112 research outputs found

    Historical and topographic drivers of tropical insular diversity: comparative phylogeography of Eleutherodactylus antillensis and E. portoricensis, two ecologically distinctive frogs of the Puerto Rican Bank

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    Topographically complex islands present opportunities for in situ (within-island) allopatric speciation because of increased chances for isolation in separate mountain ranges, as well as greater opportunity for fragmentation by high sea levels and climate-driven changes in habitat distribution. Climatic oscillations of the Quaternary (Pleistocene - Holocene; ~2.5 million years ago to the present) may have influenced the severity of vicariant barriers among and within islands, yet how these events influenced evolution of tropical insular biota is not well understood. This dissertation explores the role of topographic complexity and climate-driven range shifts resulting from sea-level changes and habitat suitability in shaping genetic diversity of two Eleutherodactylus frogs (Anura: Eleutherodactylidae) in the Puerto Rican Bank, an archipelago in the eastern Caribbean Sea. Sea level changes significantly altered the size, area, and degree of isolation of terrestrial habitats in the Puerto Rican Bank, and habitat shifts may have occurred in the main island of Puerto Rico. Whereas the Mountain Coquí, E. portoricensis, is restricted to cool and moist understory montane forest habitat in Puerto Rico, the Red-eyed Coquí, E. antillensis, is a habitat generalist with a broad elevational distribution on most of the larger islands of the Puerto Rican Bank. Hypotheses of population history were formulated using data from paleoenvironmental records and ecological niche models, and tested using a suite of population genetic, phylogenetic, and coalescent analyses of DNA sequence data. I show how basin barriers and Quaternary climatic fluctuations shaped the distribution of genetic diversity in E. portoricensis in the Luquillo and Cayey Mountains in eastern Puerto Rico, and how varying degrees of terrestrial connectivity and isolation influenced the persistence and colonization dynamics of E. antillensis across the Puerto Rican Bank. To infer whether climate-driven, historical shifts in distributions occurred in E. portoricensis and E. antillensis, this dissertation also compares patterns of genetic isolation and demography of these species in Puerto Rico, where elevational gradients may have accommodated range shifts during climatic extremes of the Quaternary. The collective findings of this dissertation improve our understanding of topographic and historic factors that promote population divergence and that ultimately produce regional patterns of biodiversity in tropical archipelagos

    Reclaiming Indigenous Identities: Culture as Strength Against Suicide Among Indigenous Youth in Canada

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    In Canada, Indigenous youth suicide represents one of several health disparities burdening Indigenous populations, and like many other of these disparities, can be understood as an expression of societal, historical, cultural and familial trauma. As the number of Indigenous youth who take their own lives every year in Canada continues to far exceed national averages, it appears that conventional suicide prevention efforts remain ineffective among this population. A growing body of research argues that conventional interventions, largely rooted in Western individual-level behavioural change frameworks, are culturally discordant with Indigenous paradigms. In response, some Indigenous communities are turning to cultural revitalization as a holistic community-driven response to suicide prevention and treatment. The following commentary explores the emerging evidence base for "culture as treatment" - a novel approach to suicide that emphasizes the significance of interconnectedness in healing, alongside the revitalization of traditional values to reclaim community wellness. In doing so, we seek to contribute to a changing discourse surrounding Indigenous youth suicide by acknowledging culture as strength against this national crisis

    An Analysis of Black, Latinx, Multicultural and Asian/Pacific Islander Fraternity/Sorority Organizational Values

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    The purpose of this study was to examine the espoused values of historically Black, Latinx, Multicultural and Asian/Pacific Islander fraternity/sorority organizations. This study reports the types of values discovered, as well as their alignment with universally accepted values that included: self-enhancement, openness to change, self-transcendence and conservation. Further examination included comparisons between the espoused universally accepted values of the above-identified organizations with those of historically White fraternity/sorority organizations

    Avian malaria co-infections confound infectivity and vector competence assays of Plasmodium homopolare.

