortisol levels increased after the birth of the infants, mainly in RMs. The longitudinal profile of androgens fluctuates more in response to agonistic encounters and sexual behavior than that of cortisol. The mean basal excretion of both hormones was significantly higher in RMs and seems to reflect their higher participation in territorial vigilance and mate guarding behaviors. Significant positive correlations were found between agonism and cortisol and androgen hormones. These results describe, for the first time, the behavioral and hormonal profiles of common marmosets living in free-ranging groups and suggest that reproductive males are more responsive both behaviorally and hormonally to social group dynamics / Ao contr?rio do que ocorre para as f?meas da esp?cie Callithrix jacchus, as intera??es sociais e perfis hormonais de machos s?o pouco estudados, principalmente em grupos naturais. O objetivo desse estudo foi estabelecer os perfis comportamental e end?crino de machos adultos reprodutores (MRs) e n?o reprodutores (MnRs) vivendo em ambiente natural em dois grupos silvestres (GC1 e GR2). Os grupos habitavam a ?rea da Escola Agr?cola de Jundia?/UFRN, localizada no munic?pio de Maca?ba. A coleta de fezes para dosagem de cortisol e andr?genos e o monitoramento comportamental foram feitas uma vez por semana durante a fase de atividade no per?odo de abril a setembro de 2005. A coleta de dados comportamentais foi feita usando o m?todo focal instant?neo a cada 5 minutos para cada animal, em um total de observa??o de 11.563 registros. Para a an?lise estat?stica, foram utilizados testes n?o param?tricos e p < 0,05. Al?m de apresentarem varia??o diurna significativa, a freq??ncia de comportamentos afiliativos foi maior entre os pares reprodutores, comparado aos registros entre os MnRs e as f?meas reprodutoras. As intera??es afiliativas dos MRs com as f?meas reprodutoras foram semelhantes a freq??ncia de intera??es entre os focais (MRs e MnRs), possivelmente em fun??o da liga??o do par e recrutamento de ajudantes, respectivamente. O comportamento de cuidado com o infante tamb?m foi semelhante entre os MRs e MnRs e os n?veis de cortisol e andr?genos se elevaram ap?s o nascimento dos filhotes, principalmente nos MRs. O perfil longitudinal dos andr?genos flutuou mais em resposta aos encontros agonistas e contextos de c?pulas do que o cortisol. A excre??o basal m?dia de cortisol e andr?genos foi significativamente maior nos MRs e parecem refletir o maior envolvimento destes em contextos de territorialidade, vigil?ncia e guarda da parceira no grupo social. Correla??es positivas significativas foram detectadas entre a freq??ncia de comportamentos agon?sticos e os horm?nios cortisol e andr?genos. Estes resultados descrevem pela primeira vez o perfil comportamental associado ao perfil hormonal de machos de C. jacchus vivendo em grupos silvestres e sugerem que o macho reprodutor ? mais responsivo tanto comportamental como hormonalmente a din?mica do grupo social

O objetivo do presente trabalho foi investigar a relação do núcleo pré-mamilar ventral (PMV): 1) na regulação do sistema reprodutivo em fêmeas, 2) como mediador dos efeitos da leptina e 3) na resposta à estimulação feromonal. Para tanto, induzimos lesão bilateral do PMV em ratas. Foi observado que a lesão do PMV promove: alteração no ciclo estral e da histologia ovariana; redução dos níveis de estradiol e LH; e supressão de vias neurais que controlam o eixo reprodutivo. Além disso, a lesão do PMV impediu que a administração central de leptina induzisse secreção de LH durante o jejum. Em outros experimentos, realizados em ratos machos, verificou-se que neurônios que sintetizam óxido nítrico no PMV e no núcleo medial da amígdala são ativados em resposta ao odor de conspecíficos, em especial o de fêmeas. Assim, foi demonstrado que o PMV exerce papel relevante na regulação do sistema reprodutivo e media a ação estimulatória da leptina na secreção do LH. Além disso, o PMV faz parte do circuito neural relacionado com a resposta aos feromônios. / The objective of this study was to assess the role played by the ventral premammillary nucleus (PMV): 1) in the regulation of the female reproductive system, 2) as a mediator of the effects of leptin and 3) in response to pheromonal stimulation. For this purpose, we produced bilateral PMV lesions in female rats. We observed that PMV lesion: disrupted the estrous cycle and altered the number of ovarian antral follicles; reduced the estradiol and LH levels; and suppressed neural pathways that control the reproductive axis. We found that lesions of the PMV blocked leptin stimulation of LH secretion during fasting. In another experiment using male rats, we showed that nitric oxide synthesizing neurons in the PMV and medial nucleus of amygdala are activated by conspecific odors, especially female odors. Thus, we showed that PMV plays an important role in the control of females reproductive system and mediates the stimulatory effects of leptin on LH secretion. Also, PMV is part of the neural circuitry related to pheromonal responses.

