Monoecy, the production of distinct male and female flowers on the same plant, is an important, though little studied, sexual strategy in the rainforest understory. This study of a monoecious plant discovered a cue to induce flowering, explored the interplay of gender constraint vs. plasticity in a natural population, and tested possible causes of gender in two laboratory experiments. An experiment in the lab found that reduced photoperiod for three weeks is an unambiguous cue for flowering. The remarkably long inductive period is followed by a long and variable period of floral initiation. This results in only partial synchronization of flowering among plants in a patch, which enhances mating opportunities in this protandrous plant. Inflorescence architecture is highly constrained, and ideally produces a phenotypic gender (proportion female) of about 0.5. However, in the forest at Las Cruces, Costa Rica, most plants were less female than predicted, mostly through abortion of female buds. Plants showed gender plasticity between and within years. Large plants produced more flowers and were more female in gender, and less variable in gender, than small plants. Reproduction was poorly correlated with environmental resource availability, measured as canopy openness, soil moisture, pH, and soil phosphorus, ammonium and nitrate. Phenotypic selection analysis on seed production suggests an optimal gender of 50-60% female, yet plasticity to be less female than this optimum, and in particular to express only male function, has been maintained. In a factorial experiment in the lab, high light or high nitrogen caused plants to produce more flowers and to be proportionally more female, and larger in weight, than low light or nitrogen. The effects of light and nitrogen on reproduction, plant size, and leaf greenness suggest an energy based determination of gender. Gender may be mostly influenced by plant size, but sometimes also opportunistically by environment. Inoculation with mycorrhizas caused plants to be less female in gender, and smaller in weight, than plants that were not inoculated. This suggests a net cost of mycorrhizas under experimental conditions, and supports the emerging view of the mycorrhizal symbiosis as not necessarily mutualistic under all circumstances.

Sex ratio theory suggests that the strength of intersexual selection will increase as a population more male-biased; reflecting increased selectivity in mate choice. Populations of pond turtle have varying adult sex ratios, in painted turtles (Chrysemys picta), reported sex ratios range from female biased (1:3) to male biased (3:1). I investigated the effect of sex ratio on male reproductive success (quantified as “fertilization success”) in painted turtles. I examined the mating system of painted turtles in a female-biased population using microsatellite paternity analysis, relating variation in male fertilization success to male phenotype and offspring survival, employed ex situ behavioural observation to clarify the mechanism behind the variation in male fertilization success and used agent-based modeling to simulate the effects of changing sex ratio, population density and proportions of male phenotype on male fertilization success. Small males contributed sperm to a greater number of clutches than did larger males, but were not more likely to reproduce in a season than larger males. There was no offspring fitness advantage related to male body size and no relationship between male claw length and fertilization success. Large male painted turtles courted at a higher frequency than small males. I found no relationship between male courtship behavior and claw length. Females showed no preference for males of any phenotype. Agent-based simulations were based on the distribution of best fit from the observed data; an amalgam of two Poisson distributions, each with its own probability of success and proportional representation in the final distribution. Increased female sex ratio bias, increased population density and increased proportions of “more successful” males all increased the mean and variance of male fertilization success, based on increased encounter rate among turtles. Small and large male painted turtles enjoy different fertilization success. It is uncertain whether this difference is based on active female choice, cryptic female choice, sperm competition or a combination of factors. Sex ratio simulations predict the opposite result as that predicted by sex ratio theory. These contrary results should be compared to simulations manipulating choosiness and field data from painted turtle populations to clarify mechanisms influencing male reproductive success.

Macoun’s arctic (Oeneis macounii) is a biennial satyrine butterfly found predominantly in boreal forests of North America. I monitored populations of O. macounii in Riding Mountain National Park (RMNP) in 2011 and in Sandilands Provincial Forest in 2012. I captured, sexed, marked and took UTM coordinates of butterflies to compare population sizes, sex ratios, longevity, dispersal and behaviour. I measured habitat variables around capture sites at RMNP, to establish environmental characteristics associated with butterfly occurrence. Population estimates at Sandilands show that the population size there is robust, but could not be calculated at RMNP. The number of butterflies observed at RMNP suggests that the population there is small and localized. In RMNP, males were more often in forested sites with sunny clearings, while female encounter sites were dominated by grasses, suggesting sexual segregation. The data collected from this survey is important for conservation strategies for the declining population at RMNP.

