======================================================= W A T E R F R O G N E W S L E T T E R November 1997 ======================================================= The Water Frog Information Pool can be reached through its home page at http://waterfrogs.scs.fsu.edu/waterfrogs.html You can send email to firstname.lastname@example.org ======================================================= EDITORAL ======================================================= by Thomas Uzzell (email@example.com or firstname.lastname@example.org) Surely someone besides the webmaster for this site must have a controversial idea to discuss in an editorial! Since the water frog site was instituted in 1995, there have been over 15,000 hits recorded, excluding those of the webmaster. The counter on the site was reset most recently on 1 January 1997, and 7850 hits have been recorded since then. And yet there has been little input from the members of the water frog research community or from casual visitors to the site. If you want this site to be vibrant, to reflect the excitement of water frog research, to serve as a vehicle for sharing ideas and information, active participation (contributions) is needed, not passive participation (use of information deposited by others). We need as a minimum your name and email address. We'd also like a statement both brief and extended, of your interests. People not registered can add their address by going to the researcher page and filling out a simple form. If you're already registered and want to update your entry, send an email to Peter Beerli (email@example.com) if your last name begins with letters A through L, or to Dirk Schmeller (firstname.lastname@example.org) if it begins with M through Z. Download the bibliography file or browse it on the web and scan it for missing literature; check especially to see if *your* publications are included. Help us keep the 'current literature' and 'current abstracts' current: submit titles and abstracts as soon as papers are published to email@example.com; please also send literature updates to Hansjurg Hotz at firstname.lastname@example.org. It would be nice if notes of jobs or research positions, opportunities for research, preliminary findings, points of view, and whatever else might interest your colleagues were also contributed. If this is going to be a ****water frog information pool,**** it needs information. ================================================================= News and Views ================================================================= The information here, including links to other relevant sections, can be found at http://waterfrogs.scs.fsu.edu/waterfrogs.html L-E versus L-LR terminology --------------------------- Hansjurg Hotz (email@example.com) sent us the following remarks as a response to a query: It has been stated that people are more and more often using the term 'L-LR' rather than 'L-E' for population systems with Rana lessonae and hybridogenetic Rana esculenta. I think there is some misunderstanding. I don't think that the term 'L-RL system' or any such construction is increasingly used. What is often used recently in abstracts and figures (I and my colleagues do it too, to increase clarity for readers not familiar with these frogs) are genome abbreviations (L, R, ...) to distinguish parental and hybrid somatic or gametic genome compositions. This is nothing but a shorthand for easier grasping. I see no reason whatsoever to replace the very well-established term L-E system with anything else. In L-E systems, hybridogenetic Rana esculenta coexist and reproductively depend on the sexual host species Rana lessonae. This is by far the most widespread population system and it clearly needs a label for referring to it. 'L-E system' certainly doesn't mean mere coexistence of Rana lessonae and Rana esculenta. Although some people may use it that way, this clearly differs from its original meaning given in 1975, when Uzzell and Berger introduced it. Rainer Gunther has created a much more extended terminology to cover the variety of population compositions observed in his area. These describe in detail the different situations occurring in different habitats or locales (although there may be more of a continuum than his classes suggest), but the gain in precision is counterbalanced by a loss in both generality and information. L-E system is a term for the most common host-hybridogen reproductive system, irrespective of hybrid frequency and other particulars. It can readily be applied to the exactly analogous perezi-hybridogen system; "P-RP" was used as a convenient shorthand (Graf and Polls Pelaz 1989, Hotz et al. 1994) while there was no name for the hybridogen, but now that it's been described as Rana grafi (Crochet et al. 1995), P-G system can be used (Pagano et al. 1997) and is clearly better because it implies reproductive mode of the hybrids rather than just coexistence. There are two significant disadvantages to using a genome-based nomenclature for hybridogens and for sexual-hybridogen population systems. For example, hybrids between Rana ridibunda and Rana lessonae, genomically RL, may be hybridogenetic and parts of hemiclonal lineages; or, alternatively, they may be nonhybridogenetic and sterile. This distinction cannot be made if RL is used for both; whereas calling the hybridogenetic lineages Rana esculenta makes this distinction clear. Similarly, if RL is used always for the hybrids, L-RL can indicate either coexistence of Rana lessonae and sterile, non-hybridogenetic hybrids between Rana ridibunda and Rana lessonae (such populations do exist in some parts of Rana lessonae's range); or it can refer to population systems in which such hybrids are 1) hybridogenetic and 2) sexual parasites on the host species Rana lessonae. For the latter, it seems to me far preferable to use L-E system, with its specification of both reproductive mode and sexual dependency. It is only watering down information content if special terms like "XY system" are used for mere syntopies. Moreover, given that L-E system has been used in dozens of publications since 1975, nomenclatural stability almost requires continued usage of L-E system. We would like to hear your opinion. Send your thoughts to firstname.lastname@example.org. New literature with abstracts ---------------------------------- Guerrini, F., S. Bucci, M. Ragghianti, G. Mancino, H. Hotz, T. Uzzell, and L. Berger. 