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| Author(s): |
Renato Cavasini
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2015-08-28 |
| Examining board members: |
Louis Bernard Klaczko;
Vera Nisaka Solferini;
Luciana Lasry Benchimol Reis;
Maura Helena Manfrin;
Evandro Marsola de Moraes
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| Advisor: | Marcos Roberto Dias Batista; Louis Bernard Klaczko |
| Abstract | |
Drosophila mediopunctata is a forest dwelling species endemic from Neotropics. This species is widely distributed and frequently found, during cold months, in altitudinal forest Southern Brazil. Along these last 30 years, our research group has been using this species as a model organism to study evolutionary genetics. Several aspects of its biology were investigated and characterized. Although, so far, all studies have suggested the action of natural selection over chromosomal inversion polymorphism and morphological traits, demographical processes and stochastic events could not be discarded in the formation of the observed patterns. Therefore, it is extremely important to contrast with previous results, a genetic structure analysis of Drosophila mediopunctata natural populations using microsatellite markers for the understanding of how evolutionary factors shape the genetic and phenotypic variation. In this thesis, results are shown from different analysis concerning D. mediopunctata microsatellite loci variation. First, we carried out a genetic (chromosomal) analysis to increase the number of available loci with known chromosomal location. We made a simultaneous analysis of visible mutant phenotypes and microsatellite genotypes of flies from a backcross between a mutant strain and the F1 from a standard strain crossed to a tetra-mutant strain, with each major autosome marked. Hence, we could establish the chromosomal location of 17 loci; including one from each of the five major linkage groups previously published, and twelve new loci. Our results increase the number of microsatellite loci with known location from 49 to 61. Microsatellite variation of four populations using eleven loci from two inversion-free chromosomes (chromosomes III and V) was also characterized. No evidence of genetic structure was found. Moreover, migration rate estimates indicated the existence of connectivity and intense gene flow among all populations. Effective population size were also estimated and showed that all populations were large enough to restrict genetic drift effects. Thus, we could infer that geographical variation previously described for chromosome II inversion frequencies were probably caused by the action of natural selection. We sampled Itatiaia population in six different altitudes and contrasted altitudinal variation of ten microsatellite loci from the two inversion-free chromosomes (III and V) with eleven loci of chromosome II, polymorphic for chromosomal inversions. Microsatellite data did not show divergence among altitudes suggesting that they were large populations in panmixia, greatly influenced by gene flow. However, significative differences were found when we compared parameters of loci in inversion-free chromosomes and loci in a polymorphic chromosome. Genetic variability were higher in loci of inversion-free chromosomes III and V, while effective population size and number of migrants of chromosome II were higher. These differences are probably associated to the presence and absence of inversions and how evolutionary factors act over these chromosomes. This result shows the importance of locating microsatellite loci before using these markers in studies of population genetic structure (AU) | |
| FAPESP's process: | 11/02897-2 - Genetic structure analysis of Drosophila mediopunctata natural populations with microsatellite markers |
| Grantee: | Renato Cavasini |
| Support Opportunities: | Scholarships in Brazil - Doctorate |