Indian Ocean crossroads: human genetic origin and population structure in the Maldives

The peopling of Lakshadweep Archipelago

The archipelago of Lakshadweep is considered as a stopover to the maritime route since ancient time. It is not very clear when the human first occupied these islands, however in the long history of the islands, the local legends suggest that Lakshadweep has been ruled by different kingdoms. To have a better understanding of peopling of Lakshadweep, we have analysed 557 individuals from eight major islands for mitochondrial DNA and 166 individuals for Y chromosome markers. We found a strong founder effect for both paternal and maternal lineages. Moreover, we report a close genetic link of Lakshadweep islanders with the Maldives, Sri Lanka and India. Most of the Lakshadweep islands share the haplogroups specific to South Asia and West Eurasia, except Minicoy Island that also shares haplogroups of East Eurasia. The paternal and maternal ancestries of the majority of island populations suggest their arrival from distinct sources. We found that the maternal ancestry was closer to South Indian populations, whereas the paternal ancestry was overwhelmed with the haplogroups, more common in the Maldives and North of India. In conclusion, our first genetic data suggest that the majority of human ancestry in Lakshadweep is largely derived from South Asia with minor influences from East and West Eurasia.

Local Perceptions of Climate Change Impacts in St. Kitts (Caribbean Sea) and Malé, Maldives (Indian Ocean)

Small Island Developing States (SIDS) are now experiencing the local consequences of a changing climate, environment, and society. Nonetheless, climate change research frequently remains at regional or national levels. Without locally grounded data, islanders’ perceived impacts of the changes might not be considered, thereby causing difficulties when policy and practice responses are implemented without accounting for local understandings. To contribute to addressing this gap, this study examines perceptions of climate change and associated environmental and social changes in two SIDS case studies: St. Kitts in the Caribbean Sea and Malé Atoll, Maldives in the Indian Ocean. Through these two case studies, we assess perceptions of changing social and natural environments through a closed-question, face-to-face survey. Our results suggest that in both island case studies, communities perceive environmental changes to be happening that demand negotiation with the social changes of daily life. Results also suggest that perceived climate change impacts are only part of the equation, as social and economic impacts reveal two case studies of changing island societies. While the geographic context in each case study differs, this study reveals the perceived impacts of climate change and social changes at a local level, providing valuable insights and angles for formulating policies and actions to deal with the myriad of social and environmental changes affecting SIDS.

Carrier screening for beta-thalassemia in the Maldives: perceptions of parents of affected children who did not take part in screening and its consequences

The Republic of Maldives (Maldives) is an island nation in the Indian Ocean with a population of 344, 023. Studies show that Maldives has one of the world's highest thalassemia carrier rates. It is estimated that 16-18 % of the Maldivians are β-thalassemia carriers, and approximately 28 new β-thal cases are recorded annually. Poor uptake of screening for the condition is one of the main reasons for this high number of new cases. The aim of this study was to explore the reasons for not testing for thalassemia in Maldives before or after marriage. Findings show that participants did not undergo carrier tests because of poor awareness and not fully knowing the devastating consequences of the condition. The outcomes of not testing were distressing for most participants. Religion played a vital role in all the decisions made by the participants before and after the birth of a β-thal child.

Autosomal admixture levels are informative about sex bias in admixed populations

Sex-biased admixture has been observed in a wide variety of admixed populations. Genetic variation in sex chromosomes and functions of quantities computed from sex chromosomes and autosomes have often been examined to infer patterns of sex-biased admixture, typically using statistical approaches that do not mechanistically model the complexity of a sex-specific history of admixture. Here, expanding on a model of Verdu and Rosenberg (2011) that did not include sex specificity, we develop a model that mechanistically examines sex-specific admixture histories. Under the model, multiple source populations contribute to an admixed population, potentially with their male and female contributions varying over time. In an admixed population descended from two source groups, we derive the moments of the distribution of the autosomal admixture fraction from a specific source population as a function of sex-specific introgression parameters and time. Considering admixture processes that are constant in time, we demonstrate that surprisingly, although the mean autosomal admixture fraction from a specific source population does not reveal a sex bias in the admixture history, the variance of autosomal admixture is informative about sex bias. Specifically, the long-term variance decreases as the sex bias from a contributing source population increases. This result can be viewed as analogous to the reduction in effective population size for populations with an unequal number of breeding males and females. Our approach suggests that it may be possible to use the effect of sex-biased admixture on autosomal DNA to assist with methods for inference of the history of complex sex-biased admixture processes.