Historical and ecological factors determining the geographical distribution of beetles (Coleoptera: Scarabaeidae: Scarabaeinae)

BIOGEOGHAPHIA — vo/. XV ~ 1991 (Pubblicato il 31 dicembre 1991 Biogeografia de//e comunita‘ Historical and ecological factors determining the geographical distribution of beetles (1) (Coleoptera: Scarabaeidae: Scarabaeinae) GONZALO HALFFTER I5z‘z'tz1Z0 die Ecologitz /lpamzdo Portal 63 — Xtzlzzpzz, Vemcmz 91000, Mexico SUMMARY In an attempt to answer the question, «Does community biogeography exist other than at the de— scriptive level?», the relation of the Scarabs (Coleoptera: Scarabaeidae: Scarabaeinae) with the tropical forests of the Americas, Africa and Southeast Asia is analyzed. More than a synthesis of what is known of the Scarabaeinae guild in the tropical forests of the three continents, it is a journey into the structure as well as the similarities and differences of the guild on each continent. In addition, as far as current information allows, these are compared with the guild in the savannas. For several aspects (for example, species richness of the guild in the American tropical forests) answers (e.g. necrophagy) and possible hypotheses are proposed. Gaps in the available information are identified. A review of the growing bibliography on the theme is included, as well as unpublished data. INTRODUCTION If we wish to investigate the biogeography of communitites, the first thing we must ask is: What is a community? I was studying, forty years ago, the answer was very clear. Frederic E. Clements and V.E. Shelford’s ideas, so brightly and elegantly synthesized by Eugene P. Odum, defined the commu- nity as a unit, an evolving continuity in space as well as in time. The commu- nity was seen as a kind of superorganism. To base biogeographical investiga- tion on this concept was a very logical and advantageous thing to do. However, progress in mathematics was, and still is, a problem for biol- ogists, especially for ecologists. In the 1950’s ecology was shocked by the development of information theory. The perception of the similarity between Shannon’s diversity equation and Bolzmann’s equation for entropy provided the temptation to analyze the diversity of a community as a thermodynamic phenomenon. In the early 70’a the community—superorganism concept was (1) This paper was presented at the XXVIII Congress of the Societa Italiana di Biogeografia as the introductory conference to the theme «Community Biogeography», Turin, September, 1990. The work forms part of the project «Animal Ecology and Behaviour» of the Instituto de Ecologia, Mexico and was supported by the project «Ecology of the nesting behaviour of dung—rolling beetles (Coleoptera: Scara- baeinae) from tropical forests» No. D112—903528, CONACyT, Mexico, and by the project «Animal ecoe- thology in the State of Veracruz», No. DGICSA-902467, Secretaria de Educacien Pftblica, Mexico.