Browsing by Subject "Madagascar"

A fundamental goal in the diverse field of evolutionary biology is reconstructing the historical processes that facilitated lineage diversification and the current geographic distribution of species diversity. Oceanic islands provide a view of evolutionary processes that may otherwise be obscured by the complex biogeographic histories of continental systems, and have thus provided evolutionary biology with some of its most lasting and significant theories. The Indian Ocean island of Madagascar is home to an extraordinarily diverse and endemic biota, and reconstructing the historical processes responsible for this diversity has consumed countless academic careers. While the flowering plant genus Coffea is but one lineage contributing to Madagascar's staggering floral diversity, it is representative of the common evolutionary theme of adaptive radiation and local endemism on the island. In this dissertation, I employ the genus Coffea as a model for understanding historical biogeographic processes in the Indian Ocean using methods of molecular phylogenetics and population genetics. In the molecular phylogenetic study of Coffea presented in chapter 2, I show that Madagascan Coffea diversity is likely the product of at least two independent colonization events from Africa, a result that contradicts current hypotheses for the single origin of this group.

Species of Coffea are known to exhibit self-incompatibly, which can have a dramatic affect on the geographic distribution of plant genetic diversity. In chapter 3, I identify the genetic mechanism of self-incompatibility in Coffea as homologous to the canonical eudicot S-RNase system. Baker's Rule suggests that self-incompatible lineages are very unlikely to colonize oceanic islands, and in chapter 4, I test this hypothesis by characterizing the strength of self-incompatibility and comparing S-RNase polymorphism in Coffea populations endemic to isolated Indian Ocean islands (Grande Comore and Mauritius) with that of Madagascan/African species. My findings suggest that while island populations show little evidence for genetic bottleneck in S-RNase allelic diversity, Mauritian endemic Coffea may have evolved a type of "leaky" self-incompatibility allowing self-fertilization at some unknown rate. Through the application of traditional phylogenetic methods and novel data from the self-incompatibly locus, my dissertation contributes a wealth of new information regarding the evolutionary and biogeographic history of Coffea in the Indian Ocean.

Background: Approximately 3.8 million people die annually from illnesses caused by household air pollution (HAP). Cooking related HAP is the second leading cause of disease in Madagascar. Our exploratory study aims to examine the effect of cooking fuel smoke exposure on lung function and respiratory symptoms.Methods: A cross-sectional study was conducted in Mandena, Madagascar from 2016 through 2018. Adults aged ≥18 years completed a survey on respiratory symptoms and cooking habits and performed spirometry for FEV1 and FEV6 values. Results: Of the 140 participants, 95 individuals were included in the multiple regression model. Being the primary cooks was significantly associated with decreasing FEV1 (-0.30; 95% CI: -0.57, -0.04) and FEV6 (-0.32, 95% CI: -0.57,-0.06). Cooking indoors significantly decreases FEV6 compared to cooking outdoors (-0.26, 95% CI: -0.50,-0.03). Conclusion: Reduced lung function and increased respiratory disease are most common among primary cooks. Reduced lung function was associated with cooking indoors. Further studies are essential to investigate HAP’s effect on Madagascar communities.

Introduction: Hypertension, the primary risk factor for the leading cause of mortality, cardiovascular diseases, is increasing in all parts of the world, including low-income countries. This thesis explores the prevalence and predictors of elevated blood pressure in rural farmers in northeastern Madagascar. The prevalence of hypertensive blood pressure was compared as defined by two commonly used hypertension standards, the World Health Organization (WHO), and the American College of Cardiology & the American Heart Association (ACC/AHA). The hypothesized drivers of systolic and diastolic blood pressure were investigated, focusing specifically on age, gender, body mass index (BMI), salt intake, and stress. Methods: Over 1,200 surveys were conducted from 2019 to 2022 in four villages in the Sava Region of Madagascar, where blood pressure readings were obtained on each participant. A subset of the sample in the last field season, participated in additional questions related to salt consumption and a measurement of salt taken over the course of seven days. A subsample of forty-eight participants completed an additional survey regarding stress. Generalized linear mixed models were run to assess associations involving blood pressure, salt intake and stress, and other predictions involving age, gender, and BMI. Results: The different standards of hypertension, as defined by the WHO and the ACC/AHA, changed the respective prevalence of elevated blood pressure for this population markedly, nearly doubling the prevalence of hypertension if the more stringent American standard was used (WHO=29.7%, ACC/AHA=59.6%). Age was found to be a strong predictor of blood pressure as well as BMI, while salt intake, stress, and gender had weaker associations. Conclusion: The prevalence of elevated blood pressure in this population was markedly higher than that found in other studies conducted in this region and globally. Findings regarding lifestyle factors, salt intake and stress, as individual drivers of blood pressure were found to be inconclusive. Further research should be performed in this population to determine the predictors and lifestyle factors associated with blood pressure and the extent of their influence in this region. Consideration for standards of practice and diagnosis should be carefully considered in this population, as the burden of hypertension would potentially increase with a change in practice standard.