Local parasite lineage sharing in temperate grassland birds provides clues about potential origins of G alapagos avian P lasmodium

Oceanic archipelagos are vulnerable to natural introduction of parasites via migratory birds. Our aim was to characterize the geographic origins of two P lasmodium parasite lineages detected in the G alapagos I slands and in N orth A merican breeding bobolinks ( D olichonyx oryzivorus ) that regularly stop in G alapagos during migration to their S outh A merican overwintering sites. We used samples from a grassland breeding bird assemblage in N ebraska, U nited S tates, and parasite DNA sequences from the G alapagos I slands, E cuador, to compare to global data in a DNA sequence registry. Homologous DNA sequences from parasites detected in bobolinks and more sedentary birds (e.g., brown‐headed cowbirds M olothrus ater , and other co‐occurring bird species resident on the N orth A merican breeding grounds) were compared to those recovered in previous studies from global sites. One parasite lineage that matched between Galapagos birds and the migratory bobolink, P lasmodium lineage B , was the most common lineage detected in the global M al A vi database, matching 49 sequences from unique host/site combinations, 41 of which were of S outh A merican origin. We did not detect lineage B in brown‐headed cowbirds. The other G alapagos‐bobolink match, P lasmodium lineage C , was identical to two other sequences from birds sampled in C alifornia. We detected a close variant of lineage C in brown‐headed cowbirds. Taken together, this pattern suggests that bobolinks became infected with lineage B on the S outh A merican end of their migratory range, and with lineage C on the N orth A merican breeding grounds. Overall, we detected more parasite lineages in bobolinks than in cowbirds. Galapagos P lasmodium had similar host breadth compared to the non‐ G alapagos haemosporidian lineages detected in bobolinks, brown‐headed cowbirds, and other grassland species. This study highlights the utility of global haemosporidian data in the context of migratory bird–parasite connectivity. It is possible that migratory bobolinks bring parasites to the G alapagos and that these parasites originate from different biogeographic regions representing both their breeding and overwintering sites.