Le bar (Dicentrarchus labrax) est une espèce majeure de l'aquaculture méditerranéenne, dont la production est passée de presque rien en 1985 à plus de 100 000 tonnes annuelles aujourd'hui. Dans un grand nombre de cas, des géniteurs sauvages sont encore utilisés pour produire des juvéniles chez cette espèce, et l'on constate une forte prédominance des mâles, aux performances zootechniques inférieures, dans les populations d'élevage. Le but du présent travail de recherche était tout d'abord de quantifier les variations génétiques de la croissance et du sex ratio entre familles de bar produites par fécondation artificielle et élevées en commun, en utilisant le génotypage de locus microsatellites pour reconstruire les pedigrees des animaux mesurés. Dans un second temps, nous avons également étudié la réponse en termes de croissance et de sex ratio à une sélection expérimentale sur la croissance en longueur. Nous avons tout d'abord pu montrer que la technique expérimentale choisie (fécondation artificielle, élevage en commun et reconstruction des pedigrees par génotypage) était efficace et susceptible d'être appliquée non seulement en expérimentation, mais aussi pour la mise en place de programmes de sélection chez le bar. La croissance chez le bar montre une héritabilité élevée pour le poids à taille commerciale de 400g environ (h²=0.38-0.44), mais plus modeste pour le taux de croissance de 35 à 400g (0.16-0.34), montrant l'importance de la croissance précoce, très héritable (h²=0.61) dans la construction de la performance à taille commerciale. Par ailleurs, la croissance du bar n'est pas significativement influencée par des effets maternels non génétiques ou de dominance. Nous avons estimé les interactions génotype-milieu pour la croissance entre des sites de grossissement très différents, et si ces interactions se sont révélées modestes pour le poids à taille commerciale (rA=0.70-0.99 entre sites), elles étaient beaucoup plus fortes pour le taux de croissance (rA=0.21-0.61 entre sites). Bien que nous ayons à dessein choisi des environnements très différents pour ce test, ceci souligne l'importance de conduire les programmes de sélection dans un environnement proche de l'environnement d'élevage. Nous avons montré que le sex-ratio des populations naturelles de bar ne différait pas de 50-50 en moyenne, mais que certaines classes d'âge pouvaient avoir un sex-ratio biaisé, vraisemblablement du fait d'effets environnementaux. En élevage, les sex-ratios sont variables entre familles et influencés à la fois par le père et par la mère. Aucun modèle purement génétique ne permet d'expliquer les distributions observées, qui peuvent être décrites soit par un modèle ayant au moins deux loci bialléliques et une variance micro-environnementale, soit par un modèle polygénique à seuil (h²=0.62 pour la tendance sexuelle sur l'échelle sous-jacente). Avec ce dernier modèle, on note une corrélation génétique positive (rA=0.50) entre tendance sexuelle et croissance. Ceci permet de prédire que la domestication devrait permettre un rééquilibrage du sex-ratio vers 50-50, la sélection croissance biaisant le sex-ratio vers plus de femelles. C'est ce que nous observons ensuite dans notre expérience de réponse à la sélection pour la croissance. Cette même expérience nous permet de confirmer le potentiel de l'espèce pour une amélioration génétique de la croissance, avec un gain de 23% en première génération. Le modèle polygénique (ou à tout le moins polyfactoriel) de déterminisme du sexe est a priori rare chez les Vertébrés. Après avoir développé son utilisation possible pour obtenir à terme des populations de bars d'élevage monosexes femelles, le modèle polygénique est replacé dans la théorie du déterminisme du sexe chez les Vertébrés ectothermes, où il semble pouvoir être considéré comme beaucoup plus répandu qu'on ne le considère classiquement. [...] Suite et fin du résumé dans la thèse.

