title: Spermatozoa Production by Triploid Males in the New Zealand Freshwater SnailPotamopyrgus antipodarum.
abstract: Asexual lineages derived from dioecious taxa are typically assumed to be all female. Even so, asexual females from a variety of animal taxa occasionally produce males. The existence of these males sets the stage for potential gene flow across asexual lineages as well as between sexual and asexual lineages. A recent study showed that asexual triploid femalePotamopyrgus antipodarum, a New Zealand freshwater snail often used as a model to study sexual reproduction, occasionally produce triploid male offspring. Here, we show that these triploid maleP. antipodarum1) have testes that produce morphologically normal sperm, 2) make larger sperm cells that contain more nuclear DNA than the sperm produced by diploid sexual males, and 3) produce sperm that range in DNA content from haploid to diploid, and are often aneuploid. Analysis of meiotic chromosomes of triploid males showed that aberrant pairing during prophase I likely accounts for the high variation in DNA content among sperm. These results indicate that triploid maleP. antipodarumproduce sperm, but the extent to which these sperm are able to fertilize female ova remains unclear. Our results also suggest that the general assumption of sterility in triploid males should be more closely examined in other species in which such males are occasionally produced.
authors.affiliation: Indiana University, Department of Biology, Bloomington, IN.
authors.forename: D M
authors.initials: DM
authors.lastname: Soper
authors.forename: M
authors.initials: M
authors.lastname: Neiman
authors.forename: O P
authors.initials: OP
authors.lastname: Savytskyy
authors.forename: M E
authors.initials: ME
authors.lastname: Zolan
authors.forename: C M
authors.initials: CM
authors.lastname: Lively
keywords: gametogenesis; ploidy evolution; polyploidy; reproduction; sperm; triploid fertility