Orientador: Louis Bernard Klaczko / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-04T11:23:51Z (GMT). No. of bitstreams: 1 Montenegro_Horacio_D.pdf: 10351368 bytes, checksum: 5516ef31afbe4c57e6bf15156c33fdb7 (MD5) Previous issue date: 2005 / Resumo: Elementos genéticos egoístas são partículas herdáveis de etiologia e mecanismos de ação variados, mas com a caracterítica em comum de modificar a segregação mendeliana dos alelos em favor próprio, aumentando a própria freqüência. Elementos citoplásmaticos egoístas são um caso especial de elementos genéticos egoístas, como são herdados apenas pelo citoplasma materno, eles sofrem seleção para causar desvios na proporção sexual, em favor de um excesso de fêmeas. A proporção sexual nas progênies de organismos que se reproduzem sexualmente é, em geral, 1.___.__)LVKHU________SURS{V_D_SULPHLUD_H[SOLFDoão baseada em seleção natural para esta proporção. O princípio de Fisher prediz que o sexo mais raro tem maior valor adaptativo, pois sua contribuição média por indivíduo é maior. Assim, a seleção favorecerá alelos que aumentem a freqüência do sexo raro nas progênies. Quando a proporção chegar a 1.___.__indivíduos dos dois sexos terão o mesmo valor adaptativo. Parasitas reprodutivos, endosimbiontes herdados maternalmete, representam a maior parte dos elementos citoplasmáticos egoístas, e uma das causas mais comuns de desvios à proporção de 1.___.__ Agentes androcidas, endossimbiontes que matam os embriões machos, são um destes parasitas reprodutivos. Como conseqüência, a proporção sexual da prole das fêmeas infectadas afasta-se de 1.___.__apresentando excesso ou totalidade de fêmeas. Agentes androcidas foram encontrados em mais de 40 espécies de 6 ordens de insetos. Várions táxons de bactérias já foram associados com o fenótipo, e a filogenia dos parasitas e hospedeiros não é congruente, indicando transmissão horizontal freqüente. Neste trabalho, estudamos o agente androcida de Drosophila melanogaster, descrito recentemente. Sistemática molecular mostrou que trata-se de uma bactéria do gêneroSpiroplasma, muito próxima ao agente androcida encontrado em D. nebulosa. As seqüências comparadas (3000 pares de base, representando seqüências parciais de 3 genes) são idênticas, portanto, as duas bactérias têm um ancestral comum muito recente. De fato, possivelmente as duas espécies de Drosophila só entraram em contato há 4 ou 5 séculos, com a expansão mundial de D. melanogaster, e a transmissão do Spiroplasma de D. nebulosa para D. melanogaster deve ter ocorrido depois disso. Em uma coleta em Recife, foi encontrado que 2,3% das fêmeas estavam infectadas com Spiroplasma; outro parasita reprodutivo, a bactéria Wolbachia (que causa incompatibilidade citoplasmática) infectava 96% das fêmeas. Além disso, as duas bactérias co-infectavam os mesmos indivíduos, uma observação até agora incomum para parasitas reprodutivos com fenótipos diferentes. Como parasitas reprodutivos tem transmissão exclusivamente materna, seu valor adaptativo é altamente correlacionado com o das fêmeas hospedeiras. Desta forma, espera-se que parasitas reprodutivos não tenham efeitos deletérios no valor adaptativo das fêmeas hospedeiras, ou até que sejam benéficos. Por outro lado, a eficiência de transmissão ou a intensidade do fenótipo de manipulação reprodutiva podem estar positivamente correlacionados com a densidade de bactérias no hospedeiro, de forma que parasitas mais eficientes causem efeitos deletérios no valor adaptativo da fêmea. Para verificar se existem efeitos de Spiroplasma e Wolbachia no valor adaptativo de fêmeas, medimos a viabilidade larval e a fecundidade de fêmeas adultas, comparando com a de fêmeas não-infectadas. Nenhuma das duas características parece ser afetada por Spiroplasma ou Wolbachia, nem por infecção com as duas bactérias simultaneamente. Finalmente, foi verificado que temperaturas baixas (em torno de 16,5°C) interrompem a transmissão do agente androcida para a progênie das moscas infectadas / Abstract: Selfish genetic elements are inheritable particles with diverse ethiology and mechanisms, but sharing the fact that they modify the Mendelian segregation for their own benefit, thus increasing their own frequency. Selfish cytoplasmic elements are a special instance of selfish genetic elements, as they are inherited only by maternal cytoplasm, they suffer strong selection to alter the sexual proportion, in direction to an excess of females. The usual sexual proportion in sexually reproducing organisms is 1.