![]() Reproduction of animals in human care sometimes requires more than simple cohabitation of females and males as the physiological and behavioral processes involved can be complex ( Ottinger and Mench, 1989). With further development, artificial insemination represents a powerful tool that could be used for maintaining genetic diversity for animals housed in aquaria and conservation-based breeding programs for elasmobranchs. This study successfully employed artificial insemination to circumvent barriers to natural reproduction in Zebra Sharks. ![]() All females produced at least one hatched parthenote. For the two females housed with the male, no sexual offspring resulted. After the second insemination (September 24 th, 2013), 62 yolked eggs resulted in two sexually produced offspring, 18 and 33 days after insemination, and three parthenogenetic offspring > 213 days post-insemination. After the first insemination (December 15 th, 2011), 143 yolked eggs resulted in no sexually produced offspring and four genetically-confirmed, parthenogenetic offspring. Hatching success for eggs laid by all three females was monitored to compare natural and artificial insemination modes. To determine if assisted techniques could be used to rescue sexual reproduction, artificial insemination was performed in a singleton female twice over a three-year period using freshly collected semen. Among a population of three female and one male Zebra Sharks ( Stegostoma tigrinum), production of young failed despite constant male presence with two of the females. Maintaining self-sustaining populations of zoo and aquarium collections can be challenged when natural reproduction fails within mixed-sex populations however, reproductive success can sometimes be restored with the application of reproductive technologies. 4Delaware Biotechnology Institute, Center for Bioinformatics & Computational Biology, University of Delaware, Newark, DE, United States.3Wildlife Genetics, Department of Comparative Medicine, Loyola University Medical School, Maywood, IL, United States. ![]() 2Research and Conservation, Georgia Aquarium, Atlanta, GA, United States.1Aquarium of the Pacific, Long Beach, CA, United States.The third diagram shows carpet sharks related to the whale shark, sharing similar characteristics and all having the nurse shark as a root.Lance Adams 1*, Kady Lyons 2, Elizabeth Larkin 1, Nicole Leier 1, Janet Monday 1, Chris Plante 1, Jean Dubach 3 and Jennifer Wyffels 4 This furthers the second diagram, continuing the Orectolobiformes branch. Furthermore, the third diagram shows the relatives of the whale shark: nurse sharks, bamboo sharks, wobbegongs, and zebra sharks. The diagrams above show this order, indicating that it is in this branch where the whale shark begins to emerge. This is otherwise known as the order of the whale shark. Because of the filter feeding of plankton, different orders of sharks begin to arise, one of them being the Orectolobiformes. The filter feeders emerge sometime during the Tertiary Period, 65 to 35 million years ago. After these sharks come the filter feeders. The Hexanchiformes, Chlamydoselachiformes, and frilled sharks reside in deep waters, living during the Jurassic and Cretaceous periods. From this, the first modern sharks begin to appear: the sixgill, sevengill, and frilled. The adaptive radiation that gave way for modern species of sharks occurred about 200 million years ago. These mass extinctions allow adaptive radiation to occur for the sharks, since extinctions remove predators from their habitats. As the mass extinctions begin to occur, the sharks survive through all of them. Sharks then begin to emerge at around the time of 455 or 425 million years ago. This is shown in the first diagram above, where ostracoderms are the root of the cladogram. The evolution of sharks begins about 510 million years ago, where the first fish, ostracoderms, arrived. The whale shark may have a very limited past, but its roots as a shark and relatives can be found and observed.
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