Tardigrades are generally gonochoristic. Many moss-dwelling species propagate by parthenogenesis, but heterogony has not yet been found. Milnesium tardigradum, a carnivorous tardigrade, also has both sexes, but males are usually rare and many populations appear to have only parthenogenetic reproduction. Since 2000, I have maintained a thelytokous strain of Milnesium cf. tardigradum that originated from one female. Individuals of this strain were thought to be all females, but here I report that males have emerged in this strain at a very low frequency. This is the first report of the appearance of males in parthenogenetic tardigrades. On the first pair of legs of some individuals, I observed the modified claws characteristic of males of this species. It is unknown whether these males can actually function in sexual reproduction; however, they might allow some possibility of genetic exchange among clonal populations. No environmental factors that generate males were determined.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.