Peter Beerli (beerli@scs.fsu.edu)
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W A T E R F R O G N E W S L E T T E R
December 1997
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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
frog@genetics.washington.edu
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EDITORAL
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**What's Happening in Water frog Research**
We're starting a column for the water frog newsletter in which
various laboratories and research groups take turns describing
their current research on water frogs. This will help members of
the water frog community get to know each other better. It may
help us find ways of cooperating and collaborating with each
other, but it will also let us know what exciting things are
happening in water frog research. Let us know if you'd like
to describe your program soon.
Our first contribution comes from the Institute of Zoology of the
Ukrainian National Academy of Science in Kiev, Ukraine.
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Current research on water frogs
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Sergei Mezhzherin, Institute of Zoology of the
Ukrainian National Academy of Science in Kiev, Ukraine
At the Institute of Zoology, we are investigating hybrid
populations of water frogs from within Kiev and from neighboring
regions. The main aim of this investigation is to describe the
pattern, in space and time, of introgression of an Ldh-B allele
characteristic of Rana lessonae into Rana ridibunda. One of the
most interesting results so far is that introgressive alleles
accumulate in Rana ridibunda populations of urbanized localities.
The usual frequency of the introgressive allele is about 5-10%,
but in some populations within Kiev, the frequency reaches about
50%.
This year, we compared the frequencies of the introgressive Ldh-B
allele in freshly metamorphosed marsh frogs collected in the
summer of 1997 with the frequencies in freshly metamorphosed marsh
frogs collected at the same localities in 1991. This comparison
demonstrates frequency stability of the introgressive allele for
the last six years. This observation is rather interesting, given
the neutralistic-adaptationistic discussion, because the
introgressed allele has an aberrant phenotype and presumably is
not coadapted with genome of Rana ridibunda. The observation of
nuclear gene introgression is similar to observations of Rana
lessonae mtDNA introgression into Rana ridibunda in many central
European populations. It would be very interesting to integrate
these investigations by comparing both Ldh-B alleles and mtDNA
phenotypes in marsh frogs with different genomes; investigation
of the chromosomes of these frogs would also be interesting.
The general directions of our current investigation is
integration of morphometric and genetical data, and specifically,
to define the influence, at the phenotypic level, of allelic
introgression at single loci. It would also be very interesting
to study the relationships between developmental stability of
characters and allelic introgression.
A future direction of our water frog investigation is the
analysis of the genetic structure of these species and the
specificity of hybridization processes as influenced by the
radioactive pollution released at Chernobyl.
Our recent investigations are reflected in the following
publications:
Mezhzherin, S. V., and S. Y. Morozov-Leonov. 1996. Genetical
analysis of hybrid population structure of green frog complex
Rana esculenta L. (Amphibia, Ranidae) from Vohlin'. Tsitologia i
Genetika 30(1): 48-53 (in Russian with English translation).
Pisanetz, E. M., S. V. Mezhzherin, and N. N. Scherbak. 1996.
Hybridization and external morphology studying of Asian toads
(Amphibia: Bufonidae) with description of a new species Bufo
shaartusiensis sp. nova. Dopovidy of National Academy of Science
of Ukraine 5:147-151 (in Russian).
Mezhzherin, S.V., S. Y. Morozov-Leonov, and E. A. Piontkovskaya.
1997. Allozyme variability of endemic species of amphibians in
the eastern Carpathians. Biological Diversity of Carpathian
Reserve, Kiev 352-367 (in Ukrainian).
Mezhzherin, S. V., and S. Y. Morozov-Leonov. 1997. Gene
introgression in hybrid populations of green frogs of Rana
esculenta L., 1758 complex (Amphibia, Ranidae) from the Dnieper
Basin. Russ. J. Genet. 33(1): 358-364 (English translation).
Mezhzherin, S. V. 1997. Mutation units of loci coding of lactate
dehydrogenase and their directed changes on the phylogenesis of
vertebrates. Biol. Bull. (1): 27-34 (English translation).
Mezhzherin, S. V. 1997. Genetic differentiation and species
identity of the marsh frog, Rana ridibunda Pall. (Amphibia,
Ranidae) from Eastern Kazakhstan. Zoological zhurnal 76(8):
933-939 (English translation).
Mezhzherin, S. V., and S. Y. Morozov-Leonov. 1998. Allozyme
variation and genetic relationships of hylid frog Hyla arborea
(Amphibia, Hylidae) of the Mountainous Crimea. Tsitologia i
genetika (in press).
Mezhzherin, S. V., S. Y. Morozov-Leonov, T. I. Kotenko, and E. A.
Piontkovskaya. 1998. Biochemical genetic differentiation of the
newts (Amphibia, Salamandridae, Triturus). Dopovidi NAN Ukrainy
(in press).
Mezhzherin, S. V. 1998. Allozyme variation character of the
lactate dehydrogenase (E.C. 1.1.1.27) in vertebrate animals.
Russ. J. Genet. (in press)
Perspective directions of our investigations are biochemical
systematics and genogeography of anuran amphibians, with emphasis
on the Rana esculenta and Bufo viridis complexes. We are
especially interested in Asian taxa. We plan further
investigations of hybrid water frog populations, and seek
cooperation with DNA and cytological methods. We are also
interested in comparative evolutionary genetic of allozyme
variation and genetic differentiation of amphibians in
comparisons with other classes of vertebrates. In addition to
our work on water frogs, we continue working with all Ukrainian
species of amphibians.
