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This study analyzed the morphometric, microsatellite loci and mitochondrial control region variation of the striped weakfish from two feeding and spawning grounds in the coastal area of Buenos Aires province. The characterization of the body shape proved to be different between sites. Genetic structure analysis showed that the main source of genetic variation was within populations rather than among populations and low genetic differentiation was observed between sites. The striped weakfish inhabiting the coastal areas of Buenos Aires would exhibit two management units in agreement with other fishes studied in both areas.

SUMMARY:The genetic structure of populations/species was established during the Quaternary glaciations. Over the last 250 ka (Pleistocene), the South American marine biogeographic history recorded three main glaciations: the most extensive one between 140 and 180 ka, a minor one between 60 and 70 ka, and the last glaciation approximately between 15 and 35 ka. With the aim of assessing the pattern of molecular diversity and historical demography of weakfish (Cynoscion guatucupa), a 365 bp sequence of the mitochondrial control region was amplified at four coastal sites located in the southwestern Atlantic. Haplotype diversity was high, whereas nucleotide diversity was low and similar at each sample site. AMOVA failed to detect population structure. This lack of differentiation was subsequently observed in the distribution of samples sites in the haplotype network. Fu's Fs was negative and highly significant while the mismatch analysis yielded a unimodal distribution, indicating a global population expansion. The Bayesian skyline plot revealed a coalescence time of weakfish population at approximately 210 ka, and a very rapid expansion from 180-190 ka, probably caused by a habitat expansion, as these two events coincide in time.Keywords: bayesian skyline plots, glacial cycles, mitochondrial DNA, control region, population genetics, marine fish, Atlantic coast, Pleistocene. RESUMEN: Filogeografía de la pescadilla de red CynosCion guatuCupa (Perciformes: Sciaenidae) del Atlántico suroccidental. -La estructura genética de las poblaciones/especies se ha establecido principalmente durante las glaciaciones del Cuaternario. La historia biogeográfica marina en Sudamérica en los últimos 250 ka registra durante el Pleistoceno tres glaciaciones importantes: la más extensa entre 140-180 ka, una menor entre 60-70 ka y la última glaciación aproximadamente entre 15-35 ka. Para evaluar el patrón de diversidad molecular y de demografía histórica en la pescadilla de red (Cynoscion guatucupa) se analizó una secuencia de 365 pb de la región control del ADN mitocondrial en cuatro zonas costeras del Atlán-tico suroccidental. La diversidad haplotípica fue alta mientras que la diversidad nucleotídica fue baja y ambos índices fueron similares en cada sitio de muestreo. El análisis de varianza molecular (AMOVA) no detectó estructura poblacional. Esta falta de diferenciación posteriormente se pudo observar en la distribución de los sitios de muestreo en la red de haplotipos. El test de Fu fue negativo y altamente significativo y el análisis de falta de coincidencia produjo una distribución unimodal indicando expansión poblacional. El skyline plot indicó un tiempo a la coalescencia de 210 ka y una expansión poblacional que comenzó hace 180-190 ka que probablemente se produjo por la expansión del hábitat ya que ambos eventos coinciden en el tiempo.

This study highlights the analysis of the morphological and genetic variation of the common sea bream Pagrus pagrus, and compares its two main areas of concentration: the northern (35ºS -38°S) and the southern areas (39°S -41°S) of the Buenos Aires coast of the Argentine Sea. Body shape characterization presented two significantly different morphotypes (Wilks' Lambda=0.224, P<0.001). Northern individuals displayed a higher middle area while southern ones were smaller and their caudal peduncle was shorter. The northern and southern areas did not yield significant genetic differences either with the control region or the microsatellite loci, revealing that P. pagrus is not genetically structured. However, individuals from these areas should not be managed as a single group since they display distinct life history traits, responsible for morphological differentiation. The presence of two spawning areas with distinctive characteristics would define two stocks of P. pagrus from the Buenos Aires coast.El estudio comprende un análisis de la variación morfológica y genética del besugo Pagrus pagrus, comparando dos áreas principales de concentración, una Norte (35°S -38°S) y otra Sur (39°S -41°S) en la costa bonaerense del Mar Argentino. La caracterización de la forma del cuerpo mostró dos morfotipos diferenciados significativamente (Wilks´ Lambda= 0.224, P<0.001), presentando en el área Norte una mayor altura en la parte media del cuerpo y una menor longitud y altura del pedúnculo caudal que los correspondientes al área Sur. Las áreas Norte y Sur no presentaron diferencias genéticas significativas, tanto para la región control del ADN mitocondrial como para los loci microsatélites, revelando que P. pagrus no está estructurado genéticamente. Sin embargo, los individuos de estas áreas no deberían manejarse como un mismo grupo ya que presentan distintas características de historia de vida, responsables de la diferenciación morfológica. La presencia de dos sitios de cría con características distintivas, definiría para P. pagrus dos stocks en la costa bonaerense.

Allele frequencies for the 15 short tandem repeats (STRs) loci included in the AmpFlSTR® Identifiler kit were estimated in a sample of unrelated individuals from Mar del Plata (MDQ; N = 180) and Bahia Blanca (BB; N = 85) (Buenos Aires, Argentina). Biological samples were obtained from voluntary donors and forensic cases. Both populations were in Hardy-Weinberg equilibrium after Bonferroni correction, except for locus vWA in MDQ and D2S1338 in BB. FGA was the most informative locus, and the least discriminating locus was TPOX in both samples. The combined power of discrimination (PDc) and the combined probability of exclusion (PEc) were similar in MDQ and BB samples (0.999999998 < PDc < 0.999999999 and 0.999999979 < PEc < 0.999999989). The multidimentional scaling plot from Rst genetic distance matrix and the interethnic admixture estimation supported a higher European contribution in populations of the central region compared with populations from other regions of Argentina with higher Amerindian composition. These results enlarge the Argentine databases of autosomal STR loci, revealed as an excellent tool for human identification tests and population genetic analysis.

The variants found have not been described previously, suggesting they could be mutations that might affect protein function.

Allele frequencies and forensic parameters for 15 autosomal loci included in the AmpFlSTR® Identifiler kit were estimated in a sample of 57 unrelated Afro-descendants from Nor Yungas (Bolivia). Buccal swabs samples were obtained from voluntary donors, after consent was given. All loci were in Hardy-Weinberg equilibrium after Bonferroni correction. D21S11 was the most informative locus, while the least discriminating locus was D3S1358. The combined power of discrimination and the combined probability of exclusion were >0.99999999 and >0.99997, respectively. The multidimensional scaling (MDS) plot generated by Rst matrix supported that Afro-Bolivians of Nor Yungas preserved a stronger African descent compared to other admixed Latin American populations. These results amplified the Bolivian databases of autosomal STR loci and may provide a useful tool for human identification tests and population genetic studies.

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