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Dedukh D, Riumin S, Kolenda K, Chmielewska M, Rozenblut-Kościsty B, Kaźmierczak M, Ogielska M, Krasikova A. Maintenance of pure hybridogenetic water frog populations: Genotypic variability in progeny of diploid and triploid parents. PLoS One 2022; 17:e0268574. [PMID: 35793279 PMCID: PMC9258834 DOI: 10.1371/journal.pone.0268574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/02/2022] [Indexed: 11/19/2022] Open
Abstract
An intriguing outcome of hybridisation is the emergence of clonally and hemiclonally reproducing hybrids, that can sustain, reproduce, and lead to the emergence of polyploid forms. However, the maintenance of diploid and polyploid hybrid complexes in natural populations remains unresolved. We selected water frogs from the Pelophylax esculentus complex to study how diploid and triploid hybrids, which reproduce hemiclonally via hybridogenesis, are maintained in natural populations. During gametogenesis in diploid hybrids, one of the parental genomes is eliminated, and the remaining genome is endoreplicated. In triploid hybrids, the single-copy genome is typically eliminated, while genome endoreplication does not occur. To investigate how diploid and triploid hybrid frogs reproduce in populations without parental species, we crossed these hybrid animals from two separate pure hybrid populations located in Poland. Using cytogenetic analysis of tadpoles that emerged from the crosses, we established which gametes were produced by parental hybrids. The majority of hybrid females and hybrid males produced one type of gamete with the P. ridibundus genome. However, in both studied populations, approximately half of the diploid and triploid hybrids simultaneously produced gametes with different genome compositions and ploidy levels, specifically, the P. ridibundus and P. lessonae genomes, as well as diploid gametes with genomes of both parental species. Triploid hybrid males and females mostly produced haploid gametes with the P. lessonae genome; however, gametes with the P. ridibundus genome have also been observed. These results suggest that not all hybrids follow the classical hybridogenetic reproduction program and reveal a significant level of alterations in the gametogenesis pathways. In addition, we found a variable survival rate of particular progeny genotypes when we crossed hybrid females with different males suggesting the important role of postzygotic barriers on the maintenance of pure hybrid systems. We suggest that the observed variability in produced gametes and the different survival rate of the progeny with certain genotypes is crucial for the existence of pure hybrid systems.
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Affiliation(s)
- Dmitrij Dedukh
- Department of Cytology and Histology, Saint-Petersburg State University, Saint-Petersburg, Russia
| | - Sergey Riumin
- Department of Cytology and Histology, Saint-Petersburg State University, Saint-Petersburg, Russia
- Raisa Gorbacheva Мemorial Research Institute for Pediatric Oncology, Hematology and Transplantation, Pavlov First St. Petersburg State Medical University, Saint-Petersburg, Russia
| | - Krzysztof Kolenda
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Magdalena Chmielewska
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Beata Rozenblut-Kościsty
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Mikołaj Kaźmierczak
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Maria Ogielska
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Alla Krasikova
- Department of Cytology and Histology, Saint-Petersburg State University, Saint-Petersburg, Russia
- * E-mail:
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Svinin A, Dedukh DV, Borkin LJ, Ermakov O, Ivanov A, Litvinchuk J, Zamaletdinov R, Mikhaylova R, Trubyanov AB, Skorinov D, Rosanov Y, Litvinchuk S. Genetic structure, morphological variation, and gametogenic peculiarities in water frogs (
Pelophylax
) from northeastern European Russia. J ZOOL SYST EVOL RES 2021. [DOI: 10.1111/jzs.12447] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anton Svinin
- Mari State University Yoshkar‐Ola Russia
- National Research Tomsk State University Tomsk Russia
| | | | - Leo J. Borkin
- Zoological Institute Russian Academy of Sciences Saint‐Petersburg Russia
| | | | | | | | | | | | | | - Dmitriy Skorinov
- Institute of Cytology Russian Academy of Sciences Saint‐Petersburg Russia
| | - Yurij Rosanov
- Institute of Cytology Russian Academy of Sciences Saint‐Petersburg Russia
| | - Spartak Litvinchuk
- Institute of Cytology Russian Academy of Sciences Saint‐Petersburg Russia
- Dagestan State University Makhachkala Russia
