Geographic and Ecological Dimensions of Host Plant-Associated Genetic Differentiation and Speciation in the Rhagoletis cingulata (Diptera: Tephritidae) Sibling Species Group.

Ascertaining the causes of adaptive radiation is central to understanding how new species arise and come to vary with their resources. The ecological theory posits adaptive radiation via divergent natural selection associated with novel resource use; an alternative suggests character displacement following speciation in allopatry and then secondary contact of reproductively isolated but ecologically similar species. Discriminating between hypotheses, therefore, requires the establishment of a key role for ecological diversification in initiating speciation versus a secondary role in facilitating co-existence. Here, we characterize patterns of genetic variation and postzygotic reproductive isolation for tephritid fruit flies in the Rhagoletis cingulata sibling species group to assess the significance of ecology, geography, and non-adaptive processes for their divergence. Our results support the ecological theory: no evidence for intrinsic postzygotic reproductive isolation was found between two populations of allopatric species, while nuclear-encoded microsatellites implied strong ecologically based reproductive isolation among sympatric species infesting different host plants. Analysis of mitochondrial DNA suggested, however, that cytoplasmic-related reproductive isolation may also exist between two geographically isolated populations within R cingulata. Thus, ecology associated with sympatric host shifts and cytoplasmic effects possibly associated with an endosymbiont may be the key initial drivers of the radiation of the R. cingulata group.

Project ROADMAP: Reeducating Older Adults in Maintaining AIDS Prevention: a secondary intervention for older HIV-positive adults.

The number of older adults living with HIV/AIDS is larger than ever. Little is known about their sexual behaviors, although contrary to stereotypes, older adults desire and engage in sexual activity. Despite increased recognition of the need for prevention interventions targeting HIV-positive individuals, no secondary HIV prevention interventions have specifically targeted the older HIV-positive adult. Efforts to target high-risk sexual behaviors may be even more critical in the older population because of sociocultural, biological, and behavioral vulnerabilities. In response, Project ROADMAP (Reeducating Older Adult in Maintaining AIDS Prevention) intervention was developed to reduce high-risk sexual behaviors among older HIV-positive patients in primary care clinics. The purpose of this article is to report the 6-month outcomes of a behavioral intervention designed to reduce sexual risk behaviors in older HIV-positive adults.