ISSN:
1432-0886
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract The chromosomes of the South American marsupial frogs Gastrotheca fissipes, G. ovifera, G. walkeri and Flectonotus pygmaeus were analyzed by means of conventional and various banding techniques. The karyotypes of G. ovifera and G. walkeri are characterized by highly differentiated XY♂/XX♀ sex chromosomes. Whereas the X chromosomes and autosomes contain large amounts of constitutive heterochromatin, extremely little heterochromatin is located in the Y chromosomes. This is in contrast to all previously known amphibian Y chromosomes and the Y chromosomes of most other vertebrates. In the male meiosis of G. walkeri, the euchromatic segments of the heteromorphic XY chromosomes show the same pairing configuration as the autosomal bivalents. The karyotype of F. pygmaeus is remarkable for the unique presence of telocentric chromosomes and the high frequency of interstitially located chiasmata in the meiotic bivalents. The evolution of the karyotypes and sex chromosomes, the structure of the various classes of heterochromatin and the data obtained from meiotic analyses of the marsupial hylids are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00331793
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