___.__)LVKHU________ was the first to propose an explanation based on the natural selection for this proportion. Fisher¿s principle predicts that, if one of the sexes is rarer, it will have higher fitness, because its individual average contribution will be larger. Thereafter, selection will favour alleles that increase the frequencies of the rarer sex in broods. When the proportion reaches 1.___.__both sexes will have the same fitness. Reproductive parasites, maternally inherited endosymbionts, are the majority of selfish cytoplasmic elements, and one of the most common causes of departures from the 1.___._sexual proportion. Male killers, endosymbionts that kill male embryos, are one of these reproductive parasites. Consequently, the sexual proportion of infected females deviates from 1.___.__towards an excess or totality of females. Male killers have been found in more than 40 species of 6 insect orders. Several bacterial taxa have been associated with male-killing phenotype, and the phylogeny of parasites ad hosts is not congruent, indicating frequent horizontal transmission. In this work, we studied the recently described male killer agent found in Drosophila melanogaster. Molecular systematics showed that this agent is a Spiroplasma bacterium, closely related to the D. nebulosa male-killer. The compared sequences (3000 base pairs, partial sequence from 3 genes) are identical, thus both bacteria share a very recent common ancestral. Indeed, only since D. melanogaster worldwide expansion, 4 or 5 centuries ago, both Drosophila species overlap in their distribution, and the Spiroplasma transmission from D. nebulosa to D. melanogaster probably occurred after this. In one collection in Recife, Spiroplasma has been found infecting 2.3% of all females, another reproductive parasite, the bacterium Wolbachia (which causes cytoplasmic incompatibility) infected 96% of all females. Wolbachia was also found co-infecting flies alongside with Spiroplasma, a rather uncommon observation for reproductive parasites with different phenotypes. As reproductive parasites have exclusively maternal transmission, their fitness is highly correlated with its female host fitness. Consequently, it is expected that reproductive parasites do not pose deleterious fitness effects to their female hosts, or even be beneficial. However, transmission efficiency or the intensity of the reproductive manipulation phenotype could be positively correlated to the bacterial load on the host, in a way that more efficient parasites will have a deleterious fitness effect on females. In order to verify if Spiroplasma and Wolbachia have any kind of fitness effects on female hosts, we assessed larval viability and fecundity of adult females, in relation to uninfected females. Both characteristics showed signs of being affected by Spiroplasma or Wolbachia, nor by double-infection with both bacteria. Finally, low temperature (approximately 16.5°C) interrupts transmission of the male killing agent to the progeny of infected females / Doutorado / Genetica Animal e Evolução / Doutor em Genetica e Biologia Molecular

La sélection de la parentèle est le concept actuellement le plus fréquemment avancé pour justifier l’évolution et le maintien d'une caste ouvrière stérile chez les Hyménoptères sociaux. La fourmi méditerranéenne Cataglyphis cursor possède plusieurs traits biologiques qui font de cette espèce un modèle particulièrement intéressant pour tester les prédictions de la théorie de la sélection de la parentèle, le plus important d'entre eux étant la capacité des ouvrières, qui ne s'accouplent jamais, à produire une descendance mâle (haploïde) par parthénogenèse arrhénotoque, ou femelle (diploïde) par parthénogenèse thélytoque. Nos analyses génétiques, basées sur des marqueurs microsatellites développés au préalable pour cette espèce, ont révélé que les reines utilisent la reproduction sexuée et asexuée respectivement pour la production de la caste ouvrière et reproductrice. L'analyse du pedigree des reproductrices issues de la reproduction asexuée nous a permis d'identifier le mécanisme cytologique de la parthénogenèse thélytoque et d'estimer la proportion de reines issues de la reproduction des ouvrières au sein de la population. De plus, bien que les reines soient capables de produire une descendance diploïde (femelle) par parthénogenèse thélytoque, elles ont conservé la reproduction sexuée pour la caste ouvrière et