Shape and evolution of the fundamental niche in marine Vibrio

Abstract

Hutchinson’s fundamental niche, defined by the physical and biological environments in which an organism can thrive in the absence of inter-species interactions, is an important theoretical concept in ecology. However, little is known about the overlap between the fundamental niche and the set of conditions species inhabit in nature, and about natural variation in fundamental niche shape and its change as species adapt to their environment. Here, we develop a custom-made dual gradient apparatus to map a cross-section of the fundamental niche for several marine bacterial species within the genus Vibrio based on their temperature and salinity tolerance, and compare tolerance limits to the environment where these species commonly occur. We interpret these niche shapes in light of a conceptual model comprising five basic niche shapes. We find that the fundamental niche encompasses a much wider set of conditions than those strains typically inhabit, especially for salinity. Moreover, though the conditions that strains typically inhabit agree well with the strains’ temperature tolerance, they are negatively correlated with the strains’ salinity tolerance. Such relationships can arise when the physiological response to different stressors is coupled, and we present evidence for such a coupling between temperature and salinity tolerance. Finally, comparison with well-documented ecological range in V. vulnificus suggests that biotic interactions limit the occurrence of this species at low-temperature—high-salinity conditions. Our findings highlight the complex interplay between the ecological, physiological and evolutionary determinants of niche morphology, and caution against making inferences based on a single ecological factor.

A Small Number of Phylogenetically Distinct Clonal Complexes Dominate a Coastal Vibrio cholerae Population

“…The lagoon waters also generally exhibit higher salinity levels than the pond (5 to 10 ppt versus 0 to 5 ppt). CCs might differ in their growth rates at different salinities, although V. cholerae displays species-wide tolerances to salinities far exceeding those found in this lagoon (26,47). A possible indirect influence of location in the different prevalence of these CCs is the composition of the prokaryotic microbiota of the pond and lagoon, as abundances of bacterial taxa have been shown to correlate stronger with each other than with abiotic factors or eukaryotes in marine environments (48).…”

Multiple stressor interactions influence embryo development rate in the American horseshoe crab, Limulus polyphemus

“…Construction of niche-space models has been applied to predicting how global climate change and increasing sea surface temperatures will influence the spatial distribution of the marine copepod Calanus finmarchicus (Beaugrand et al, 2013), and the fundamental niche has been described for the water flea Daphnia magna along a pH and calcium gradient (Hooper et al, 2008;Materna et al, 2012). In these examples, the constructed fundamental niche was used to predict the distribution of the organism in natural habitats.…”

The Ecological Coherence of Temperature and Salinity Tolerance Interaction and Pigmentation in a Non-marine Vibrio Isolated from Salar de Atacama

“…This resemblance could explain a linking between physiological, ecological and evolutionary aspects in determining their niche shapes (Materna et al, 2012). Moreover, the coupling between temperature and salinity tolerance might be explained by the effect of chaotropic ions (like chloride) that may counter the macromolecular rigidification induced by low temperature (Chin et al, 2010).…”