r
[Who am I] [Research] [Fishes West Ecuador] [The New World Sciaenidae] [Bell Lab] [EE SUNY Stony Brook]


Phylogeny of the Cynoscion group (Teleostei: Sciaenidae)


Introduction: Cynoscion (Teleostei: Sciaenidae) is a relatively large genus with 24 species (Eschmeyer, 1998) that occurs in coastal tropical and subtropical waters of the New World (Figures 1 and 2). Cynoscion spp. are very important ecologically because they are major predators of fishes and crustaceans in coastal estuaries (León, 1973; Araya, 1984), as well as prey of other commercially important fishes and threatened marine mammals such as bottlenose dolphins (Félix, 1994). The genus is also among the most valuable for the coastal fisheries of Latin America. Despite its ecological and economic importance, little is known about its phylogeny. There have been phylogenetic analyses of the four species from the U.S. Atlantic and Gulf coasts (Moshin, 1973; Weinstein and Yerger, 1977; Paschall, 1986), but the only hypothesis of phylogenetic relationships of the entire genus was based on a single morphological structure, otoliths (Schwarzhans, 1993).

I am presently working on a phylogeny of the genus Cynoscion and closely related genera (Isopisthus, Macrodon, Atractoscion, and Totoaba) using mitochondrial DNA sequence data. A phylogenetic hypothesis for this group will provide important insight into part of the evolutionary history of the family Sciaenidae and provide a basis for future comparative studies of morphological, ecological, and behavioral characters. Presently, I have sequences for a fragment of the 12S and 16S mitochondrial rRNA genes for nine species of Cynoscion and one species of the genus Isopisthus. In the near future I hope to obtain sequences for the remaining species and expand the study to include a fragment of the cytochrome b gene.

Figure 1. A. Cynoscion arenarius, a typical species of Cynoscion. B. Isopisthus remifer, a species from a closely related genus.
Figure 2. Distribution Map for Cynoscion spp. This map is based on distributions given by Chao (1981, 1995). The map is only intended to provide a rough idea of where particular species are found, it's accuracy is limited. C. guatucupa and C. striatus are not listed yet.

Methods: The methods I am using are fairly standard. I use QIAGEN kits for DNA extraction* and gel purification of PCR products (*For some specimens I used a phenol based DNA extraction procedure). Gel purified PCR products are direct sequenced. For PCR reactions of the 12S and 16S genes, I used published universal primers from Palumbi (1996) to obtain sequences for a 2100 bp fragment of the 12S and 16S rRNA genes for C. arenarius and C. nebulosus (NCBI accession numbers: AF128401 and AF128402; Figure 3). Specific primers were then designed that amplify a fragment extending from approximately the center of the mitochondrial 12S rRNA gene, through the valine tRNA to about 240 bp within the mitochondrial 16S rRNA gene (~840bp; Figure 3). This is the 12S/16S fragment I am using for the phylogenetic analysis. The species I already have sequence data for are: C. albus, C. analis, C. phoxocephalus, C. squamipinnis, C. xanthulus, and Isopisthus remifer from the eastern Pacific, and C. arenarius, C. nebulosus, C. nothus, and C. regalis from the western Atlantic (3 specimens per species). The outgroups I am using are: Plagioscion squamosissimus, Nebris occidentalis, and Larimus pacificus. Plagioscion is a genus occurring in freshwaters of South America; it has been suggested to be relatively close to Cynoscion (Chao, 1978; Sasaki, 1989). Nebris occidentalis and Larimus pacificus occur in the eastern Pacific.

In terms of the cytochrome b gene, I obtained sequence data some time ago for a small fragment which is available on genbank (C. arenarius - accession number: AF093819). Universal primers published in Palumbi (1996) were also used to obtain this sequence. I am currently experimenting with other universal primers for cytochrome b and hope to have complete gene sequences for two or three species in the near future.

Figure 3. Fragment of the 12S/16S genes selected for phylogenetic analysis. The yellow band represents a portion of the mitochondrial genome, the red bands are tRNA's, the dark blue band is the initial 2,100 bp fragment amplified, the light blue band is the fragment selected for the phylogenetic analysis, and the violet bands are the designed specific primers.


Preliminary Results: Although I presently have data for less than half the species that will eventually be included in this study, I present below a distance matrix for the 12S/16S fragment and a neighbor-joining tree that summarizes relationships based on distances to provide a sense of what the data is suggesting. The matrices and tree were generated with MEGA version 2.1 (Kumar et al., 2001). They are based on consensus sequences for each species.

The distance matrix below (Table 1) is of pairwise nucleotide differences. The overall average for nucleotide differences is 43.49 and the average for the ingroup species (Cynoscion and Isopisthus) is 33.62. The overall average transition to transversion ratio is 3.64 and for the ingroup species is 4.411.

The tree below (Figure 4) is a neighbor-joining tree based on another matrix created using the Tamura-Nei model. It is too early to say if the results below will hold as more data accumulates, however the position of the genus Isopisthus on the tree and the relationship between C. albus* and C. xanthulus* are particularly interesting (*these two species were identical for the fragment sequenced; C. albus was collected from the southern limit of its range, in the Gulf of Guayaquil, Ecuador, and C. xanthulus was collected from the Salton Sea, California, where it is introduced).



