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  • 1
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    Online Resource
    Electrophoretic and vocalization comparisons among three leptodactylid frogs ( Pleurodema spp.) from northwestern Argentina
    Canadian Science Publishing ; 1991
    In:  Canadian Journal of Zoology Vol. 69, No. 9 ( 1991-09-01), p. 2397-2403
    Details
    In: Canadian Journal of Zoology, Canadian Science Publishing, Vol. 69, No. 9 ( 1991-09-01), p. 2397-2403
    Abstract: Enzyme electrophoresis of three species of Pleurodema (38 specimens) collected from six sites in northwestern Argentina resolved 44 allozymes for 15 loci. Pleurodema cinerea and P. borellii, which are morphologically similar, are believed to be reproductively isolated by habitat differences. Although the genetic distance was smallest between the two P. borellii populations, P. borellii was not genetically distant from P. cinerea (average values for Nei's and Rogers' intersite genetic distance indices (D) were 0.155 and 0.229, respectively). Pleurodema tucumana was genetically distant from both P. cinerea and P. borellii (average Nei's D = 1.918; average Rogers' D = 0.799). A comparison of mating calls also suggested that P. cinerea and P. borellii are very similar to each other. The calls of P. borellii and P. cinerea differed only in average pulse rate (100.4 and 59.9 pulses per second, respectively) but this difference may have been temperature related. No conclusive evidence was found in this study to indicate that P. cinerea and P. borellii are distinct species.
    Type of Medium: Online Resource
    ISSN: 0008-4301 , 1480-3283
    URL: Article
    DOI: 10.1139/z91-336
    RVK:
    WA 15000
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1991
    detail.hit.zdb_id: 1490831-1
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  • 2
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    Reproduction and the origin of polyploids in hybrid salamanders of the genus Ambystoma
    Canadian Science Publishing ; 1986
    In:  Canadian Journal of Genetics and Cytology Vol. 28, No. 4 ( 1986-08-01), p. 605-617
    Details
    In: Canadian Journal of Genetics and Cytology, Canadian Science Publishing, Vol. 28, No. 4 ( 1986-08-01), p. 605-617
    Abstract: Eggs and larvae produced by diploid, triploid, and tetraploid females collected from breeding ponds on Pelee Island in Lake Erie were studied to examine the reproductive mechanism. No instance of parthenogenesis was found as all examined females required sperm to produce viable progeny. Diploid females produced diploid and triploid larvae, triploid females produced triploid and tetraploid larvae, and tetraploid females produced triploid and tetraploid larvae. The majority of the eggs produced by hybrid females do not develop or do not complete embryogenesis. Electrophoretic examination of females and their offspring demonstrate that the male genome is being incorporated in reduced as well as unreduced eggs produced by all three ploidy classes of females. The elevation of ploidy among Pelee Island Ambystoma is attributed to sperm incorporation in unreduced eggs. Triploid as well as tetraploid individuals are constantly being produced. A critical examination of the literature on parthenogenetic or gynogenetic modes of reproduction in North American Ambystoma hybrids shows no conclusive evidence supporting these modes and it is suggested that the reproductive mechanism found among Pelee Island female hybrids may be more generally applied to other hybrid Ambystoma populations.Key words: Ambystoma, polyploids, hybrids, electrophoresis, reproduction.
    Type of Medium: Online Resource
    ISSN: 0008-4093
    URL: Article
    DOI: 10.1139/g86-089
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1986
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  • 3
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    Online Resource
    Unisexual salamanders (genus Ambystoma) present a new reproductive mode for eukaryotes
    Canadian Science Publishing ; 2007
    In:  Genome Vol. 50, No. 2 ( 2007-02), p. 119-136
    Details
    In: Genome, Canadian Science Publishing, Vol. 50, No. 2 ( 2007-02), p. 119-136
    Abstract: To persist, unisexual and asexual eukaryotes must have reproductive modes that circumvent normal bisexual reproduction. Parthenogenesis, gynogenesis, and hybridogenesis are the modes that have generally been ascribed to various unisexuals. Unisexual Ambystoma are abundant around the Great Lakes region of North America, and have variously been described as having all 3 reproductive modes. Diploid and polyploid unisexuals have nuclear genomes that combine the haploid genomes of 2 to 4 distinct sexual species, but the mtDNA is unlike any of those 4 species and is similar to another species, Ambystoma barbouri . To obtain better resolution of the reproductive mode used by unisexual Ambystoma and to explore the relationship of A. barbouri to the unisexuals, we sequenced the mitochondrial control and highly variable intergenic spacer region of 48 ambystomatids, which included 28 unisexuals, representatives of the 4 sexual species and A. barbouri. The unisexuals have similar sequences over most of their range, and form a close sister group to A. barbouri, with an estimated time of divergence of 2.4–3.9 million years ago. Individuals from the Lake Erie Islands (Kelleys, Pelee, North Bass) have a haplotype that demonstrates an isolation event. We examined highly variable microsatellite loci, and found that the genetic makeup of the unisexuals is highly variable and that unisexual individuals share microsatellite alleles with sexual individuals within populations. Although many progeny from the same female had the same genotype for 5 microsatellite DNA loci, there was no indication that any particular genome is consistently inherited in a clonal fashion in a population. The reproductive mode used by unisexual Ambystoma appears to be unique; we suggest kleptogenesis as a new unisexual reproductive mode that is used by these salamanders.
