The genetic variation and biogeography of catostomid fishes based on mitochondrial and nucleic DNA sequences

Abstract

The genetic variation, phylogeny and biogeography of catostomid fishes were investigated based on mitochondrial cytochrome b and nuclear 18S-ITS1-5.8S DNA sequences. The pair-wise genetic distance of cytochrome b for 17 catostomids varied considerably, from 1Á00% (Chasmistes brevirostris and Deltistes luxatus) to 23Á3% (Cycleptus elongatus and Moxostoma anisurum). The size of the 18S-ITS1-5.8S sequence ranged from 315 bp (Moxostoma robustum) to 575 bp (Ictiobus cyprinellus). The 18S-5.8S region was conservative and the length of ITS1 regions was found to vary considerably among the seven catostomids. It is interesting that the primitive I. cyprinellus and Myxocyprinus asiaticus had longer ITS1 regions than suckers from the Catostominae. Based on the nucleotide substitution model, the nuclear 18S-5.8S gene had a faster evolution rate than the mitochondrial cytochrome b gene. In a phylogenetic analysis, 17 catostomids from 14 genera representing three subfamilies were not distinctly divergent. Nevertheless, three major genetically divergent clades were identified. Clade I (95% bootstrap) included general Catostomus, Thoburnia, Xyrauchen, Chasmistes and Deltistes. Clade II (94% bootstrap) included Hypentelium, Moxostoma and Scartomyzon. Clade III (77% bootstrap) was a monophyletic Ictiobinae containing I. cyprinellus and Carpiodes carpio. The biogeography of old world catostomids followed a disperse event, and the speciation of the extant catostomids was a vicariance event. The earliest catostomid evolved in Asia from one branch of ostariophysans in the early Tertiary. Before the Eocene, catostomids belonging to the genus Amyzon had a wide, trans-Pacific distribution over Asia and North America. Later, oceanic ingression and the Tertiary glacial event forced catostomids to evolve on both mainlands, respectively. The present disjunct distribution pattern of catostomids was presumably due to competitive pressure from cyprinids, geographical events, their Late Cenozoic radiation in North America and glacial events. The divergence time based on the mitochondrial and nuclear DNA sequences suggests that catostomids began to diverge in the early or mid-Miocene, which agrees with the fossil evidence.

A new Eocene catostomid (Teleostei: Cypriniformes) from northeastern China and early divergence of Catostomidae

“…Recent works on molecular systematics of the Catostomidae [28,29] are, on the whole, consistent with that of Smith [1] , showing differences mainly in the composition and position of the Cycleptinae. In Harris and Mayden's [28] analysis based on the mitochondrial rDNA sequences, the Cycleptinae (sensu Smith [1] ) resulted not as a monophyletic group, with Myxocyprinus as the basal-most taxon of the Catostomidae, and Cycleptus as sister to the Catostominae.…”

“…They suggested setting up a new subfamily Myxocyprininae to include only Myxocyprinus asiaticus from China and confine the Cyclepitinae to the two species of Cycleptus from North America. Sun et al [29] , based on the analysis of mitochondrial cytochrome b and nuclear 18S-ITS1-5.8S DNA sequences, suggested that catostomids began to diverge in the early or mid-Miocene, which agrees with the fossil evidence known from North America. With the discovery of †Plesiomyxocyprinus arratiae the divergence time of the Catostomidae goes further back, at least, to the middle of the Eocene or even earlier.…”

“…However, Nelson [24] proposed that Myxocyprinus may form a subfamily of its own based on the morphology of Weberian complex. This suggestion is supported by recent phylogenetic analyses based on molecular data, which claim that Myxocyprinus should be removed from Cycleptinae and form a subfamily of its own, Myxocyprininae [28,29] .…”

“…hunanensis [5] , 21-23 in †A. gosiutensis [41] , [28][29][30][31][32][33][34][35][36][37] in Cycleptus, 22-32 in ictiobines, and 10-18 in catostomines [2] . The number of anal fin rays in Myxocyprinus asiaticus is also the highest among the known catostomids, yet is lower than that of †Plesiomyxocy-prinus arratiae (see above).…”

A synoptic review of Promonobothrium Mackiewicz, 1968 (Cestoda: Caryophyllidea), parasites of suckers (Catostomidae) in North America, with description of two new species

“…According to recent phylogenetic analyses (Sun et al 2007, Doosey et al 2010, Chen and Mayden 2012, Ictiobus Rafinesque and Carpiodes Rafinesque, which belong to the monophyletic subfamily Ictiobinae, represent two of the oldest lineages of suckers. Within the most derived subfamily Catostominae, phylogenetic position of M. melanops is not well resolved (Doosey et al 2010, Chen andMayden 2012).…”