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Fitness Variation Due To Sexual Antagonism and Linkage Disequilibrium
Extensive fitness variation for sexually antagonistic characters has been detected in nature. However, current population genetic theory suggests that sexual antagonism is unlikely to play a major role in the maintenance of variation. We present a two-locus model of sexual antagonism that is capable of explaining greater fitness variance at equilibrium than previous single-locus models. The second genetic locus provides additional fitness variance in two complementary ways. First, linked loci can maintain gene variants that are lost in single-locus models of evolution, expanding the opportunity for polymorphism. Second, linkage disequilibrium results between any two sexually antagonistic genes, producing an excess of high and low fitness haplotypes. Our results uncover a unique contribution of conflicting selection pressures to the maintenance of variation, which simpler models that neglect genetic architecture overlook.Organismic and Evolutionary Biolog
Estudio de Viabilidad Económica de una Explotación Agrícola en Almussafes (Valencia)
[ES] El trabajo final de grado se basa en el análisis de inversión de una explotación agrícola situada en el término municipal de Almussafes (Valencia). La inversión se va a centrar en cultivos leñosos, con una vida útil de la inversión de 15 años, y se optará por diferentes especies de cultivos leñosos con objeto de repartir el riesgo de la inversión y planificación de los trabajos en la propia explotación. Se realizada un estudio económico de los cultivos leñosos, para determinar cuáles son los más interesantes desde un punto de vista económico, de gestión y planificación de los trabajos de la explotación. El análisis económico se basará en determinar el VAN, TIR y TIEMPO DE RECUPERACIÓN de la inversión aunque para la elección final se tendrán también en cuenta otros puntos como es la gestión de la mano de obra en la explotación.Orobal Ubeda, D. (2016). Estudio de Viabilidad Económica de una Explotación Agrícola en Almussafes (Valencia). http://hdl.handle.net/10251/65012.TFG
Star Formation Histories of the LEGUS dwarf galaxies. II. Spatially resolved star formation history of the Magellanic irregular NGC 4449
We present a detailed study of the Magellanic irregular galaxy NGC 4449 based
on both archival and new photometric data from the Legacy Extragalactic UV
Survey, obtained with the Hubble Space Telescope Advanced Camera for Surveys
and Wide Field Camera 3. Thanks to its proximity ( Mpc) we
reach stars 3 magnitudes fainter than the tip of the red giant branch in the
F814W filter. The recovered star formation history spans the whole Hubble time,
but due to the age-metallicity degeneracy of the red giant branch stars, it is
robust only over the lookback time reached by our photometry, i.e.
Gyr. The most recent peak of star formation is around 10 Myr ago. The average
surface density star formation rate over the whole galaxy lifetime is
M yr kpc. From our study it emerges that NGC 4449 has
experienced a fairly continuous star formation regime in the last 1 Gyr with
peaks and dips whose star formation rates differ only by a factor of a few. The
very complex and disturbed morphology of NGC 4449 makes it an interesting
galaxy for studies of the relationship between interactions and starbursts, and
our detailed and spatially resolved analysis of its star formation history does
indeed provide some hints on the connection between these two phenomena in this
peculiar dwarf galaxy.Comment: 16 pages, 25 figures. Accepted for publication in the Astrophysical
Journa
A Tale of 3 Dwarfs: No Extreme Cluster Formation in Extreme Star-Forming Galaxies
Nearly all current simulations predict that outcomes of the star formation
process, such as the fraction of stars that form in bound clusters (Gamma),
depend on the intensity of star formation activity (SigmaSFR) in the host
galaxy. The exact shape and strength of the predicted correlations, however,
vary from simulation to simulation. Observational results also remain unclear
at this time, because most works have mixed estimates made from very young
clusters for galaxies with higher SigmaSFR with those from older clusters for
galaxies with lower SigmaSFR. The three blue compact dwarf (BCD) galaxies
ESO185-IG13, ESO338-IG04, and Haro11 have played a central role on the
observational side because they have some of the highest known SigmaSFR and
published values of Gamma. We present new estimates of Gamma for these BCDs in
three age intervals (1-10 Myr, 10-100 Myr, 100-400 Myr), based on age-dating
which includes Halpha photometry to better discriminate between clusters
younger and older than ~10 Myr. We find significantly lower values for Gamma
(1-10 Myr) than published previously. The likely reason for the discrepancy is
that previous estimates appear to be based on age-reddening results that
underestimated ages and overestimated reddening for many clusters, artificially
boosting Gamma (1-10 Myr). We also find that fewer stars remain in clusters
over time, with ~15-39% in 1-10 Myr, ~5-7% in 10-100 Myr, and ~1-2% in 100-400
Myr clusters. We find no evidence that Gamma increases with SigmaSFR. These
results imply that cluster formation efficiency does not vary with star
formation intensity in the host galaxy. If confirmed, our results will help
guide future assumptions in galaxy-scale simulations of cluster formation and
evolution.Comment: Accepted for publication in Ap
Hierarchical Star Formation in Nearby LEGUS Galaxies
Hierarchical structure in ultraviolet images of 12 late-type LEGUS galaxies
is studied by determining the numbers and fluxes of nested regions as a
function of size from ~1 to ~200 pc, and the number as a function of flux. Two
starburst dwarfs, NGC 1705 and NGC 5253, have steeper number-size and flux-size
distributions than the others, indicating high fractions of the projected areas
filled with star formation. Nine subregions in 7 galaxies have similarly steep
number-size slopes, even when the whole galaxies have shallower slopes. The
results suggest that hierarchically structured star-forming regions several
hundred parsecs or larger represent common unit structures. Small galaxies
dominated by only a few of these units tend to be starbursts. The
self-similarity of young stellar structures down to parsec scales suggests that
star clusters form in the densest parts of a turbulent medium that also forms
loose stellar groupings on larger scales. The presence of super star clusters
in two of our starburst dwarfs would follow from the observed structure if
cloud and stellar subregions more readily coalesce when self-gravity in the
unit cell contributes more to the total gravitational potential.Comment: 9 pages, 4 figures, accepted for ApJ
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