Isolation and Characterization of Nuclear and Mitochondrial Genetic Markers for Population Studies of /Ucides cordatus cordatus/ (Decapoda: Brachyura)
|Other Titles:||Isolation und Charakterisierung von nuklearen und motochondrialen genetischen Markern zur Populationsstudie von / Ucides cordatus cordatus/ (Decapoda: Brachyura)||Authors:||Ewald, Marco||Supervisor:||Blohm, Dietmar||1. Expert:||Blohm, Dietmar||2. Expert:||Schneider, Horacio||Abstract:||
The mangrove ecosystem has fundamental influences on storm protection of the coast, erosion control, and wastewater cleanup. In Brazil, one of the key species of this ecosystem is Ucides cordatus. Further, there is a high significance of crustacean fisheries in general and of U. cordatus especially as a major financial income for rural populations in coastal regions. In parts of the mangrove forests the same amount of this resource produced each year is harvested. Due to this economically and ecologically importance of U. cordatus this species should be included into a coastal management plan to protect the mangrove forests and to manage the edible resources like U. cordatus. Therefore information about distribution and population dynamics is necessary to adequate elements for sustainable exploitation and managing. The objective of this study is to develop a DNA based marker system to analyze the following questions. Are there polymorphisms between morphologically equal individuals in selected potentially variable DNA markers and are they available to measure gene flow, genetic population structure and exchanges of individuals between separated geographically locations? Further it should be examined if there are any indications that the species U. cordatus is still over fished. As nuclear genetic marker in this study 110 microsatellite loci were successfully isolated from different enriched partial libraries of U. cordatus and with 5 of them population analyzes were done using 135 individuals from BraganÃ ï¿½Ã §a and ParanÃ ï¿½Ã ¡. The microsatellite markers developed here are the first for Ucides and show high polymorphism with 16 to 47 different alleles, respectively and values of observed heterozygosity from 0.23 to 0.88 with values of expected heterozygosity from 0.87 to 0.98. Significant deviations from Hardy Weinberg equilibrium (HWE) were detected for all tests at each locus in the population of BraganÃ ï¿½Ã §a and ParanÃ ï¿½Ã ¡ with a deficit of heterozygosity of -0.08 to -0.72 and zero allele estimation with an amount of 0.043 to 0.417. F-statistics detects a low but highly significant variability between the populations of BraganÃ ï¿½Ã §a and ParanÃ ï¿½Ã ¡ with Fst values of 0.011 to 0.048 in 4 of 5 loci and therefore restricted gene flow supported by P values lowers than 0.01. Because of the possible error rate in genotyping through stutter bands and suggested high amounts of zero alleles the weak population structure found in U. cordatus was confirmed using an additional different marker. A part of the mitochondrial gene coding for the Cytochrome oxidase subunit I (COI), was amplified and 600 bp were sequenced using 223 individuals pooled from the regions Ã ¯Ã ¿Ã ½Upper AmazonÃ ¯Ã ¿Ã ½, Ã ¯Ã ¿Ã ½Lower AmazonÃ ¯Ã ¿Ã ½ and Ã ¯Ã ¿Ã ½South BrazilÃ ¯Ã ¿Ã ½. A high amount of polymorphism was found with 132 different haplotypes resulting in a diversity of 0.97 within the haplotypes and 0.0063 to 0.0065 within the nucleotides from one individual to the other. In spite of the low variability with significant Фst values of 2.1% between Upper Amazon and Lower Amazon, 2.2% between Lower Amazon and South Brazil and 3.9% between Upper Amazon and South Brazil it is shown that between the analyzed populations a restricted gene flow exists and the null hypothesis of panmixing was rejected with P values lower than 0.05. Further all tests show a population expansion for the overall population and for the local populations.
|Keywords:||Microsatellite, mitochondrial genetic marker, COI, population study, Ucides cordatus, new method, brazil, screening||Issue Date:||6-Jun-2006||URN:||urn:nbn:de:gbv:46-diss000114329||Institution:||Universität Bremen||Faculty:||FB2 Biologie/Chemie|
|Appears in Collections:||Dissertationen|
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