Good alpha taxonomy is central to biology. On the basis of a survey of arthropod studies that used multiple disciplines for species delimitation, we evaluated the performance of single disciplines. All included disciplines had a considerable failure rate. Rigor in species delimitation can thus be increased when several disciplines chosen for complementarity are used. We present a flexible procedure and stopping rule for integrative taxonomy that uses the information from different disciplines separately. Disagreement among disciplines over the number and demarcation of species is resolved by elucidating and invoking evolutionary explanations for disagreement. With the identification of further promising study organisms and of new questions for in-depth analysis, evolutionary biology should profit from integrative taxonomy. An important rationale is clarity in researcher bias in the decision-making process. The success of integrative taxonomy will further increase through methodological progress, taxonomic training of evolutionary biologists, and balanced resource allocation.

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Spatial modelling of species distributions has become an important tool in the study of biological invasions. Here, we examine the utility of combining distribution and ecological niche modelling for retrieving information on invasion processes, based on species occurrence data from native and introduced ranges. Specifically, we discuss questions, concerning (1) the global potential to spread to other ranges, (2) the potential to spread within established invasions, (3) the detectability of niche differences across ranges, and (4) the ability to infer invasion history through data from the introduced range. We apply this approach to two congeneric pavement ants, Tetramorium sp.E (formerly T. caespitum (Linnaeus 1758)) and T. tsushimae Emery 1925, both introduced to North America. We identify (1) the potential of both species to inhabit ranges worldwide, and (2) the potential of T. sp.E and T. tsushimae, to spread to 23 additional US states and to five provinces of Canada, and to 24 additional US states and to one province of Canada, respectively. We confirm that (3) niche modelling can be an effective tool to detect niche shifts, identifying an increased width of T. sp.E and a decreased width of T. tsushimae following introduction, with potential changes in niche position for both species. We make feasible that (4) combined modelling could become an auxiliary tool to reconstruct invasion history, hypothesizing admixture following multiple introductions in North America for T. sp.E, and a single introduction to North America from central Japan, for T. tsushimae. Combined modelling represents a rapid means to formulate testable explanatory hypotheses on invasion patterns and helps approach a standard in predictive invasion research.

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Mutualism, whereby species interact to their mutual benefit, is extraordinary in a competitive world. To recognize general patterns of origin and maintenance from the plethora of mutualistic associations proves a persisting challenge. The simplest situation is believed to be that of a single mutualist specific to a single host, vertically transmitted from one host generation to the next. We characterized ascomycete fungal associates cultured for nest architecture by the ant subgenera Dendrolasius and Chthonolasius. The ants probably manage their fungal mutualists by protecting them against fungal competitors. The ant subgenera display different ant-to-fungus specificity patterns, one-to-two and manyto-one, and we infer vertical transmission, in the latter case overlaid by horizontal transmission. Possible evolutionary trajectories include a reversal from fungiculture by other Lasius subgenera and inheritance of fungi through life cycle interactions of the ant subgenera. The mosaic indicates how specificity patterns can be shaped by an interplay between host life-cycles and transmission adaptations.insect fungiculture ͉ Lasius ants ͉ mutualism ͉ social insects C ooperation is improbable (1, 2) and it is only through evolution that these interactions become reliable for the players. Cooperation is needed to forge new levels of organization, from genomes to human society (2). Mutualism, species interactions beneficial for all players, offers some of the most arresting cases of evolution (3). These cases stimulated the development of theoretical frameworks on the why and how of mutualism (e.g., refs. 3-7), but true life examples are needed to test any hypothesis (8). Finding suitable model systems is not a trivial task (9). Only a fraction of the extant associations have been studied (10), with the number and identities of the players often unknown.Insect fungiculture provides prime systems for studying mutualism (11). The New World attine ants (Myrmicinae: Attini) that cultivate fungi for food have especially served as models for investigating host-use specificity and transmission patterns (12-15). Another ant-fungus association has been less investigated: Old World Lasius ants (Formicinae) of the subgenera Dendrolasius and Chthonolasius nourish fungi with honeydew to bind shredded wood or soil into a composite building material (16,17). The fungi are used for reinforcement of the nest walls, which allows building stable nests in tree and soil cavities. Little has been known about the associations' phylogenetic and ecological specificities, and the transmission mode, but it has been generally accepted (18) that the Lasius-fungi associations are simple with each of the two subgenera culturing a single fungus (19)(20)(21)(22). Chthonolasius and Dendrolasius are both obligate temporary social parasites, i.e., young queens enter an established colony of another Lasius subgenus and replace the queen. Dendrolasius is confined to the Palearctic and hyperparasitizes Chthonolasius (16). Chthonolasius exhibits complexity wit...