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    Currently, there are very few studies of avian malaria that investigate relationships among the host-vector-parasite triad concomitantly. In the current study, we experimentally measured the vector competence of several Culex mosquitoes for a newly described avian malaria parasite, Plasmodium homopolare. Song sparrow (Melospiza melodia) blood infected with a low P. homopolare parasitemia was inoculated into a naïve domestic canary (Serinus canaria forma domestica). Within 5 to 10 days post infection (dpi), the canary unexpectedly developed a simultaneous high parasitemic infection of Plasmodium cathemerium (Pcat6) and a low parasitemic infection of P. homopolare, both of which were detected in blood smears. During this infection period, PCR detected Pcat6, but not P. homopolare in the canary. Between 10 and 60 dpi, Pcat6 blood stages were no longer visible and PCR no longer amplified Pcat6 parasite DNA from canary blood. However, P. homopolare blood stages remained visible, albeit still at very low parasitemias, and PCR was able to amplify P. homopolare DNA. This pattern of mixed Pcat6 and P. homopolare infection was repeated in three secondary infected canaries that were injected with blood from the first infected canary. Mosquitoes that blood-fed on the secondary infected canaries developed infections with Pcat6 as well as another P. cathemerium lineage (Pcat8); none developed PCR detectable P. homopolare infections. These observations suggest that the original P. homopolare-infected songbird also had two un-detectable P. cathemerium lineages/strains. The vector and host infectivity trials in this study demonstrated that current molecular assays may significantly underreport the extent of mixed avian malaria infections in vectors and hosts

    Increased Burden of Suicidality Among Young Street-Involved Sex Workers who Use Drugs in Vancouver, Canada

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    Abstract: Background: The risks of suicidality among street-involved youth who use drugs and engage in sex work is not well described. This study sought to evaluate if street-involved youth who engage in sex work were at an elevated risk for attempting suicide. Methods: Data were derived from the At-Risk Youth Study, a prospective cohort of street-involved youth who use drugs in Vancouver, Canada. Multivariable generalized estimating equation analyses were employed to examine whether youth who engaged in sex work were at elevated risk of attempting suicide, controlling for possible confounders. Results: Between September 2005 and May 2015, 1210 youth were recruited into the cohort, of whom, 173 (14.3%) reported recently attempting suicide at some point during the study period. In multivariable analysis, youth who engaged in sex work were significantly more likely to report a recent suicide attempt (adjusted odds ratio=1.93; 95% confidence interval: 1.28-2.91). Conclusions: Street-involved youth who engage in sex work were observed to be at a significantly higher risk for suicidality. Systematic discrimination and unaddressed trauma may contribute to the observed increased burden of suicidality among this population. Interventions that support the mental health and well-being of street-involved youth who engage in sex work are urgently needed

    Coercion Into Addiction Treatment and Subsequent Substance Use Patterns Among People Who Use Illicit Drugs in Vancouver, Canada

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    Background and Aims: Many people who use drugs (PWUD) are coerced into receiving treatment. This study aimed to assess changes in substance use and related outcomes before versus after treatment in people coerced into treatment, voluntarily attending treatment or not attending treatment.   Design: Data from three linked prospective cohort studies of PWUD were used. McNemar’s test and non-linear growth curve modeling were employed to: a) assess changes in substance use patterns before and after coerced addiction treatment and b) compare these changes with changes in PWUD who 1) voluntarily accessed and 2) did not access treatment.   Setting: Vancouver, Canada.   Participants: 3,196 community-recruited PWUD.   Measurements: The outcome variables were substance use and related outcomes assessed by self-reported questionnaire. The input variable was self-reported coerced addiction treatment (defined as being forced into addiction treatment by a doctor or the criminal justice system), voluntary treatment versus no treatment.   Findings: Between September 2005 and June 2015, 399 (12.5%) participants reported being coerced into addiction treatment. In McNemar’s test, there were no statistically significant reductions in within-group substance use outcomes for people coerced into treatment, voluntarily attending treatment or not attending treatment. In non-linear growth curve analyses, there were no statistically significant differences in the before and after substance use patterns between those coerced into treatment versus either of the two control groups (all p>0.05). In sub-analyses, we found no statistically significant differences in substance use patterns between people who reported formal coerced treatment through the criminal justice system and people who reported informal coerced treatment through a physician.   Conclusions: Among PWUD in Vancouver, Canada, there appear to be no statistically significant improvements in substance use outcomes among those reporting coerced addiction treatment, those voluntarily accessing treatment, and those not attending treatment
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