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American zoologists concluded that sawtooth rays able to reproduce without sexual intercourse. According to experts, such an evolutionary advantage was probably acquired due to the threat of extinction of the species.
Parthenogenesis, or “virgin pregnancy”, is breeding species, which involves the development of female germ cells in the female body without fertilization. Despite that in parthenogenetic reproduction, male and female gametes do not merge, parthenogenesis is considered to be sexual reproduction, because organisms still evolve from genital cells. Parthenogenesis is an evolutionary acquisition dioecious forms and manifests itself most often with a lack of genital acts between females and males.
Scientists say that among vertebrates virgin reproduction not previously observed. At least in the wild. Not less, in 2001, experts found that under certain in circumstances, captive fish may bring offspring without partners of the opposite sex. Staff The Sydney Aquarium, which contained such a fish, came to a real shock when a few years later with his mother in in a solitary reservoir, fry suddenly began to swim.
It is noteworthy that parthenogenesis can be induced. IN 2004, Japanese scientists took haploid oocytes from two mice and achieved their fusion, having received a viable diploid cell, which allowed the formation of a viable embryo. It is anticipated that such experiments may in future allow to establish the production of pluripotent (diverse) stem cells, which will greatly facilitate the work with this material.
And such interesting facts about the life of fish – do not count. For instance, well-known predatory piranhas are actually just darlings. It is they with hunger is so aggressive, but free food is enough for them, therefore, a person calmly bathes with them in one pond. Without any consequences …
Fish
