title: Phenotypic constraints and community structure: linking trade-offs within and among species.
abstract: Trade-offs are central to many topics in biology, from the evolution of life histories to ecological mechanisms of species coexistence. Trade-offs observed among species may reflect pervasive constraints on phenotypes that are achievable given biophysical and resource limitations. If so, then among-species trade-offs should be consistent with trade-offs within species. Alternatively, trait variation among co-occurring species may reflect historical contingencies during community assembly rather than within-species constraints. Here, we test whether a key trade-off between relative growth rate (RGR) and water-use efficiency (WUE) among Sonoran Desert winter annual plants is apparent within four species representing different strategies in the system. We grew progeny of maternal families from multiple populations in a greenhouse common garden. One species, Pectocarya recurvata, displayed the expected RGR-WUE trade-off among families within populations. For other species, although RGR and WUE often varied clinally among populations, among-family variation within populations was lacking, implicating a role for past selection on these traits. Our results suggest that a combination of limited genetic variation in single traits and negative trait correlations could pose constraints on the evolution of a high-RGR and high-WUE phenotype within species, providing a microevolutionary explanation for phenotypes that influence community-level patterns of abundance and coexistence.
authors.affiliation: Departments of Botany and Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. amy.angert@botany.ubc.ca.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Angert
authors.forename: Sarah
authors.initials: S
authors.lastname: Kimball
authors.forename: Megan
authors.initials: M
authors.lastname: Peterson
authors.forename: Travis E
authors.initials: TE
authors.lastname: Huxman
authors.forename: David L
authors.initials: DL
authors.lastname: Venable
mesh_terms: D019659:Asteraceae / Q000145:classification* / Q000235:genetics*; D058448:Biota; D014644:Genetic Variation; D005828:Genetics, Population
keywords: Community assembly; G-matrix; genetic correlation; growth rate; stress tolerance; water-use efficiency; winter annual plants