Taxonomic sufficiency in ecological studies of terrestrial invertebrates

The concept of taxonomic sufficiency (identifying organisms only to a level of taxonomic resolution sufficient to satisfy the objectives of a study) h as received little attention in ecological studies of terrestrial invertebr ate assemblages. Here we critically evaluate three approaches to taxonopnic sufficiency: the use of morphospecies, genera and functional groups. The o bjective was to compare estimates of richness (alpha diversity) and turnove r (beta diversity) of ant. assemblages generated by these data with estimat es produced using data for ant species. Ground-active ants were sampled usi ng pitfall trapping within three habitat types: a eucalypt plantation, wood land regrowth patches and the surrounding grassland at a study site in the upper Hunter Valley, New South Wales. Comparisons of assemblage richness an d turnover among taxonomic data sets and habitats and after different data transformations used univariate (simple correlation and ANOVA) and multivar iate (Mantel tests, ANOSIM and SSHMDS) techniques. Our study found: (i) mor phospecies and genus richness was highly correlated with species richness a er the study area; (ii) ordination scatterplots using species, morphospeci es and genus data revealed similar patterns of site separation for the thre e habitats; (iii) the results were very similar using untransformed, log tr ansformed and binary data; (iv) functional group ordinations separated all three habitat types for untransformed abundance data; and (v) estimates of species turnover were highly correlated with estimates of morphospecies and genus turnover. These results are discussed in relation to future monitori ng of ant community structure.