Gene transfer drives community cooperation in geothermal habitats.

Abstract

Cyanidiophyceae red algae dominate many geothermal habitats and provide important tools for investigating the evolution of extremophilic eukaryotes and associated microbial communities. We propose that resource sharing drove genome reduction in Cyanidiophyceae and enabled the neofunctionalization of genes in multi-enzyme pathways. Utilizing arsenic detoxification as a model, we discuss how the sharing of gene functions by other members of the microbial assemblage weakened selection on homologs in the Cyanidiophyceae, allowing long-term gene persistence via the putative gain of novel functions. This hypothesis, referred to as the Integrated Horizontal Gene Transfer (HGT) Model (IHM), attempts more generally to explain how extremophilic eukaryotes may have transitioned from 'hot start' milieus by functional innovations driven by the duplication and divergence of HGT-derived genes.