Walter Wheaton Dimmick

The interrelationships of Acanthomorph fishes: A total evidence approach using molecular and morphological data

DNA sequence and morphological data were analyzed for specimens of twenty-five species of acanthomorph fishes and two specimens representing the outgroups Aulopiformes and Myctophiformes. A 572 base-pair (bp) segment of the 12S ribosomal mitochondrial gene, 1112 bp from three regions of the 28S ribosomal nuclear gene, and 38 morphological transformation series were analyzed under the criterion of maximum parsimony. The total evidence analysis resulted in a set of four most parsimonious trees. Relationships common to all trees are largely congruent with the hypothesis articulated by Johnson and Patterson (1993. Bull. Mar. Sci. 52, 554-626).

Phylogenetic Relationships of Pleuronectiformes Based on Molecular Evidence

Abstract Phylogenetic analyses based on nucleotide sequence data of the 12S and 16S mitochondrial ribosomal genes were performed for representatives of the Pleuronectiformes (flatfishes). Two parsimony analyses with percomorphs and basal acanthopterygians designated as outgroups were conducted; equal weighting of all nucleotides and loop regions analyzed for transversions only. A bayesian analysis was performed under the likelihood model TrN+I+Γ. A monophyletic Pleuronectiformes was resolved in all analyses. Results are consistent with the current higher level classification, recognizing the suborders Psettodoidei and Pleuronectoidei. Psettodoidei consists of a single family, Psettodidae, that is sister to all other flatfishes. Within the Pleuronectoidei three clades are identified. Bothids plus paralichthyids (in part) form a clade in all analyses. A solelike clade containing citharids, cynoglossids, samarids, soleids, Trinectes (Achiridae), and Poecilopsetta (Poecilsopsettidae), is identified in the parsimony analyses. However, a solelike clade was not recovered in the bayesian analysis. A flounderlike clade is identified containing Pleuronectidae and Paralichthyidae (in part) in all analyses. The position of Scophthalmus (Scophthalmidae) differed among all analyses. The results further support the conclusion that eye position is not a useful source of information for the classification of flatfishes. This study provides a new framework for future studies.

Genetic Comparison of Three Barbus (Cyprinidae) Morphotypes from the Genale River, Ethiopia

Abstract The large barbs of East Africa are well known for their morphological plasticity. Mitochondrial DNA sequences were compared for specimens of three distinctive barb morphotypes collected syntopically from the Genale River in southeastern Ethiopia. The “normal,” “lipped,” and “large-mouthed” morphotypes are putatively referable to Barbus gananensis. An analysis of molecular variance revealed that the lipped and normal morphotypes are not genetically distinct (ϕST < 0.0001, P = 0.80) and that the group of large-mouthed haplotypes is significantly differentiated from a combined group of normal and lipped haplotypes (ϕST = 0.54, P < 0.001). The evolutionary relationships among the haplotypes were assessed with phylogenetic and minimum-length spanning trees. The results of the phylogenetic and spanning tree analyses are consistent with the analysis of molecular variance. The normal and lipped morphotypes represent morphological variants of B. gananensis, and the large-mouthed morphotype represents a genetically distinctive undescribed species.

Evolutionary genetics of the endemic Schizorathicine (Cypriniformes: Cyprinidae) fishes of Lake Rara, Nepal

The three endemic species of Schizothorax from Lake Rara, Nepal comprise a putative cyprinid species flock. Mitochondrial DNA sequences were compared for specimens of the endemic species S. raraensis, S. macrophthalmus, and S. nepalensis, and specimens of S. richardsonii and S. progastus from the Karnali River, Koshi River, and Kali Gandaki River drainages. An analysis of molecular variance demonstrated that S. nepalensis is genetically distinct from a group composed of S. raraensis and S. macrophthalmus. Phylogenetic analyses based on parsimony failed to corroborate or conclusively reject a hypothesis of monophyly for the three endemic species of Schizothorax from Lake Rara. The mtDNA haplotypes of S. richardsonii and S. progastus from the Karnali River drainage were not significantly differentiated from one another, but pairwise comparisons of haplotypes from the Lake Rara basin, Karnali River drainage, Koshi River drainage, and Kali Gandaki River drainage were significantly differentiated from one another.

