Niche Partitioning Among Prochlorococcus Ecotypes Along Ocean-Scale Environmental Gradients

Abstract

Prochlorococcus is the numerically dominant phytoplankter in the oligotrophic oceans, accounting for up to half of the photosynthetic biomass and production in some regions. Here, we describe how the abundance of six known ecotypes, which have small subunit ribosomal RNA sequences that differ by less than 3%, changed along local and basin-wide environmental gradients in the Atlantic Ocean. Temperature was significantly correlated with shifts in ecotype abundance, and laboratory experiments confirmed different temperature optima and tolerance ranges for cultured strains. Light, nutrients, and competitor abundances also appeared to play a role in shaping different distributions.

Phytoplankton community structure in relation to vertical stratification along a north‐south gradient in the Northeast Atlantic Ocean

“…The contribution to total biomass (i.e., 32% and 48% in the spring and summer, respectively) and geographic distribution of Prochlorococcus are both in the upper range of those reported in the literature (i.e., 21-43% and typically found 408S-458N; Johnson et al 2006;Whitton and Potts 2012). The northern edge of the distribution of Prochlorococcus coincided closely with a reduction in temperature, supporting evidence that temperature acts as a critical factor regulating the distribution of this genus (Johnson et al 2006;Zinser et al 2007;Flombaum et al 2013).…”

“…The contribution to total biomass (i.e., 32% and 48% in the spring and summer, respectively) and geographic distribution of Prochlorococcus are both in the upper range of those reported in the literature (i.e., 21-43% and typically found 408S-458N; Johnson et al 2006;Whitton and Potts 2012). The northern edge of the distribution of Prochlorococcus coincided closely with a reduction in temperature, supporting evidence that temperature acts as a critical factor regulating the distribution of this genus (Johnson et al 2006;Zinser et al 2007;Flombaum et al 2013). The ubiquity and numerical dominance of Prochlorococcus within stratified oligotrophic waters of the world's oceans is thought to be a consequence of both genetic streamlining (and subsequent reduction in cell size), and diversity in genomic evolution within the genus facilitating a range of niche partitioning (Partensky and Garczarek 2010).…”

Evaluating community–environment relationships along fine to broad taxonomic resolutions reveals evolutionary forces underlying community assembly

“…For example, the best taxonomic resolution and key environmental factor might differ when considering whole prokaryotic communities versus focusing on a particular taxonomic group (Johnson et al, 2006;Martiny et al, 2009). The main objective of this study is to demonstrate the potential of our approach, which assesses community-environment relationships while taking into consideration hierarchical taxonomic information and the concept of phylogenetic niche conservatism; rather than stressing specific conclusions associated with any particular data set.…”

Subspecies in the global human gut microbiome

“…Subspecies showing adaptation to different environments are also referred to as “ecotypes”, a prominent example being the ocean‐dwelling Prochlorococcus spp. (Johnson et al , 2006), for which specific subspecies are specialized for different environmental conditions (Biller et al , 2014). In regard to the human microbiome, extensive work has been undertaken to characterize population structure and describe subspecies in species that include pathogenic bacteria, such as Escherichia coli , different Salmonella species, and a few others, for which multiple typing schemes exist (Gordienko et al , 2013; Chakraborty et al , 2015; Bale et al , 2016; Sharma et al , 2016), but not for the vast majority of human gut commensals.…”