title: Evolutionary relationships between digeneans of the family Brachycladiidae Odhner, 1905 and their marine mammal hosts: A cophylogenetic study.
abstract: Cophylogenetic studies examine the congruence between host and parasite phylogenies. There are few studies that quantify the relative contribution of coevolutionary events, i.e. duplication, loss, failure-to-diverge, host-switching and spreading in trophically-transmitted parasites at the marine realm. We addressed this issue in the Brachycladiidae, a cosmopolitan digenean family specific to marine mammals. We used, for the first time, distance-based and event-based methods to explicitly test the coevolutionary events that have shaped the current brachycladiid-marine mammal associations. Parasite phylogeny was constructed using mtDNA ND3 sequences of nine brachycladiid species, and host phylogeny using cytochrome b sequences of 104 mammalian species. A total of 50 host-parasite links were identified. Distance-based methods supported the hypothesis of a global non-random association of host and parasite phylogenies. Significant individual links (i.e., 24 out of 50) were those related to Campula oblonga, Nasitrema delphini, N. globicephalae and Brachycladium atlanticum and their associated taxa from the Delphinoidea. Regarding event-based methods, we explored 54 schemes using different combinations of costs for each potential coevolutionary event. Three coevolutionary scenarios were identified across all schemes and in all cases the number of loss events (87-156) was the most numerous, followed by failure-to-diverge (40), duplication (3-6), host-switching (0-3) and cospeciation (0-2). We developed a framework to interpret the evolution of this host-parasite system and confirmed that failure-to-diverge and colonization with or without subsequent diversification could have been decisive in the establishment of the associations between brachycladiids and marine mammals.
authors.affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, Science Park, University of Valencia, C/Catedrático José Beltrán 2, 46980 Paterna, Spain. Electronic address: natalia.fraija@uv.es.
authors.forename: Natalia
authors.initials: N
authors.lastname: Fraija-Fernández
authors.affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, Science Park, University of Valencia, C/Catedrático José Beltrán 2, 46980 Paterna, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Aznar
authors.affiliation: Histology and Pathology, Institute for Animal Health, University of Las Palmas de Gran Canaria, C/Trasmontaña s/n, 35416, Las Palmas, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Fernández
authors.affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, Science Park, University of Valencia, C/Catedrático José Beltrán 2, 46980 Paterna, Spain.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Raga
authors.affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, Science Park, University of Valencia, C/Catedrático José Beltrán 2, 46980 Paterna, Spain.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Fernández
mesh_terms: D000818:Animals; D059001:Aquatic Organisms; D005075:Biological Evolution; D045303:Cytochromes b / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D006790:Host-Parasite Interactions; D008322:Mammals / Q000469:parasitology*; D010802:Phylogeny; D017422:Sequence Analysis, DNA / Q000662:veterinary; D013045:Species Specificity; D014200:Trematoda / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D004272:DNA, Mitochondrial; D045303:Cytochromes b
keywords: Brachycladiidae; Cetacea; Cophylogeny; Digenea; Pinnipedia; Sea otter