Causal mechanisms explaining a species' environmental requirements are rooted in species traits (e.g. diapausing eggs, parental care, development time). By investigating interrelations between traits and interpreting their function, it was possible to define 'sets of co-adapted traits designed by natural selection to solve particular ecological problems', which are termed life-history tactics. Species with alternative suites of traits that solved environmental problems in a similar way were assigned to the same tactic. This provided a functional classification spanning species from different systematic groups.

Data on aquatic macroinvertebrates from 45 pools were analyzed to test whether these theoretically derived life-history tactics provided insight in the functioning of existent water types for aquatic macroinvertebrates. Based on differences in abiotic conditions (acidity, dimensions en trophic status) the sampled pools were grouped in 8 water types.

Results show large and significant differences in tactic composition between the different water types, which could be related to the prevailing environmental conditions through mechanistic explanations.

Life-history tactics can aggregate information over many different species without sacrificing information on the underlying causal mechanisms. Therefore, life-history tactics can be used to reduce often very complex, biodiverse assemblages into a few meaningful, easily interpretable relationships.