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Titolo:
COMPETITION AMONG TADPOLES OF COEXISTING HEMICLONES OF HYBRIDOGENETICRANA-ESCULENTA - SUPPORT FOR THE FROZEN NICHE VARIATION MODEL
Autore:
SEMLITSCH RD; HOTZ H; GUEX GD;
Indirizzi:
UNIV MISSOURI,DIV BIOL SCI COLUMBIA MO 65211 UNIV ZURICH,INST ZOOL CH-8057 ZURICH SWITZERLAND UNIV ZURICH,ZOOL MUSEUM CH-8057 ZURICH SWITZERLAND
Titolo Testata:
Evolution
fascicolo: 4, volume: 51, anno: 1997,
pagine: 1249 - 1261
SICI:
0014-3820(1997)51:4<1249:CATOCH>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
LIFE-HISTORY TRAITS; ALSOPHILA-POMETARIA LEPIDOPTERA; CLONAL DIVERSITY; ENVIRONMENTAL TOLERANCE; GENETIC-VARIATION; SIB-COMPETITION; HYBRID FROG; WATER FROG; POECILIOPSIS; POPULATIONS;
Keywords:
AMPHIBIAN; CLONAL; COMPETITION; FROZEN NICHE VARIATION MODEL; GENERAL-PURPOSE GENOTYPE; GROWTH; HYBRIDOGENESIS; METAMORPHOSIS; RANA ESCULENTA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
96
Recensione:
Indirizzi per estratti:
Citazione:
R.D. Semlitsch et al., "COMPETITION AMONG TADPOLES OF COEXISTING HEMICLONES OF HYBRIDOGENETICRANA-ESCULENTA - SUPPORT FOR THE FROZEN NICHE VARIATION MODEL", Evolution, 51(4), 1997, pp. 1249-1261

Abstract

Vertebrate animals reproducing without genetic recombination typically are hybrids, which have large ranges, are locally abundant, and livein disturbed or harsh habitats. This holds for the hemiclonal hybridogenetic frog Rana esculenta: it is widespread in Europe and commonly is found in disturbed habitats such as gravel pits. We hypothesize thatits widespread occurrence may either be the result of natural selection for a single hemiclone acting as a broadly adapted ''general-purpose'' genotype, or of interclonal selection, which maintains multiple hemiclones that each are relatively narrowly adapted and perform differently across environments, that is, the Frozen Niche Variation model. We tested these competing hypotheses using 1000-L outdoor artificial ponds to rear tadpoles of the parental species (Rana lessonae [LL] and Rana ridibunda [RR]) alone, and each of three hemiclones of Rana esculenta (GUT1, GUT2, GUT3) alone, and in mixed hemiclonal populations fromhatching to metamorphosis. Tadpoles of three coexisting hemiclones from, a single natural population (near Gutighausen, Switzerland) were reared in both two-and three-way mixtures in equal total numbers at high and low density. For each species and hemiclone, the proportion of tadpoles metamorphosing decreased as the density of tadpoles increased,with the three hemiclones spanning the range of values exhibited by the two parental species. LL and GUT1 tadpoles produced the highest proportion of metamorphs, where;ls tadpoles of RR produced the fewest metamorphs at both densities. GUT1 tadpoles also produced the largest metamorphs at low density, GUT2 and GUT3 tadpoles produced smaller metamorphs than did GUT1 tadpoles at the low density, but the three hemiclones did not differ from each other at high density. The parental species (LL and RR) were: intermediate in metamorphic size to the hemiclonesat low density, but all genotypes converged on a similar size at highdensity. Length of the larval period also was affected by density, but its effect was dependent on genotype. GUT1 tadpoles had the shortestlarval period at the low density, but larval period was longer and not different between GUT1, GUT3, and LL at high density. RR tadpoles had the longest larval period at both densities. The most dramatic: results were that three genotypes (GUT1, GUT2, and RR) maintained rank order and increased days to metamorphosis from low to high density, whereas two genotypes (GUT3 and LL) changed rank order and decreased days to metamorphosis from low to high density. Mixtures of hemiclones in two-and three-way combinations facilitated the proportion of tadpoles metamorphosing for GUT1 and GUT2 at both densities, but only at the low density for GUT3 tadpoles. Results from this experiment are incompatible with the General-Purpose Genotype model as a global explanation of hybrid abundance in these frogs. Alternatively, the Frozen Niche Variation prediction of general performance superiority of clonal mixtures relative to single clone populations is strongly supported. The data confirm that fitness advantages of hemiclones change, depending on the environment, such that in temporally and spatially heterogeneous habitats like ponds, frequency-dependent selection among hemiclones may promote coexistence in hemiclonal assemblages. Yet, differential dispersal or colonization ability and historical factors affecting hemiclone distribution may also be important in shaping patterns of clonal coexistence.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/07/20 alle ore 19:12:25