Molecular Phylogeny of Asian Freshwater and Marine Stingrays Based on the DNA Nucleotide and Deduced Amino Acid Sequences of the Cytochrome &lt;i&gt;b&lt;/i&gt; Gene

The major branches of life diversified in the marine realm, and numerous taxa have since transitioned between marine and freshwaters. Previous studies have demonstrated higher rates of molecular evolution in crustaceans inhabiting continental saline habitats as compared with freshwaters, but it is unclear whether this trend is pervasive or whether it applies to the marine environment. We employ the phylogenetic comparative method to investigate relative molecular evolutionary rates between 148 pairs of marine or continental saline versus freshwater lineages representing disparate eukaryote groups, including bony fish, elasmobranchs, cetaceans, crustaceans, mollusks, annelids, algae, and other eukaryotes, using available protein-coding and noncoding genes. Overall, we observed no consistent pattern in nucleotide substitution rates linked to habitat across all genes and taxa. However, we observed some trends of higher evolutionary rates within protein-coding genes in freshwater taxa-the comparisons mainly involving bony fish-compared with their marine relatives. The results suggest no systematic differences in substitution rate between marine and freshwater organisms.

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“…For example, shifts from marine to FW have occurred multiple times in fish (Sezaki et al. ; Lovejoy and Collette ; Yamanoue et al. ; Bloom et al.…”

Section: Metabolic Ratementioning

confidence: 99%

Do saline taxa evolve faster? Comparing relative rates of molecular evolution between freshwater and marine eukaryotes

et al. 2016

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“…Obligate Freshwater elasmobranchs are dominated (30 species) by myliobatoid stingrays, of which twothirds (22 species) are potamotrygonid river stingrays, Glantz & Feingold, 1990;Smith et al, 1991 By-catch Direct removal; reduction of prey base; changes in aquatic community composition & structure Miller et al, 1990;Nichols et al, 1990;Murray et al, 1992;Perra, 1992 Illegal trade in aquarium/ornamental ¢sh Direct removal; use of toxins (sodium cyanide) to collect ¢sh; decline of native ¢sh diversity Conroy et al, 1981;Derr, 1992 Introduced species Introduced predators, competition, hybridization, introduced parasites & disease, ballast water introduction Population reduction or extermination of native ¢sh, loss of prey base Taylor et al, 1984;Helfman et al, 1997 endemic to Atlantic drainages of South America. Sezaki et al (1999) found that DNA nucleotide and amino acid sequences in Indian and Thai populations of the Obligate Freshwater stingray Himantura chaophraya were clearly di¡erent, suggesting that signi¢cant evolutionary divergence occurred since their ecological isolation in di¡erent river systems. Such isolation may account for the relatively high diversity and incidence of endemism among Obligate Freshwater elasmobranchs.…”

