Integrating pattern with process at biogeographic boundaries: the legacy of Wallace

Abstract

Biogeography is a vital discipline today because ofits extraordinarily integrative nature, drawing from andinforming biological and Earth sciences in order to explainthe history and future of life on our planet. Yet, even aswe continue to build more sophisticated syntheses usingmolecular genetics, GIS-based distribution modelling, andever-better analytical and visualizing approaches, we shouldrecall that exploring causal connections between biologicaland Earth history is not a particularly new endeavor. Forexample, the biogeographic principles advocated in the late1800s by Alfred Russel Wallace (see Box 2.1 in Lomolinoet al. 2006) were infused with ideas associating distribu-tional and diversification histories of organisms with geo-logy and climate. But even a century before Wallace, in1761 Compte de Buffon had recognized the differencesbetween mammals in the New World and Old Worldtropics and proposed a rudimentary evolutionary causationfor their divergence and distribution based on separationof formerly united continents.Certainly, de Buffon and Wallace were not alone duringtheir times in describing the non-random distributionsof animals and plants, exploring causal explanations (seecontributions reproduced in the ‘‘Early Classics’’ section ofLomolino et al. 2004), and recognizing regions of rapidtransition between geographically distinct biotas. Wallacestood out, however, in the magnitude and synthetic natureof his focus on a single biogeographic boundary. Afterspending eight years exploring the mosaic of islands that laybetween southeast Asia and New Guinea/Australia, Wallaceconcluded that ‘‘...we may consider it established that theStrait of Lombock (only 15 miles wide) marks the limitsand abruptly separates two of the great zoological regions ofthe world’’ (Wallace 1860, pp. 173 (Wallace 1876 v. I, p. 389).174). He called thisregion the Malay Archipelago and it includes the mostfamous biogeographic transition of all, named Wallace’sLine by T. H. Huxley in 1868.The four papers in this Special Feature were firstpresented in January 2009 in the ‘‘Patterns and Processesat Biogeographic Boundaries’’ symposium convened at the4th Biennial Meeting of the International BiogeographySociety in Me´rida, Me´xico. Here, we develop a back-ground to these papers (Cody et al. 2010, Daza et al.2010, Morrone 2010, Smith and Klicka 2010) by summar-izing several highlights in the historical focus of biogeo-graphers on boundaries.