Julia Van Etten

1 Introduction Horizontal genetic transfer (HGT) is a driver of genomic novelty in prokaryotes and more recently, its significance has become recognised in eukaryotes (Ochman, Lawrence, and Groisman 2000; Koonin, Makarova, and Aravind 2001; Dagan, Artzy-Randrup, and Martin 2008; Corel et al. 2018; Soucy, Huang, and Gogarten 2015; Van Etten and Bhattacharya 2020).

Abstract We investigated an alga-dominated geothermal spring community in Yellowstone National Park, USA. Our goal was to determine how cells cope with abiotic stressors during diurnal sampling that spanned over two orders of magnitude in solar irradiance. We report a community level response to toxic metal resistance and energy cycling that spans the three domains of life. Arsenic detoxification is accomplished via complementary gene expression by different lineages.

INTRODUCTION Horizontal genetic transfer (HGT), once deemed highly unlikely in eukaryotes due to the presence of a nuclear envelope and in many cases, a sequestered germline, is now accepted as a common feature across the tree of life (Van Etten & Bhattacharya, 2020). Yet, the mechanisms that drive HGT persistence and integration into host pathways are poorly understood.