| The first two chapters of this work use molecular phylogenies to describe the evolution of the most important groups of fig wasps (Agaonidae, Chalcidoidea). Phylogenetic analyses were performed using nucleotide sequences of mitochondrial genes (12S, COI, COII) collected from 78 species representing the major taxonomic and ecological groups of fig wasps. The phylogenies show that fig wasps are not monophyletic, providing evidence for independent colonization of figs by unrelated groups of chalcid wasps. It is shown that similar ecological strategies have evolved independently in different lineages of fig wasps, and that there are incongruencies between the phylogeny of the pollinating wasps and a morphology-based phylogeny of the figs.; Analyses of mitochondrial sequences from species of pollinating wasps (Pegoscapus, Tetrapus), non-pollinating wasps (Idarnes, Critogaster) and nematodes (Parasitodiplogaster) associated with 17 species of Panamanian figs, coupled with a detailed knowledge of their natural history and population biology, allowed to investigate the effect that similar generation times and different population sizes have on the accumulation of genetic differences among lineages (Chapter 3). Differences in silent substitution rate among organisms that have similar generation times were found. Some of the differences are due to phylogenetic effects because the organisms were not closely related (nematodes and wasps), but even closely related groups showed differences in silent rates (two different radiations of Idarnes non-pollinators). A correlation between small population size (census or effective) and increased rates of amino acid substitution was found in the non-pollinating fig wasps. However, a population genetic study (Chapter 4) showed that natural selection and not small population size was responsible for most of the amino acid substitutions in the Idarnes non-pollinator lineages. No positive correlation was found between population size and nucleotide diversity. A negative correlation was found between levels of inbreeding and nucleotide diversity in 6 species of pollinating wasps. |
