Table 2.

Comparison of models explaining microbial nutrient response with microbial life history strategy defined at different taxonomic levels.

Assignment of life history strategy	df	ΔAICC-trt	ΔAICCN-trt
Genus	9	0	0
Family	9	50.3	104.5
Order	9	65.3	129.5
Class	9	92.5	158.8
Phylum	9	92.5	158.8
No life history strategy	8	103.0	166.8

Results from the hierarchical linear models on the responses of bacterial amplicon sequence variants (ASVs) to carbon (C-trt) and carbon and nitrogen (CN-trt) addition. ΔAIC represents the model fit of hierarchical models describing the relationship between joint ¹⁸O–¹³C enrichment (condensed via principal components analysis) and life history strategy (i.e., whether organisms were identified as oligotrophic or copiotrophic). Life history strategy of ASVs was inferred based on whether the average measured nutrient response of a taxonomic group was clustered into a high or low growth category as determined by gaussian finite mixture models. Life history strategies were made at increasingly finer levels of taxonomic organization (i.e., phylum, class, order, family, and then genus). df indicates model degrees of freedom.