Thesis (M.Sc.) Uppsala : Sveriges lantbruksuniv.

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-10-02Bitstream added on 2014-06-13T20:26:43Z : No. of bitstreams: 1 nomura_e_dr_rcla.pdf: 1710426 bytes, checksum: 66fb4725979c73d334727039604ebc56 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Lagartas das traças-da-cera Galleria mellonella e Achroia grisella foram oferecidas a fêmeas do endoparasitóide solitário Apanteles galleriae de uma população mantida em condições de laboratório (população de laboratório), e a fêmeas de uma população selvagem, formada a partir de casulos coletados em apiários de Rio Claro e Araras, SP, Brasil (população de campo). Os parasitóides de cada população foram criados por 4 gerações consecutivas. Dois parasitóides machos e uma fêmea, emergidos no mesmo dia e da mesma espécie de hospedeiro foram transferidos para frascos de 30 mL, para propiciar o acasalamento. A cada fêmea fecundada de A. galleriae foram oferecidas 5, 10, 15 ou 20 lagartas de Galleria mellonella ou Achroia grisella de 5º e 6º instar, respectivamente, por uma hora. Após este período, a fêmea foi devolvida ao frasco de origem e as lagartas receberam dieta “ad libidum”. Tal procedimento foi realizado a cada 2 dias, desde o 3º dia de vida da fêmea, até a sua morte. O objetivo da pesquisa foi comparar as proles obtidas de ambas as populações, em relação ao número de descendentes e à razão sexual, bem como avaliar a capacidade de parasitismo do parasitóide, em função da idade da fêmea e da densidade de hospedeiros submetidos ao parasitismo. Utilizou-se um teste de proporções para comparar as freqüências de lagartas de G. mellonella e A. grisella parasitadas por fêmeas de A. galleriae de cada população (F4 ou Lab) e uma análise de variâncias para testar o efeito da idade das fêmeas das duas populações sobre o número de descendentes emergidos, para as quatro densidades de hospedeiros. Uma análise de correlação de Pearson foi usada para avaliar o efeito da idade materna sobre a razão sexual registrada para os parasitóides obtidos em cada grupo experimental. As maiores eficiências de parasitismo registradas foram 42,59% para... / Caterpillars of Galleria mellonella and Achroia grisella were offered to females of the solitary endoparasitoid Apanteles galleriae from a population maintained under laboratory conditions (laboratory population), and females from a wild population, formed from cocoons collected in apiaries of Rio Claro and Araras, SP, Brazil (field population). The parasitoids of each population were reared by four consecutive generations. Two males and a female, emerged on the same day and reared in the same host species, were transferred to a 30 mL vial in order to allow mating. Caterpillars of A. grisella (sixth instar) or G. mellonella (fifth instar) were offered for sixty minutes to each mated and expert female, with 2 to 5 days of age, in one of the four host densities used in this research (5, 10, 15 and 20 hosts/female). After this period, the female was given back to the original vial, and the caterpillars received diet ad libidum. Such procedure was accomplished every 2 days, since the 3rd day of the female life until her death. The objective of this research was to compare the offsprings from both populations, in relation to the number of descendants and sex ratio, and also the capacity of parasitism of A. galleriae in relation to the age of the female and the density of hosts submitted to the parasitism. A test for difference of proportions was applied to compare the frequencies of caterpillars of G. mellonella and A. grisella parasitized by A. galleriae females of each population (F4 or Lab), and an analysis of variances was used to evaluate the effect of the age of females from both populations on the number of descendants emerged, as a function of the host densities. A Pearson’s correlation analysis was utilized to test the effect of maternal age on sexual proportion recorded for parasitoids of each experimental group. The highest efficiencies of parasitism recorded were 42.59% to ... (Complete abstract click electronic access below)

Food, growth, sex ratio and depth distribution of perch (Perca fluviatilis L.) were studied in Milada Lake, Most Lake and Barbora Lake. These lakes were artificialy created after a coal mining. Sex ratio and depth distribution were also compared with data gathered from Vír Reservoir and Římov Reservoir. Fish designed for the research were captured by gillnets. Age analysis was carried out by otolite scanning. Food, growth and depth distribution were analysed with consideration of size and sex of the fish.

