Teenage Pregnancy in Mexico: Evolution and Consequences

We analyze the consequences of a teenage pregnancy event in the short- and long-run in Mexico. Using longitudinal and cross-section data, we match females who got pregnant and those that did not based on a propensity score. Several balancing tests and specifications indicate that the main assumptions to estimate the average treatment effect on the treated using a propensity score are satisfied. In the short-run, we find that a teenage pregnancy causes a decrease of 0.6-0.8 years of schooling, lower attendance to school, less hours of work and a higher marriage rate. At the household level, we do not find any effect in parental hours of work or income per capita. In the long-run, we find a loss in years of education of 1-1.2 and a higher probability of being married, but also higher probability of being separated or divorced. We also find that household income per capita is lower at least in the long-run.teenage, pregnancy, labor outcomes, propensity score, matching

UNCOVERING THE CONSEQUENCES OF CO-FLOWERING AND POLLINATOR SHARING: EFFECTS OF LOCAL COMMUNITY CONTEXT ON POLLEN TRANSFER DYNAMICS, FEMALE REPRODUCTIVE SUCCESS AND FLORAL EVOLUTION IN MIMULUS GUTTATUS

While plant-pollinator interactions commonly take place within a larger community context, studies of plants and their pollinators have typically focused on pair-wise interactions. Co-flowering species whithin multi-species communities may influence pollinator foraging decisions and hence plant reproductive success and floral evolution. For instance, plants growing in highly diverse areas may be more pollen limited than plants in species-poor areas due to the high levels of pollinator competition and interspecific pollen transfer. As a result, stronger selection pressures can also be expected in highly diverse areas in order to increase the quantity and/or quality of pollen reaching conspecific stigmas. However, how plant community composition contributes to the severity of pollen limitation, what the potential underlying mechanisms are and how selection on floral traits changes with increasing community diversity is still unclear. In this study I use Mimulus guttatus as a model system to evaluate the effect of local co-flowering community context on quantity and quality aspects of pollen limitation, pollen transfer dynamics, heterospecific pollen effects and selection processes in high and low diversity areas. I show that the relative contribution of pollen quantity and quality limitation to overall pollen limitation of reproductive success depends on the co-flowering community context in which M. guttatus exists. I further uncover heterospecific pollen receipt as a potential mechanism underlying decreased reproductive success in highly diverse areas by showing that complex interactions among multiple heterospecific pollen donors can exacerbate its effects and that heterospecific pollen receipt can have an even greater detrimental effect on self compared to outcross conspecific pollen. Finally, I show that co-flowering community context can be an important driver of selection that promotes floral trait differentiation among populations, in the case of M. guttatus in flower longevity. By combining observational, experimental, field and greenhouse approaches, this study extends our knowledge of the processes underlying insufficient pollination in natural communities, reveals new complexities in our understanding of heterospecific pollen effects and advances our understanding of the community properties shaping the evolutionary dynamics of constituent populations

Race and Marriage in the Labor Market: A Discrimination Correspondence Study in a Developing Country

In Mexico, as in most Latin American countries with indigenous populations, it is commonly believed that European phenotypes are preferred to mestizo or indigenous phenotypes. However, it is hard to test for such racial biases in the labor market using official statistics since race can only be inferred from native language. Moreover, employers may think that married females have lower productivity, and hence they may be more reluctant to hire them. We are interested in testing both hypotheses through a field experiment in the labor market. The experiment consisted on sending fictitious curriculums (CVs) responding to job advertisements with randomized information of the applicants. The CVs included photographs representing three distinct phenotypes: Caucasian, mestizo and indigenous. We also randomly vary marital status across gender and phenotype. Hence, our test consists on finding whether there are significant differences in the callback rates. We find that females have 40 percent more callbacks than males. We also find that indigenous looking females are discriminated against, but the effect is not present for males. Interestingly, married females are penalized in the labor market and this penalty is higher for indigenous-looking women. We did not find an effect of marital status on males

Alignment of the ALICE Inner Tracking System with cosmic-ray tracks

37 pages, 15 figures, revised version, accepted by JINSTALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 micron in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10^5 charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.Peer reviewe

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

The effects of urbanization on avian seed dispersal success of Eastern Poison Ivy (Anacardiaceae)

