Comparative genomics supports ecologically induced selection as a putative driver of banded penguin diversification.

The relative importance of genetic drift and local adaptation in facilitating speciation remains unclear. This is particularly true for seabirds, who can disperse over large geographic distances, providing opportunities for intermittent gene flow among distant colonies that span the temperature and salinity gradients of the oceans. Here, we delve into the genomic basis of adaptation and speciation of banded penguins, Galápagos (Spheniscus mendiculus), Humboldt (S. humboldti), Magellanic (S. magellanicus) and African penguins (S. demersus), by analyzing 114 genomes from the main 16 breeding colonies. We aim to identify the molecular mechanism and genomic adaptive traits that have facilitated their diversifications. Through positive selection and gene family expansion analyses, we identified candidate genes that may be related to reproductive isolation processes mediated by ecological thermal niche divergence. We recover signals of positive selection on key loci associated with spermatogenesis, especially during the recent peripatric divergence of the Galápagos penguin from the Humboldt penguin. High temperatures in tropical habitats may have favored selection on loci associated with spermatogenesis to maintain sperm viability, leading to reproductive isolation among young species. Our results suggest that genome-wide selection on loci associated with molecular pathways that underpin thermoregulation, osmoregulation, hypoxia, and social behavior appear to have been crucial in local adaptation of banded penguins. Overall, these results contribute to our understanding of how the complexity of biotic, but especially abiotic, factors, along with the high dispersal capabilities of these marine species, may promote both neutral and adaptive lineage divergence even in the presence of gene flow.

History of Diversification and Adaptation from North to South Revealed by Genomic Data: Guanacos from the Desert to Sub-Antarctica.

The increased availability of quality genomic data has greatly improved the scope and resolution of our understanding of the recent evolutionary history of wild species adapted to extreme environments and their susceptibility to anthropogenic impacts. The guanaco (Lama guanicoe), the largest wild ungulate in South America, is a good example. The guanaco is well adapted to a wide range of habitats, including the Sechura Desert, the high Andes Mountains to the north, and the extreme temperatures and conditions of Navarino Island to the south. Guanacos also have a long history of overexploitation by humans. To assess the evolutionary impact of these challenging habitats on the genomic diversity, we analyzed 38 genomes (∼10 to 16×) throughout their extensive latitudinal distribution from the Sechura and Atacama Desert to southward into Tierra del Fuego Island. These included analyses of patterns of unique differentiation in the north and geographic region further south with admixture among L. g. cacsilensis and L. g. guanicoe. Our findings provide new insights on the divergence of the subspecies ∼800,000 yr BP and document two divergent demographic trajectories and to the initial expansion of guanaco into the more southern portions of the Atacama Desert. Patagonian guanacos have experienced contemporary reductions in effective population sizes, likely the consequence of anthropogenic impacts. The lowest levels of genetic diversity corresponded to their northern and western limits of distribution and some varying degrees of genetic differentiation. Adaptive genomic diversity was strongly linked with environmental variables and was linked with colonization toward the south followed by adaptation.

Uso de la reacción en cadena de la polimerasa para Borrelia burgdorferi en lesiones de esclerodermia localizada (morfea), en pacientes venezolanos / Using the polymerase chain reaction to Borrelia burgdorferi infection in localized scleroderma injure (morphea), in venezuelan patients

Borrelia burgdorferi es el agente causal de Borreliosis de Lyme, una enfermedad infecciosa multisistémica transmitida al humano por la picadura de garrapatas del género Ixodes. En los últimos años se ha postulado una posible asociación entre ésta espiroqueta y esclerodermia localizada (morfea). Sin embargo, los datos publicados no han proporcionado pruebas inequívocas de tal asociación. En Suramérica, incluida Venezuela (estado Zulia) se han detectado pruebas serológicas positivas en pacientes con morfea. El objetivo de este estudio fue buscar evidencia definitiva de la infección por Borrelia burgdorferi en pacientes con morfea, mediante la detección del ADN bacteriano en muestras de piel. En los 21 pacientes la PCR resultó negativa. La ausencia de amplificación de la secuencia blanco seleccionada en las muestras estudiadas no apoyan una asociación entre la infección por Borrelia burgdorferi y las lesiones escleróticas de morfea, pero tampoco descartan la posibilidad de una relación entre morfea y una genoespecie desconocida del complejo Borrelia burgdorferi sensu lato, entre morfea y una especie diferente de Borrelia o entre morfea y otra espiroqueta, como agente etiológico de la lesión en la localidad.

Borrelia burgdorferi is the causative agent of Lyme Borreliosis, an infectious multisystemic disease transmitted to humans by the Ixodes ticks bite. A possible association of Borrelia burgdorferi with localized scleroderma has been postulated. However, published data do not provide unequivocal results. Previus serologic analysis of patients with localized scleroderma in South American countries (including Venezuela), have been reported as yielding some reactivity. The present study looked for evidence of Borrelia burgdorferi infection in venezuelan patients with localized scleroderma, using the polymerase chain reaction to analyze 21 skin samples of patients with this skin condition. The results were negative in all the samples studied. Our data do not support an association of Borrelia burgdorferi infection and the sclerotic lesions of localized scleroderma; but do not rule out the possibility of a relationship between localized scleroderma and an unknown geno-specie of Borrelia burgdorferi sensu lato complex, a different Borrelia specie or a different spirochetal organism, as the etiological agents of the skin lesions in this area.

Absence of borrelia burgdorferi antibodies in the sera of Venezuelan patients with localized scleroderma (morphea)

En los últimos años se ha postulado una posible asociación entre Borrelia burgdorferi ( Bb ) y esclerodermia localizada (morfea). Sin embargo, los datos publicados no han proporcionado pruebas inequívocas de tal asociación. En Suramérica se han realizado estudios serológicos que han evidenciado resultados positivos. El objetivo de este estudio fue buscar evidencia de la infección por Bb en pacientes venezolanos con morfea, mediante la detección de anticuerpos antibacterianos, usando el protocolo de dos pasos recomendado por el Center for Disease Control and Prevention de Atlanta (Estados Unidos). Veintiún muestras de suero de pacientes con morfea y veintiún muestras de sujetos sanos (control) fueron analizadas. Cuatro muestras resultaron ELISA positivas: tres correspondieron a pacientes con morfea y una, a un sujeto control. Todas las muestras ELISA positivas fueron negativas en la prueba IgG Western Blot. Los resultados obtenidos no soportan una asociación entre la infección por Bb y las lesiones escleróticas de morfea, pero tampoco descartan la posibilidad de una relación entre morfea y una genoespecie desconocida del complejo Bb sensulato, entre morfea y una especie diferente de Borrelia o entre morfea y otra espiroqueta, como agente etiológico de la lesión en la localidad