Metapopulations in miniature: connectivity, subpopulation extinction, and recovery in microbial microcosms

摘要: Author(s): Kurkjian, Helen | Advisor(s): Simms, Ellen L Abstract: Metapopulations occupy spatially divided habitats and understanding how that fragmentation affects their survival, growth, dispersal, persistence is critical to conservation. Researchers in many sub-fields of ecology evolutionary biology test hypotheses relating metapopulation dynamics landscape spatial structure. Key aspects these are sometimes (a) large numbers subpopulations dispersal corridors (b) positions relative each other. Comparing such using traditional lab equipment methods impractical, unwieldy, expensive, or impossible.I invented the Metapopulation Microcosm Plate (MMP) overcome drawbacks. This device resembles a 96-well microtiter plate; 96 wells represent habitat patches they connected by can be modified position create various artificial landscapes, with hundreds non-intersecting varying lengths. The filled nutrient broth used culture microbial metapopulations.In Chapter One, I first demonstrate bacterial travel time significantly faster through MMP shorter, but unaffected corridor vertical within plate. Thus, MMPs satisfy necessary assumptions for use experiments. Furthermore, bacteria fully functional flagella was than disabled flagella, indicating actively swim corridors, rather traveling simple diffusion. account behavioral responses. have previously been prohibitively difficult test. Further, incorporating individual responses within-patch conditions, incorporate greater realism do directed pipetting other methods.In Two, explore recolonization recovery after subpopulation extinction differs metapopulations which different arrangements. Some spread relatively evenly space homogeneous arrangement most few neighbors, while others clustered heterogeneous arrangement, creating highly leaving only one two neighbors. Graph theory empirical data from biological non-biological networks suggest should robust extinction. Here, compared arrangements following small, medium, events. found had fastest rates events all sizes shortest absolute medium-sized events, smallest Finally, Three conducted an experiment whether recover more slowly extinctions targeted at high connectivity random low subpopulations. Simulations World Wide Web demonstrated that, very loss nodes, attacks on nodes lead failure entire network. Based simulations, predicted would when occurred wells, regardless event size. Unlike theoretical networks, however, cultured cannot completely homogeneous, because edge will slightly less those center. However, small deviation unimportant not affected were wells. Instead, both medium levels subpopulations, recovered quickly went extinct, work demonstrates theory, especially involving corridors. shown extinction, rate translates shorter larger smaller go targeted. suggests may help alleviate effects some circumstances, exacerbate them others.