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Pollo FE, Grenat PR, Otero MA, Babini S, Salas NE, Martino AL. Evaluation in situ of genotoxic and cytotoxic response in the diploid/polyploid complex Odontophrynus (Anura: Odontophrynidae) inhabiting agroecosystems. CHEMOSPHERE 2019; 216:306-312. [PMID: 30384299 DOI: 10.1016/j.chemosphere.2018.10.149] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 10/18/2018] [Accepted: 10/21/2018] [Indexed: 06/08/2023]
Abstract
Polyploidization has been documented across a wide range of vertebrates. Gene duplication could promote better adaptation to environmental changes and to chronic injury or stress. We investigated if genotoxic and cytotoxic responses to agricultural impact are affected by ploidy. We evaluate syntopic populations of the cryptic diploid/polyploid complex Odontophrynus cordobae/O. americanus breeding in an agroecosystem from Central Argentina. The blood of 72 adult anurans was analysed. We used erythrometry to distinguish Odontophrynus individuals with different ploidy levels. We calculated micronucleus frequencies (Mn) and erythrocytic nuclear abnormalities (ENAs) as genotoxic effects and enucleated, mitotic, pyknotic and immature erythrocytes as cytotoxic endpoints (CYT). Mn, ENAs and CYT frequencies were significantly different between diploid and polyploid organisms. The higher frequencies of Mn and CYT were recorded in polyploid organisms, and the higher frequency of ENAs was recorded in diploids. These results indicate that stress response, as indicated by most genotoxic and cytotoxic endpoints, was higher in polyploids respect to diploids. Polyploidy could provide greater genetic flexibility increasing buffering against exogenous DNA-damaging agents and thus confer an advantage over diploids under certain environmental conditions.
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Affiliation(s)
- Favio E Pollo
- Ecología-Educación Ambiental, Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, National University of Río Cuarto, ruta 36km 601, Río Cuarto, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Pablo R Grenat
- Ecología-Educación Ambiental, Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, National University of Río Cuarto, ruta 36km 601, Río Cuarto, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
| | - Manuel A Otero
- Ecología-Educación Ambiental, Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, National University of Río Cuarto, ruta 36km 601, Río Cuarto, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Selene Babini
- Ecología-Educación Ambiental, Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, National University of Río Cuarto, ruta 36km 601, Río Cuarto, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Nancy E Salas
- Ecología-Educación Ambiental, Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, National University of Río Cuarto, ruta 36km 601, Río Cuarto, Córdoba, Argentina
| | - Adolfo L Martino
- Ecología-Educación Ambiental, Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, National University of Río Cuarto, ruta 36km 601, Río Cuarto, Córdoba, Argentina
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The programmed DNA elimination and formation of micronuclei in germ line cells of the natural hybridogenetic water frog Pelophylax esculentus. Sci Rep 2018; 8:7870. [PMID: 29777142 PMCID: PMC5959867 DOI: 10.1038/s41598-018-26168-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 04/30/2018] [Indexed: 01/15/2023] Open
Abstract
DNA elimination is a radical form of gene silencing and occurs both in somatic and germ cells. The programmed DNA elimination occurs during gametogenesis in interspecies hybrids that reproduce by hybridogenesis (stick insects, fishes, and amphibians) and concerns removal of whole genomes of one of the parental species and production of clonal gametes propagating the genome of the other species. The cellular mechanisms differ considerably in hybridogenetic insects and fishes but remains unknown in edible frogs Pelophylax esculentus, natural hybrids between Pelophylax lessonae and Pelophylax ridibundus. Here we report DNA elimination mechanism in early developing gonads of diploid and triploid hybrid frogs, studied by TEM, immunofluorescence, and cytochemistry. In gonocytes of both sexes (primary oogonia and prespermatogonia), micronuclei emerge as detached nuclear buds formed during interphase. We found depletion of nuclear pore complexes in micronuclear membrane and chromatin inactivation via heterochromatinization followed by degradation of micronuclei by autophagy. Micronuclei formation does not lead to apoptotic cell death showing that genome elimination is a physiological process. Chromatin elimination via micronuclei in P. esculentus is unique among hybridogenetic animals and contributes to broadening the knowledge about reproductive modes in animals.
