Sasa Stefanovic
Miguel A. Garcia
Susan De La Cruz
Michael L. Casazza
Andy J. Green
Mihai Costea
2016
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<p id="p-1"><span>REMISE OF THE STUDY:</span> Dispersal of parasitic <i>Cuscuta</i> 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 <i>Cuscuta</i> seeds.</p>
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<p id="p-2"><span>METHODS:</span> Twelve northern pintails (<i>Anas acuta</i>) 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.</p>
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<p id="p-3"><span>KEY RESULTS:</span> Four hundred and twenty dodder seeds were found in the rectum of four northern pintails. From these, 411 seeds were identified as <i>Cuscuta campestris</i> and nine as most likely <i>C. pacifica</i>. The germination rate of <i>C. campestris</i> 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.</p>
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<p id="p-4"><span>CONCLUSIONS:</span> Endozoochory by waterbirds may explain the historical LDD cases in the evolution of <i>Cuscuta</i>. This also suggests that current border quarantine measures may be insufficient to stopping spreading of dodder pests along migratory flyways.</p>
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application/pdf
10.3732/ajb.1500507
en
Botanical Society of America
Waterfowl endozoochory: An overlooked long-distance dispersal mode for <i>Cuscuta</i> (dodder)
article