Study of plastic marine debris (PMD) has revealed widespread distribution of plastics within the ocean, and investigated how PMD influences marine ecosystems. However, few studies have investigated microorganismal interactions with PMD. I addressed this gap by studying the development and structure of PMD colonizing microbial communities. Plastic resin samples including polyethylene, polypropylene, polystyrene and a glass control were submerged in the waters of Woods Hole, MA and sampled from 1 week to 6 months after immersion. Microbial community structure was analyzed over time with scanning electron microscopy (SEM) and next generation sequencing of the 16S rRNA sequence. Next generation sequencing provided comprehensive taxonomic data allowing analysis of community structure over time. Analysis of Bray-Curtis dissimilarity values and community membership over time showed the glass and plastic colonizing communities were largely similar in structure. SEM micrographs allowed the calculation of diatom abundance and observation of ecological interactions. 16S and SEM data both reported patterns in community development of initial autotroph dominance followed by a decline and replacement by heterotrophic groups. These results enhance our understanding of the succession and community structure of PMD colonizing microorganisms.
Andinia Luer (Orchidaceae: Pleurothallidinae) is a small genus from the Andes mountains. Generic circumscriptions within the large subtribe Pleurothallidinae have been under debate as newer molecular evidence aims to correct polyphyletic genera that were created based on potentially homoplasious floral characteristics. Data from the nuclear internally transcribed spacer (ITS) gene region have previously indicated that Andinia should be expanded to include the pleurothallid genera Neooreophilus, Masdevalliantha, and Xenosia. In this study, phylogenetic trees were constructed from an expanded ITS data set, a new data set from the matK gene of the plastid genome, and composite of the two sequences. This broader phylogenetic analysis shows strong support for the monophyly of an expanded Andinia, reinforcing the original recommendation that Andinia be expanded. Additionally, scanning electron microscopy (SEM) was used to image morphological floral characteristics from an array of species spanning the breadth of the analyzed taxa. SEM images suggest multiple pollinator attraction strategies within Andinia sensu lato. Many of the floral characteristics and inferred pollinator attraction strategies are evident elsewhere in Pleurothallidinae, supporting the idea that certain floral characteristics have evolved multiple times and are therefore unreliable for organizing Pleurothallidinae.