P. J. DEN BOER & Th. S. Van DIJK Biological Station, Wijster, The Netherlands LIFE-HISTORY PATTERNS AMONG CARAB SPECIES yBRARY m 2 w 6 Den Boer, P. J. & Th. S. Van Dijk, 1996. 'Lite-history pattpiïiS among carabid species. -Tijdschrift voor Entomologie 139: 1-16, ^N^tableT *l-3. [ISSN 0040-7496]. Published 15 October 1996. Evolutionary biologists aim to get a grip on evolutionary processes by assuming that natural se-lection would control special life-history traits, which are assumed to promote the fitness of species. With the help of models they try to explain the effect of special life-history traits in the evolution of life histories in general. Many of the models used are, in fact, extensions of the con-cept of r and K selection or are based on similar deterministic ideas. Examples of vertebrates are usually preferred, though invertebrates are thought to be subject to the same 'rules'. In the pres-ent paper by comparing the more generally occurring life-history traits among carabid species it is tried to find out which life-history traits dominate the life histories of West-European cara-bid species. Most of these traits governing the populations of carabid species of Drenthe (the Netherlands) appear to differ from those advanced by evolutionary biologists. 'Dispersal pow-er' and 'turnover frequency' are especially significant. They show remarkable departures from the generally accepted schemes. These divergencies are explained and the possible causes of di-verging life-history traits among carabid species are discussed. The need to do more compara-tive investigations of life-history traits in groups of related species in order to test the current thoughts about the role of life-history patterns in the course of evolution is emphasized. P. J. den Boer & Th. S. van Dijk, Biological Station (Communication No. 548 of the Biological Station "Wijster), Kampsweg 27, 9418 PD Wijster, The Netherlands. Key-words. -Evolution, life histories, carabid beetles, dispersal power, turnover of populations, survival. Since the publication of MacArthur & Wilson's 'Island biogeography' (1967), in which the concept of r and K selection was introduced, the study of life-his-tory traits has become highly fashionable, especially among population ecologists and American evolu-tionary biologists. It is a pity, however, that these studies were mainly restricted to vertebrates and were theoretical. Apparently, many evolutionary biologists thought it possible to predict which life-history pat-terns (combinations of life-history traits) were most important for evolutionary progress, and with the help of mathematical models they tried to illustrate the effects of these life-history patterns on the success and survival of species (e.g. Gadgil & Bossert 1970, Cody 1971, Schaffer 1972, 1974a, b). This trend in evolutionary biology was severely criticized by Stearns (1976). Regrettably, however, Stearns did not suggest doing comparative investiga-tions among genetically related species on life-history traits in relation to the prevailing properties of the en-vironments where these respective species thrive best (are most 'fit'). It might be expected that life-history traits, which improve survival and reproduction, are most favoured by natural selection in environments where the species is most fit. Therefore, when com-paring these life-history traits for genetically related species, i.e. species in the same taxonomie gtoup (see e.g. Den Boer 1980), but living in different lands of habitat, one can expect to get some insight into the relationship between life-history patterns and prevail-ing environmental conditions. It would especially be interesting, to check whether or not the theoretically predicted patterns indeed emerge as the most impor-tant patterns from such a comparative field study. After a symposium 'On the evolution of behaviour in carabid beetles' (Den Boer et al. 1979), and stimu-lated by the paper of Stearns (1976), the first author tried to make a provisional comparison of the life-his-tory traits of carabid species of stable habitats (forests) with those of carabid species of unstable habitats (banks of rivers and pools, and agricultural fields) (Den Boer 1979a). Since that time the comparison of life-history traits always has been a point of general interest somewhere in the background of the investi-gations on the population dynamics of carabid beetles at the Wijster Biological Station. In the present paper we will give and discuss the re-sults of a comparison of life-history patterns among the carabid species of our area (Drenthe), which are representative for the greater part of western Europe.