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Genetic diversity of Cingulata assessed by mitochondrial and microsatellite markers: the case of a Tolypeutes tricinctus (Linnaeus, 1758) population from Cerrado

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Helena Tadiello de Moraes
Total Authors: 1
Document type: Master's Dissertation
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
Defense date:
Examining board members:
Nadia de Moraes Barros; Adriana Bocchiglieri; Denise Selivon Scheepmaker
Advisor: Nadia de Moraes Barros

Tolypeutes tricinctus, the three-banded armadillo, is a Neotropical mammal that belongs to Xenarthra group. This species is endangered and endemic to Brazil occurring only in Caatinga and Cerrado biomes. The previous genetic study available analyzed the genetic diversity on Cytochrome Oxidase I (COI) gene and found only one haplotype among 30 individuals of a single population, the only one sampled so far. Considering this result and the lack of genetic and phylogenetic studies, the present work was proposed to better understand the genetic diversity of this population, from the Cerrado biome of the Bahia state, the Fazenda Jatobá population. We used microsatellite markers selected by next generation sequencing and the mitochondrial DNA control region (D-loop). A field research and contact with other researchers were made to obtain samples of the T. matacus and T. tricinctus samples from different localities. In addition, we also tested the power of COI gene to differentiate eight species of Cingulata order and to estimate the phylogeny using the DNA barcoding approach. Sixty microsatellite loci were selected and tested and 23 showed positive amplification results among individuals from Jatobá Farm population. Only two were polymorphic with two and three alleles respectively. Museum samples and individuals from other localities did not present positive results after amplification tests. The obtained result was unexpected and prevents any further population parameters estimates such as effective population size and inbreeding. Any chance of limitation or error was refuted and the low number of polymorphic loci probably express the low genetic diversity of the population. Low levels of genetic diversity were also observed in 386bp of D-loop (h = 0.4032±0.0909 e π = 0.002084±0.001737). Only two haplotypes were observed among 23 individuals from the Jatobá population. A third haplotype was observed when in a sample from Ceará (h = 0.4529±0.0948 e π = 0.002125±0.001757). In the DNA barconding study the COI gene was effective to differentiate most of armadillo species. The phylogeny did not show high support for the nodes representing subfamily level. Considering the evidences of low genetic diversity for the T. tricinctus Jatobá population and the menaces to species\' survival it possible that a similar scenario be present in other populations. Therefore, the obtained results indicate that a larger sampling along different localities of the species\' distribution is needed in order to understand the genetic diversity of T. tricinctus. Preserving the extant three-banded armadillo populations avoiding decline in size should be a priority in future conservation actions. Preserving the genetic diversity of the tree-banded armadillo is essential, especially for Jatobá population. This population may be an example of local extinction, or at least suffer from the negative effects of inbreeding depression and resulting impacts on its viability and survival. (AU)