THE HYDRA PHYLOGENY


THE HYDRA LIBRARY


WINGED_HELIX PROTEINS


POMONA COLLEGE BIOLOGY DEPARTMENT

 

 

 

 

 

 

 

 

 

 

Daniel E. Martínez
Associate Professor of Biology
dmartinez@pomona.edu

 

Molecular Phylogeny of Hydra

The freshwater polyps of the genus Hydra have been collected from all continents with the exception of Antartica. There are several dozen described species of hydra that have been assigned by Campbell (1987) into four distinct groups: Viridissima, Braueri, Oligactis, and Vulgaris. Even though these groups have been considered cosmopolitan, only two (Viridissima and Vulgaris) have been found in South America, Oceania, and Africa. We have built a molecular phylogeny of hydra using the ITS1 and ITS2 regions of nuclear ribosomal DNA, and two mitochondrial genes: 16S and CO1. To date hydra have been collected from more than 150 populations from around the world. Special efforts have been made to collect from areas that have been scarcely sampled in the past including Iceland, Scandinavia, Chile, Argentina, Australia, New Zealand and South Africa. Important areas of the world still remain to be sampled (e.g. Siberia, Southeast Asia).

Sequencing of the genome of Hydra magnipapillata has been recently completed. This particular species of Hydra was selected for the genome project because it is widely used in research. Our preliminary analyses of the ITS region suggests that H. magnipapillata cannot be easily distinguished from other species in the Vulgaris group. The same it is true for morphological characters: Hydra magnipapillata and several other “species” in the Vulgaris group can only be distinguished based on their geographical origin (Campbell, 1983). It seems quite important to determine the true affinity of H. magnipapillata with the other species of the Vulgaris group.

This work is being done in collaboration wiith Richard Campbell, University of California Irvine and is currently being supported by a grant by the National Science Foundation awarded to Daniel Martinez as part of the Cnidarian Tree of Life project. The bulk of the laboratory work for this project has been carried out by undergraduate students of a course in Molecular Evolution: The Tree of Life (Bio 109) at Pomona College.

References

Campbell, R.D.. 1987. A new species of Hydra (Cnidaria: Hydrozoa) from North America with comments on species clusters within the genus. Zool. J. Linnean Soc. 91: 253-263

Campbell, R. D., 1983. Collecting hydra, in: Hydra: research methods, edited by Lenhoff, H. M., Plenum Press, New York, 1983, p. 17-18.

 

Characterization of Aulactinia (Actiniaria: Actiniidae) species from Mar del Plata (Argentina)

Two anemones of the genus Aulactinia, A. marplatensis and A. reynaudi, inhabit the inertidal zone of the area of Mar del Plata (Argentina). These two species show remarkable morphological and ecological similarity which suggests there should probably be considered a single species, A. marplatensis. We built a molecular phylogeny using the ITS1 and ITS2 regions of nuclear ribosomal DNA. The molecular analyses provided support to the assertion that there is no clear distinction between A. marplatensis and A. reynaudi. Our phylogeny showed that all the individuals of A. marplatensis and A. reynaudi appear together intermixed in a monophyletic group clearly distinct from the outgroup species A. incubans and A. verrucosa.

This work was done in collaboration with Fabián Acuña and Adriana C. Excoffon fom the Departamento de Ciencias Marinas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina.

Reference

Acuña, F.H., A. C. Excoffon, S. R. McKinstry* and D. E. Martínez, 2007. Revision of species of the genus Aulactinia (Cnidaria, Actiniaria) from Mar del Plata (Argentina) using morphological and molecular characters.  Hydrobiologia (in press).

* Pomona College Undergraduate.