s'accouplent avec plusieurs mâles. Ceci indique que la reproduction sexuée a une fonction importante au niveau de la colonie, et nous avons testé certaines des hypothèses avancées pour justifier l'évolution de la polyandrie. Finalement, nous avons étudié l'impact des stratégies de dispersion de cette espèce sur le sex-ratio de la descendance sexuée. Ces résultats confirment l'intérêt que représente l'étude des stratégies reproductrices chez les Hyménoptères sociaux pour tester les prédiction de diverses théories en biologie évolutives et ouvrent également de nouvelles perspectives de recherche, tant chez C. cursor que chez d'autres espèces appartenant au genre Cataglyphis. / Kin selection is, to date, the most widely accepted theory to justify the evolution of a sterile worker caste among social Hymenoptera. The Mediterranean ant Cataglyphis cursor represents an interesting biological model for several reasons, the most important of them being the ability for unmated workers to produce haploid (male) offspring, through arrhenotokous parthenogenesis, and diploid (female) offspring, through thelytokous parthenogenesis. Our genetic analyses, based on microsatellite loci developed for this purpose, revealed that queens selectively use sexual and asexual reproduction to produce workers and sexuals, respectively. Pedigree analyses allowed us to identify the cytological mechanism involved in thelytokous parthenogenesis and to estimate the proportion of worker-produced queens in the study population. Although C. cursor queens do not require mating to produce diploid offspring, they have retained sexual reproduction and mate multiply with up to 8 males. This suggests that sexual reproduction has important benefits for colony function, and we tested several hypotheses accounting for the evolution of polyandry. Eventually, we studied the effect of dispersal strategies on sex-ratio of the sexual brood. These results confirm the interest of investigating the reproductive strategies of social Hymenoptera to test the predictions of diverse theories in the field of evolutionary biology, and open new research perspectives in C. cursor and other ants of the Cataglyphis genera. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The most speciose group of fishes in the Gulf of Mexico is the dragonfishes (Family: Stomiidae). These fishes are dominant mesopelagic predators occurring throughout the world’s oceans, including the Antarctic seas. Little is known regarding their reproductive ecology, a consequence attributed to insufficient sample sizes of mature adults due to inadequacies of sampling gear; larger, sexually mature stomiid adults are more adept at net avoidance, thereby obfuscating synoptic reproductive biology studies. Between 2010-2011, the Offshore Nekton Sampling and Analysis Program was initiated in the northern Gulf of Mexico over all four seasons using a discrete-depth sampling system (MOCNESS) and a large, commercial-sized midwater trawl (Irish herring trawl). Gonads were dissected from 714 individuals belonging to 47 species of stomiids, of which the most 12 abundant species were subjected to detailed analysis. Female ovaries possessed an asynchronous oocyte development, suggesting that females are iteroparous. Males exhibited a similar pattern. Chauliodus sloani had an overall sex ratio that favored females, and was the only species in which the overall sex ratio significantly differed from the expected 1:1 ratio (male:female) (P < 0.05). Considering just mature specimens, Aristostomias xenostoma, Malacosteus niger, Eustomias fissibarbis, and Eustomias schmidti had sex ratios that favored males, and were the only species in which the sex ratio significantly differed from even (P < 0.05). Eustomias hypopsilus was the only species in which mean biomass significantly differed between sexes. Histological analysis and binomial regression indicated that females of the 12 most abundant species matured at larger lengths than males. Generally, only females were present in the larger size classes, suggesting that females also become larger than males. Size distribution plots by gear type to assess gear selectivity revealed two patterns: the MOCNESS caught fewer specimens per species than the Irish herring trawl, and the MOCNESS caught predominantly smaller specimens. These data are essential for ecosystem-based modeling of global deep-pelagic ecosystems, which contain the overwhelming majority of Earth’s fish biomass.

