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Cycad classification: concepts and recommendations.

Book cover for Cycad classification: concepts and recommendations.

Description

This book presents the current state of our knowledge of the systematics of the approximately 300 species of cycads. It has been developed from 15 papers presented at the conference in Miami. Guidelines are presented for the designation of species, species boundaries and species groupings, thus clarifying what has been a confused area of research. Two appendices are included in this volume. The fi...

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Chapter 11 (Page no: 137)

Hypotheses on the relationship between biogeography and speciation in Dioon (Zamiaceae).

Hypotheses are presented on the relationships between palaeoclimatic conditions during the late Pleistocene and Holocene, and the current biogeography of cycads in the genus Dioon. A proposal is made that Dioon populations have migrated up and down in elevation, and north and south, with the warming and cooling climatic cycles corresponding to glaciations. This suggests that since the end of the Wisconsin glaciation Dioon populations have moved upward in elevation in southern Mexico with shifts in their preferred transition zone habitat. This migration has sometimes resulted in disjunction and rapid speciation within river canyon systems. Mechanisms for these activities are discussed. The chapter culminates with the proposal that the extant Dioon species are the result of rapid evolution in a dynamic and viable group of plants instead of the classical concept that they are slowly evolving relicts.

Other chapters from this book

Chapter: 1 (Page no: 1) 'We Hold these Truths ...'. Author(s): Walters, T. Osborne, R. Decker, D.
Chapter: 2 (Page no: 13) Saving ghosts? The implications of taxonomic uncertainty and shifting infrageneric concepts in the cycadales for red listing and conservation planning. Author(s): Donaldson, J.
Chapter: 3 (Page no: 23) Character evolution, species recognition and classification concepts in the Cycadaceae. Author(s): Hill, K. D.
Chapter: 4 (Page no: 45) Morphological characters useful in determining species boundaries in Cycas (Cycadaceae). Author(s): Lindström, A.
Chapter: 5 (Page no: 57) Comments on Cycas, Dyerocycas and Epicycas (Cycadaceae). Author(s): Chen ChiaJui Hill, K. D. Stevenson, D. W.
Chapter: 6 (Page no: 69) Classification concepts in Encephalartos (Zamiaceae). Author(s): Vorster, P.
Chapter: 7 (Page no: 85) Classification concepts in Macrozamia (Zamiaceae) from Eastern Australia. Author(s): Forster, P. I.
Chapter: 8 (Page no: 95) Classification concepts in Ceratozamia (Zamiaceae). Author(s): Whitelock, L. M.
Chapter: 9 (Page no: 109) Relationships and phytogeography in Ceratozamia (Zamiaceae). Author(s): Vovides, A. P. Pérez-Farrera, M. A. González, D. Avendaño, S.
Chapter: 10 (Page no: 127) A morphometric analysis of the Ceratozamia norstogii complex (Zamiaceae). Author(s): Pérez-Farrera, M. A. Vovides, A. P. Hernández-Sandoval, L. González, D. Martínez, M.
Chapter: 12 (Page no: 149) Molecular phylogeny of Zamia (Zamiaceae). Author(s): Caputo, P. Cozzolino, S. Luca, P. de Moretti, A. Stevenson, D. W.
Chapter: 13 (Page no: 159) Systematics of Meso-American Zamia (Zamiaceae). Author(s): Schutzman, B.
Chapter: 14 (Page no: 173) Zamiaceae of Bolivia, Ecuador and Peru. Author(s): Stevenson, D. W.
Chapter: 15 (Page no: 195) In search of the true tree: guidelines for classification. Author(s): Osborne, R. Walters, T.

Chapter details

  • Author Affiliation
  • Montgomery Botanical Center, 11901 Old Cutler Road, Miami, FL 33156-4242, USA.
  • Year of Publication
  • 2004
  • ISBN
  • 9780851997414
  • Record Number
  • 20043021922