Species richness is greatest in the tropics, and much of this diversity is concentrated in mountains. Janzen proposed that reduced seasonal temperature variation selects for narrower thermal ...tolerances and limited dispersal along tropical elevation gradients Janzen DH (1967) Am Nat 101:233–249. These locally adapted traits should, in turn, promote reproductive isolation and higher speciation rates in tropical mountains compared with temperate ones. Here, we show that tropical and temperate montane stream insects have diverged in thermal tolerance and dispersal capacity, two key traits that are drivers of isolation in montane populations. Tropical species in each of three insect clades have markedly narrower thermal tolerances and lower dispersal than temperate species, resulting in significantly greater population divergence, higher cryptic diversity, higher tropical speciation rates, and greater accumulation of species over time. Our study also indicates that tropical montane species, with narrower thermal tolerance and reduced dispersal ability, will be especially vulnerable to rapid climate change.
In discipline-based education research (DBER), early career scholars, such as graduate students and postdoctoral researchers, observe a slew of possible career pathways. Yet, there is a lack of ...opportunities to learn about such pathways, particularly when transitioning from traditional science, technology, engineering, or math (STEM) disciplinary training into a DBER position. Thus, the DBER Scholars-in-Training Professional Development subcommittee was created within the Society for the Advancement of Biology Education Research (SABER) community to develop a collection of workshops that would serve the greatest professional development needs of early career scholars entering DBER. Through a series of surveys disseminated over multiple years, early career scholars expressed interest in better navigating their career options, which led to the development of the career panel workshop, held during the 2019 and 2020 SABER Annual National Conferences. In this report, we explore the development, implementation, and results of two career panel workshops and compare and contrast the 2019 in-person workshop with the 2020 virtual workshop. We also offer our insights on the value of the career workshop, discuss the next steps, and explore valuable resources for those planning on organizing similar events.
Although 1 billion people live in informal (slum) settlements, the consequences for respiratory health of living in these settlements remain largely unknown. This study investigated whether children ...living in an informal settlement in Nairobi, Kenya are at increased risk of asthma symptoms.
Children attending schools in Mukuru (an informal settlement in Nairobi) and a more affluent area (Buruburu) were compared. Questionnaires quantified respiratory symptoms and environmental exposures; spirometry was performed; personal exposure to particulate matter (PM
) was estimated.
2373 children participated, 1277 in Mukuru (median age, IQR 11, 9-13 years, 53% girls), and 1096 in Buruburu (10, 8-12 years, 52% girls). Mukuru schoolchildren were from less affluent homes, had greater exposure to pollution sources and PM
. When compared with Buruburu schoolchildren, Mukuru schoolchildren had a greater prevalence of symptoms, 'current wheeze' (9.5% vs 6.4%, p=0.007) and 'trouble breathing' (16.3% vs 12.6%, p=0.01), and these symptoms were more severe and problematic. Diagnosed asthma was more common in Buruburu (2.8% vs 1.2%, p=0.004). Spirometry did not differ between Mukuru and Buruburu. Regardless of community, significant adverse associations were observed with self-reported exposure to 'vapours, dusts, gases, fumes', mosquito coil burning, adult smoker(s) in the home, refuse burning near homes and residential proximity to roads.
Children living in informal settlements are more likely to develop wheezing symptoms consistent with asthma that are more severe but less likely to be diagnosed as asthma. Self-reported but not objectively measured air pollution exposure was associated with increased risk of asthma symptoms.
Terrestrial breeding is a derived condition in frogs, with multiple transitions from an aquatic ancestor. Shifts in reproductive mode often involve changes in habitat use, and these are typically ...associated with diversification in body plans, with repeated transitions imposing similar selective pressures. We examine the diversification of reproductive modes, male and female body sizes, and sexual size dimorphism (SSD) in the Neotropical frog genera Cycloramphus and Zachaenus, both endemic to the Atlantic rainforest of Brazil. Species in this clade either breed in rocky streams (saxicolous) or in terrestrial environments, allowing us to investigate reproductive habitat shifts. We constructed a multilocus molecular phylogeny and inferred evolutionary histories of reproductive habitats, body sizes, and SSD. The common ancestor was small, saxicolous, and had low SSD. Terrestrial breeding evolved independently three times and we found a significant association between reproductive habitat and SSD, with shifts to terrestrial breeding evolving in correlation with decreases in male body size, but not female body size. Terrestrial breeding increases the availability of breeding sites and results in concealment of amplexus, egg-laying, and parental care, therefore reducing malemale competition at all stages of reproduction. We conclude that correlated evolution of terrestrial reproduction and small males is due to release from intense male-male competition that is typical of exposed saxicolous breeding.