Made available in DSpace on 2017-07-10T17:48:17Z (GMT). No. of bitstreams: 1 Eder_Morschbacher.pdf: 604897 bytes, checksum: 185b7a10312912e21907fcdb57556daf (MD5) Previous issue date: 2009-05-25 / This present study aimed to evaluate the use of prebiotic mannanoligosaccharide (Bio-Mos®) during the sexual reversion to larvae of Nile tilapia. The study was realized in the Laboratory of Aquaculture of the Western Parana State University (Unioeste). Onethousand nd eighty larvae of Nile tilapia with three days old and initial average weight of 10.9 ± 1.2 mg were used. The larvae were distributed in 36 aquariums with 30 liters of usable volume each, in a completely randomized experimental design with six treatments and six replications. The treatments consisted of five levels, 0.2%, 0.4%, 0.6%, 0.8% and 1% for inclusion of Bio-Mos® and a control without the inclusion.The ad libitum feeding was carried out six times a day with diet formulated to obtain 38.6% of digestible protein, 3,500 kcal of digestible energy and 60 mg/kg of hormone masculine 17-α- methyltestosterone, keeping them isocaloric, isonitrogenous and isophosphoric. Aquariums were cleaned two times a day for withdrawal of surplus of feed and feces, and water renewal. The temperature was measured daily in the early morning and late afternoon. Dissolved oxygen, pH and conductivity were measured weekly. At the end of 30 days of reared period the fish were weighed and measured individually to obtain the zootechnical parameters as to final average weight, length, final biomass, survival, specific growth, condition factor and homogeneity of the lots. Ten fish from each replicate were preserved in formalin (10%) for later determination of sex ratio. The water quality parameters such as temperature, dissolved oxygen, pH and conductivity ranged from 24.76 to 26.16 °C, 5.7 to 5.85 mg/L, 7.32 to 7.65 and 87.67 to 111.33 μS/cm, respectively. The values of productive performance did not differ significantly (P>0.05). The values of final average weight, length, survival, specific growth and condition factor were 620 mg, 32.62 mm, 91.85%, 13.34%/day and 1.31, respectively. The effectiveness of sex reversal was 100% and there was not difference (P>0.05) in uniformity of lots of fish fed with different levels of inclusion of prebiotic in the ration. The average values of dry matter, ash, ether extract and crude protein from carcasses of fingerlings ranged from 22.93 to 28.45%, 11.80 to 13.61%, 23.67 to 29.97% and 60, 64 to 64.34%, respectively, but did not differ significantly (P>0.05) between the levels of prebiotic studied. The inclusion up to 1.0% Bio-Mos® did not affect the parameters of performance, sex ratio, survival, uniformity of lots and chemical composition of carcass of Nile tilapia during the sexual reversion. / O presente estudo teve como objetivo avaliar a utilização do prebiótico mananoligossacarídeo (Bio-Mos®) durante a fase de reversão sexual de tilápia do Nilo. O estudo foi realizado no Laboratório de Aquicultura da Universidade Estadual do Oeste do Paraná (Unioeste). Foram utilizadas 1.080 larvas de tilápia do Nilo com três dias de idade e peso médio inicial de 10,9 ± 1,2 mg. As larvas foram distribuídas em 36 aquários de 30 litros de volume útil cada, em um delineamento experimental completamente casualizado com seis tratamentos e seis repetições. Os tratamentos foram constituídos de cinco níveis, 0,2%, 0,4%, 0,6%, 0,8% e 1,0% de inclusão de Bio-Mos® e um tratamento controle. A alimentação foi realizada ad libitum seis vezes ao dia com ração formulada para se obter 38,6% de proteína digestível, 3.500 kcal de energia digestível e 60 mg/kg de hormônio masculinizante 17-α-metiltestosterona, mantendo-as isocalóricas, isoprotéicas e isofosfóricas. Os aquários foram sifonados duas vezes ao dia para retirada das sobras de ração e fezes e para renovação da água. A temperatura foi aferida diariamente no início da manhã e final da tarde. Oxigênio dissolvido, pH e condutividade foram mensurados semanalmente. Ao final de 30 dias de cultivo os peixes foram pesados e medidos individualmente para se obter os parâmetros zootécnicos de peso médio final, comprimento, biomassa final, sobrevivência, crescimento específico, fator de condição e uniformidade dos lotes. Dez peixes de cada repetição foram conservados em formalina (10%) para posterior determinação da