Os cromossomos sexuais como fonte geradora de diferenciação genética. O gênero Pyrrhulina (Characiformes, Lebiasinidae) como modelo
Fecha
2021-11-11Autor
Ferreira, Pedro Henrique Narciso
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Allopatric processes are generally considered among the main causes of the striking
Neotropical biodiversity. However, the role of chromosomal rearrangements and neo-sex
chromosomes in genetic diversity and speciation remains still little investigated. Here, we
aimed to infer the relative contribution of allopatry, chromosomal rearrangements, and sex
chromosomes to genetic divergence in five Pyrrhulina species using population genomic
analyses coupled with cytogenetic data. Our results highlighted that the distribution of the
genetic diversity is consistent with their chromosomal and geographical data and was mainly
influenced by long-distance allopatry. The results of PCoA indicated a clear clustering of
species located in the same geographical region, except for P. semifasciata, that is in sympatry
with P. brevis. In fastStructure K=4 result, only P. australis and P. marilynae were grouped,
and with K=3 P. obermulleri and P. brevis were further combined. In this case, geographically
close species showed genetically similarity, indicating speciation mechanisms that are largely
dependent of allopatry. The effect of allopatry also were amplified when coupled with the
occurrence of chromosomal rearrangements, as observed for P. marilynae, the species with
highly rearranged karyotype (2n=32). Besides, the genetic structure analyzes indicated great
differentiation in P. semifasciata, suggesting that the presence of the X1X2Y sex chromosome
system, exclusively present in individuals of this species, caused high genetic differentiation
and showing that such effect was significant even in sympatry. In summary, the distribution of
genetic diversity among the analyzed species is mainly influenced long-distance allopatry, but
the occurrence of chromosomal rearrangements, especially the sex-related ones contributed to
the fixation of genetic differences which may lead to reproductive isolation and a consequent
speciation process within the genus
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