A striking variation in the behaviour of pollinating fig wasps (Agonidae) is the occurrence of male fighting in some species while in others it is completely absent. Fighting behaviour was investigated at two levels. Firstly, the variation in fighting behaviour between the species was used to examine factors that might cause the evolution thereof. Comparisons across species were done using phylogenetic regression. This method takes similarity due to phylogenetic constraints into account when data are compared. Kin selection theory implies that fighting is barred by the high degree of relatedness in competing males. We however find that the relatedness of the males do not have an influence on the evolution of fighting and this finding supports models suggesting that high LMC cancels benefits due to relatedness. Rather, that the only factor having a significant correlation with fighting is the release sex ratio. The release sex ratio and dispersal is also associated. Fighting and dispersal are not expected to have direct influence on each other and the association of both with the release sex ratio imply that this may be an indirect link between these two behaviours. A syndrome where fighting and dispersal is found together is in part explained by the release sex ratio. We conclude that the release sex ratio is the most likely cause of the evolution of fighting behaviour in pollinating fig wasps. The second part of this study deals with the proximal determinants causing fighting, in the males of the species Platyscapa awekei. We show that the sex ratio which, is less female biased than non-fighting pollinator species, rapidly becomes even less female biased as soon as both sexes becomes active. Numerous fights are fought by the males in the female limited environment. The activity of the wasps is shown to be regulated by the gaseous environment, which change from a high to a low CO2 concentration with the construction of an exit hole from the fig. The males of the species P. awekei are inactive, and do not engage in mating or fighting activities, in high CO2, contrasted to males of other species, which are active in this environment. P. awekei females rapidly release once the CO2 level is lowered and mating behaviour is only observed in this environment. The number of female to male encounters of every male decrease as the operational sex ratio becomes less female biased. Male fighting in this species is therefore expected due to the high sex ratio, which is enforced by the increase thereof. We conclude that the physical environment, in this species, affects the mating environment. The resultant reduction in the number of potential mating opportunities therefore escalates fighting between the males. / Dissertation (MSc)--University of Pretoria, 2008. / Genetics / unrestricted

Made available in DSpace on 2014-12-17T14:33:11Z (GMT). No. of bitstreams: 1 TalitaFA_DISSERT.pdf: 2140188 bytes, checksum: 0083999c43d74876b9f2f21898381161 (MD5) Previous issue date: 2014-04-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Understand the origin, maintenance and the mechanisms that operate in the current biodiversity is the major goal of ecology. Species ecology can be influenced by different factors at different scales. There are three approaches about the ecological differences between species: the first brings that differences result from current processes on niche characteristics (e.g. diet, time, space); the second that species differences are explained by random patterns of speciation, extinction and dispersion, the third that historical events explain the formation and composition of species in communities. This study aims to evaluate the influence of phylogenetic relationships in determining ecological characteristics in amphibians (globally) and test with that, if ecological differences between species of frogs are the result of ancient pre-existing differences or as result of current interactions. Another objective of this study is to verify if ecological, historical or current characteristics determine the size of species geographical distribution. The diet data for analysis of trophic ecology were collected from published literature. We performed a non-parametric MANOVA to test the existence of phylogenetic effects in diet shifts on frogs history. Thus, it is expected to know the main factors that allow the coexistence of anuran species. We performed a phylogenetic regression to analyze if niche breadth, body size and evolutionary age variables determine the size of the geographical distribution of amphibians in the Amazon. In the present study, new contributions to knowledge of major ecological patterns of anurans are discussed under a phylogenetic perspective / Entender a origem, manuten??o e os mecanismos que operam na biodiversidade atual s?o um dos principais objetivos da Ecologia. A ecologia das esp?cies pode ser influenciada por diferentes fatores em diferentes escalas. Existem tr?s abordagens a cerca das diferen?as ecol?gicas entre as esp?cies: a primeira traz essas diferen?as resultam de processos atuais atuando sobre as caracter?sticas do nicho (dieta, tempo, espa?o, etc); a segunda que diverg?ncias no nicho das esp?cies s?o explicadas por padr?es rand?micos de especia??o, dispers?o e extin??o; a terceira que eventos hist?ricos explicam a forma??o e a composi??o das esp?cies nas comunidades. Este estudo tem como objetivo avaliar a influ?ncia das rela??es filogen?ticas na determina??o de caracter?sticas ecol?gicas em anf?bios (globalmente) e testar, com isso, se as diferen?as ecol?gicas entre as esp?cies de anuros s?o resultado de diferen?as antigas pr?-existentes ou como o resultado de intera??es ecol?gicas mais recentes. Outro objetivo deste estudo ? verificar que caracter?sticas ecol?gicas, hist?ricas ou atuais, determinam e influenciam o tamanho da distribui??o geogr?fica das esp?cies. Os dados de dieta para a an?lise da ecologia tr?fica dos anf?bios foram coletados a partir da literatura j? publicada. Realizamos uma MANOVA n?o param?trica para testar a exist?ncia de efeitos filogen?ticos nas principais diverg?ncias na dieta dos anuros. Com isso, espera-se conhecer os principais fatores que permitem a coexist?ncia das esp?cies de anf?bios anuros e quais os principais n?s da filogenia de anf?bios respons?veis pelas diferen?as observadas atualmente no nicho tr?fico das esp?cies. Realizamos uma regress?o filogen?tica para analisar se as vari?veis de largura de nicho, tamanho corporal e tempo de diverg?ncia determinam o tamanho da distribui??o geogr?fica dos anf?bios anuros da Amaz?nia. Neste trabalho, novas contribui??es ao conhecimento dos padr?es ecol?gicos apresentados pelos anuros s?o fornecidas e discutidas sob uma perspectiva filogen?tica