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Doležálková-Kaštánková M, Pruvost NBM, Plötner J, Reyer HU, Janko K, Choleva L. All-male hybrids of a tetrapod Pelophylax esculentus share its origin and genetics of maintenance. Biol Sex Differ 2018; 9:13. [PMID: 29609661 PMCID: PMC5880063 DOI: 10.1186/s13293-018-0172-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 03/15/2018] [Indexed: 02/07/2023] Open
Abstract
Background Sexual parasites offer unique insights into the reproduction of unisexual and sexual populations. Because unisexuality is almost exclusively linked to the female sex, most studies addressed host-parasite dynamics in populations where sperm-dependent females dominate. Pelophylax water frogs from Central Europe include hybrids of both sexes, collectively named P. esculentus. They live syntopically with their parental species P. lessonae and/or P. ridibundus. Some hybrid lineages consist of all males providing a chance to understand the origin and perpetuation of a host-parasite (egg-dependent) system compared to sperm-dependent parthenogenesis. Methods We focused on P. ridibundus-P. esculentus populations where P. ridibundus of both sexes lives together with only diploid P. esculentus males. Based on 17 microsatellite markers and six allozyme loci, we analyzed (i) the variability of individual genomes, (ii) the reproductive mode(s) of all-male hybrids, and (iii) the genealogical relationships between the hybrid and parental genomes. Results Our microsatellite data revealed that P. esculentus males bear Mendelian-inherited ridibundus genomes while the lessonae genome represents a single clone. Our data indicate that this clone did not recently originate from adjacent P. lessonae populations, suggesting an older in situ or ex situ origin. Conclusions Our results confirm that also males can perpetuate over many generations as the unisexual lineage and successfully compete with P. ridibundus males for eggs provided by P. ridibundus females. Natural persistence of such sex-specific hybrid populations allows to studying the similarities and differences between male and female reproductive parasitism in many biological settings. Electronic supplementary material The online version of this article (10.1186/s13293-018-0172-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marie Doležálková-Kaštánková
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, 277 21, Liběchov, Czech Republic. .,Department of Zoology, Faculty of Science, Charles University in Prague, 128 43, Praha 2, Czech Republic.
| | - Nicolas B M Pruvost
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Jörg Plötner
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115, Berlin, Germany
| | - Heinz-Ulrich Reyer
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Karel Janko
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, 277 21, Liběchov, Czech Republic.,Department of Biology and Ecology, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00, Ostrava, Czech Republic
| | - Lukáš Choleva
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, 277 21, Liběchov, Czech Republic. .,Department of Biology and Ecology, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00, Ostrava, Czech Republic.
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Zaleśna A, Florek M, Rybacki M, Ogielska M. Variability of NOR patterns in European water frogs of different genome composition and ploidy level. COMPARATIVE CYTOGENETICS 2017; 11:249-266. [PMID: 28919963 PMCID: PMC5596979 DOI: 10.3897/compcytogen.v11i2.10804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 02/14/2017] [Indexed: 05/28/2023]
Abstract
We studied water frogs from a complex composed of two species: Pelophylax lessonae (Camerano, 1882) (genome LL, 2n = 26) and P. ridibundus (Pallas, 1771) (RR, 2 = 26), and their natural hybrid P. esculentus (Fitzinger, 1843) of various ploidy and genome composition (RL, 2n = 26, and RRL or RLL, 3n = 39). Tetraploids RRLL were found (4n = 52) in juveniles. We applied cytogenetic techniques: AgNO3, chromomycin A3, PI and fluorescent in situ hybridization with a 28S rDNA probe. Results obtained by silver staining corresponded well with those stained with CMA3, PI and FISH. As a rule, NORs are situated on chromosomes 10. The number of Ag-NORs visible on metaphase plates was the same as the number of Ag-nucleoli present in interphase nuclei of the same individual. In all analyzed metaphases, NORs exhibited variations in size after AgNO3 and CMA3 stainings. Sixty-six individuals (out of 407 analyzed) were polymorphic for the localization and number of NORs. Fifty-one diploids had NORs only on one chromosome of pair 10. Three triploids (LLR and RRL) displayed two NORs, and two other triploid RRL individuals displayed one, instead of expected three NORs. In ten individuals extra NORs were detected on chromosomes other than 10 (chromosomes 2 and 9).
