tailieunhanh - UNISEXUAL SALAMANDERS (GENUS AMBYSTOMA) PRESENT A NEW REPRODUCTIVE MODE FOR EUKARYOTES

Worldwide, one in five women has a child by the age of 18. In the poorest regions of the world, this rises to over one in three women. Adolescent pregnancies are more likely to occur among poor, less educated and rural populations. WHO’s recommendations for reducing early pregnancy are informed by two graded systematic reviews, three ungraded studies, as well as the conclusions of an expert panel. The studies in the systematic reviews included those conducted in developing countries (Mexico and Nigeria) as well as those conducted among poorer socio-economic populations in developed countries. Collectively, the studies demonstrate reductions in. | 119 Unisexual salamanders genus Ambystoma present a new reproductive mode for eukaryotes James P. Bogart Ke Bi Jinzong Fu Daniel . Noble and John Niedzwiecki 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 inter-genic spacer region of 48 ambystomatids which included 28 unisexuals representatives of the 4 sexual species and A. bar-bouri. 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 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 .

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