proporção sexual. Os parâmetros de qualidade de água como a temperatura, oxigênio dissolvido, pH e condutividade variaram entre 24,76 a 26,16 ºC, 5,7 a 5,85 mg/L, 7,32 a 7,65 e 87,67 a 111,33 μS/cm, respectivamente. Os valores de desempenho zootécnico não diferiram significativamente (P>0,05). Os valores médios finais de peso, comprimento, sobrevivência, crescimento específico e fator de condição foram, 620 mg e 32,62 mm, 91,85%, 13,34%/dia e 1,31, respectivamente. A efetividade da reversão sexual foi de 100% e não houve diferença (P>0,05) na uniformidade dos lotes dos peixes alimentados com diferentes níveis de inclusão de prebiótico na ração. Os valores médios de matéria seca, matéria mineral, extrato etéreo e proteína bruta das carcaças dos alevinos variam de 22,93 a 28,45%, 11,80 a 13,61%, 23,67 a 29,97% e 60,64 a 64,34%, respectivamente, porém não diferiram significativamente (P>0,05) entre os níveis de prebióticos estudados. A inclusão até 1,0% de Bio-Mos® não afetou os parâmetros de desempenho, proporção sexual, sobrevivência, uniformidade dos lotes e composição química da carcaça de tilápia do Nilo durante a fase de reversão sexual

Orientador: Louis Bernard Klaczko / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-22T19:31:56Z (GMT). No. of bitstreams: 1 Ventura_IuriMatteuzzo_M.pdf: 2580161 bytes, checksum: ec78d3ac3a9cb1dcb0d410ab56b4d99c (MD5) Previous issue date: 2013 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Mestrado / Genetica Animal e Evolução / Mestre em Genética e Biologia Molecular

A key feature of social Hymenoptera is the division of labor in reproduction between one or a few fertile individuals – the queen(s) – and many sterile nestmates that function as helpers – the workers. The reproductive altruism of workers has long been considered as one of the most important paradox of Evolution. Today, kin selection (Hamilton 1964a,b) is recognized as a prime selective force for the evolution reproductive altruism in Hymenoptera. Hamilton’s kin selection theory states that workers may benefit helping relatives reproduce as long as the relatives they aid share a higher than average proportion of their genes with the workers and effectively pass on copies of the workers' genes to the next generation. Relatedness between colony members is therefore pivotal in kin selection theory, because it directly influences the benefits from indirect fitness. In social Hymenoptera, within-colony relatedness is usually high, because of the haplodiploid sex determinism system. However, several factors of the breeding system are known to affect the colony genetic structure and, hence, the workers’ indirect inclusive fitness: the number of breeders, their genetic relationships and their relative contribution to the reproduction. On the other hand, dispersal strategies influence the population genetic structure, which in turn may result in different interaction patterns between members from neighboring colonies. Despite its central role in the evolution of cooperation and reproductive altruism in animals, kin selection also predicts conflicts between colony members. Because the individuals from a colony are not genetically identical, their reproductive interests may be different (Trivers 1974). These conflicts are diversified, both regarding their actors and their causes (Trivers & Hare 1976; Bourke & Franks 1995; Keller 1995; Chapuisat & Keller 1999b; Keller & Reeve 1999; Sundström & Boomsma 2001). The first part of this work deals with the population genetic structure, mating system and dispersal strategies of two Pheidole ants, the Mediterranean ant Pheidole pallidula and the Mojave Desert ant Pheidole tucsonica. Chapter 1 investigates the population genetic structure, the breeding system, the colony kin composition and the colony genetic structure of the Mediterranean ant P. pallidula. This study was performed by using highly polymorphic DNA microsatellite marker loci. The results show that a single, unrelated male inseminates each queen. Colonies are monogynous (i.e. headed by one reproductive queen) or polygynous (i.e. headed by 2 to 4 functional queens). Moreover, they are genetically differentiated and form a population exhibiting significant isolation-by-distance, suggesting that some colonies originate through budding. Chapter 2 reports cross-species amplifications of microsatellite markers