EVOLUTIONARY ORIGIN AND EARLY BIOGEOGRAPHY OF OTOPHYSAN FISHES (OSTARIOPHYSI: TELEOSTEI)

The biogeography of the mega‐diverse, freshwater, and globally distributed Otophysi has received considerable attention. This attraction largely stems from assumptions as to their ancient origin, the clade being almost exclusively freshwater, and their suitability as to explanations of trans‐oceanic distributions. Despite multiple hypotheses explaining present‐day distributions, problems remain, precluding more parsimonious explanations. Underlying previous hypotheses are alternative phylogenies for Otophysi, uncertainties as to temporal diversification and assumptions integral to various explanations. We reexamine the origin and early diversification of this clade based on a comprehensive time‐calibrated, molecular‐based phylogenetic analysis and event‐based approaches for ancestral range inference of lineages. Our results do not corroborate current phylogenetic classifications of otophysans. We demonstrate Siluriformes are never sister to Gymnotiformes and Characiformes are most likely nonmonophyletic. Divergence time estimates specify a split between Cypriniformes and Characiphysi with the fragmentation of Pangea. The early diversification of characiphysans either predated, or was contemporary with, the separation of Africa and South America, and involved a combination of within‐ and between‐continental divergence events for these lineages. The intercontinental diversification of siluroids and characoids postdated major intercontinental tectonic fragmentations (<90 Mya). Post‐tectonic drift dispersal events are hypothesized to account for their current distribution patterns.     

Molecular phylogenetics of the family Cyprinidae (Actinopterygii: Cypriniformes) as evidenced by sequence variation in the first intron of S7 ribosomal protein-coding gene: further evidence from a nuclear gene of the systematic chaos in the family

The family Cyprinidae is the largest freshwater fish group in the world, including over 200 genera and 2100 species. The phylogenetic relationships of major clades within this family are simply poorly understood, largely because of the overwhelming diversity of the group; however, several investigators have advanced different hypotheses of relationships that pre- and post-date the use of shared-derived characters as advocated through phylogenetic systematics. As expected, most previous investigations used morphological characters. Recently, mitochondrial DNA (mtDNA) sequences and combined morphological and mtDNA investigations have been used to explore and advance our understanding of species relationships and test monophyletic groupings. Limitations of these studies include limited taxon sampling and a strict reliance upon maternally inherited mtDNA variation. The present study is the first endeavor to recover the phylogenetic relationships of the 12 previously recognized monophyletic subfamilies within the Cyprinidae using newly sequenced nuclear DNA (nDNA) for over 50 species representing members of the different previously hypothesized subfamily and family groupings within the Cyprinidae and from other cypriniform families as outgroup taxa. Hypothesized phylogenetic relationships are constructed using maximum parsimony and Basyesian analyses of 1042 sites, of which 971 sites were variable and 790 were phylogenetically informative. Using other appropriate cypriniform taxa of the families Catostomidae (Myxocyprinus asiaticus), Gyrinocheilidae (Gyrinocheilus aymonieri), and Balitoridae (Nemacheilus sp. and Beaufortia kweichowensis) as outgroups, the Cyprinidae is resolved as a monophyletic group. Within the family the genera Raiamas, Barilius, Danio, and Rasbora, representing many of the tropical cyprinids, represent basal members of the family. All other species can be classified into variably supported and resolved monophyletic lineages, depending upon analysis, that are consistent with or correspond to Barbini and Leuciscini. The Barbini includes taxa traditionally aligned with the subfamily Cyprininae sensu previous morphological revisionary studies by Howes (Barbinae, Labeoninae, Cyprininae and Schizothoracinae). The Leuciscini includes six other subfamilies that are mainly divided into three separate lineages. The relationships among genera and subfamilies are discussed as well as the possible origins of major lineages.     

Phylogenetic relationships of Moxostoma and Scartomyzon (Catostomidae) based on mitochondrial cytochrome b sequence data

A recent phylogenetic study based on morphological, biochemical and early life history characters resurrected the genus Scartomyzon (jumprock suckers, c . eight−10 species) from Moxostoma (redhorse suckers, c . 10–11 species) and advanced the understanding of relationships among species in these two genera, and the genealogical affinities of these genera with other evolutionary lineages within the tribe Moxostomatini in the subfamily Catostominae. To further examine phylogenetic relationships among moxostomatin suckers, the complete mitochondrial (mt) cytochrome b gene was sequenced from all species within this tribe and representative outgroup taxa from the Catostomini and other catostomid subfamilies. Phylogenetic analysis of gene sequences yielded two monophyletic clades within Catostominae: Catostomus + Deltistes + Xyrauchen + Erimyzon + Minytrema and Moxostoma + Scartomyzon + Hypentelium + Thoburnia . Within the Moxostomatini, Thoburnia was either unresolved or polyphyletic; Thoburnia atripinnis was sister to a monophyletic Hypentelium . In turn, this clade was sister to a monophyletic clade containing Scartomyzon and Moxostoma . Scartomyzon was never resolved as monophyletic, but was always recovered as a polyphyletic group embedded within Moxostoma , rendering the latter genus paraphyletic if ' Scartomyzon ' continues to be recognized. Relationships among lineages within the Moxostoma and' Scartomyzon 'clade were resolved as a polytomy. To better reflect phylogenetic relationships resolved in this analysis, the following changes to the classification of the tribe Moxostomatini are proposed: subsumption of' Scartomyzon 'into Moxostoma ; restriction of the tribe Moxostomatini to Moxostoma ; resurrect the tribe Erimyzonini, containing Erimyzon and Minytrema , classified as incertae sedis within Catostominae; retain the tribe Thoburniini.     

