title: Assessing the effects of hybridization and precipitation on invasive weed demography using strength of selection on vital rates.
abstract: BACKGROUND
  As global climate change transforms average temperature and rainfall, species distributions may meet, increasing the potential for hybridization and altering individual fitness and population growth. Altered rainfall specifically may shift the strength and direction of selection, also manipulating population trajectories. Here, we investigated the role of interspecific hybridization and selection imposed by rainfall on the evolution of weedy life-history in non-hybrid (Raphanus raphanistrum) and hybrid (R. raphanistrum x R. sativus) populations using a life table response experiment.
  
  
  RESULTS
  In documenting long-term population dynamics, we determined intrinsic (r) and asymptotic (λ) population growth rates and sensitivities, a measure of selection imposed on demographic rates. Hybrid populations experienced 8.7-10.3 times stronger selection than wild populations for increased seedling survival. Whereas crop populations generally exhibit little dormancy and wild populations often exhibit dormancy, non-hybrid populations experienced 10% stronger selection than hybrid populations for exhibiting seed dormancy. Selection on survival-to-flowering in wild, not hybrid, populations declined marginally with increasing soil moisture. Hybrid populations exhibited greater r, but not λ, than wild populations regardless of moisture environment. In general, fecundity contributed most to differences in λ but fecundity only contributed positively to hybrid λ relative to wild λ when precipitation was altered (either higher or lower than control) and not under control watering conditions.
  
  
  CONCLUSIONS
  Selection on key demographic traits may not change dramatically in response to rainfall, and hybridization may more strongly influence the demography of these weedy species than rainfall. If hybrid populations can respond to selection for increased dormancy, this may make it more difficult to deplete weed seed banks and increase the persistence of crop genes in weed populations.
authors.affiliation: Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON, M5B 2K3, Canada.|Current Address: Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Teitel
authors.affiliation: Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON, M5B 2K3, Canada.|Current Address: Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Klimowski
authors.affiliation: Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON, M5B 2K3, Canada. lesley.g.campbell@ryerson.ca.
authors.forename: Lesley G
authors.initials: LG
authors.lastname: Campbell
mesh_terms: D005075:Biological Evolution; D002170:Canada; D057231:Climate Change; D005298:Fertility; D006824:Hybridization, Genetic; D057685:Plant Weeds / Q000235:genetics / Q000254:growth & development; D011891:Rain; D031224:Raphanus / Q000235:genetics* / Q000254:growth & development; D012098:Reproduction; D058728:Weed Control
keywords: (3-10): Demography; Experimental evolution; Gene flow; Global climate change; Life Table Response Experiment; Rain-out shelter; Raphanus raphanistrum; Raphanus sativus