    Type of Medium: Online Resource
    ISSN: 0831-2796 , 1480-3321
    URL: Article
    DOI: 10.1139/G06-152
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2007
    detail.hit.zdb_id: 2020635-5
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  • 4
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    Online Resource
    Genome constitution and reproductive biology of hybrid salamanders, genus Ambystoma , on Kelleys Island in Lake Erie
    Canadian Science Publishing ; 1987
    In:  Canadian Journal of Zoology Vol. 65, No. 9 ( 1987-09-01), p. 2188-2201
    Details
    In: Canadian Journal of Zoology, Canadian Science Publishing, Vol. 65, No. 9 ( 1987-09-01), p. 2188-2201
    Abstract: On Kelleys Island, Ohio, in Lake Erie, are found bisexual Ambystoma tigrinum and Ambystoma texanum as well as five different combinations of diploid and polyploid hybrid female salamanders. Genome composition and ploidy of salamanders from five breeding sites on the island were examined using starch gel electrophoresis, erythrocyte area measurements, and chromosome counts. All of the hybrids contained at least one Ambystoma laterale genome, yet pure individuals of this species were not encountered. Embryonic mortality was severe among eggs deposited by 42 hybrid females. The few resulting offspring, when compared electrophoretically with their mothers, showed no evidence of being the product of parthenogenesis. Recently described Ambystoma nothagenes Kraus is not a valid species as this trihybrid is demonstrated to be genetically heterogeneous and independently derived from diploid A. laterale × texanum hybrids.
    Type of Medium: Online Resource
    ISSN: 0008-4301 , 1480-3283
    URL: Article
    DOI: 10.1139/z87-333
    RVK:
    WA 15000
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1987
    detail.hit.zdb_id: 1490831-1
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  • 5
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    Online Resource
    Trypanosome infection in salamanders (order: Caudata) from eastern North America with notes on the biology of Trypanosoma ogawai in Ambystoma maculatum
    Canadian Science Publishing ; 1986
    In:  Canadian Journal of Zoology Vol. 64, No. 1 ( 1986-01-01), p. 121-127
    Details
    In: Canadian Journal of Zoology, Canadian Science Publishing, Vol. 64, No. 1 ( 1986-01-01), p. 121-127
    Abstract: Using the haematocrit centrifuge technique, trypanosomes were detected in 85 of 971 (8.8%) salamanders. The prevalence ranged from about 1% (4 of 405) in 1984 to 26.1% (24 of 92) in 1981. Trypanosomes were found in Ambystoma maculatum, A. laterale, A. jeffersonianum × A. laterale triploid hybrids, and A. jeffersonianum. Detectable infections were not found in A. texanum, A. texanum × A. laterale hybrids, or Notophthalmus viridescens. Trypanosoma ogawai was isolated in A. maculatum and A. jeffersonianum and it was infective by blood inoculation. The trypanosome and its multiplication process in the salamander are redescribed. It multiplied by unequal binary fission and the progenies were a small epimastigote and a large trypomastigote. The trypanosome developed to the metatrypanosome stage in the crop of the leech Batracobdella picta in 9 days at 21 °C. Metatrypanosomes from leeches at 16 days after feeding were infective when inoculated into laboratory-raised salamanders.
