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Related: Editorials & Other Articles, Issue Forums, Alliance Forums, Region ForumsShark gives birth without having mated
http://www.cnn.com/videos/world/2017/01/17/zebra-shark-virgin-birth-orig-vstan.cnn
Cooley Hurd
(26,877 posts)cyclonefence
(4,483 posts)longship
(40,416 posts)Could not resist.
dembotoz
(16,799 posts)herding cats
(19,564 posts)Sure, she used to have a mate at the Reef HQ Aquarium in Townsville, Australia. The pair even had several litters before they were separated in 2012.
But Leonie had been living apart from males for the past few years, so her keepers were surprised when she laid eggs that produced three baby sharks in April 2016. Leonie could be the first shark ever observed to make the switch from sexual to asexual reproduction.
"We thought she could be storing sperm; but when we tested the pups and the possible parent sharks using DNA fingerprinting, we found they only had cells from Leonie," said University of Queensland biologist Christine Dudgeon, who described the case in the journal Scientific Reports
Leonie's case marks the first time scientists have seen this type of asexual reproduction known as parthenogenesisin the zebra shark (Stegostoma fasciatum).
Parthenogenesis occurs when embryos develop and mature without fertilization by a male's sperm. Rather, an egg progenitor cell that usually gets absorbed by the female's body acts as a surrogate sperm to "fertilize" her egg. This reproduction strategy is more common in plants and invertebrate organisms. However, scientists have been documenting an increasing number of vertebrate species that can have virgin births even when their species normally reproduces sexually. For example, Komodo dragons, the world's largest lizards, have given birth by parthenogenesis. So have wild pit vipers, blacktip sharks, chickens and turkeys.
In most of these previous parthenogenesis cases, the females were from captive environments and never had any exposure to male mates during their reproductive prime, Dudgeon and her colleagues wrote. That makes Leonie one of the rare individuals known to have had babies by sexual reproduction only to switch to asexual reproduction later on. (Scientists have reported similar cases in a boa constrictor and an eagle ray.)
http://www.livescience.com/57536-zebra-shark-has-virgin-births.html
Cleo and CC, shown here, are two of the zebra shark pups born without a daddy.
Credit: Tourism & Events Queensland
NRaleighLiberal
(60,014 posts)delisen
(6,042 posts)maybe the low sperm count epidemic now being documented in western countries is evolutionary in nature.