Heterosis in the common European water frog

Tunner, Heinz G.; Nopp, H.

doi:10.1007/bf00571614

Cited by 60 publications

(37 citation statements)

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“…The proportion of parental species and hybrids in natural populations depends on the environment. It it hypothesized that this is because hybrids are more tolerant to environmental stress than parental species: E, in contrast to L, appears to produce metamorphs that are better adapted to hypoxic conditions and fungicides ordinarily used in agriculture (Tunner & Nopp 1979, Semlitsch & Reyer 1992, Fioramonti et al 1997, Hotz et al 1999. Because of this apparent dichotomy in susceptibility to environmental variables, the hybridogenetic system may represent an interesting model for examining the ecology of pathogens.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Parasitism by Dermocystidium ranae in a population of Rana esculenta complex in Central Italy and description of Amphibiocystidium n. gen.

Pascolini¹,

Daszak²,

Cunningham³

et al. 2003

Dis. Aquat. Org.

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We report the enigmatic parasite Dermocystidium ranae in a green frog population (Solomeo, Umbria, Italy) of the Rana esculenta complex, consisting of the parental species R. lessonae (L) and hybrid form R. esculenta (E). In this population a rapid 50% decline of the parental form L was observed. Large dermal U-shaped cysts of D. ranae were found primarily on the ventral aspect of infected individuals, with a significantly higher incidence of infection in the parental species compared to the clonal hybrid. In each form, however, there was little pathological change associated with infection, and the cause of the recent declines of R. lessonae at this site remains unknown. In this paper we present the first ultrastructural description of an amphibian Dermocystidium sp. and we review the taxonomy of Dermocystidium, Dermosporidium and Dermomycoides spp. from amphibians. We conclude that Dermosporidium multigranulare Bro= & Kulda, 1954 is synonymous with Dermocystidium ranae Guyénot & Naville, 1922 and, due to lack of sufficient differences between genera and significant dissimilarities with fish Dermocystidium spp., the 3 amphibian genera are synonymous. We propose that they should be designated to a new genus, Amphibiocystidium n. gen., and Dermocystidium retained for those species parasitic in fish.KEY WORDS: Amphibian · Rana · Dermocystidium· Amphibiocystidium · Amphibian declines Resale or republication not permitted without written consent of the publisherDis Aquat Org 56: [65][66][67][68][69][70][71][72][73][74] 2003 undergoes a premeiotic or occasionally a prediplotene meiotic endoreduplication (Tunner & Heppich-Tunner 1991) and 2 apparently normal meiotic divisions resulting in functional, genetically identical haploid gametes that contain an unrecombined R genome. Hybridity in these lineages is restored each generation through fertilization of these gametes by gametes from syntopic L. The vast majority of E lineages coexist as sexual parasites with the host species L.The L-E system population is widespread throughout Europe (Uzzell & Berger 1975). The proportion of parental species and hybrids in natural populations depends on the environment. It it hypothesized that this is because hybrids are more tolerant to environmental stress than parental species: E, in contrast to L, appears to produce metamorphs that are better adapted to hypoxic conditions and fungicides ordinarily used in agriculture (Tunner & Nopp 1979, Semlitsch & Reyer 1992, Fioramonti et al. 1997, Hotz et al. 1999. Because of this apparent dichotomy in susceptibility to environmental variables, the hybridogenetic system may represent an interesting model for examining the ecology of pathogens. A hybridogenetic L-E system is present on the Italian peninsula; it is formed by a lessonae-like parental species and its esculenta-like hybrid (Uzzell & Hotz 1979, Uzzell 1983, Günther & Plötner 1994. Previous research on the composition of the hybridogenetic system conducted in the Trasimeno Lake district in Central Italy suggests that t...

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Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Parasitism by Dermocystidium ranae in a population of Rana esculenta complex in Central Italy and description of Amphibiocystidium n. gen.

Pascolini¹,

Daszak²,

Cunningham³

et al. 2003

Dis. Aquat. Org.