    Type of Medium: Online Resource
    ISSN: 0008-4301 , 1480-3283
    URL: Article
    DOI: 10.1139/z86-020
    RVK:
    WA 15000
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1986
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  • 6
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    Online Resource
    Electrophoretic evidence for multiple origins of triploid forms in the Ambystoma laterale – jeffersonianum complex
    Canadian Science Publishing ; 1989
    In:  Canadian Journal of Zoology Vol. 67, No. 2 ( 1989-02-01), p. 350-356
    Details
    In: Canadian Journal of Zoology, Canadian Science Publishing, Vol. 67, No. 2 ( 1989-02-01), p. 350-356
    Abstract: Variable allele frequencies and a wide range of genotypes in samples of triploid Ambystoma laterale–jeffersonianum (LLJ) hybrids indicate that these forms have arisen on many occasions. Though suggested previously, we show here the first clear evidence that this has taken place, with examples from two loci (Pgm-B, M-Aat-A) that have different biogeographic allele distributions. (i) A polymorphism at Pgm-B in Ambystoma laterale, otherwise restricted to northwestern Ontario, was found in both diploid A. laterale and co-occurring LLJ triploids in southern Ontario, where it is confined to the tip of the Bruce Peninsula. Diploids and triploids not possessing the allele also occur here and throughout the range of the A. laterale–jeffersonianum complex in eastern North America. (ii) An east coast A. laterale polymorphism at the M-Aat-A locus is also represented in both the homozygous and heterozygous condition within syntopic diploids and triploids in single populations. These data demonstrate multiple origins of triploidy, suggest continual gene exchange between diploids and triploids, and are analogous to data presented for other hybrid complexes of Ambystoma. The origins and distribution of the alleles in question are briefly considered, as they are of some biogeographic interest.
    Type of Medium: Online Resource
    ISSN: 0008-4301 , 1480-3283
    URL: Article
    DOI: 10.1139/z89-052
    RVK:
    WA 15000
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1989
    detail.hit.zdb_id: 1490831-1
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  • 7
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    Online Resource
    Revisiting the evolution of the North American tetraploid treefrog ( Hyla versicolor )
    Canadian Science Publishing ; 2020
    In:  Genome Vol. 63, No. 11 ( 2020-11), p. 547-560
    Details
    In: Genome, Canadian Science Publishing, Vol. 63, No. 11 ( 2020-11), p. 547-560
    Abstract: Hyla chrysoscelis and H. versicolor are common treefrogs in eastern North America and are a cryptic diploid–tetraploid species pair. They are morphologically identical but H. versicolor is a tetraploid. They can be identified acoustically by the male’s advertisement mating call, which has a pulse repetition rate that has twice as many pulses per second in the diploid species, H. chrysoscelis. We used isozymes, microsatellite DNA alleles, and mitochondrial cytochrome b sequences to test the hypothesis that gene exchange occurs between the diploid and tetraploid species in sympatric populations. Each method provided results that are best explained by occasional hybridization of female H. versicolor and male H. chrysoscelis. We propose that H. versicolor first arose from an autotriploid H. chrysoscelis female that produced unreduced triploid eggs. After H. versicolor became established, genes could be passed from H. chrysoscelis to H. versicolor in sympatric populations when these species hybridize. Their F 1 female progeny produce unreduced triploid eggs that are fertilized by haploid H. chrysoscelis sperm to reconstitute H. versicolor. Genes can be passed from diploid H. chrysoscelis to tetraploid H. versicolor in sympatric populations.
    Type of Medium: Online Resource
    ISSN: 0831-2796 , 1480-3321
    URL: Article
    DOI: 10.1139/gen-2020-0031
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2020
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  • 8
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    Online Resource
    Chromosomes in the African frog genus Tomopterna (Pyxicephalidae) and probing the origin of tetraploid Tomopterna tandyi
    Canadian Science Publishing ; 2022
    In:  Genome Vol. 65, No. 12 ( 2022-12-01), p. 585-604
    Details
    In: Genome, Canadian Science Publishing, Vol. 65, No. 12 ( 2022-12-01), p. 585-604
    Abstract: Speciation by polyploidization has been documented to have independently occurred in 12 families of anuran amphibians. Tomopterna tandyi was described as a South African allotetraploid species of sand frogs in the family Pyxicephalidae. Recent taxonomic revisions and new species descriptions in the genus present problems with respect to the evolution of this tetraploid species. Chromosomes, mitochondrial and nuclear gene sequences, isozymes, and male mating calls were examined for T. tandyi and for diploid species of Tomopterna. Mitochondrial sequences confirmed the diploid species, T. adiastola, to be the maternal ancestor that gave rise to the tetraploid about 5 mya. Nuclear sequences and isozymes reveal a complex reticulation of paternal ancestry that may be explained by occasional hybridization of T. tandyi with diploid species of Tompoterna at various times in sympatric populations. Interspecific diploid to tetraploid gene introgression is suspected to have also occurred in Australian and North American tetraploid species of frogs. Diploid to tetraploid introgression is facilitated through triploid hybrids that are more viable than diploid hybrids and produce unreduced triploid eggs.