The rate of global urbanization is increasing rapidly as the human population expands, leading to species loss and biotic homogenization. Less studied, however, is the effect of urbanization on the frequency and efficiency of species interactions. Animal-based seed dispersal interactions may be especially sensitive to urbanization because they depend on several factors: 1) the rate of seed dispersal interactions (feeding), 2) diversity of disperser species, 3) the probability of seed dispersal and 4) the probability of germination after seed dispersal. However, how urbanization disrupts species interactions, including seed-dispersal, is still poorly known. In this study, we evaluate differences in the frequency and efficiency of seed dispersal between urban and natural sites using Eastern Poison Ivy (Toxicodendron radicans) as the focal species. Individual T. radicans lianas within natural and urban sites were observed in twelve-minute intervals (total 185.8 hours) at urban and natural sites during which the number and identity of feeding avian species was recorded. A total of 9500 fruits between natural and urban sites were marked with a UV fluorescent dye. Undispersed marked fruits were recovered via seed traps to estimate probability of dispersal. Defecated fruits were collected from natural and urban sites to evaluate germination efficiency after dispersal. Feeding rate was twice as high in urban compared to natural sites (P=0.007). Additionally, seed disperser diversity was on average twice as high in urban sites and species composition was significantly different between natural and urban sites. However, probability of seed dispersal was not significantly different between urban and natural sites (P=0.3). Interestingly, germination rate was 20% higher in defecated seeds collected from natural sites compared to defecated seeds from urban sites (P=0.005). Our results suggest that while T. radicans attracts a higher number and greater diversity of seed dispersers in urban areas, overall dispersal success is the same or even greater at natural sites, as seeds have a higher chance of germinating after being consumed by dispersers at natural compared to urban sites. Species composition differences between sites may play an important role in germinability of seeds; differences in species’ feeding strategies result in differences in their ability to scarify seeds in their digestive systems, a necessary step for seeds that rely on animal seed dispersers. Urbanization can thus negatively affect seed dispersal interactions by altering the composition of disperser species. Other animal-based interactions may be similarly affected by urbanization, and thus we emphasize the need for further studies

Moderate Levels of Urbanization Increase Insect Abundance and Pollen Removal in Common Milkweed (Asclepias syriaca)

Urbanization, the conversion of natural habitat into area fit for human exploitation, is the greatest contemporary threat to natural ecosystems. With urbanization only projected to increase in magnitude as human populations continue to grow it is becoming increasingly important to evaluate the potential negative impacts urbanization can have on vital ecosystem functions and services. One such important ecosystem service is pollination. Roughly 87.5% of flowering plants are animal pollinated, with pollination contributing over $175 billion dollars to the global economy each year. The fundamental ecologic and economic importance of pollination, coupled with the growing threat of urbanization, makes it important to better understand how pollination success may be impacted by urban development. Though, studies on the impact of urbanization on pollination success vary wildly in their findings, with some studies finding a negative impact of urbanization, while others find a negligible or even positive impact. This discordance in past studies is likely due to the fact that pollination studies typically focus on just one aspect of the pollination process, whether that be pollinator community, pollen removal/deposition, or fruit/seed production. Urbanization, however, may induce differential impacts across different stages of the pollination process. Focusing on just one pollination aspect may limit our understanding of the potential underlying mechanisms urbanization may impart on different stages of the pollination process. The goal of this study was to evaluate multiple aspects of pollination success across an urbanization gradient. Specifically, pollinator community (in terms of visitation rate and community composition), pollen removal/deposition, and fruit/seed production were surveyed across 12 common milkweed (Asclepias syriaca) populations, six of which were in natural habitats and six of which were in areas of moderate urbanization. By evaluating all pollination aspects together we can pinpoint which step(s) of the pollination process are impacted by urbanization, which will inform decisions on how to best conserve the integrity of pollination in anthropogenically disturbed environments. Overall, urbanization increased pollinator visitation rate (0.151 visits per minute per flower in urban populations, compared to 0.067 at natural populations), and altered pollinator composition, with more small bees and beetles present in more urbanized areas. Pollen removal also increased with urbanization (2.00 pollen removals per flower in urban populations, compared to 1.41 at natural populations), while pollen deposition, fruit production, and seed production were unchanged by urbanization. Thus, suggesting that the more abundant pollinators in more urbanized areas were effective at removing pollen, but ineffective at depositing pollen, resulting in no change in reproductive output (i.e., equal fruit and seed production). The results of this study suggest that increased urbanization can variably impact various steps in the pollination process, thus stressing the importance of studying multiple pollination aspects in tandem

Understanding Variation in The Effects of Heterospecific Pollen Receipt: The Effect of Pollen and Recipient Traits

Co-flowering plants within communities typically share pollinators which can lead to the deposition of pollen grains from varying species onto stigmas; or heterospecific pollen transfer (HPT). It has been shown that HPT can have varying effects on plant reproductive success. These effects can range from an 80% reduction on seed production to no effect. However, to date, there are no studies that have evaluated the causes underlying variability of these effects. We investigated this variability through a greenhouse experiment. Hand-pollinations were conducted with a mix of conspecific and heterospecific pollen and a control (conspecific pollen only). We used six pollen recipient and four species as donors for the heterospecific pollen (5 treatments total) We conducted hand-pollinations on a minimum of 10 plants per species (584 total pollinations). After pollination seed set data was recorded for each treatment and the amount of conspecific and heterospecific pollen on stigmas was recorded. We evaluated if the effects of HPT can be explained by the recipient species, the donor species or the interaction between donor and recipient. The results show high variability in the magnitude of HPT(2-93) but this variability is not a result of donor characteristics or even recipient characteristics but a result of the interactions between donors and recipients (df=20, α=.05, p=0.015). We will further investigate if the interaction can be explained by stigma/pollen size ratio, degree of co-flowering, or phylogenetic distance between donor and recipient species. This study will contribute to advance our understanding of how co-flowering plant communities interact amongst themselves after pollination

