Thermally adaptive tradeoffs in closely related marine bacterial strains.
Time series studies have shown that some bacterial taxa occur only at specific times of the year while others are ubiquitous in spite of seasonal shifts in environmental variables. Here, we ask if these ubiquitous clades are generalists that grow over a wide range of environmental conditions, or clusters of strain-level environmental specialists. To answer this question, vibrio strains isolated at a coastal time series were phylogenetically and physiologically characterized revealing three dominant strategies within the vibrio: mesophiles, psychrophiles and apparently generalist broad thermal range clades. Thermal performance curves from laboratory growth rate experiments help explain field observations of relative abundances: the mesophilic clade grows optimally at temperatures 16°C higher than the psychrophilic clade. Strains in the broad thermal range clade all have similar optimal growth temperatures but also exhibit temperature-related tradeoffs with faster growth rates for warm temperature strains and broader growth ranges for strains from cool temperatures. Moreover, the mechanisms of thermal adaptation apparently differ based on evolutionary time scales: shifts in the temperature of maximal growth occur between deeply branching clades but thermal performance curve shape changes on shorter time scales. Thus, apparently ubiquitous clades are likely not generalists, but contain subclusters with distinct environmental preferences.
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.
Cheuk-Man
CM
Yung
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.
Marissa K
MK
Vereen
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.
Amy
A
Herbert
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.
Katherine M
KM
Davis
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.
Jiayu
J
Yang
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.
Agata
A
Kantorowska
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.|Integrated Toxicology and Environmental Health Program, Duke University, Durham, NC, 27708, USA.
Christopher S
CS
Ward
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.
Jennifer J
JJ
Wernegreen
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.|Biology Department, Duke University, Durham, NC, 27708, USA.
Zackary I
ZI
Johnson
Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.|Biology Department, Duke University, Durham, NC, 27708, USA.
Dana E
DE
Hunt
D000064:Acclimatization / Q000235:genetics / Q000502:physiology*; D005075:Biological Evolution; D017753:Ecosystem; D006358:Hot Temperature; D010802:Phylogeny; D010933:Plankton / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D014733:Vibrio / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*