1997. Genomes of two water frog species resist germ line exclusion in interspecies hybrids. Journal of Experimental Zoology 279(2): 163-176. Abstract: Abundant natural interspecies hybrids between the European water frog Rana ridibunda and at least three other taxa reproduce hemiclonally, by hybridogenesis: the non-ridibunda genome is excluded in the germ line before meiosis, and the unrecombined ridibunda genome is transmitted to haploid gametes. In contrast, natural hybrids between Rana ridibunda and either of two Balkan species (Rana shqiperica and Rana epeirotica) do not show such genome exclusion. This plausibly results from failure of Balkan Rana ridibunda genomes to "induce" such exclusion in the germ line of hybrids, from "resistance" of Rana shqiperica and Rana epeirotica genomes to such exclusion in hybrids with an "inducing" Rana ridibunda genome, or both. We tested the second hypothesis by examining lampbrush chromosome patterns in oocytes of hybrids that in the soma contain one "inducing" ridibunda genome and one genome of either of the two Balkan species. Several lampbrush chromosome markers (e.g., presence and location of certain giant loops and conspicuousness and width of centromeres) discriminate sets of Rana ridibunda chromosomes from those of Rana shqiperica and Rana epeirotica. Based on such markers, nine diploid female hybrids between Rana ridibunda or Rana esculenta from natural hybridogenetic lineages (Rana ridibunda x Rana lessonae, making ridibunda gametes) from central Poland and either Rana shqiperica or Rana epeirotica each contained both parental genomes in primary oocytes; the bivalents showed reduced numbers of chiasmata compared with parental species. It follows that none of these hybrids was hybridogenetic. This conclusion is confirmed, for two hybrids between Rana epeirotica and either Rana ridibunda or Rana esculenta, by protein electrophoretic comparison of somatic tissues with primary oocytes, all of which evidenced allelic markers of both parental species. Because Rana ridibunda genomes that are known to induce germ line genome exclusion when combined in hybrids with markers of both parental species. Because Rana ridibunda genomes that are known to induce germ line genome exclusion when combined in hybrids with Rana lessonae genomes were used, these data provide the first compelling evidence for resistance of Rana shqiperica as well as Rana epeirotica genomes to such exclusion. Pagano, A., P. Joly, and H. Hotz. 1997. Taxon composition and genetic variation of water frogs in the Mid-Rhone floodplain. C.R. Acad.Sci. Paris, Life sciences, 320: 759-766. Abstract: Natural hemiclonal hybrid lineages of water frogs reproduce by hybridogenesis, excluding one parental genome in the germ line and mating with the coexisting same parental species. Two such sexual host-hybridogen systems occur in the Rhone valley: the L-E system in the north, the P-G system in the south. Although these hybridogenetic complexes may overlap along the Rhone river, there is no evidence for a contact zone in our samples: only Rana ridibunda and R. esculenta were identified using protein electrophoresis. Whether the absence of R. perezi reflects a more southern distribution or its exclusive occurrence in other habitats, remains to be tested. Comparison of somatic and gonadal tissues reveals that gametogenesis of R. esculenta is of the L-E type: gametes carry ridibunda genomes. R. ridibunda apparently is not native, but was introduced by humans, and R. esculenta of our samples are probably immigrants from nearby L-E systems. Older abstracts newly added --------------------------- Beerli, P., H. Hotz, E., and T. Uzzell. 1996. Geologically dated sea barriers calibrate a protein clock for Aegean water frogs. Evolution 50(4): 1676-1687. Hotz, H., T. Uzzell, P. Beerli, and G.-D. Guex. 1996. Are hybrid clonals species? A case for enlightened anarchy. Amphibia-Reptilia 17: 315-320. Schmeller, D., A. Crivelli, and M. Veith. 1997. Genetic and demographic structure of populations of hybridogenetic water frogs (Rana perezi, R. ridibunda) in the Rhone-delta (Camargue, France). 3rd World Congress of Herpetology, Prague. Other Changes -------------- The Water Frog Information Pool (WIP) web site continues to develop, and several small changes have recently been made including: -Addition of a section 'literature' with links to abstracts, the bibliography, updates to the bibliography provided by Hansjurg Hotz, and past newsletters. -Inclusion of additional interesting sites to 'Other sites'. -Redesign of the layout for abstracts [not yet finished]. -Addition of several search utilities. More extensive literature coverage ---------------------------------- Although the original file for water frog literature was restricted to research on western Palearctic water frogs, it has been expanded to include publications on the eastern Palearctic water frogs as well. Research on this group, especially by the students and staff at Hiroshima University's Laboratory of Amphibian Biology, often provides interesting parallels or alternatives to work on the western Palearctic forms. Look for a more inclusive literature file on WIP in the near future. But we would also like to hear your opinions: what else should be covered? Send your thoughts to email@example.com. A water frog session or workshop at the SEH conference in Chambery, France, August 27-29 1998. ---------------------------------------------------------------------- As was discussed at the 3rd World Congress of Herpetology in Prague, having a water frog session of workshop at the upcoming conference would be useful, but we still have received no suggestions or ideas. If you have ideas or thoughts about organizing a special water frog program at the SEH meetings, send them to Dirk Schmeller (firstname.lastname@example.org or email@example.com). What topics should be covered? Send your ideas as soon as possible so that the water frog community has enough time to discuss them and get something going. The first call for papers will be in a few weeks. ================================================================= Researcher list ================================================================= PLEASE, can everybody reading this newsletter send a response (a single line saying 'YES I received it' is sufficient, although we would like to hear more). And check your entry in the researcher list for accuracy (http://waterfrogs.scs.fsu.edu/PBhtmls/people.html). If you receive this newletter more than once, then other people share your email address. In any case, please inform your coworkers and colleagues about this site and newsletter.