We show that gyrotactic motility within a steady vortical flow leads to tightly clustered aggregations of microorganisms. Two dimensionless numbers, characterizing the relative swimming speed and stability against overturning by vorticity, govern the coupling between motility and flow. Exploration of parameter space reveals a striking array of patchiness regimes. Aggregations are found to form ...

Patchiness of marine microbial communities has an important influence on microbial activities in the ocean, particularly in the oligotrophic open ocean where bioavailable nutrients are otherwise scarce. Such spatial heterogeneity is present in associations with dead and living particles, including zooplankton. The microbial community composition of mesozooplankton was investigated from the Sarg...

The relationship between DNA methylation and chromatin structure is still largely unknown. By analyzing a large set of published sequencing data, we observed a long-range power law correlation of DNA methylation with cell class-specific scaling exponents in the range of tens of kilobases. We showed that such cell class-specific scaling exponents are caused by different patchiness of DNA methyla...

The abundance and distribution of natural populations of soil organisms can be influenced greatly by the types and arrangement of habitat patchiness within a landscape. Most animal populations inhabit a variety of different habitats, even within a relatively small geographic region. The aim of our research was to determine how abiotic and biotic environmental factors, including small shrub cano...

The only thing about Nature that is certain and absolute is patchiness in space and time. All landscapes are patchy over a range of scales as consequences of natural and anthropogenic processes. To understand the dynamics of hierarchically structured, heterogeneous systems, models are important in several ways. Models can be used to generate new hypotheses, to clarify and test existing hypothes...

The importance of spatial pattern in ecosystems has long been recognized. However, incorporating patchiness into our understanding of forces regulating ecosystems has proved challenging. We used a combination of continuously sampling moored sensors, complemented by shipboard sampling, to measure the temporal variation, abundance and vertical distribution of four trophic levels in Hawaii's near ...

Remote sensing data type, classification technique and class description act together to produce, large differences in the classification of landcover. The resulting map will vary in the extent, patchiness and accuracy of classified areas. Differences in the classification of a landcover map are the result inter-relationships between a number of scale dependent factors such as pixel size, exten...

Phytoplankton blooms are geochemically and ecologically important, but current understanding of the causes of phytoplankton blooms provides little power to predict the timing, extent, and distribution of blooms. In this thesis, I discuss the implications of light limitation for phytoplankton bloom patchiness and community structure by modeling phytoplankton as reacting tracers in a reaction-adv...

†Background Patchy stomatal conductance is a poorly understood and little-studied phenomenon. It is relatively common, yet it appears to be detrimental to water-use efficiency under some conditions and has no immediately obvious physiological function of any kind. Much of the difficulty in studying patchy stomatal conductance is tied to its unpredictability, both in occurrence and in characteri...

This study explored the persistence and spatial distribution of a diverse Archaeal assemblage inhabiting a temperate mixed forest ecosystem. Persistence under native conditions was measured from 2001 to 2010, 2011, and 2012 by comparison of 16S rRNA gene clone libraries. The Archaeal assemblages at each of these time points were found to be significantly different (AMOVA, P < 0.01), and the nat...