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“…The higher growth rate of R. esculenta tadpoles apparently is underlain by their behavior: tadpoles of R. esculenta spend more time feeding and consume more food than either parental species rather than having higher physiological efficiency (36). Metamorphosed R. esculenta are more tolerant to hypoxic conditions than either parental species (37). In addition, R. esculenta tadpoles are more tolerant to a common agricultural fungicide (TPT, triphenyltin chloride) than R. lessonae tadpoles (38).…”

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confidence: 99%

Spontaneous heterosis in larval life-history traits of hemiclonal frog hybrids

Hotz

Semlitsch

Gutmann

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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European water frog hybrids Rana esculenta (Rana ridibunda ؋ Rana lessonae) reproduce hemiclonally, transmitting only their ridibunda genome to gametes. We compared fitness-related larval life-history traits of natural R. esculenta from Poland with those of the two sympatric parental species and of newly generated F 1 hybrids. Compared with either parental species, F 1 hybrid offspring had higher survival, higher early growth rates, a more advanced developmental stage by day 49, and earlier metamorphosis, but similar mass at metamorphosis. R. esculenta from natural lineages had trait values intermediate between those of F 1 offspring and of the two parental species. The data support earlier observations on natural R. esculenta that had faster larval growth, earlier metamorphosis, and higher resistance to hypoxic conditions compared with either parental species. Observing larval heterosis in F 1 hybrids in survival, growth rate, and time to metamorphosis, however, at an even higher degree than in hybrids from natural lineages, demonstrates that heterosis is spontaneous and results from hybridity per se rather than from subsequent interclonal selection; in natural lineages the effects of hybridity and of clonal history are confounded. This is compelling evidence for spontaneous heterosis in hybrid clonals. Results on hemiclonal fish hybrids (Poeciliopsis) showed no spontaneous heterosis; thus, our frog data are not applicable to all hybrid clonals. Our data do show, however, that heterosis is an important potential source for the extensively observed ecological success of hybrid clonals. We suggest that heterosis and interclonal selection together shape fitness of natural R. esculenta lineages.

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“…This observation is in good agreement with the hybrid character of the form esculenta. Just as it is in many other features (Tunner & Nopp, 1979), this form of green frogs is also intermediate between the forms lessonae and ridibunda in the secretory activity of the SCO.…”

Section: Discussionmentioning

confidence: 73%

“…The forms lessonae and ridibunda are easily to distinguish from each other; they differ in many morphological, physiological and ecological features. The form esculenta is intermediate between the two other forms (Tunner & Nopp, 1979); its features overlap those of the forms lessonae and ridibunda considerably.…”

Section: Introductionmentioning

confidence: 80%

A comparative study on the secretory activity of the subcommissural organ in the European green frogs: Rana esculenta, rana lessonae and Rana ridibunda

Diederen

Vullings

1980

Comparative Biochemistry and Physiology Part A: Physiology

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Abstract-l. The subcommissural organ (SCO), present in all vertebrates, is situated in the roof of the third brain ventricle, and secretes into this ventricle a glycoproteinaceous, fibre-like structure, the liquor fibre (LF).2. The three forms of European green frogs differ from each other in the three parameters used to measure the secretory activity of the SCO: the amounts within the SC0 of stained secretory material and of secretory material labelled by a radioactive precursor, and the growth rate of LF.3. The observed differences indicate that the secretory activity of the SC0 is distinctly higher in Rana ridibunda than in Ram lessonae, whereas in Ram esculenta this activity is intermediate.

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Heterosis in the common European water frog

Cited by 60 publications

References 4 publications

Parasitism by Dermocystidium ranae in a population of Rana esculenta complex in Central Italy and description of Amphibiocystidium n. gen.

Parasitism by Dermocystidium ranae in a population of Rana esculenta complex in Central Italy and description of Amphibiocystidium n. gen.

Spontaneous heterosis in larval life-history traits of hemiclonal frog hybrids

A comparative study on the secretory activity of the subcommissural organ in the European green frogs: Rana esculenta, rana lessonae and Rana ridibunda

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