208 research outputs found
Filogenia molecular, historia demogr?fica y estructura gen?tica de nuevas cepas de Trypanosoma terrestris aisladas de Tapirus terrestris en los biomas brasile?os de pantanal y mata atl?ntica
124 p. Recurso Electr?nicoA pesar de que los tripanosomas son un extenso grupo de par?sitos, poco se
sabe sobre los mecanismos evolutivos que est?n promoviendo divergencia en
sus poblaciones naturales, y con esto, la escala espacial y temporal en la que
est?n ocurriendo estos cambios. Para entender esta din?mica, aqu? uso
marcadores nucleares parasitarios y datos de radiotelemetr?a del hospedero
vertebrado para explorar la gen?tica de poblaciones, aspectos demogr?ficos y
relaciones filogen?ticas de nuevas cepas de Trypanosoma terrestris; una especie
recientemente descrita y aislada de tapires de Brasil. Los estudios filogen?ticos
mostraron por primera vez que el clado T. terrestris est? asociado a la historia
evolutiva de sus hospedadores Perissodactyla. De igual modo T. terrestris es el
clado hermano del clado T. grayi, corroborando el ?ecological host fitting? como
principal mecanismo evolutivo en los tripanosomas.
Las reconstrucciones demogr?ficas mostraron una fuerte reducci?n en los
tama?os poblacionales del par?sito durante el ?ltimo per?odo glacial en el
Pleistoceno, demostrando la influencia de los hospederos y las fluctuaciones
clim?ticas sobre la din?mica poblacional de los aislados de T. terrestris. A raz?n
de esto, no hubo evidencia de estructura gen?tica en los aislados parasitarios
procedentes de los biomas estudiados, excepto por un haplotipo fuertemente
diferenciado en una escala espacial microgeogr?fica en el Pantanal de
Nhecol?ndia. As? pues, aqu? se proporciona evidencia de que el vector est?
promoviendo la diferenciaci?n del par?sito mediante ?ecological host-fitting? y esto
puede ocurrir a distintas escalas espaciales. Sin embargo, los mecanismos
ecol?gicos y gen?ticos encargados de promover especializaci?n y divergencia
en poblaciones de par?sitos a?n son materia de investigaci?n y de debate.
Estudios gen?micos comparados en amplia escala, que combinen enfoques
metodol?gicos como aquellos destinados a estudiar la gen?tica del paisaje en
uni?n con la filogeograf?a hist?rica, ser?n de gran utilidad para entender la extensa radiaci?n de los tripanosomas, incluidos los tripanosomas pat?genos del
hombre.
Palabras clave: Trypanosoma terrestris, ecological host fitting, divergencia
microgeogr?fica, cuello de botella, relaciones filogen?ticas.Notwithstanding the trypanosomes are a widespread group of parasites, little is
known on evolutionary mechanisms promoting divergence over their natural
populations and thereby, the spatial and temporal scales at which these changes
are happening. To understand this dynamics, I use parasite nuclear markers and
host telemetric data to explore parasite population genetics, phylogenetic
relationships, divergence time estimation and coalescent demographic history of
Trypanosoma terrestris, a recently described clade isolated from tapirs in
Pantanal and Atlantic Forest biomes of South America. Phylogenetic
relationships and divergence times showed: i) T. terrestris clade is a basal clade
of trypanosomes diverged from an ancient Perissodactyla host during early
Eocene and ii) T. terrestris isolated from Perissodactyla hosts and T. grayi clade
isolated from crocodiles in Africa and caimans from South America are sister
clades. Therefore these results support the ?ecological host fitting? as driving
mechanism in parasite phylogenetic diversification and illustrate the complex
evolutionary dynamics of trypanosomes.
EBSPs showed a sharp reduction (population bottleneck) in parasite populations
during late Pleistocene. Along with that, Bayesian clustering analysis, AMOVA
results and barrier tests did not show evidence of population genetic structure
except by one haplotype from Nhecol?ndia landscape in Pantanal, strongly
differentiated from its dispersal neighborhood and those isolates from Atlantic
Forest (~14Km and FST= 0.808). In conjunction with host dispersal, provided by
telemetric and genetic data, here I confirm that invertebrate host is promoting
parasite divergence through colonization of new hosts at fine spatial scales
(microgeographic). Thus, these microevolutionary trends are in agreement with
?ecological host fitting? as driving mechanism in trypanosome evolution. To
understand general mechanisms shaping genetic variation and adaptation within
and among parasite populations is necessary incorporate comparative genome wide scale studies and useful methodological approaches, like those combining
historical phylogeography and landscape genetics, both at fine and wide spatial
scales.
Keywords: Trypanosoma terrestris, ecological host fitting, microgeographic
divergence, population bottle-neck, phylogenetic relationships
Wage inequality, segregation by skill and the price of capital in an assignment model
Some pieces of empirical evidence suggest that in the U.S., over the last few decades, (i) wage inequality between-plants has risen much more than wage inequality within-plants and (ii) there has been an increase in the segregation of workers by skill into separate plants. This paper presents a frictionless assignment model in which these two features can be explained simultaneously as the result of the decline in the relative price of capital. Additional implications of the model regarding the skill premium and the dispersion in labor productivity across plants are also consistent with the empirical evidence. [resumen de autor
Overlapping political budget cycles in the legislative and the executive
We advance the literature on political budget cycles by testing separately for cycles in expenditures for elections in the legislative and the executive. Using municipal data, we can separately identify these cycles and account for general year effects. For the executive branch, we show that it is important whether the incumbent re-runs. To account for the potential endogeneity associated with this decision, we apply a unique instrumental variables approach based on age and pension eligibility rules. We find sizable and significant effects in expenditures before council elections and before joint elections when the incumbent re-runs
Don't Blame the Messenger: A Field Experiment on Delivery Methods for Increasing Tax Compliance
Weak Expansions: A Distinctive Feature of the Business Cycle in Latin America and the Caribbean
Is Social Assistance Contributing to Higher Informality in Turkey?
Although still low for European standards, investments in Social Assistance (SA) transfers in Turkey have been increasing in recent years. The government is expanding access to subsidized health for individuals in the informal sector through a rapid expansion of the Green Card program. Generous non-contributory programs, such as the Green Card, may create perverse incentives for individuals to join or remain in the informal sector as they can access free services without paying taxes and/or contributions, thus potentially being able to get higher “net” labor earnings than in the formal sector. Despite the fact that the Green Card is a large and generous program offered to individuals in the informal sector, empirical analysis in this report does not find an actual impact of the program (or of its rapid expansion) on informality. The reason behind this finding is the existence of a very large differential in wages between formal and informal workers explained by differences worker’s productivity. Low-wage workers facing the possibility to move from the informal sector to the formal sector would have strong incentives to do so even if this would imply losing all SA benefits. As such, the expected monetary and job security gains of having a formal job dominate those of having an informal job even after accounting for SA transfers
The labor market effects of technology shocks
We analyze the effects of neutral and investment-specific technology shocks on hours worked and unemployment. We characterize the response of unemployment in terms of job separation and job finding rates. We find that job separation rates mainly account for the impact response of unemployment while job finding rates for movements along its adjustment path. Neutral shocks increase unemployment and explain a substantial portion of unemployment and output volatilityinvestment-specific shocks expand employment and hours worked and mostly contribute to hours worked volatility. We show that this evidence is consistent with the view that neutral technological progress prompts Schumpeterian creative destruction, while investment specific technological progress has standard neoclassical feature
The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III
The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra. \ua9 2015. The American Astronomical Society
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