Thalassia testudinum is prevalent throughout the western tropical Atlantic, Gulf of Mexico, and Florida. This seagrass inhabits a wide range of coastal ecosystems and published data suggest significant morphological variation in T. testudinum across acute physicochemical environmental gradients. Strong reliance on vegetative growth provokes expectations of a clonal signature in the population structure of this species. We utilize high resolution genetic data to explore the population structure of T. testudinum and evaluate the basis for this species' plasticity as a function of a phenotypic versus a genotypic response. We studied one of the largest populations of T. testudinum, the Florida Bay system, and found that the population exhibited high levels of genetic diversity suggesting strong recruitment of sexually derived propagules. Allelic richness was high (A RIC = 5.94 to 7.33) and expected heterozygosity was consistently high across our study subpopulations (H e = 0.558 to 0.673). There was no evidence of inbreeding within subpopulations (F IS = 0.02 to 0.13) and overall gene flow estimates were moderate to high (N m = 5.71). These data support T. testudinum in Florida Bay as a single metapopulation with high genetic connectivity among subpopulations. Models of migration utilizing Bayesian modeling revealed a distinct directionality to immigration counter to models of historical formation of Florida Bay. We also found no evidence that meadows formed genetic subpopulations suggesting morphological variability observed across environmental gradients represents norms of reaction within the genetically diverse, interbreeding metapopulation. We suggest T. testudinum evolved phenotypic plasticity as a general purpose trait under natural selection.

OBJECTIVE -Although suboptimal glycemic control is known to be common in diabetic adults, few studies have evaluated factors at the level of the physician-patient encounter. Our objective was to identify novel visit-based factors associated with intensification of oral diabetes medications in diabetic adults.RESEARCH DESIGN AND METHODS -We conducted a nonconcurrent prospective cohort study of 121 patients with type 2 diabetes and hyperglycemia (A1C Ն8%) enrolled in an academically affiliated managed-care program. Over a 24-month interval (1999 -2001), we identified 574 hyperglycemic visits. We measured treatment intensification and factors associated with intensification at each visit.RESULTS -Provider-patient dyads intensified oral diabetes treatment in only 128 (22%) of 574 hyperglycemic visits. As expected, worse glycemia was an important predictor of intensification. Treatment was more likely to be intensified for patients with visits that were "routine" CONCLUSIONS -Failure to intensify oral diabetes treatment is common in diabetes care. Quality improvement measures in type 2 diabetes should focus on overcoming inertia, improving continuity of care, and reducing racial disparities.

Many ecosystems are experiencing rapid transformations due to global environmental change. Understanding how ecological shifts affect species persistence is critical to modern management strategies. The edge of a species range is often where physiological tolerances are in conflict with ability to persist. Extreme examples of clonality over large spatial and temporal scales can occur where the life history of a species allows for it. We examine extreme clonality in an aquatic plant species at the edge if its range. Here we describe an ancient seagrass clone of unprecedented size inhabiting a 47 km stretch of a central Florida estuary, the Indian River Lagoon (IRL). Amongst the largest clones on earth detected, this Thalassia testudinum (turtlegrass) genet had ramets dispersed across 47 km of this water body. Indeed among 382 samples collections along the length of the IRL, 89% were a single shared multilocus genotype. Furthermore, this clone was the only genet detected at 63% of sample sites. The presence of such a large clone demonstrates they can form and persist over long periods. In addition, we must challenge the paradigm that fragmentation is not possible in this species. Reliance on clonality is an expected component of a classic ‘bet-hedging’ strategy enabling persistence on timescales typically not considered, including millennia. At locations near ocean inlets we did find a few other individuals of T. testudinum supporting the concept that recruitment is dispersal limited. These additional clones indicate there is the potential, albeit limited, for seeds based recruitment to occur when environmental conditions are favorable during a “window of opportunity.” Extreme clonality represents a potential strategy for survival such that in the extreme, clonal populations of a species would be the first to decline or disappear if conditions extend beyond the adaptability of the local genotype. This disappearance possibility makes the species a potential sentinel of system decline.

Seagrasses are a diverse group of clonal marine macrophytes. Their disappearance in recent decades has been an alarming component of estuarine urbanization, effectively transitioning vast portions of global coverage to disturbed or recovering states. Understanding dispersal and recruitment patterns within and among extant populations is now vitally important to predicting both the form and pace of recovery. Working with a perennial ecotype of Zostera marina within a shallow lagoon in Long Island, New York, U.S.A., we combined high resolution, decade-long seagrass mapping with polymorphic microsatellite analysis to examine the interactive effects of pollination and seed dispersal distance on the dynamics of sexual recruitment across a range of spatial scales (centimeters to decameters). We found clone structure to be restricted to less than three meter across a 56,250-m 2 study site. Pollination distances ranged from 0.57 m to 73.91 m, while seed dispersal varied systematically from 1.85 m to 5.31 m for naked seeds, and randomly throughout the study site (0.17 m to 34.54 m) for seeds deposited by floating reproductive shoots. Pedigree analyses corroborated these findings, with full sibling groups clustering neatly within larger half-sibling kinships at spatial scales of 2-6 m. We successfully demonstrate that over a four-year period sexual reproduction and seedling recruitment played appreciable roles in the colonizing process of Z. marina, configuring the landscape through the deposition of rafted seeds, and contributing to patch expansion via the limited dispersal of naked seeds.