Most organisms exhibit sexual reproduction. Rotifers of the class Bdelloidea, however, seem to be a notable exception to this pattern. No male bdelloid individuals have ever been observed, and females apparently reproduce entirely through parthenogenesis. Sexual reproduction occurs in rotifers of the class Monogononta, and in many cases it is induced by environmental cues (e.g. temperature, diet). In this study, Philodina sp. was examined to determine if variations in temperature could induce a sexual cycle in bdelloid rotifers. Sibling individuals (clones) were raised with equal amounts of food at 20°C and 30°C. Newly hatched offspring produced by these individuals were counted and removed at approximately 12 hour intervals until the parent died. Individuals exhibiting unusual characteristics were isolated as possible males and raised for closer examination. No males were positively identified. However, temperature greatly affected reproduction rates. At 30°C individuals had a significantly greater rate of reproductive (Q10 = 2.34) and produced more offspring than those at 20°C. Furthermore, age at the start of reproduction was significantly earlier at 30°C than at 20°C. Unexpectedly, presumed genetically identical clones of Philodina sp. showed significant variation in lifespan when raised in equivalent environmental conditions.



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