Relationships and genetic consequences of contrasting modes of speciation among endemic species of Robinsonia (Asteraceae, Senecioneae) of the Juan Fernández Archipelago, Chile, based on AFLPs and SSRs.

This study analyses and compares the genetic signatures of anagenetic and cladogenetic speciation in six species of the genus Robinsonia (Asteraceae, Senecioneae), endemic to the Juan Fernández Islands, Chile. Population genetic structure was analyzed by amplified fragment length polymorphism (AFLP) and microsatellite (simple sequence repeat, SSR) markers from 286 and 320 individuals, respectively, in 28 populations. Each species is genetically distinct. Previous hypotheses of classification among these species into subgenera and sections, via morphological, phytochemical, isozymic and internal transcribed spacer (ITS) data, have been confirmed, except that R. saxatilis appears to be related to R. gayana rather than R. evenia. Analysis of phylogenetic results and biogeographic context suggests that five of these species have originated by cladogenesis and adaptive radiation on the older Robinson Crusoe Island. The sixth species, R. masafuerae, restricted to the younger Alejandro Selkirk Island, is closely related to and an anagenetic derivative of R. evenia from Robinson Crusoe. Microsatellite and AFLP data reveal considerable genetic variation among the cladogenetically derived species of Robinsonia, but within each the genetic variation is lower, highlighting presumptive genetic isolation and rapid radiation. The anagenetically derived R. masafuerae harbors a level of genetic variation similar to that of its progenitor, R. evenia. This is the first direct comparison of the genetic consequences of anagenetic and cladogenetic speciation in plants of an oceanic archipelago.

Progressive migration and anagenesis in Drimys confertifolia of the Juan Fernández Archipelago, Chile.

A common mode of speciation in oceanic islands is by anagenesis, wherein an immigrant arrives and through time transforms by mutation, recombination, and drift into a morphologically and genetically distinct species, with the new species accumulating a high level of genetic diversity. We investigate speciation in Drimys confertifolia, endemic to the two major islands of the Juan Fernández Archipelago, Chile, to determine genetic consequences of anagenesis, to examine relationships among populations of D. confertifolia and the continental species D. winteri and D. andina, and to test probable migration routes between the major islands. Population genetic analyses were conducted using AFLPs and nuclear microsatellites of 421 individuals from 42 populations from the Juan Fernández islands and the continent. Drimys confertifolia shows a wide genetic variation within populations on both islands, and values of genetic diversity within populations are similar to those found within populations of the continental progenitor. The genetic results are compatible with the hypothesis of high levels of genetic variation accumulating within anagenetically derived species in oceanic islands, and with the concept of little or no geographical partitioning of this variation over the landscape. Analysis of the probability of migration within the archipelago confirms colonization from the older island, Robinson Crusoe, to the younger island Alejandro Selkirk.

Genetic variation (AFLPs and nuclear microsatellites) in two anagenetically derived endemic species of Myrceugenia (Myrtaceae) on the Juan Fernández Islands, Chile.

PREMISE OF THE STUDY: Anagenesis (or phyletic evolution) is one mode of speciation that occurs in the evolution of plants on oceanic islands. Of two endemic species on the Juan Fernández Islands (Chile), Myrceugenia fernandeziana and M. schulzei (Myrtaceae), believed to have originated anagenetically from different continental progenitors, the first is endemic to Robinson Crusoe Island and has no clear tie to continental relatives; the last is endemic to the younger island, Alejandro Selkirk Island, and has close affinity to M. colchaguensis in mainland Chile. METHODS: Using AFLPs and six nuclear microsatellites from 381 individuals representing 33 populations, we determined patterns of genetic variation within and among populations on both islands and between those of the islands and mainland. KEY RESULTS: Considerable genetic variation was found within populations on both islands. The level of gene diversity within M. schulzei was equivalent to that of its close continental relative M. colchaguensis. Genetic diversity was not partitioned geographically in M. fernandeziana and was weakly so and nonsignificantly in M. schulzei. CONCLUSIONS: The high genetic variation in both taxa is most likely due to anagenetic speciation. Subsidence of the older island Robinson Crusoe, landscape erosion, and restructuring of communities have severely reduced the overall island population to a single panmictic system. On the younger and less modified Alejandro Selkirk Island, slightly stronger patterns of genetic divergence are seen in M. schulzei. Because both species are genetically diverse and number in the thousands of individuals, neither is presently endangered in the archipelago.

Strong indication of an extinction-based saturation of the flora on the Pacific Robinson Crusoe Islands.