Magister Philosophiae - MPhil / In many countries, an enumeration of all household members remains the most important source of population statistics. According to Statistics South Africa, two population censuses and quite a few household surveys have taken place across the country. The quality of data recorded varies according to the operation. Despite great improvement in data collection and analysis capacities,some of the demographic data provided have not been assessed in terms of quality. The aim of this study was to ascertain the accuracy of demographic data on age and sex collected and the coverage during the population census 2001, General Household Surveys (2004 and 2007), Labour Force Surveys (2005 and 2007) and Community survey 2007 in South Africa. Two methods were applied to assess the quality of data. First, the direct method consists of checking the content and coverage (errors during enumeration, errors of exploitation, concordance in questionnaire). Second, the indirect method lies in the calculation of some indexes, age ratios,sex ratios, graphing of population pyramids and sex ratios curves. The indexes are Whipple’s index, Myer’s index and the Combined index of United Nations. Therefore, the main variables of interest are age, sex, place of residence and ethnic groups. Differentials in the quality according to declaration on age by gender, by ethnic group, by place of residence have been explored. This study has identified some variations in different indexes between 2001 and 2007 and has also evaluated the ethnic, gender and regional differentials. Comparison between indexes of each instrument has been done to measure some variations over years. Also, time-space comparisons were conducted across indexes of different instruments. The quality of data on age was better at national level compared to provincial level. Therefore, based on the measurements and patterns observed in the census and surveys data, the study has made some recommendations on the need for an integrated approach to reduce the gap and improve the quality of declarations on age and sex.

By controlling the inheritance of sex, the sex determination mechanism constrains sex allocation strategies and sex ratio adaptation; however, sex ratio selection also influences the evolution of sex determination mechanisms. Much of the sex determination literature focuses on how sex determination mechanisms transition between genetic and environmental factors (i.e. GSD vs. ESD), and if genetic sex factors are involved, how many (e.g. chromosomal vs polygenic systems). The study of sex allocation largely focuses on deviations in sex ratio from a theoretically 1:1 evolutionarily stable strategy, such as when sex ratios reflect ‘cost’ differences between the sexes. Tigriopus californicus is a tidepool copepod with polygenic sex determination, and shows wide variability in sex ratios in the field and lab that cannot be explained by genetic and stochastic processes alone, which suggests that an environmental variable might influence sex ratio. Females and their offspring were fed diets of different nutritional quality in a crossed design, and the sex ratio of each clutch was recorded for up to 8 clutches from a given female: this design allowed the influence of female diet vs. that of her offspring to be distinguished. The clutch sex ratio changed over the laying order according to the offspring’s diet, which is evidence for environmental sex determination in this species. Sex ratio also showed the influence of maternal diet, consistent with sex allocation theory. While dietary carotenoids showed no association with sex ratio or clutch size, long chain polyunsaturated fatty acids (particularly EPA and DHA) were implicated as the agent of sex ratio effect, providing a direction for future studies. The situation of T. californicus at the intersection of major themes in sex evolution makes this system an ideal model for selection studies. / Graduate / 2018-09-13

Environmental constraints can limit a population to a certain size, which is usually called the carrying capacity of a habitat. Besides to this 'external' factor, which is mainly determined by the limitation of resources, we investigate here another set of population-intrinsic factors that can limit a population size significantly below the maximum sustainable size. Firstly, density-independent mortality is a prominent factor in all organisms that show age-related and/or accidental death. Secondly, in sexually reproducing organisms the sex ratio and the success of pairing is important for finding reproductive partners. Using a simple model, we demonstrate how sex ratio, mating success and gender-specific mortality can strongly affect the speed of population growth and the maximum population size. In addition, we demonstrate that density-independent mortality, which is often neglected in population models, adds a very important feature to the system: it strongly enhances the negative influence of unbiased sex ratios and inefficient pairing to the maximum sustainable population size. A decrease of the maximum population size significantly affects a population's survival chance in inter-specific competition. Thus, we conclude that the inclusion of density-independent mortality is crucial, especially for models of species that reproduce sexually. We show that density-independent mortality, together with biased sex ratios, can significantly lower the abilities of a population to survive in conditions of strong inter-specific competition and due to the Allee effect. We emphasize that population models should incorporate the sex ratio, male success and density-independent mortality to make plausible predictions of the population dynamics in a gender-structured population. We show that the population size is limited by these intrinsic factors. This is of high ecological significance, because it means that there will always be resources available in any habitat that allows other species (e.g., invaders) to use these resources and settle successfully, if they are sufficiently adapted.