Big bluestem (Andropogon gerardii) is an ecologically dominant grass with wide distribution across the environmental gradient of U.S. Midwest grasslands. This system offers an ideal natural ...laboratory to study population divergence and adaptation in spatially varying climates. Objectives were to: (i) characterize neutral genetic diversity and structure within and among three regional ecotypes derived from 11 prairies across the U.S. Midwest environmental gradient, (ii) distinguish between the relative roles of isolation by distance (IBD) vs. isolation by environment (IBE) on ecotype divergence, (iii) identify outlier loci under selection and (iv) assess the association between outlier loci and climate. Using two primer sets, we genotyped 378 plants at 384 polymorphic AFLP loci across regional ecotypes from central and eastern Kansas and Illinois. Neighbour‐joining tree and PCoA revealed strong genetic differentiation between Kansas and Illinois ecotypes, which was better explained by IBE than IBD. We found high genetic variability within prairies (80%) and even fragmented Illinois prairies, surprisingly, contained high within‐prairie genetic diversity (92%). Using Bayenv2, 14 top‐ranked outlier loci among ecotypes were associated with temperature and precipitation variables. Six of seven BayeScanFST outliers were in common with Bayenv2 outliers. High genetic diversity may enable big bluestem populations to better withstand changing climates; however, population divergence supports the use of local ecotypes in grassland restoration. Knowledge of genetic variation in this ecological dominant and other grassland species will be critical to understanding grassland response and restoration challenges in the face of a changing climate.
Individuals spend about 25% of their time in non-residential indoor microenvironments. For some of these microenvironments, particularly stores and restaurants, exposures to volatile organic ...compounds (VOCs), have not been well characterized. In the Boston Exposure Assessment in Microenvironments (BEAM) study, sampling using scripted activities was conducted in stores, restaurants, and transportation in the summer of 2003 and winters of 2004 and 2005. A suite of VOCs including hydrocarbons, several chlorinated compounds, and aldehydes was analyzed. Nine store types were sampled using a composite design to enable a greater number of stores to be visited. Stores had higher concentrations of formaldehyde, toluene, ethylbenzene, xylenes, and styrene than other microenvironments, particularly in certain store types. Geometric mean formaldehyde levels were highest in the housewares stores, at 53 μg/m3 (95% CI = 43, 66). Geometric mean toluene levels were highest in multipurpose stores, at 76 μg/m3 (95% CI = 50, 118). The levels observed in stores were several times higher than levels found in transportation microenvironments, and indicate strong indoor sources. In contrast, benzene did not have significantly higher levels in stores than typically found outdoors. Concentrations of formaldehyde and benzene, ethylbenzene, xylenes, and styrene were strongly influenced by the presence of smoking in the dining microenvironment. Chloroform levels were higher in restaurants than in other microenvironments, with a geometric mean of 1.1 μg/m3 (95% CI = 0.7, 1.8). The VOC concentrations found in stores and restaurants in this study are a potentially important source of exposure for sensitive individuals or people who work in these microenvironments.
Transition through telomere crisis is thought to be a crucial event in the development of most breast carcinomas. Our goal in this study was to determine where this occurs in the context of ...histologically defined breast cancer progression. To this end, we assessed genome instability (using fluorescence in situ hybridization) and other features associated with telomere crisis in normal ductal epithelium, usual ductal hyperplasia, ductal carcinoma in situ and invasive cancer. We modeled this process in vitro by measuring these same features in human mammary epithelial cell cultures during ZNF217-mediated transition through telomere crisis and immortalization. Taken together, the data suggest that transition through telomere crisis and immortalization in breast cancer occurs during progression from usual ductal hyperplasia to ductal carcinoma in situ.
Abstract
Big bluestem (
A
ndropogon gerardii
) is an ecologically dominant grass with wide distribution across the environmental gradient of U.S. Midwest grasslands. This system offers an ideal ...natural laboratory to study population divergence and adaptation in spatially varying climates. Objectives were to: (i) characterize neutral genetic diversity and structure within and among three regional ecotypes derived from 11 prairies across the U.S. Midwest environmental gradient, (ii) distinguish between the relative roles of isolation by distance (
IBD
) vs. isolation by environment (
IBE
) on ecotype divergence, (iii) identify outlier loci under selection and (iv) assess the association between outlier loci and climate. Using two primer sets, we genotyped 378 plants at 384 polymorphic
AFLP
loci across regional ecotypes from central and eastern Kansas and Illinois. Neighbour‐joining tree and PCoA revealed strong genetic differentiation between Kansas and Illinois ecotypes, which was better explained by
IBE
than
IBD
. We found high genetic variability within prairies (80%) and even fragmented Illinois prairies, surprisingly, contained high within‐prairie genetic diversity (92%). Using
Bayenv
2, 14 top‐ranked outlier loci among ecotypes were associated with temperature and precipitation variables. Six of seven
BayeScan
F
ST
outliers were in common with
Bayenv
2 outliers. High genetic diversity may enable big bluestem populations to better withstand changing climates; however, population divergence supports the use of local ecotypes in grassland restoration. Knowledge of genetic variation in this ecological dominant and other grassland species will be critical to understanding grassland response and restoration challenges in the face of a changing climate.
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