The Impact of Urbanization on Pollination Success in Asclepias syriaca (Common Milkweed), A Comprehensive Study

Human encroachment on ecosystems is one of the key environmental stressors facing natural habitats. Understanding how individual species are affected by these disturbances is therefore fundamental to preserving the stability of vital ecosystem services, such as pollination. Roughly 87.5% of plants are animal pollinated, with pollination contributing over $175 billion to the global economy each year. Despite its ecological and economic importance, studies that have comprehensively evaluated how multiple components of pollination success are impacted by human disturbances are limited. Here we evaluate how different aspects of pollination success, including patterns of pollinator visitation, pollen removal (male fitness), and deposition, fruit and seed production (female fitness) vary across an urbanization gradient in populations of Asclepias syriaca (Common Milkweed). Preliminary data was collected on four naturally occurring Asclepias syriaca sites (Watauga Lake, Warrior’s Path, Lake Ridge, Jacob’s Nature Park) in Northeast Tennessee. Urbanization around each site was quantified using ArcGIS and the National Land Cover Database. Sites were visited every other day (5-12 visits per population) during the flowering season and data was collected on male reproductive success (proportion of pollinaria removed), female reproductive success (proportion of flowers receiving pollinaria), pollinator visitation rate and composition, fruit production, and seed set. Preliminary data on four Asclepias syriaca populations shows large among-site variation in male and female reproductive success, pollinator visitation rate, pollinator community composition, fruit abundance, and seed set. Specifically, the quantity and quality of pollen received varies between all four sites. Pollen quality was highest at Lake Ridge (mean 2.57 fruits per plant and 278 seeds per fruit), and lowest at Warrior’s Path (mean 1.54 fruits and 199 seeds), the most agricultural site. Male success was highest at Warrior’s Path (0.492) and lowest at Watauga Lake (0.308). Female success was approximately equal between three of the sites (between 0.208 and 0.179), but lower at Jacob’s Nature Park (0.072). There was significant among-site variation in pollinator community, not only in terms of composition, but also visitation rate. Visitation rate was highest at Warrior’s Path and Lake Ridge (0.214 and 0.283, respectively), and lowest at Watauga Lake and Jacob’s Nature Park (0.126 and 0.123, respectively). Interestingly, Jacob’s Nature Park and Watauga Lake represent the most and least developed sites, respectively, though the Watauga Lake population was adjacent to a major road. Among-site variation in pollination success is likely due to variation in pollinator community across the sites

Patterns and Sources of Variation in Heterospecific Pollen Deposition in Flowers of the Native Blue Cardinal Flower (Lobelia Siphilitica)

Plants species interactions via pollinators are a model system to understand the mechanisms that generate plant diversity in nature. However, most studies have focused on plant-plant interactions via pollinator attraction while ignoring the role of plant-plant interactions via pollen transfer. Heterospecific pollen transfer (henceforth HP) can be common and have negative fitness effects. Negative HP fitness effects may prompt the evolution of adaptive strategies to minimize them. However, the extent of spatial variation in HP load size within and among populations, a tenet for natural selection, remains unexplored. Such knowledge would hence constitute a first step in advancing our understanding of the importance of HP transfer as an evolutionary force promoting plant diversification. For instance, the opportunity for natural selection would only be expected under strong among population variation in HP load size. In this study we aim to answer the following specific questions: Is there variation in the amount and diversity of HP load in Lobelia Siphilitica? How is the variation partitioned across different levels of organization (populations, individuals, and flowers among an individual)? Greater among-population variance would suggest that community attributes, such as plant density and diversity are the major drivers of HP load size. Greater among-plant variance would indicate plant traits that affect pollinator foraging behavior may play an important role. Greater variance among flowers within an individual plant, would suggest stochastic events may underlie variation in HP load size and diversity. In order to test these hypotheses, samples of the native perennial Lobelia siphilitica were taken from 10 populations in the Northeast Tennessee region (500 total). The styles were processed in the lab and pollen grains counted separating them into two categories, heterospecific and conspecific pollen. There was variation in the amount and diversity of HP load received. Populations are expected to have the largest variation among them due to different environments (disturbance levels, pollinators, plant communities, etc.) Since populations are expected to have the largest variation in HP received, they are also expected to have the greatest opportunity for natural selection to act. Looking at HP receipt within-species is important for identifying the mechanisms that can generate diversity in plant communities