Two important relationships in parasitoid evolutionary ecology are those between adult size and fitness and between host quality and sex ratio. Sexually differential size-fitness relationships underlie predicted sex-ratio relationships. Despite each relationship receiving considerable attention, they have seldom been studied simultaneously or using field data. Here we report the biology of Anoplius viaticus paganus Dahlbom, a little known parasitoid of spiders, using field and laboratory data. We found that larger foraging females were able to select larger host spiders from the field, thus identifying a relatively novel component of the size-fitness relationship. Larger offspring developed from larger hosts and, in agreement with the prediction of the host quality model of sex allocation, were generally female. Data on the size-fitness relationship for males are lacking and, in common with many prior studies, we could not evaluate sexually differential size-fitness relationships as an explanation for the observed sex-ratio patterns. Nonetheless, A. v. paganus exhibited one of the strongest relationships between host size and offspring sex ratio yet reported.

The observation that more boys were born than girls was noted in the late 1660’s. Recent studies suggest the secondary sex ratio (SSR) is declining in industrialized countries. SSR is proposed as a sentinel for reproductive health. Declining SSR may reflect environmental factors or other influences of reproductive outcomes. We evaluated maternal age, birth order and SSR in the Old Order Amish (OOA), a homogenous sub-group with large family sizes. We used data from the Anabaptist Genealogy Database consisting of records for live births from 1696-2003. We used t-tests to compare mean maternal age and birth order by offspring sex, ANOVA to evaluate whether SSR has changed over time, and logistic regression for multivariable models. We evaluated clustering of SSR within families using random effects models and likelihood ratio tests of random effects. Maternal age was not associated with SSR (OR=1.003 [95% CI, 0.995-1.010), even after adjusting for birth order (AOR=1.000 [95% CI, 0.989-1.012). Similarly, we did not find an association between birth order and SSR in both unadjusted models (OR=1.007 [95% CI, 0.991-1.022), and those adjusted for maternal age (AOR= 1.006 [95% CI, 0.982-1.032]). The proportion of male births varied, however, there was no significant trend overtime. Lastly, we found a significant random effect (P<0.05), which may provide indication that having male births is heritable in families. Conclusions: Neither maternal age nor birth order is associated with the sex of an offspring. These findings suggest that decreases in SSR are unrelated to demographic factors, and rather may be related to other factors such as environmental exposures or other xenobiotic chemicals. These results may be relevant in providing information to the leading indicators to the decline in SSR.

This thesis studies the relationship between a skewed sex ratio and female empowerment in India. The study uses cross-sectional survey data from 2015-16, defining empowerment with an index that compiles questions directed toward women regarding if they have been subjected to violence and violations by their husbands or partners. We investigate if there is a negative relationship between sex ratio and the empowerment index by examining previous studies as well as conducting a multivariable regression analysis. The results show a statistically significant negative relationship at the 5% significance level when controlling for son preference, wealth index, education, habit of reading the news, and identification as Hindu and Muslim respectively. Furthermore, we find that a negative correlation persists when separately performing the regression for the wealth index levels “middle” and “richer”. Although statistically significant, the coefficients are relatively small and the economic significance of the results is hence debatable.

The Trivers-Willard hypothesis predicts a sex ratio bias contingent on maternal condition in species characterized by variation in male reproductive success. A male-biased sex ratio among mothers in good condition, and a female-biased sex ratio among mothers in poor condition is expected. Studies in humans have thus far provided mixed answers to the question of whether or not sex ratio is affected by maternal condition. The present study assessed whether or not the introduction of a western cash economy influenced the observed secondary sex ratio in Nepal's Khumbu region. Because acculturated villages provided better access to the cash economy and to health facilities, residence in an acculturated village was used as a proxy for "good" maternal condition. I analyzed demographic data gathered by survey in 1971 and 1982. The sample included 734 children from the 1971 survey and 1598 children from the 1982 survey. Using Poisson regression I analyzed the extent to which the sex ratios in age-stratified groups differed between the acculturated and unacculturated villages. In the 1971 dataset, the younger women in the acculturated villages displayed a significantly higher (p=.014) proportion of male offspring. It is likely that older women were subjected to minimal acculturation effects during their child-bearing years and among these data there was a lack of significant deviation between acculturated and unacculturated post-menopausal women. The rapid overall increase in acculturation between 1971 and 1982 likely made conditions in the two sets of villages much more similar by 1982. The results of this study underscore the impact that the transition to a market economy had on women in Nepal's Khumbu region. / Anthropology