I must emphasize the dangerous situation in fundamental sciences
in Ukraine. To my mind, the situation is worse than in any other
well-developed post-Soviet Union country. I haven't received my
real wages for four months. Moreover, the Institute has no
postal service except for e-mail and therefore I can not
distribute my reprints of our publications. Reagents for
molecular genetics research and support for travel are especially
difficult to obtain.
Sergei Mezhzherin
email: root@iz.freenet.kiev.ua
tel: (380-44) 225-1070
fax: (380-44) 224-1569
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News and Views
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The information here, including links to other relevant
sections, can be found at
http://waterfrogs.scs.fsu.edu/waterfrogs.html
New literature with abstracts
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Plotner, J. (in press). Genetic diversity in mitochondrial
12S rDNA of western palearctic water frogs (Anura, Ranidae)
and implications for systematics. Journal of Zoological
Systematics and Evolutionary Research.
Abstract -- The nucleotide sequence of a part of the
mitochondrial 12S rRNA gene of eight western palearctic
water frog species was analyzed. The results support the
species status of Rana bedriagae, R. bergeri, R. epeirotica,
R. lessonae, R. perezi, R. ridibunda, R. saharica, and
R. shqiperica. Furthermore, the differences between the
mt 12S rDNA segments of lake frogs from Greece and Yugoslavia
on the one hand and the 12S rDNA segments of lake frogs from
Georgia, Uzbekistan, and Turkmenistan on the other hand provide
new evidence for the existence of two cryptic species. It seems
very probable that lake frogs from Georgia, Uzbekistan, and
Turkmenistan belong to R. ridibunda whereas lake frogs from
Greece and Yugoslavia represent R. kurtmuelleri, a form which
had already been described by Gayda (1940). Additional
investigations are needed to clarify this problem. The very
high similarity between the analyzed 12S rDNA segments of German
R. ridibunda and R. lessonae support the hypothesis that mtDNA
of R. lessonae was transmitted into the mitochondrial gene pool
of R. ridibunda probably as a result of backcrosses with the
hybridogenetic hybrid R. kl. esculenta. The obtained genetic
data confirm the very close phylogenetic relations between
R. perezi and R. saharica. However, it is not yet clear
whether both species represent an adelphotaxon. Furthermore,
R. shqiperica, R. lessonae, and R. bergeri on the one hand
and R. ridibunda and R. bedriagae on the other hand are
considered to be seperate lineages which seem to be
sister taxa.
According to the mt 12S rDNA data R. epeirotica seems to
be closer related to the supraspecific taxon
R. ridibunda/R. bedriagae than to
R. lessonae/R. bergeri/R. shqiperica. Thus, it can be excluded
that R. shqiperica and R. epeirotica represent sister species.
Key words:Ranidae, Rana, western palearctic water frogs, systematics,
mitochondrial 12S rDNA, sequence analysis
Schmidt, B. R., Hotz, H., Anholt, B. R., Guex, G.-D. and Semlitsch,
R. D. (in press). Factors contributing to the maintenance of the genetic
polymorphism at the locus LDH-B in the pool frog, Rana lessonae.
Canadian Journal of Zoology.
Abstract -- We tested for environmental factors that may lead to
balancing selection and to the maintenance of a genetic polymorphism at
the enzyme locus lactate dehydrogenase B (LDH-B) in the pool frog, Rana
lessonae. We raised tadpoles individually in a factorial experiment
where we manipulated temperature, food level, and food quality. The
only statistically significant difference among LDH-B genotypes was for
growth rate with the heterozygote performing best. Although the
difference was not significant, heterozygotes also tended to perform
best for size at metamorphosis. However, heterozygotes did not perform
best for other traits (age at metamorphosis, survival and rate of
metamorphosis) where differences among LDH-B genotypes were not
significant as well. The size of the effect of LDH-B genotype depended
on the environment, suggesting that the locus may be
selectively neutral in some environments. There were no
genotype-environment interactions in the sense that reaction norms
along environmental gradients did not cross. When we raised tadpoles
in groups, e/e homozygotes had a significantly higher mass and
developed at the significantly highest rate. In addition, there may
be a trade off between larval and adult performance: adult frogs show
a different ranking in performance of LDH-B genotypes than tadpoles do.
These results suggest that the genetic polymorphism is maintained
through heterozygote advantage, possibly in conjunction with
antagonistic pleiotropy.
Older abstracts newly added
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Buckley, D., B. Arano, P. Herrero, and G. Llorente. 1996. Population
structure of Moroccan water frogs: genetic cohesion despite a
fragmented distribution. Journal of Zoological
Systematics and Evolutionary Research 34:173-179.
Kovacs, T. and J. Torok. 1995. Dietary responses by Edible Frog
(Rana esculenta complex) to wetland habitat change in Hungary.
Proceedings of Workshop 2 of the International Conference on Wetlands
and Development, Kuala Lumpur, Malaysia, 9-13 October 1995, 79-86.
Schmidt, B. R. 1996. Sexual and asexual reproduction in vertebrates.
Trends in Ecology and Evolution 11: 253-254.
Waterfrog bibliography
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This has been updated to add publications noted between September and now.
If you have new literature citations send them to
Hansjurg Hotz (hotz@zoolmus.unizh.ch); if you have new abstracts
send them either to frog@genetics.washington.edu or
beerli@scs.fsu.edu.
Other Changes
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- update of the index, corrections of misspelling of names.
More extensive literature coverage
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We haven't heard any opinion on this and haven't seen any contribution
towards a more complete coverage.
A water frog session or workshop at the SEH conference in
Chambery, France, August 27-29 1998.
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Nobody is intending to go to this meeting? Or do you have
absolutely no idea about what you want to present?
We print the following again as a reminder:
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
Peter Beerli (beerli@scs.fsu.edu)