Reevaluation of the Lythrurus ardens (Cypriniformes: Cyprinidae) Complex with Recognition of Three Evolutionary Species

Samples were taken from throughout the range of the three nominal taxa that comprise the Lythrurus ardens species-complex: L. fasciolaris (Ohio basin and Black Warrior River system, Alabama), L. ardens (York, Roanoke, James, and upper New River drainages), and L. matutinus (Tar and Neuse River drainages, North Carolina). Based on breeding tubercle patterns, color of nuptial males, anal-fin ray number, and general body shape, the three taxa were diagnosed and recognized as species. Lythrurusfasciolaris has a mode of 10 anal rays, and nuptial males have a keeled nape, deep body, several blue-gray bars on the dorsum, and intense red or orange on the fins but not on top of the head. Lythrurus matutinus has a mode of 11 anal rays and is slender bodied; nuptial males have blood-red on top of the head, no red in the paired fins, and no blue-gray bars on the dorsum; nuptial females are masculinized, with extensive tubercle development on the head. Lythrurus ardens has a mode of 11 anal rays and is moderately slender bodied; nuptial males have faint red in the fins and on top of the head, faint blue-gray bars on the dorsum, and blue on the side; females are not masculinized. Fourteen of 29 presumptive gene loci examined were polyallelic. Allelic and genotypic variation of three loci (Est-2, Pgm-A, Est-3) support genetic isolation of the western species, L. fasciolaris, from the two eastern species, L. ardens and L. matutinus. The magnitude of allozymic differentiation between eastern and western species is similar to differences reported for other species of the genus Lythrurus. The three taxa represent three evolutionary species. Evidence for lineage independence among the three species includes an array of intrinsic characters with independent corroboration from extrinsic biogeographic evidence. Recognition of L. fasciolaris and L. matutinus as species brings the total

Spliceosomal Introns and Fish Phylogeny: A Critical Reanalysis

Abstract The currently available spliceosomal intron data were found to be of limited utility as phylogenetic characters for resolving the phylogeny of several clades of fishes. Phylogenetic relationships were inferred from a parsimony analysis of the distribution of introns among representatives of 18 major groups of vertebrates for seven genes. Phylogenetic signal of the spliceosomal intron data was limited to support for the monophyly of the Teleostei. The spliceosomal intron based phylogeny of B. Venkatesh, Y. Ning, and S. Brenner (in the Proceedings of the National Academy of Science, 1999) was evaluated and found to be fundamentally flawed. The analysis of B. Venkatesh, Y. Ning, and S. Brenner (in the Proceedings of the National Academy of Science, 1999) was compromised by errors in the treatment of missing and polymorphic data, the arbitrary exclusion of taxa, the assessment of homology, outgroups and rooting, the ordering and polarization of character states, and a failure to follow the logical implications of multiple equally parsimonious trees.

Introduction to Invertebrates of Inland Waters

Publisher Summary This chapter introduces freshwater invertebrates, with focus on those found in inland waters of North America. North American freshwater habitats support about 213 species of free-living oligochaete worms, 107 species of ectocommensal/predaceous branchiobdellidans, and 76 species of leeches. About 32 species of sponges colonize freshwater habitats in the continental North America. About 526 species of snails (Gastropoda) are present in North American freshwaters or humid terrestrial environments. The North American fauna of freshwater bivalves is the richest in the world, with about 350 species of mussels and clams, nine or so of which are exotic. The phylum Annelida consists primarily of three relatively diverse freshwater groups (oligochaete worms, leeches, and branchiobdellidans), a few species of polychaetes, and the leech-like Acanthobdella peledina , a temporary ectoparasite of salmonid fishes. Although the diversity of freshwater bryozoans is not high (24 ectoproct species in North America), they are actually quite common occupants of hard, relatively stationary, and biologically inactive substrates. The most successful terrestrial phylum and one of the most prominent freshwater taxa is Arthropoda. Its three subphyla with freshwater members—Chelicerata (water mites and a few semiaquatic spiders), Hexapoda (aquatic insects), and Crustacea (e.g., crayfish, fairy shrimp, copepods)—are all diverse and important components of lakes and streams. The chapter presents an overview of the aspects of the biology, ecology, and classification of freshwater and other inland aquatic invertebrates.

