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Author Darling, Emily ♦ Samis, Karen E. ♦ Eckert, Christopher G.
Source World Health Organization (WHO)-Global Index Medicus
Content type Text
Publisher Wiley
File Format HTM / HTML
Language English
Difficulty Level Medium
Subject Domain (in DDC) Social sciences ♦ Sociology & anthropology ♦ Natural sciences & mathematics ♦ Life sciences; biology ♦ Physiology & related subjects ♦ Natural history of organisms ♦ Technology ♦ Medicine & health ♦ Human anatomy, cytology, histology ♦ Human physiology
Subject Domain (in MeSH) Plant Structures ♦ Anatomy ♦ Eukaryota ♦ Organisms ♦ Reproductive and Urinary Physiological Phenomena ♦ Biological Phenomena ♦ Biological Sciences ♦ Social Sciences ♦ Anthropology, Education, Sociology and Social Phenomena ♦ Geographic Locations ♦ Geographic Locations
Subject Keyword Discipline Botany ♦ Ecosystem ♦ Nyctaginaceae ♦ Physiology ♦ Seeds ♦ California ♦ Demography ♦ Flowers ♦ Mexico ♦ Oregon ♦ Reproduction ♦ Journal Article ♦ Research Support, Non-u.s. Gov't
Abstract Dispersal may be favoured at geographic range edges by unstable population and metapopulation dynamics. However, dispersal may also evolve in response to geographic variation in other life-history traits, especially the mating system. Here, increased dispersal at range margins was tested for with a range-wide analysis of seed dispersal and mating system traits in Abronia umbellata, a plant endemic to Pacific coastal dunes of North America. Seeds disperse within winged anthocarps. Anthocarps from 34 populations varied widely in wing size (mass-corrected wing index). Wing index correlated negatively with threshold wind velocity for dispersal in wind tunnel tests, suggesting that wings facilitate tumbling over open sandy substrate. As predicted, wing index increased and threshold velocity decreased towards both range limits. Flower size, herkogamy and self-incompatibility declined towards range limits, indicating a shift to self-fertilization, and flower size and wing index correlated negatively. However, the increase in wing index towards range limits remained after statistically controlling flower size. These results are consistent with selection favouring dispersal at range margins. The evolutionary lability of dispersal across the range may affect the interaction between selection and gene flow in the establishment and maintenance of geographic range limits.
Spatial Coverage Oregon ♦ Mexico ♦ California
Description Country affiliation: Canada
Author Affiliation: Darling E ( Department of Biology, Queen's University, Kingston, Ontario, Canada.)
ISSN 0028646X
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Reading ♦ Research ♦ Self Learning
Interactivity Type Expositive
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2008-01-01
Publisher Place Great Britain (UK)
e-ISSN 14698137
Journal New Phytologist
Volume Number 178
Issue Number 2


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Source: WHO-Global Index Medicus