Sturgeons (Chondrostei: Acipenseridae) and Their Metazoan Parasites: Patterns and Processes in Historical Biogeography

• Published in: Journal of biogeography 2001-11, Vol.28 (11/12), p.1411-1439
• Main Authors: Choudhury, Anindo, Dick, Terry A.
• Format: Article
• Language: English
• Subjects: Acipenseridae; Agnatha. Pisces; Biogeography; Biological and medical sciences; Fauna; Fresh water; Freshwater fishes; Fundamental and applied biological sciences. Psychology; Parasite hosts; Parasites; Phylogenetics; Special Research Paper; Sturgeon; Taxa; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; We they distinction
• ISSN: 0305-0270; 1365-2699
• DOI: 10.1046/j.1365-2699.2001.00635.x

Aim The historical biogeography of host-parasite associations is examined in a geologically old group of fishes, the sturgeons (Osteichthyes: Acipenseridae), and their parasite assemblage. Evidence from phylogenetics and biogeographical studies of several parasite groups is used to formulate and evaluate hypotheses about the coevolutionary history of this host-parasite association and, ultimately, the origin of sturgeons. Location The geographical areas discussed in this study are the temperate regions of North America and Eurasia, including the North Atlantic, North Pacific, Mediterranean and Ponto-Caspian basins and their drainages. Methods Relationships of parasites in several clades (Truttaedacnitis, Diclybothriidae, Deropristiidae, Spinitectus and Acrobothriidae) are analysed or re-analysed using cladistics. These results are combined with hypotheses of relationships of sturgeons and their biogeography. We largely follow an 'empirical synthetic pattern approach' (Grande & Bemis, 1998) where the search is primarily for broadly congruent patterns, keeping interpretations close to the data and to known or postulated Earth history (palaeogeography). The evidence from the cladistic analyses is first interpreted within the context of vicariance events, but dispersalist scenarios are also discussed where warranted. We also use the concept of Croizat's 'biogeographical tracks' to characterize broadly congruent distributional patterns. Results Phylogenetic hypotheses and biogeography of parasites indicate three major biogeographical tracks, of which a Holarctic track involving northern and north-eastern Asian regions and North America is predominant (in Crepidostomum auriculatum, Polypodium hydriforme, Truttaedacnitis, Capillospirura, Diclybothriidae, Amphilina), with evidence for a recurring basal trans-Pacific track (in Truttaedacnitis, Diclybothriidae). Trans-Atlantic tracks appear to be either independent of (in Deropristidae) or secondarily derived from (in Bothrimonus and Truttaedacnitis sphaerocephala) a Holarctic track. Evidence from parasites supports the hypothesis of sister relationships between Acipenser medirostris and A. mikadoi, and between A. fulvescens and A. brevirostrum. Main conclusions This host-parasite association was historically structured by colonization and subsequent coevolution. Dispersal and vicariance of acipenserids resulted in small but widespread, highly distinct, monophyletic parasite lineages. Species of such parasite clades