Ecology of Trifolium stoloniferum (Muhl. ex A. Eaton), a federally endangered vascular plant, at the Fernow Experimental Forest in West Virginia

This thesis presents work addressing the ecology of Trifolium stoloniferum, a federally endangered vascular plant species, in the Fernow Experimental Forest, West Virginia. In this thesis, I describe the historical ecology of this species and make a case that at one time it occurred in great abundance in association with trails created by large mammals and humans that intersected rich, open forests. Similar conditions exist at the Fernow Experimental Forest in West Virginia, but instead of large mammals, the requisite soil disturbance, control of competing vegetation, and canopy perforation are created by timber-harvesting related disturbances, particularly gap creation by tree felling and skidding of trees from the forest.;I conducted two distinct studies to quantitatively and qualitatively describe the habitat conditions that promote T. stoloniferum success. The first study occurred at the scale of a forested stand. At the level of the stand, total number of logging-related disturbances since 1945 was the most important characteristic in determining the presence or absence of the species, with greater number of disturbances strongly related to the presence of the species. Time since last disturbance and aspect interacted to affect T. stoloniferum density within a stand, with west-facing stands that had been disturbed more recently than 14.5 years supporting the greatest densities of T. stoloniferum. This study revealed that stands managed in uneven-aged silvicultural systems with frequent management entrances that also received high levels of light were most capable of supporting vigorous occurrences of T. stoloniferum..;The second study consisted of a detailed habitat assessment of T. stoloniferum patches. I stratified patches at the Fernow Experimental Forest based upon patch abundance and inflorescence production and conducted detailed habitat assessment of a representative sample of patch sizes and relative inflorescence production. I assessed the vegetation, substrate, physiography, and localized disturbance history, and also took canopy photographs using a hemispherical lens. Patch abundance was the result of a suite of interactions between canopy structure, tree basal area, and disturbance history. Abundant sites also had high diversity of associated herbaceous species, suggesting that good sites for T. stoloniferum are also good for a suite of early and mid-successional forest herbs. Inflorescence production was the consequence of light levels, with high light levels associated with increased inflorescence production.;The management and conservation of Trifolium stoloniferum should focus on maintaining and encouraging those processes and activities that periodically disturb soil and create light gaps in mixed, mesophytic forests. In addition to the deliberate efforts of managers, incidental management opportunities, or situations in which the promotion of T. stoloniferum is an unintended outcome, should be identified and fostered

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Local and regional factors influence the structure of treehole metacommunities

Abstract Background Abiotic and biotic factors in a local habitat may strongly impact the community residing within, but spatially structured metacommunities are also influenced by regional factors such as immigration and colonization. We used three years of monthly treehole census data to evaluate the relative influence of local and regional factors on our study system. Results Every species responded to at least one of three local environmental factors measured: water volume, leaf litter mass, and presence of a top predator. Several species were affected by water volume, and a non-exclusive group of species were influenced by leaf litter mass. Relative abundance of Aedes triseriatus was higher in treeholes with higher volumes of water, and relative abundances of three out of six other species were lower in treeholes with higher volumes of water. Leaf litter mass positively affected densities of Aedes triseriatus and relative abundance of several dipteran species. The density of the top predator, Toxorhynchites rutilus, affected the relative abundance of the two most common species, A. triseriatus and Culicoides guttipennis. Treeholes with T. rutilus had an average of two more species than treeholes without T. rutilus. We found little evidence of synchrony between pairs of treeholes, either spatially or temporally. There were high levels of spatial and temporal turnover, and spatial turnover increased with distance between patches. Conclusion The strong effects of water volume, leaf litter mass, and presence of a top predator, along with the high temporal turnover strongly suggest that species presence and density are determined by local factors and changes in those factors over time. Both low water volume and high predator densities can eliminate populations in local patches, and those populations can recolonize patches when rain refills or predators exit treeholes. Population densities of the same species were not matched between pairs of treeholes, suggesting variation in local factors and limited dispersal. Distance effects on spatial turnover also support limitations to dispersal in the metacommunity, and we conclude that the weight of evidence favors a strong influence of local factors relative to regional factors.</p

Occurrence of Carcharhinus isodon (Finetooth Shark) in Florida Bay

Carcharhinus isodon (finetooth shark) is a migratory shark found in coastal waters of the southeastern United States and is well documented in the waters of north Florida in both the Gulf of Mexico and the Atlantic Ocean. The southernmost reports are from Lemon Bay (27°N), just north of Charlotte Harbor on the west coast and from Port Salerno (27°N) on the east coast. Four C. isodon were captured on bottom-set longline in Florida Bay, just north of 25°N latitude, during routine sampling for Pristis pectinata (smalltooth sawfish). These captures extend the southern range of C. isodon in Florida to approximately 25°N and increase the likelihood of exchange between the Atlantic and Gulf stocks