The pig, Sus scrofa, is a foreign species to the American continent. Although pigs originally introduced in the Americas should be related to those from the Iberian Peninsula and Canary islands, the phylogeny of current creole pigs that now populate the continent is likely to be very complex. Because of the extreme climates that America harbors, these populations also provide a unique example of a fast evolutionary phenomenon of adaptation. Here, we provide a genome wide study of these issues by genotyping, with a 60k SNP chip, 206 village pigs sampled across 14 countries and 183 pigs from outgroup breeds that are potential founders of the American populations, including wild boar, Iberian, international and Chinese breeds. Results show that American village pigs are primarily of European ancestry, although the observed genetic landscape is that of a complex conglomerate. There was no correlation between genetic and geographical distances, neither continent wide nor when analyzing specific areas. Most populations showed a clear admixed structure where the Iberian pig was not necessarily the main component, illustrating how international breeds, but also Chinese pigs, have contributed to extant genetic composition of American village pigs. We also observe that many genes related to the cardiovascular system show an increased differentiation between altiplano and genetically related pigs living near sea level.

Domestic species allow us to study dramatic evolutionary changes at an accelerated rate due to the effectiveness of modern breeding techniques and the availability of breeds that have undergone distinct selection pressures. We present a worldwide survey of haplotype variability around a known causative mutation in porcine gene IGF2, which increases lean content. We genotyped 34 SNPs spanning 27 kb in 237 domestic pigs and 162 wild boars. Although the selective process had wiped out variability for at least 27 kb in the haplotypes carrying the mutation, there was no indication of an overall reduction in genetic variability of international vs. European local breeds; there was also no evidence of a reduction in variability caused by domestication. The haplotype structure and a plot of Tajima's D against the frequency of the causative mutation across breeds suggested a temporal pattern, where each breed corresponded to a different selective stage. This was observed comparing the haplotype neighbor-joining (NJ) trees of breeds that have undergone increasing selection pressures for leanness, e.g., European local breeds vs. Pietrain. These results anticipate that comparing current domestic breeds will decisively help to recover the genetic history of domestication and contemporary selective processes.

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En el desarrollo de híbridos trilineales de maíz se requiere conocer los parámetros genéticos de las poblaciones que se usan para derivar sus líneas progenitoras. En este estudio se estimó la varianza aditiva directamente del componente genotípico del Anova en la evaluación aleatoria de 182 líneas S1 derivadas de la población ‘P’ (productores). Ésta participa en un patrón heterótico PxA (agricultores) en mejoramiento continuo mediante el método de la selección recíproca recurrente (SRR). En 2014 se evaluaron las líneas en Xalisco, Compostela y Santa María del Oro, Nayarit. El Anova combinado detectó diferencias significativas entre las líneas para la mayoría de las variables estudiadas. Altas estimas de varianza aditiva resultaron para rendimiento de grano y otras características agronómicas. Altas estimas de heredabilidad en sentido estricto fueron observadas debido a las altas estimas de varianza aditiva. El rendimiento de grano mostró una alta heredabilidad de 0.63, similar a la mayoría de las estimas estudiadas en maíz. Una alta heredabilidad fue observada en todos los caracteres de los componentes de rendimiento. Las estimas de heredabilidad variaron del 0.54 al 0.87 y se encuentran en los rangos similares que se han observado en la mayoría de los estudios realizados en maíz. Los valores son adecuados para el progreso en los caracteres evaluados de la población P; lo que permitirá para el caso de híbridos trilineales encontrar combinaciones intra-cruzas simples que se pueden usar como cruzas simples hembra en la producción de grano y semilla