Gynogenetic diploids, tetraploids, or octoploids, and a path to polyploidy in Anuran Amphibians

Unreduced gametes have been implicated in the evolution of polyploid species of plants and animals and are normally produced by female anuran amphibians. Such eggs may initiate the evolution of polyploid species that have independently arisen in several anuran families. Polyploid females could also produce unreduced eggs that might lead to species with higher ploidy levels or their eggs may develop gynogenetically to reduce the ploidy level. Diploid Hyla chrysoscelis (2n=24) and tetraploid H. versicolor (4n=48) are sibling cryptic species of North American Grey Treefrogs. Artificial crosses using H. versicolor females and genetically distant diploid males were performed to produce haploid H. versicolor and to assess the production of unreduced eggs in this tetraploid species. Gynogenetic diploid (haploid H. versicolor), allotriploid, gynogenetic tetraploid, allopentaploid, autohexaploid, and gynogenetic octoploid tadpoles were confirmed using chromosome counts from tadpole tail tip squashes. Transformation and survival of the different ploidies varied. Gynogenetic diploids transformed but expressed aspects of the haploid syndrome and died before or shortly after transformation.

Haematology of gynogenetic diploids of Siberian sturgeon Acipenser baerii Brandt

Haematological analyses were conducted in gynogenetic diploids and control diploids of Siberian sturgeon (Acipenser baerii). Gynogenetic diploid fish were obtained from Polish aquaculture after induction of meiotic gynogenesis based on application of UV-irradiated hybrid Siberian sturgeon × Russian sturgeon (A. gueldenstaedtii) sperm (for eggs activation) and heat shock for inhibiting the second polar body retention. A total of fifteen 30-month-old specimens of Siberian sturgeon from the gynogenetic diploid group and 12 specimens from the control diploid group were randomly sampled. There were no differences in the number of erythrocytes and haematocrit values between gynogenetic diploids and normal diploids of Siberian sturgeon. However, the percentage of normal erythrocytes was lower in the gynogenetic group of fish and the higher percentage of the atypical red blood cell forms (microcytes, sphaerocytes, erythrocytes with displaced nuclei and with divided nuclei) were observed in this group of fish. Additionally all the haemoglobin indices (haemoglobin concentration, the mean corpuscular haemoglobin and the mean corpuscular haemoglobin concentration) were significantly reduced in gynogenetic diploids of Siberian sturgeon. These results could suggest depletion of oxygenation capacity of the blood of gynogenetic sturgeons. This is the first report of a haematological study in gynogenetic diploids of sturgeon fish.