Species [ 1] [ 2] [ 3] [ 4] [ 5] [ 6] [ 7] [ 8] [ 9] [ 10] [ 11] [ 12] [ 13]
[ 1. C. are.] - - - - - - - - - - - - -
[ 2. C. reg.] 11.000 - - - - - - - - - - - -
[ 3. C. neb.] 29.000 30.00 - - - - - - - - - - -
[ 4. C. nth.] 29.000 25.00 29.00 - - - - - - - - - -
[ 5. C. alb.] 33.000 34.00 32.00 30.00 - - - - - - - - -
[ 6. C. xan.] 33.000 34.00 32.00 30.00 0.00 - - - - - - - -
[ 7. C. ana.] 38.000 35.00 41.00 33.00 40.00 40.00 - - - - - - -
[ 8. C. squ.] 36.000 34.00 40.00 37.00 41.00 41.00 29.00 - - - - - -
[ 9. C. phx.] 38.000 42.00 38.00 39.00 41.00 41.00 26.00 30.00 - - - - -
[ 10. I. rem.] 37.000 36.00 36.00 40.00 46.00 46.00 24.00 30.00 27.00 - - - -
[ 11. L. pac.] 49.000 51.00 57.00 52.00 61.00 61.00 59.00 55.00 52.00 56.00 - - -
[ 12. N. occ.] 48.000 50.00 54.00 53.00 53.00 53.00 57.00 54.00 51.00 60.00 31.00 - -
[ 13. P. squ.] 62.000 64.00 57.00 61.00 69.00 69.00 63.00 64.00 64.00 64.00 54.00 63.00 -

Table 1. Pairwise distance matrix of the number of nucleotide differences between species for the 12S/16S fragment. The fragment used to create this matrix was 754 bp long.




Figure 4. Neighbor-joining tree for 12S/16S fragment. The Tamura-Nei model was used with a gamma value of 1. This tree is a bootstrap consensus tree, numbers are bootstrap values for 1000 replicates. Species with a red dot next to their name are from the eastern Pacific, species with a blue dot are from the western Atlantic.




Acknowledgements: Walter Grater assisted and Ken Stuck, William Hawkins and Stuart Poss (Gulf Coast Research Laboratory) provided support for the first part of this study. The Lerner-Gray Fund for Marine Research (AMNH), the Department of Ecology and Evolution (SUNY at Stony Brook) and Geeta Bharathan are providing support for the second part of the study. Mike Bell has provided useful comments. Special thanks to those who have provided tissue samples: Tim Targett, Robert McMichael, Debbie Leffler, Jeanne Boylan, Barry Costa-Pierce, Ralf Riedel, Mike Littmann, and David Chiluiza. Thanks as well to those who have offered specimens.


Materials Cited:

Araya, H.A. 1984. Los sciaenidos (corvinas) del Golfo de Nicoya, Costa Rica. Revista de Biologia Tropical 32:179-196.

Chao, L.N. 1978. A basis for classifying western Atlantic Sciaenidae (Teleostei: Perciformes). NOAA Technical Report Circular- 415. 64 pp.

Chao, L.N. 1981. Sciaenidae. In Fischer, W., G. Bianchi, and W.B. Scott (eds.). FAO Species Identification Sheets for Fishery Purposes. Eastern Central Atlantic. Volume III. Food and Agriculture Organization of the United Nations- Department of Fisheries and Oceans, Canada. Ottawa.

Chao, N.L. 1995. Sciaenidae. Pages 1427-1518 in W. Fischer, F. Krupp, W. Schneider, W. Sommer, K.E. Carpenter, and V.H. Niem (eds). Guia Fao para la identificacion de especies para los fines de la pesca. Pacifico-centro Oriental. Volumen III. Vertebrados - Parte II. FAO. Roma.

Eschmeyer, W.N. 1998. Catalog of Fishes. Special Publication No. 1 of the Center of Biodiversity Research and Information, California Academy of Sciences. San Fransisco.

Félix, F. 1994. Ecology of the coastal bottlenose dolphin Tursiops truncatus in the Gulf of Guayaquil Ecuador. Pages 235-256 in G. Pilleri (ed.), Investigations on Cetacea. Vol. XXV.

Kumar, S., K. Tamura, I.B. Jakobsen, and M. Nei. 2001. MEGA2: Molecular Evolutionary Genetics Analysis software, Arizona State University, Tempe, Arizona, USA.

Moshin, A.K.M. 1973. Comparative osteology of weakfishes (Cynoscion) of the Atlantic and Gulf coasts of the United States. Ph.D. Dissertation, Texas A&M University. 148 pp.

Palumbi, S.R. 1996. Nucleic acids II: The polymerase chain reaction. Pages 205-247 in D.M. Hillis, C. Moritz, and B.K. Mable (eds.), Molecular Systematics. Sinauer Associates, Inc. Sunderland, Maryland.

Paschall, R.L., Jr. 1986. Biochemical systematics of seatrouts of the western Atlantic, genus Cynoscion. M.S. Thesis University of New Orleans. 99 pp.

Sasaki, K. 1989. Phylogeny of the family Sciaenidae, with notes on its zoogeography (Teleostei, Perciformes). Mem. of the Faculty of Fisheries, Hokaido University 36:1-137.

Schwarzhans, W. 1993. A comparative morphological treatise of recent and fossil otoliths of the family Sciaenidae (Perciformes). Piscium catalogus: Part Otolithi Piscium. Vol. I. Verlag Dr. Freidrich Pfeil. Munchen. 245 pp.

Weinstein, M.P., and R.W. Yerger. 1976. Protein taxonomy of the Gulf of Mexico and Atlantic coasts seatrouts, genus Cynoscion. Fishery Bulletin 74:599-607.


Last Updated: 4 August 2001


[Who am I] [Research] [Fishes West Ecuador] [The New World Sciaenidae] [Bell Lab] [EE SUNY Stony Brook]