title: The evolution of seeds.
abstract: The evolution of the seed represents a remarkable life-history transition for photosynthetic organisms. Here, we review the recent literature and historical understanding of how and why seeds evolved. Answering the 'how' question involves a detailed understanding of the developmental morphology and anatomy of seeds, as well as the genetic programs that determine seed size. We complement this with a special emphasis on the evolution of dormancy, the characteristic of seeds that allows for long 'distance' time travel. Answering the 'why' question involves proposed hypotheses of how natural selection has operated to favor the seed life-history phenomenon. The recent flurry of research describing the comparative biology of seeds is discussed. The review will be divided into sections dealing with: (1) the development and anatomy of seeds; (2) the endosperm; (3) dormancy; (4) early seed-like structures and the transition to seeds; and (5) the evolution of seed size (mass). In many cases, a special distinction is made between angiosperm and gymnosperm seeds. Finally, we make some recommendations for future research in seed biology.
authors.affiliation: Botany/Plant Physiology, Institute for Biology II, Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany (http://www.seedbiology.de).
authors.forename: Ada
authors.initials: A
authors.lastname: Linkies
authors.affiliation: Botany/Plant Physiology, Institute for Biology II, Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany (http://www.seedbiology.de).
authors.forename: Kai
authors.initials: K
authors.lastname: Graeber
authors.affiliation: Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93401, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Knight
authors.affiliation: Botany/Plant Physiology, Institute for Biology II, Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany (http://www.seedbiology.de).
authors.forename: Gerhard
authors.initials: G
authors.lastname: Leubner-Metzger
mesh_terms: D005075:Biological Evolution; D056625:Endosperm / Q000254:growth & development / Q000378:metabolism; D009929:Organ Size; D012639:Seeds / Q000033:anatomy & histology / Q000254:growth & development*
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