Crevice spawning behavior in Dionda dichroma,with comments on the evolution of spawning modes in North American shiners (Teleostei: Cyprinidae)

The crevice spawning behavior of Diondadichroma is described for the first time, andcompared to spawning behavior in the genusCyprinella. The evolution of crevice spawningwith respect to other spawning behaviors ofNorth American shiners is examined usingexplicitly phylogenetic hypotheses for thisgroup. We present evidence that broadcastspawning is plesiomorphic and all otherspawning behaviors are independently derived. There is evidence that crevice spawning hasevolved independently at least three timeswithin the shiner clade. There is no supportfor an evolutionary transition between eggclustering and crevice spawning. Nestassociation, spawning on habitat prepared byother species, has also evolved multiple timeswithin this clade. Evolution of spawning inshiners is best described by phylogeneticstasis with several independent origins ofspecialized spawning stragegies.     

Phylogenetic relationships of Cypriniformes and plasticity of pharyngeal teeth in the adaptive radiation of cyprinids

The Cypriniformes comprise approximately 4,200 species accounting for 25% of the diversity of all freshwater fish, which is widely distributed across the world's continents except Antarctica, South America, and Australia. The highest species diversity is found in Southeastern Asia. Despite its remarkable species diversity and broad-scale geographic patterns of distribution, the evolutionary history of this major freshwater fish group remains largely unresolved. To gain insight of the evolutionary history of Cypriniformes, we present a phylogeny of this group using 1 mitochondrial gene and 15 nuclear genes comprising a total of14,061 bp. Bayesian inference using all gene fragments yielded a well resolved phylogeny, which is mostly consistent with topologies obtained from Maximum Likelihood analyses. Our results further confirmed the monophyly of Cypriniformes and seven constituent subclades including Cyprinidae, Catostomidae, Gyrinocheilidae, Balitoridae, Cobitidae, Nemacheilidae, and Botiidae. Bayesian divergence time analysis indicated that the origin of the Cypriniformes was about 193 Mya during the early Jurassic, coinciding with the onset of the Pangaea breakup. The basal divergence of Cypriniformes is 154 Mya during the late Jurassic. Our findings from molecular divergence and biogeographical analysis indicate the most likely initial geographical range of the ancient Cypriniformes was both East and South Asia(Southeastern area of Mesozoic Laurasia). Moreover, the burst in species diversity in Cyprinidae afforded by the nearly worldwide colonization is possibly in response to the plasticity of pharyngeal dentition. The present study demonstrates that the Cypriniformes was about 193 Mya during the early Jurassic,coinciding with the onset of the Pangaea breakup. The plasticity of pharyngeal dentition of cyprinids might contribute to the burst and radiation of this lineage. The phylogenetic and biogeographic analyses in this study help to improve our understanding of the evolutionary history of this diverse and important freshwater fish group.     

Phylogeny and biodiversity: Conserving our evolutionary legacy

Historical ecological studies provide information about the origins of species in an area and the origins of traits characterizing the interactions between those species and their environment. Incorporating this evolutionary information into conservation policies will broaden the base of options for making effective decisions about the preservation of biodiversity.     

On the inhibition of muscle membrane chloride conductance by aromatic carboxylic acids

25 aromatic carboxylic acids which are analogs of benzoic acid were tested in the rat diaphragm preparation for effects on chloride conductance (G(Cl)). Of the 25, 19 were shown to reduce membrane G(Cl) with little effect on other membrane parameters, although their apparent K(i) varied widely. This inhibition was reversible if exposure times were not prolonged. The most effective analog studied was anthracene-9-COOH (9-AC; K(i) = 1.1 x 10(-5) M). Active analogs produced concentration-dependent inhibition of a type consistent with interaction at a single site or group of sites having similar binding affinities, although a correlation could also be shown between lipophilicity and K(i). Structure-activity analysis indicated that hydrophobic ring substitution usually increased inhibitory activity while para polar substitutions reduced effectiveness.

These compounds do not appear to inhibit G(Cl) by altering membrane surface charge and the inhibition produced is not voltage dependent. Qualitative characteristics of the I-V relationship for Cl(-) current are not altered. Conductance to all anions is not uniformly altered by these acids as would be expected from steric occlusion of a common channel. Concentrations of 9-AC reducing G(Cl) by more than 90 percent resulted in slight augmentation of G(I). The complete conductance sequence obtained at high levels of 9-AC was the reverse of that obtained under control conditions. Permeability sequences underwent progressive changes with increasing 9-AC concentration and ultimately inverted at high levels of the analog. Aromatic carboxylic acids appear to inhibit G(Cl) by binding to a specific intramembrane site and altering the selectivity sequence of the membrane anion channel.

     

Barley aleurone cells contain two types of vacuoles. Characterization Of lytic organelles by use of fluorescent probes

Light microscopy was used to study the structure and function of vacuoles in living protoplasts of barley (Hordeum vulgare cv Himalaya) aleurone. Light microscopy showed that aleurone protoplasts contain two distinct types of vacuole: the protein storage vacuole and a lysosome-like organelle, which we have called the secondary vacuole. Fluorescence microscopy using pH-sensitive fluorescent probes and a fluorogenic substrate for cysteine proteases showed that both protein storage vacuoles and secondary vacuoles are acidic, lytic organelles. Ratio imaging showed that the pH of secondary vacuoles was lower in aleurone protoplasts incubated in gibberellic acid than in those incubated in abscisic acid. Uptake of fluorescent probes into intact, isolated protein storage vacuoles and secondary vacuoles required ATP and occurred via at least two types of vanadate-sensitive, ATP-dependent tonoplast transporters. One transporter catalyzed the accumulation of glutathione-conjugated probes, and another transported probes not conjugated to glutathione.