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Affiliation(s)
- Anna Zaleśna
- Department of Evolutionary Biology and Conservation of Vertebrates, Institute of Environmental Biology, University of Wrocław, Poland
| | - Maria Florek
- Department of Evolutionary Biology and Conservation of Vertebrates, Institute of Environmental Biology, University of Wrocław, Poland
| | - Mariusz Rybacki
- Department of Zoology, Kazimierz Wielki University, Al. Ossolińskich 12, 85–067, Poland
| | - Maria Ogielska
- Department of Evolutionary Biology and Conservation of Vertebrates, Institute of Environmental Biology, University of Wrocław, Poland
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Hermaniuk A, Rybacki M, Taylor JRE. Metabolic Rate of Diploid and Triploid Edible Frog Pelophylax esculentus Correlates Inversely with Cell Size in Tadpoles but Not in Frogs. Physiol Biochem Zool 2017; 90:230-239. [DOI: 10.1086/689408] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Hermaniuk A, Rybacki M, Taylor JRE. Low Temperature and Polyploidy Result in Larger Cell and Body Size in an Ectothermic Vertebrate. Physiol Biochem Zool 2016; 89:118-29. [PMID: 27082722 DOI: 10.1086/684974] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Previous studies reported that low temperatures result in increases in both cell size and body size in ectotherms that may explain patterns of geographic variation of their body size across latitudinal ranges. Also, polyploidy showed the same effect on body size in invertebrates. In vertebrates, despite their having larger cells, no clear effect of polyploidy on body size has been found. This article presents the relationship between temperature, cell size, growth rate, and body size in diploid and polyploid hybridogenetic frog Pelophylax esculentus reared as tadpoles at 19° and 24°C. The size of cells was larger in both diploid and triploid tadpoles at 19°C, and triploids had larger cells at both temperatures. In diploid and triploid froglets, the temperature in which they developed as tadpoles did not affect the size of their cells, but triploids still had larger cells. Triploid tadpoles grew faster than diploids at 19°C and had larger body mass; there was no clear difference between ploidies in growth rate at 24°C. This indicates better adaptation of triploid tadpoles to cold environment. This is the first report on the increase of body mass of a polyploid vertebrate caused by low temperature, and we showed relationship between increase in cell size and increased body mass. The large body mass of triploids may provide a selective advantage, especially in colder environments, and this may explain the prevalence of triploids in the northern parts of the geographic range of P. esculentus.