    Type of Medium: Online Resource
    ISSN: 0831-2796 , 1480-3321
    URL: Article
    DOI: 10.1139/gen-2022-0053
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2022
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  • 9
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    Online Resource
    Chromosomes and sex ratio of the collared lemming, Dicrostonyx richardsoni
    Canadian Science Publishing ; 1986
    In:  Canadian Journal of Zoology Vol. 64, No. 1 ( 1986-01-01), p. 12-15
    Details
    In: Canadian Journal of Zoology, Canadian Science Publishing, Vol. 64, No. 1 ( 1986-01-01), p. 12-15
    Abstract: The chromosomes of 18 laboratory-born Dicrostonyx richardsoni (= D. groenlandicus richardsoni) were examined. Eight females had 2n = 44 and two large metacentric chromosomes, three females and two males had 2n = 43 and three large metacentrics, and two females and three males had 2n = 42 and four large metacentrics. The observed chromosomal polymorphism was explained as a Robertsonian transformation in which metacentrics underwent centric fission to form two telocentrics, or two telocentrics fused to form a metacentric. No chromosomal differences were observed between males and females that had the same number of large metacentrics. The laboratory sex ratio at weaning was 0.38:1 (363 males, 596 females). Observed and expected distributions of proportions of male offspring among dams were significantly different if dams were assumed to produce males with binomial probability 0.5, or with probability 0.38. There was qualitative support for three female types, each producing males with probability 0.50, 0.25, or 0.33, as has been hypothesized for Dicrostonyx torquatus from Asia.
    Type of Medium: Online Resource
    ISSN: 0008-4301 , 1480-3283
    URL: Article
    DOI: 10.1139/z86-003
    RVK:
    WA 15000
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1986
    detail.hit.zdb_id: 1490831-1
    SSG: 12
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  • 10
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    Online Resource
    Growth and sexual maturation in diploid and polyploid salamanders (genus Ambystoma )
    Canadian Science Publishing ; 1989
    In:  Canadian Journal of Zoology Vol. 67, No. 4 ( 1989-04-01), p. 812-818
    Details
    In: Canadian Journal of Zoology, Canadian Science Publishing, Vol. 67, No. 4 ( 1989-04-01), p. 812-818
    Abstract: On Pelee Island, Ontario, mole salamanders, Ambystoma laterale and Ambystoma texanum, coexist with their diploid, triploid, and tetraploid hybrids. In an initial study, A. laterale and hybrid larvae were raised in groups, but from metamorphosis to 5 months postmetamorphosis, individuals were raised in isolation. In a second study, A. texanum and hybrids were raised as isolated individuals under uniform feeding and laboratory conditions from the egg stage to 22 months postmetamorphosis. The total length of larvae at 14 days posthatching was correlated with size of eggs. Tetraploids originated from larger eggs, were larger at 2 weeks posthatching, and maintained their larger size throughout larval development. Tetraploids metamorphosed later and were heavier than all other genotypes. The heavier mass at metamorphosis was maintained and relatively increased so that by 22 months postmetamorphosis, when compared with other groups, tetraploids were heavier in mass, but not larger in snout–vent length. Bodies of tetraploids were more robust and tails, although not longer, were thicker. In contrast to A. texanum and diploid and triploid hybrids, among which 50% of individuals developed fully pigmented, yolk-filled ova by 22 months, no tetraploids showed such signs of sexual maturity. The growth and reproductive patterns of diploids and polyploids are discussed.
    Type of Medium: Online Resource
    ISSN: 0008-4301 , 1480-3283
    URL: Article
    DOI: 10.1139/z89-119
    RVK:
    WA 15000
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1989
    detail.hit.zdb_id: 1490831-1
    SSG: 12
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