Made available in DSpace on 2015-04-11T13:56:32Z (GMT). No. of bitstreams: 1 DISSERTACAO WENDEL DE SOUZA.pdf: 5629447 bytes, checksum: 13038eaa6fd701b4cd869b3f30051ba5 (MD5) Previous issue date: 2009-12-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This aimed to evaluate the effect of sex ratio on the reproductive behavior of freshwater shrimp Macrobrachium amazonicum in captivity. The collection of players happened at the end of October on the Catalão Lake/Amazonas state. After the collection shrimps were identified, transported in cool boxes and taken to the lab of the Agroindustrial Tambaqui LTDA. Farm, Itacoatiara city/Amazonas state for the start of experimental activities. The prawns were tested to four different sex ratios: (T01) = 01 male/02 females; (T02) = 01 male/04 females; (T03) = 01 male/06 females; (T04) = 01 male/08 females. At the end of experiment ovigerous females were identified and their oocytes were counted to determine the fertility rates. The treatment that shown the best fertility index was used six females per male (T03). / Este trabalho teve como objetivo avaliar o efeito da proporção sexual no comportamento reprodutivo do camarão de água doce Macrobrachium amazonicum em cativeiro. A coleta dos reprodutores aconteceu no final do mês de outubro no lago do Catalão/AM. Após a coleta, os camarões foram identificados e acondicionados em caixas isotérmicas. Posteriormente, foram transportados até as dependências da Fazenda Agroindustrial Tambaqui LTDA., no município de Itacoatiara/AM, para início das atividades experimentais. Os camarões foram submetidos a quatro diferentes proporções sexuais: (T01) = 01 macho/02 fêmeas; (T02) = 01 macho/04 fêmeas; (T03) = 01 macho/06 fêmeas; (T04) = 01 macho/08 fêmeas. Ao final do experimento, as fêmeas ovígeras foram identificadas e tiveram seus ovócitos contados para determinação dos índices de fecundidade. O tratamento que apresentou os melhores índices de fecundidade foi o que utilizou seis camarões fêmeas para cada macho (T03).

O objetivo deste trabalho foi estudar os níveis séricos dos hormônios esteróides (estradiol e progesterona) e analisar as possíveis relações destes com o desenvolvimento do comportamento reprodutivo em fêmeas jovens de avestruzes (Struthio camelus) durante a maturação sexual. No primeiro experimento, duas fêmeas jovens foram avaliadas, três vezes por semana, através de colheitas de sangue para dosagem de estradiol e progesterona e de observações para avaliação do comportamento reprodutivo. No segundo experimento, 20 fêmeas jovens foram selecionadas de acordo com a intensidade de comportamento reprodutivo e tiveram seu comportamento reprodutivo monitorado semanalmente. Foram realizadas colheitas de sangue semanais nos mesmos dias das observações comportamentais. No primeiro experimento, através da comparação das médias dos valores de estradiol nas fases de presença (CCOMP) ou ausência de comportamento reprodutivo (SCOMP), verificou-se uma igualdade entre as médias nas duas fêmeas estudadas e não foi verificada correlação entre os níveis séricos de estradiol e o comportamento reprodutivo. No segundo experimento, a comparação das médias de estradiol entre as amostras dos animais SCOMP e CCOMP apresentou diferença significativa. A comparação das médias entre as 4 categorias comportamentais estabelecidas - sem comportamento (SCOMP), com baixo comportamento (COMPBX), com alto comportamento sem aceitação de cópula (COMPALTSACC), com alto comportamento com aceitação de cópula (COMPALTCACC) - demonstraram haver diferença significativa entre os valores de estradiol encontrados, também sendo verificada correlação entre as 4 categorias e os níveis médios de estradiol (r = 0,64). Para a progesterona, no primeiro experimento, os valores médios foram significativamente maiores nas amostras SCOMP do que nas CCOMP, sendo que a progesterona apresentou uma correlação negativa com a intensidade do comportamento reprodutivo nas duas fêmeas (r = -0,54 e r = -0,33). No segundo experimento, os valores médios de progesterona foram significativamente maiores nas amostras CCOMP do que nas amostras SCOMP. As médias de progesterona das 4 categorias comportamentais apresentaram diferenças significativas e houve correlação positiva (r = 0,43) dos níveis de progesterona com as 4 categorias comportamentais. Os resultados sugerem que exista uma relação entre os níveis de estradiol e progesterona e a modulação da intensidade de comportamentos reprodutivos, mas não necessariamente entre estes níveis hormonais e a iniciação destes comportamentos e que os perfis séricos de estradiol e progesterona em fêmeas de avestruz na fase de maturação sexual apresentam semelhanças com outras espécies de aves. / The purpose of this work was to study the serum levels of estradiol and progesterone and analyze their relationship with the development of the reproductive behavior in young female ostriches (Struthio camelus) during sexual maturity. The first experiment studied two young females, through blood samples, three times a week, for measurement of estradiol and progesterone and was performed behavioral observations at the same time. In the second experiment, twenty young female ostriches had their reproductive behavior monitored weekly and blood samples were collected for hormone assays in the same days of the observations. The results of the first experiment showed no differences between the mean of estradiol levels in the two phases, with and without reproductive behavior. In the same way there were no correlations between estradiol levels and frequency of behaviors. In the second experiment, there were significant differences between the mean of estradiol levels with and without reproductive behavior. When it was considered four categories of behavior (without behavior, low behavior, high behavior and no copulation posture, and high behavior and copulation posture display), the mean estradiol levels showed significant differences. There was positive correlation between the categories and the estradiol levels (r = 0,64). Regarding progesterone, the first experiment, demonstrated significantly higher hormonal levels in the absence than in the presence of reproductive behavior and a negative correlation between the occurrence of behaviors and the hormonal levels for both females (r = -0,54 and r = -0,33). In the second experiment, the means of progesterone levels were significantly higher in the phase with behavioral displays than with none. For the four behavioral categories, the means of progesterone levels differed significantly and showed a positive correlation (r = 0,43) with the reproductive behavior. The results suggest that there is a relationship between estradiol and progesterone levels and the occurence of the reproductive behavior, but not necessarily between these hormone levels and the initiation of the process. The hormonal levels of estradiol and progesterone found in ostriches were similar to some domestic avian species.