J Syst Evol ›› 2018, Vol. 56 ›› Issue (5): 430-448.DOI: 10.1111/jse.12422

• Reviews • Previous Articles     Next Articles

Long distance dispersal in the assembly of floras: A review of progress and prospects in North America

AJ Harris1*+, Stefanie Ickert-Bond2, and Aarón Rodríguez3   

  1. 1Department of Botany, Smithsonian Institution, MRC 166, Washington, D.C. 20013-7012, USA
    2UA Museum of the North and Department of Biology and Wildlife, University of Alaska Fairbanks, 907 Yukon Dr., PO Box 756960, Fairbanks, Alaska 99775-6960, USA
    3Departamento de Botánica y Zoología, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, México
  • Received:2018-02-04 Accepted:2018-04-23 Published:2018-09-27

Abstract: Here, we review progress and prospects to explicitly test for long distance dispersal biogeographic events. Long distance dispersal represents a “jump” across some kind of barrier, such as a topographic feature or a zone of unsuitable climate and may include repeated jumps, or stepping‐stone dispersals. Long distance dispersals were considered integral for explaining the organization of biodiversity at large and small scales by early biogeographers, such as Darwin and Wallace. Darwin, Wallace, and others envisioned that long distance dispersals were predictable events because the vectors for dispersal, such as animals, winds, and currents, behaved in non‐random ways. However, these early biogeographers found that dispersal was hard to observe, and, later, with the advent of the theory of Continental Drift, vicariance became regarded as a better scientific explanation for the arrangement of biodiversity, because it represented a falsifiable hypothesis. Thus, long distance dispersal was reduced to a nuisance parameter in biogeography; a random possibility that could never fully be ruled out in a scenario in which evidence supported vicariance. Today, there is strong interest to more fully integrate long distance dispersal into understanding the assembly and organization of biodiversity on earth. In this review, we discuss progress and prospects for explicitly testing long distance dispersal hypotheses including through uses of molecular, morphological, paleontological, and informatics methods. We focus on hypothesis testing of long distance dispersals involved in the assembly of the flora of North America, which is a robust preliminary study system on account of its extant and extinct biodiversity being well‐catalogued.

Key words: Arctic, boreal, Canada, desert, dispersal vectors, hypothesis testing, Mexico, temperate forest, tropics, United States