developed for the ant P. pallidula on 13 ant species belonging to the sub-family Myrmicinae. Moreover, levels of genetic diversity within a colony, as well as relationship among colonies are studied for the black ant Pheidole tucsonica. Chapter 3 characterizes the level of inter-nest aggression, the spatial distribution and the genetic structure of a P. tucsonica population. The results show that inter-colony aggression varies from none to “all out” fights and that it is largely non-transitive. No effect of geographical distance or genetic structure on inter-nest aggression levels is detected. Moreover, genetic data reveal high rates of polygyny and/or polyandry. Overall, these results do not support the idea of a simple mechanism of nestmate recognition through queen or worker-produced pheromones or environmental cues. The second part of this work is devoted to the queen-queen conflict over reproduction, and the queen-workers conflict over sex allocation in P. pallidula. Chapter 4 is a detailed analysis on the partitioning of reproduction among queens in polygynous colonies of the species. Our results show a significant departure from equal contribution of queens to reproductive female, male and worker production. Reproductive skew is greater for male production than for queen and worker production. There is no relationship between the magnitude of the reproductive skew and (i) the number of reproductive queens per colony, (ii) their relatedness and (iii) the overall colony productivity, some of the factors predicted to influence the extent of reproductive skew. Finally, this study reveals a trade-off in the relative contribution of nestmate queens to reproductive female and worker production. The queens contributing more to reproductive female production contribute significantly less to worker production. To our knowledge, such a trade-off is shown for the first time in the Formicidae. Chapter 5 focuses on queen-workers conflict over sex allocation. Colonies of the Mediterranean ant P. pallidula show a strong split sex ratio, with 85% colonies producing more than 80% sexuals of one sex. Genetic analyses reveal that this species has an unusual breeding system, with colonies being headed by a single or a few unrelated queens. As expected in such a breeding system, our results show no variation in relatedness asymmetry between monogynous (single queen per colony) and polygynous colonies. Nevertheless, sex allocation is tightly associated with the breeding structure, with monogynous colonies producing a male-biased brood and polygynous colonies almost only females. In addition, sex allocation is closely correlated with colony total sexual productivity. Overall, our data show that when colonies become more productive (and presumably larger) they shift from monogyny to polygyny and from male production to female production, a pattern that has never been reported in social insects so far. A new explanation based on the concept of the “tragedy of the commons” is proposed to explain the strong sex ratio specialization observed in P. pallidula and in other species characterized by facultative polygyny. Chapter 6 investigates the relationship between the breeding system (monogynous vs. polygynous colonies) and the biosynthesis rate of juvenile hormone. Previous works in P. pallidula showed (i) that maternal effects induced by hormones and/or other compounds transferred to the eggs could influence the caste fate of female eggs and (ii) that sex specialization is tightly associated with the breeding structure (monogynous colonies produce a male-biased brood and polygynous colonies almost only females - Chapter 5). This study reveals a strong relationship between the biosynthetic rate of juvenile hormone (JH) production and the breeding system. Because in this species the breeding structure is closely associated with colony sex ratio, we propose that the rate of JH in queens could be a critical parameter in colony sex ratio determination. Queens of P. pallidula would exert partial control over sex ratio by laying different proportions of worker-destined eggs and queen-destined eggs according to the structure monogynous or polygynous of their colony. To conclude, some perspectives for future research on the different topics presented in this work are suggested. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished