The presence of endosymbiotically derived organelles with their own genomes (mitochondria and plastids) is a defining characteristic of eukaryotes, but the mechanisms by which these genomes are maintained and expressed differs wildly across the eukaryotic tree of life. I will present work from our group on how fundamental features of DNA repair and gene expression in plant organelles contrast with other eukaryotic lineages and how these differences have been shaped by horizontal/endosymbiotic gene transfer events. Specifically, I will show how plant MSH1, an enigmatic member of the MutS DNA repair family that was likely acquired from giant viruses, is responsible for the remarkably low mutation rates in land plant organelle genomes. In addition, I will describe how bacterial-like MutS2 genes were acquired via plastid endosymbiosis and, thus, distinguish plants from other eukaryotic lineages. Recent work in our lab suggests that these genes play key roles in maintaining plant organelle gene expression. Therefore, peculiarities of the Central Dogma of Molecular Biology in plant organelles reflect their complex evolutionary history and acquisition of foreign MutS genes.

Soil is the most biodiverse habitat on Earth and regulates global biogeochemical cycles. This "life support system" provides crucial resources for humanity. However, it has been degraded by past land-use practices and is increasingly threatened by changing climatic conditions, as well as the pressures resulting from growing populations and economies. Microbes play a vital role in soil function, and consequently, our understanding of soil function and our ability to predict it are limited by our knowledge of the functional traits of soil microbes, most of which may never be cultivated for isolated study.

Advancements in technology continue to unveil new lineages and hypothesized functions of soil microbes. Importantly, the functions of soil microbes can now be linked within 'species' units by directly assembling genomes from soil communities. To address the complexity of soil microbiomes we have developed a hierarchical trait-based approach that distills microbial functional diversity into tractable units (guilds). In this seminar, I will discuss recent work harnessing the expanding resource of soil bacterial and archaeal genomes to investigate trait variation and trait linkage. I will also present our research on the development of trait-based models, including a novel approach to derive parameters for uptake kinetics directly from genomes, and provide examples of emergent behavior resulting from the interactions of metabolic, thermodynamic, and life history traits. Finally, I will conclude by sharing some thoughts and examples of how to apply these data-driven microbial simulation approaches to complex ecosystems.

In this talk I will discuss the use of monkeyflowers to probe the genetic and molecular bases of floral trait variation among species, to characterize the developmental mechanisms of pattern formation, and to test the adaptive significance of floral trait variation in the evolution of pollination syndromes.