Filogeografía de las sacha perdices del género nothoprocta y la filogenia de las sachaperdices

TesisComo se genera y mantiene la biodiversidad, es una de las preguntas centrales en biología. Para responderla en un conteo andino, uso el género Nothoprocta de la familia TINAMIDAE con modelo, aprovechando atributos que los hacen ideales para estudiar especiación y diversificación: tamaño manejable de especies, distribución casi exclusivamente andina, distribuciones multiespecíficas y parapátricas y limitación de dispersión. Primero construyo un marco filogenético con un gen nuclear y dos mitocondriales. La filogenia resultante es la más completa que se tenga de la familia TINAMIDAE. La topografía de la filogenia concuerda con divisiones subfamiliares conocidas, sin embargo la parafilia de Nothoprocta pentlandii, implica separar las poblaciones peruanas como una especie: Nothoprocta oustaleti y se considera una especia no descrita de Nothoprocta en el norte del Perú. Finalmente combino los datos de los capítulos anteriores para entender el patrón de distribución parapátrica dentro del Nothoprocta y concluyo que el mecanismo de especiación es el de fraccionamiento de distribuciones montanas largas y delgadas, seguido por diversificación en alopatría y eventualmente por contacto secundario posterior.Tesi

Filogeografía de las sacha perdices del género nothoprocta y la filogenia de las sachaperdices

Como se genera y mantiene la biodiversidad, es una de las preguntas centrales en biología. Para responderla en un conteo andino, uso el género Nothoprocta de la familia TINAMIDAE con modelo, aprovechando atributos que los hacen ideales para estudiar especiación y diversificación: tamaño manejable de especies, distribución casi exclusivamente andina, distribuciones multiespecíficas y parapátricas y limitación de dispersión. Primero construyo un marco filogenético con un gen nuclear y dos mitocondriales. La filogenia resultante es la más completa que se tenga de la familia TINAMIDAE. La topografía de la filogenia concuerda con divisiones subfamiliares conocidas, sin embargo la parafilia de Nothoprocta pentlandii, implica separar las poblaciones peruanas como una especie: Nothoprocta oustaleti y se considera una especia no descrita de Nothoprocta en el norte del Perú. Finalmente combino los datos de los capítulos anteriores para entender el patrón de distribución parapátrica dentro del Nothoprocta y concluyo que el mecanismo de especiación es el de fraccionamiento de distribuciones montanas largas y delgadas, seguido por diversificación en alopatría y eventualmente por contacto secundario posterior.Tesi

THE REDISCOVERY AND NATURAL HISTORY OF THE WHITE‐MASKED ANTBIRD (PITHYS CASTANEUS)

Volume: 118Start Page: 13End Page: 2

Gene Flow in the Face of Countervailing Selection: Adaptation to High-Altitude Hypoxia in the βA Hemoglobin Subunit of Yellow-Billed Pintails in the Andes

When populations become locally adapted to contrasting environments, alleles that have high fitness in only one environment may be quickly eliminated in populations adapted to other environments, such that gene flow is partly restricted. The stronger the selection, the more rapidly immigrant alleles of lower fitness will be eliminated from the population. However, gene flow may continue to occur at unlinked loci, and adaptive divergence can proceed in the face of countervailing gene flow if selection is strong relative to migration (s > m). We studied the population genetics of the major hemoglobin genes in yellow-billed pintails (Anas georgica) experiencing contrasting partial pressures of oxygen in the Andes of South America. High gene flow and weak population subdivision were evident at seven putatively neutral loci in different chromosomal linkage groups. In contrast, amino acid replacements (Ser-β13, Ser-β116, and Met-β133) in the βA hemoglobin subunit segregated by elevation between lowland and highland populations with significantly elevated F ST. Migration rates for the βA subunit alleles were approximately 17-24 times smaller than for five unlinked reference loci, the αA hemoglobin subunit (which lacks amino acid replacements) and the mitochondrial DNA control region. The βA subunit alleles of yellow-billed pintails were half as likely to be transferred downslope, from the highlands to the lowlands, than in the opposite direction upslope. We hypothesize that migration between the lowlands and highlands is restricted by local adaptation, and the βA hemoglobin subunit is a likely target of selection related to high-altitude hypoxia; however, gene flow may be sufficiently high to retard divergence at most unlinked loci. Individuals homozygous for lowland alleles may have relatively little difficulty dispersing to the highlands initially but may experience long-term fitness reduction. Individuals homozygous for highland genotypes, in contrast, would be predicted to have difficulty dispersing to the lowlands if their hemoglobin alleles confer high oxygen affinity, predicted to result in chronic erythrocytosis at low elevation. Heterozygous individuals may have a dispersal advantage if their hemoglobin has a wider range of function due to the presence of multiple protein isoforms with a mixture of different oxygen affinities

Adaptive introgression of the beta-globin cluster in two Andean waterfowl

Introgression of beneficial alleles has emerged as an important avenue for genetic adaptation in both plant and animal populations. In vertebrates, adaptation to hypoxic high-altitude environments involves the coordination of multiple molecular and cellular mechanisms, including selection on the hypoxia-inducible factor (HIF) pathway and the blood-O transport protein hemoglobin (Hb). In two Andean duck species, a striking DNA sequence similarity reflecting identity by descent is present across the ~20 kb β-globin cluster including both embryonic (HBE) and adult (HBB) paralogs, though it was yet untested whether this is due to independent parallel evolution or adaptive introgression. In this study, we find that identical amino acid substitutions in the β-globin cluster that increase Hb-O affinity have likely resulted from historical interbreeding between high-altitude populations of two different distantly-related species. We examined the direction of introgression and discovered that the species with a deeper mtDNA divergence that colonized high altitude earlier in history (Anas flavirostris) transferred adaptive genetic variation to the species with a shallower divergence (A. georgica) that likely colonized high altitude more recently possibly following a range shift into a novel environment. As a consequence, the species that received these β-globin variants through hybridization might have adapted to hypoxic conditions in the high-altitude environment more quickly through acquiring beneficial alleles from the standing, hybrid-origin variation, leading to faster evolution