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Reyer HU, Arioli-Jakob C, Arioli M. Post-zygotic selection against parental genotypes during larval development maintains all-hybrid populations of the frog Pelophylax esculentus. BMC Evol Biol 2015; 15:131. [PMID: 26141702 PMCID: PMC4491251 DOI: 10.1186/s12862-015-0404-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 06/02/2015] [Indexed: 11/10/2022] Open
Abstract
Background Hybridization between two species usually leads to inviable or infertile offspring, due to endogenous or exogenous selection pressures. Yet, hybrid taxa are found in several plant and animal genera, and some of these hybrid taxa are ecologically and evolutionarily very successful. One example of such a successful hybrid is the water frog, Pelophylax esculentus which originated from matings between the two species P. ridibundus (genotype RR) and P. lessonae (LL). At the northern border of the distribution all-hybrid populations consisting of diploid (LR) and one or two triploid (LLR, LRR) frog types have been established. Here, the hybrid has achieved reproductive independence from its sexual ancestors and forms a self-sustaining evolutionary unit. Based on the gamete production of these hybrids, certain mating combinations should lead to LL and RR offspring, but these parental forms are absent among the adults. Results In order to investigate the mechanisms that maintain such an all-hybrid system, we performed a field study and a crossing experiment. In the field we sampled several ponds for water frog larvae at different developmental stages. Genotype compositions were then analysed and life-history differences between the genotypes examined. In the experiment we crossed diploid and triploid males and females from different ponds and determined fertilization success as well as development speed and survival rates of the offspring under high, medium and low food availability. In both parts of the study, we found numerous LL and RR offspring during the egg and early larval stages; but the frequency of these parental genotypes decreased drastically during later stages. In natural ponds almost all of them had disappeared already before metamorphosis; under the more benign experimental conditions the last ones died as juveniles during the following year. Conclusions From the combined results we conclude that the absence of parental genotypes in all-hybrid populations is due to post-zygotic selection against them, rather than to pre-zygotic mechanisms that might prevent their formation in the first place. For this post-zygotic selection, genetic mechanisms resulting from low genetic diversity and fixation of deleterious mutations seem to be a more likely explanation than ecological factors.
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Affiliation(s)
- Heinz-Ulrich Reyer
- Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, Zürich, CH-8057, Switzerland.
| | - Christian Arioli-Jakob
- Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, Zürich, CH-8057, Switzerland.
| | - Martina Arioli
- Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, Zürich, CH-8057, Switzerland.
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Abstract
This review summarizes the current status of the known extant genuine polyploid anuran and urodelan species, as well as spontaneously originated and/or experimentally produced amphibian polyploids. The mechanisms by which polyploids can originate, the meiotic pairing configurations, the diploidization processes operating in polyploid genomes, the phenomenon of hybridogenesis, and the relationship between polyploidization and sex chromosome evolution are discussed. The polyploid systems in some important amphibian taxa are described in more detail.
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Hoffmann A, Reyer HU. Genomic effects on advertisement call structure in diploid and triploid hybrid waterfrogs (Anura, Pelophylax esculentus). BMC Ecol 2013; 13:47. [PMID: 24304922 PMCID: PMC4235041 DOI: 10.1186/1472-6785-13-47] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 11/23/2013] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND In anurans, differences in male mating calls have intensively been studied with respect to taxonomic classification, phylogeographic comparisons among different populations and sexual selection. Although overall successful, there is often much unexplained variation in these studies. Potential causes for such variation include differences among genotypes and breeding systems, as well as differences between populations. We investigated how these three factors affect call properties in male water frogs of Pelophylax lessonae (genotype LL), P. ridibundus (RR) and their interspecific hybrid P. esculentus which comes in diploid (LR) and triploid types (LLR, LRR). RESULTS We investigated five call parameters that all showed a genomic dosage effect, i.e. they either decreased or increased with the L/R ratio in the order LL-LLR-LR-LRR-RR. Not all parameters differentiated equally well between the five genotypes, but combined they provided a good separation. Two of the five call parameters were also affected by the breeding system. Calls of diploid LR males varied, depending on whether these males mated with one or both of the parental species (diploid systems) or triploid hybrids (mixed ploidy systems). With the exception of the northernmost mixed-ploidy population, call differences were not related to the geographic location of the population and they were not correlated with genetic distances in the R and L genomes. CONCLUSIONS We found an influence of all three tested factors on call parameters, with the effect size decreasing from genotype through breeding system to geographic location of the population. Overall, results were in line with predictions from a dosage effect in L/R ratios, but in three call parameters all three hybrid types were more similar to one or the other parental species. Also calls of diploid hybrids varied between breeding systems in agreement with the sexual host required for successful reproduction. The lack of hybrid call differences in a mixed-ploidy population at the northern edge of the water frog distribution is likely to be associated with genetic particularities, including a) low genetic variability and/or b) a local loss of genes coding for genotype-dependent call differentiation under conditions where female discrimination between diploid and triploid males is not beneficial.
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Affiliation(s)
- Alexandra Hoffmann
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Heinz-Ulrich Reyer
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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