Phylogenetic relationships of the suckermouth minnows, genus Phenacobius, inferred from parsimony analyses of nucleotide sequence, allozymic and morphological data (Cyprinidae: Cypriniformes)

Abstract We investigated the phylogenetic relationships among the five species of the genus Phenacobius (Cyprinidae: Cypriniformes) using a combined analysis of molecular and morphological characters. The nucleotide characters were comprised of 208 potentially informative sites among a total 1773 aligned base pairs from several segments of mitochondrial genes that encode the large and small RNA subunits, the valine transfer RNA, and the NADH ubiquinone oxidoreductase subunit 2. Allelic data from 23 polymorphic allozyme loci and nine morphological characters taken from the literature were also included in the total evidence analysis. Third position codon characters were demonstrated to be saturated for transitional changes and unsuitable for phylogeny estimation among the species studied here. The total evidence phylogeny is isomorphic with Mayden’s (1989) morphological hypothesis. Phenacobius mirabilis was found to be basal, followed in ascending order by P. teretulus, P. catostomus and a clade comprised of P. crassilabrum and P. uranops .

Threatened fishes of the world: Barbus ethiopicus Zolezzi, 1939 (Cyprinidae)

Presence of this species in the other significant tributary of Lake Zwai, the Katar River, has not been verified. Habitat and ecology: Large individuals (>220mm SL) were found in the lake, while small ones (<220mm SL, both juvenile and mature) were found in the Meki River. This suggests an annual cycle of feeding in the lake and breeding in its tributaries during the rainy season (June‐November), a pattern similar to other species of large African barbs (Dgebuadze et al. 1999). The presence of mature fish up to 210mm SL in the river during the dry season (in January‐March)suggeststhepresenceofindependentriverineandlacustrinepopulations.Reproduction:Presenceofjuveniles(21‐35.5mmSL inFebruaryand38‐43mmSLinMarch),apparentlyyoungerthan1year,intheupperreachesoftheMekiRiverduringthedryseasonisevidence of spawning at the end of the previous rainy season. Ripe running males (minimum 156mm SL) at this locality were recorded also in January and February. Threats: The Lake Zwai basin is a region of intensive human population growth, agricultural, and urban development. The main threat to B. ethiopicus is the degradation of water quality and availability due to human pollution and exploitation. Additional potential threats are overfishing and competition with exoticfish species introduced into the basin (Golubtsov et al. 2002). BecauseB. ethiopicusis coincidentally caught with the more abundant B. intermedius by commercial fishermen, continued exploitation of B. intermedius could cause extermination of B. ethiopicus from Lake Zwai. At least one species of exotic fish (the Far East crusian carp) introduced into the basin may compete for food with B. ethiopicus in the lower reaches of the system. Conservation recommendations: A search for populations of B. ethiopicus and its spawning grounds in the two main tributaries of Lake Zwai is urgently needed. Spawning grounds should be demarcated and legally protected. The barb fisheries in the lake needs to be immediately regulated and restricted during the period of barb breeding migrations. The possibility of artificial propagation of B. ethiopicus should be studied. Remarks: B. ethiopicus is most likely a unique representative of phylogenetic lineage quite distantly related to other Ethiopian large barbs as demonstrated by recent molecular data (Dimmick, unpubl.).