title: Waterfowl endozoochory: An overlooked long-distance dispersal mode for Cuscuta (dodder).
abstract: Dispersal of parasitic Cuscuta species (dodders) worldwide has been assumed to be largely anthropomorphic because their seeds do not match any previously known dispersal syndrome and no natural dispersal vectors have been reliably documented. However, the genus has a subcosmopolitan distribution and recent phylogeographic results have indicated that at least18 historical cases of long-distance dispersal (LDD) have occurred during its evolution. The objective of this study is to report the first LDD biological vector for Cuscuta seeds.
  
  
  
  Twelve northern pintails (Anas acuta) were collected from Suisun Marsh, California and the contents of their lowest part of the large intestine (rectum) were extracted and analyzed. Seed identification was done both morphologically and using a molecular approach. Extracted seeds were tested for germination and compared to seeds not subjected to gut passage to determine the extent of structural changes caused to the seed coat by passing through the digestive tract.
  
  
  
  Four hundred and twenty dodder seeds were found in the rectum of four northern pintails. From these, 411 seeds were identified as Cuscuta campestris and nine as most likely C. pacifica. The germination rate of C. campestris seeds after gut passage was 55%. Structural changes caused by the gut passage in both species were similar to those caused by an acid scarification.
  
  
  
  Endozoochory by waterbirds may explain the historical LDD cases in the evolution of Cuscuta. This also suggests that current border quarantine measures may be insufficient to stopping spreading of dodder pests along migratory flyways.
authors.affiliation: Department of Biology, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada mcostea@wlu.ca.
authors.forename: Mihai
authors.initials: M
authors.lastname: Costea
authors.affiliation: Department of Biology, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada.
authors.forename: Saša
authors.initials: S
authors.lastname: Stefanović
authors.affiliation: Department of Biology, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: García
authors.affiliation: U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, 505 Azuar Drive, Vallejo, California 94592 .SA.
authors.forename: Susan
authors.initials: S
authors.lastname: De La Cruz
authors.affiliation: U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Dixon, California 95620 .SA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Casazza
authors.affiliation: Wetland Ecology Department, Estación Biológica de Doñana (EBD-CSIC), Sevilla 41092 Spain.
authors.forename: Andy J
authors.initials: AJ
authors.lastname: Green
mesh_terms: D000818:Animals; D034182:Cuscuta / Q000033:anatomy & histology / Q000502:physiology* / Q000648:ultrastructure; D005247:Feeding Behavior / Q000502:physiology*; D011200:Poultry / Q000502:physiology*; D058614:Seed Dispersal / Q000502:physiology*; D012639:Seeds / Q000502:physiology / Q000648:ultrastructure
keywords: Anas acuta; Convolvulaceae; identification; invasive plants; long-distance dispersal; northern pintail; parasitic plants; pest; seed viability