Section: Biology Of Freshwater and Euryhaline Elasmobranchsmentioning

confidence: 99%

conservation of freshwater and euryhaline elasmobranchs: a review

Martin¹

2005

J. Mar. Biol. Ass.

117

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Published data on the diversity, life history, ecology, and status of freshwater and euryhaline elasmobranchs was reviewed in the context of anthropogenic threats and principles of conservation biology. At least 171 species of elasmobranch, representing 68 genera and 34 families, are recorded from fresh or estuarine waters. Of these, over half are marginal in estuaries, less than one-tenth are euryhaline, and one-¢fth are obligate in fresh water. Obligate freshwater elasmobranchs are dominated by myliobatoid stingrays, of which two-thirds are potamotrygonids endemic to Atlantic drainages of South America. Freshwater and euryhaline elasmobranchs adhere to strongly K-selected life histories and feed at high trophic levels, similar to those of their marine relatives. However, freshwater and euryhaline elasmobranchs are also subject to habitat constraints, notably more limited volume and physicochemical variability than the ocean, that may render them more vulnerable than marine elasmobranchs to the e¡ects of human activities. The greatest diversity and abundance of freshwater and euryhaline elasmobranchs occur in tropical countries with enormous and rapidly increasing human populations, notably South America, West Africa, and south-east Asia. Knowledge of the biology, distribution, ecology, and status of freshwater and euryhaline elasmobranchs is frustrated by unresolved taxonomic problems, which are brie£y summarized. To clarify selected issues in the conservation of freshwater and euryhaline elasmobranchs, special attention is given to sharks of the genus Glyphis, pristids, and potamotrygonids. To foster live release when possible as well as prevent discard of specimens and loss of data, an illustrated key to di¡erentiate Carcharhinus from Glyphis sharks is provided. Obligate freshwater elasmobranchs with limited geographic ranges are deemed most vulnerable to extinction, but euryhaline elasmobranchs that require access to the sea to breed are also at signi¢cant risk. Based on the foregoing data and principles of conservation biology, suggested action plans for the conservation of freshwater and euryhaline elasmobranchs and the conservation of freshwater habitats are provided.

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“…Molecular phylogeny suggests that freshwater stingrays from Southeast Asia, including H. signifer , have only marine species as their nearest relative, and they underwent multiple colonizations rather than speciations within freshwater [46]. Since the invasion of the H. signifer lineage into freshwater habitats appears to be relatively recent [47], it is not unexpected that H. signifer would experience higher salinity stress in freshwater than in brackish water.…”

Section: Discussionmentioning

confidence: 99%

Ascorbic Acid Biosynthesis and Brackish Water Acclimation in the Euryhaline Freshwater White-Rimmed Stingray, Himantura signifer

et al. 2013

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L-gulono-γ-lactone oxidase (Gulo) catalyzes the last step of ascorbic acid biosynthesis, which occurs in the kidney of elasmobranchs. This study aimed to clone and sequence gulonolactone oxidase (gulo) from the kidney of the euryhaline freshwater stingray, Himantura signifer, and to determine the effects of acclimation from freshwater to brackish water (salinity 20) on its renal gulo mRNA expression and Gulo activity. We also examined the effects of brackish water acclimation on concentrations of ascorbate, dehydroascorbate and ascorbate + dehydroascorbate in the kidney, brain and gill. The complete cDNA coding sequence of gulo from the kidney of H. signifer contained 1323 bp coding for 440 amino acids. The expression of gulo was kidney-specific, and renal gulo expression decreased significantly by 67% and 50% in fish acclimated to brackish water for 1 day and 6 days, respectively. There was also a significant decrease in renal Gulo activity after 6 days of acclimation to brackish water. Hence, brackish water acclimation led to a decrease in the ascorbic acid synthetic capacity in the kidney of H. signifer. However, there were significant increases in concentrations of ascorbate and ascorbate + dehydroascorbate in the gills (after 1 or 6 days), and a significant increase in the concentration of ascorbate and a significant decrease in the concentration of dehydroascorbate in the brain (after 1 day) of fish acclimated to brackish water. Taken together, our results indicate that H. signifer might experience greater salinity-induced oxidative stress in freshwater than in brackish water, possibly related to its short history of freshwater invasion. These results also suggest for the first time a possible relationship between the successful invasion of the freshwater environment by some euryhaline marine elasmobranchs and the ability of these elasmobranchs to increase the capacity of ascorbic acid synthesis in response to hyposalinity stress.

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Molecular Phylogeny of Asian Freshwater and Marine Stingrays Based on the DNA Nucleotide and Deduced Amino Acid Sequences of the Cytochrome <i>b</i> Gene

Cited by 30 publications

References 6 publications

Do saline taxa evolve faster? Comparing relative rates of molecular evolution between freshwater and marine eukaryotes

Do saline taxa evolve faster? Comparing relative rates of molecular evolution between freshwater and marine eukaryotes

conservation of freshwater and euryhaline elasmobranchs: a review

Ascorbic Acid Biosynthesis and Brackish Water Acclimation in the Euryhaline Freshwater White-Rimmed Stingray, Himantura signifer

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