Oceanic islands are vulnerable ecosystems and their flora has been under pressure since the arrival of the first humans. Human activities and both deliberately and inadvertently introduced biota have had and continue to have a severe impact on island endemic plants. The number of alien plants has increased nearly linearly on many islands, perhaps resulting in extinction-based saturation of island floras. Here, we provide evidence for such a scenario in Alejandro Selkirk, Robinson Crusoe Islands (Archipelago Juan Fernández, Chile). We compared species richness and species composition of historical vegetation samples from 1917 with recent ones from 2011. Changes in species' relative occurrence frequency were related to their taxonomic affiliation, dispersal mode, distribution status, and humidity and temperature preferences. While total species richness of vascular plants remained relatively similar, species composition changed significantly. Plants endemic to the Robinson Crusoe Islands declined, exotic species increased substantially within the period of ca. 100 years. Further, the relative occurrence frequency of plants with preferences for very warm and humid climate decreased, while the opposite was found for plants preferring drier and colder environments. Potential drivers responsible for this dramatic shift in the vegetation within only one century might have been the large goat population affecting especially small populations of endemic plants and climatic changes. Taking into account a substantial extinction debt, we expect further shifts in the vegetation of this small oceanic island toward alien plants. This would have significant negative consequences on global biodiversity, considering that island floras contribute substantially to global plant species richness due to their high proportion of endemics.

Genetic consequences of cladogenetic vs. anagenetic speciation in endemic plants of oceanic islands.

Adaptive radiation is a common mode of speciation among plants endemic to oceanic islands. This pattern is one of cladogenesis, or splitting of the founder population, into diverse lineages in divergent habitats. In contrast, endemic species have also evolved primarily by simple transformations from progenitors in source regions. This is anagenesis, whereby the founding population changes genetically and morphologically over time primarily through mutation and recombination. Gene flow among populations is maintained in a homogeneous environment with no splitting events. Genetic consequences of these modes of speciation have been examined in the Juan Fernández Archipelago, which contains two principal islands of differing geological ages. This article summarizes population genetic results (nearly 4000 analyses) from examination of 15 endemic species, involving 1716 and 1870 individuals in 162 and 163 populations (with amplified fragment length polymorphisms and simple sequence repeats, respectively) in the following genera: Drimys (Winteraceae), Myrceugenia (Myrtaceae), Rhaphithamnus (Verbenaceae), Robinsonia (Asteraceae, Senecioneae) and Erigeron (Asteraceae, Astereae). The results indicate that species originating anagenetically show high levels of genetic variation within the island population and no geographic genetic partitioning. This contrasts with cladogenetic species that show less genetic diversity within and among populations. Species that have been derived anagenetically on the younger island (1-2 Ma) contain less genetic variation than those that have anagenetically speciated on the older island (4 Ma). Genetic distinctness among cladogenetically derived species on the older island is greater than among similarly derived species on the younger island. An important point is that the total genetic variation within each genus analysed is comparable, regardless of whether adaptive divergence occurs.

Factores psicosociales asociados a la adherencia al tratamiento de la diabetes mellitus tipo 2 / Psychosocial factors associated with adherence to treatment of type 2 diabetes mellitus

Se han reportado bajas tasas de adherencia al tratamiento de enfermedades crónicas (50 por ciento). Asimismo, los factores psicosociales estarían relacionados con la adherencia al tratamiento. Con el propósito de identificar la relación que existe entre factores psicosociales y la adherencia al tratamiento de la DM2 en usuarios del sistema de salud pública chileno, se diseñó un estudio no experimental transversal correlacional (n = 50, edad promedio 60,76 años). Se autoadministraron encuestas para evaluar estrés y estilo de afrontamiento, sintomatología depresiva, percepción de apoyo social y adherencia al tratamiento. 40 por ciento de los pacientes presenta valores de hemoglobina glicosilada (Hb1Ac) mayores a 9 por ciento, mientras que un 66 por ciento de los participantes presenta desde moderados a altos niveles de estrés. En promedio durante los últimos 7 días los participantes han cumplido con la dieta general en 4,37 días, han consumido frutas y verduras en 3,14 días y han realizado exámenes de glicemia en 1,1 días. Existe una correlación directa entre el estrés y la hemoglobina glicosilada. El apoyo social y la sintomatología depresiva no se asociaron con la adherencia al tratamiento pero sí con el estrés. Se confirman pobres cifras de adherencia, y la asociación entre alto estrés y altos índices de Hb1Ac.

It is estimated that rates of non-adherence to chronic diseases are around 50 percent. International studies have reported some psychosocial factors related to treatment adherence. The purpose of the present study was to detect the relationship between psychosocial factors and treatment adherence in a sample of Type 2 Diabetics subjects from a public health institution. To this end, a non - experimental transversal correlational study was designed with a 50 DM2 subjects sample, which average age was 60,76 years old. Self-report measures of stress level, coping style, depressive symptoms, social support perception and treatment adherence, were obtained. The results revealed that 40 percent of participants had glycosylated hemoglobin over 9 percent, and 66 percent of them shown moderate to high stress levels. In average during the last 7 days, the participants have accomplished the diet 4,37 days, consumed fruits and vegetables 3,14 days and took glycemia test in 1,1 days. There is a direct correlation between the stress level and concentrations of glycosylated hemoglobin. Unlike stress, social support and depressive symptomatology was not associated with treatment adherence. These results confirm low levels of treatment adherence and high rates of stress in DM2 patients, as well as its association with high levels of glycosylated hemoglobin.