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Large-scale processes and the Asian bias in species diversity of temperate plants

Nature volume 407, pages 180182 (14 September 2000) | Download Citation



An important issue in the study of biodiversity is the extent to which global patterns of species richness reflect large-scale processes and historical contingencies1,2. Ecological interactions in local assemblages may constrain the number of species that can coexist3,4, but differences in diversity in similar habitats within different regions (diversity anomalies) suggest that this limit is not firm. Variation in rate of species production could influence regional and perhaps local diversity independently of the ecological capacity of an area to support coexisting species, thereby creating diversity anomalies5,6. Temperate Zone genera of plants that are disjunct between similar environments in eastern Asia and eastern North America (EAS-ENA) have twice as many species in Asia as in North America7. Because lineages of these genera in Asia and North America are mostly sister pairs8, they share a common history of adaptation and ecological relationship before disjunction. Thus, the diversity anomaly in EAS-ENA genera is not an artefact of taxon or habitat sampling but reflects differences in the net diversification (speciation–extinction) of the lineages in each of the continents. Here we propose that the most probable cause of the EAS-ENA anomaly in diversity is the extreme physiographical heterogeneity of temperate eastern Asia, especially compared with eastern North America, which in conjunction with climate and sea-level change has provided abundant opportunities for evolutionary radiation through allopatric speciation.

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We thank E. Bermingham, Q.-F. Guo, S. Heard, J. Losos, I. Lovette, S. Manchester, S. Renner, D. Schluter and two anonymous reviewers for valuable comments on the manuscript.

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  1. *Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada

    • Hong Qian
  2. †Department of Biology, University of Missouri-St. Louis, St. Louis, Missouri 63121, USA

    • Robert E. Ricklefs


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