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An analysis of the reproduction of three species of medicinal leeches (genus Hirudo) was carried out. The highest fecundity (34.34 ± 3.72 hatchlings per leech) was observed in H. verbana, the lowest in H. medicinalis (11.10 ± 2.56). The heaviest hatchlings were found in H. medicinalis (0.046 ± 0.0005 g), the lightest in H. verbana (0.032 ± 0.0003 g). Hirudo orientalis had an intermediate fecundity (21.63 ± 3.39 hatchlings per leech) and its hatchlings were of intermediate weight (0.038 ± 0.0005 g). The species differ in their growth rate and mortality: Hirudo verbana had the smallest hatchlings and the lowest survivorship but its growth rate was highest among the three species. The results agree with sister relationships between H. medicinalis and H. orientalis and the basal position of H. verbana with respect to them. The reproductive traits of the three species suggest that H. verbana is an r-strategist that inhabits unstable environments, such as temporary ponds in steppe landscapes, whereas its congeners are subject to K-selection and occur in more stable and predictable habitats. [ABSTRACT FROM AUTHOR]

Since the 18th century, the medicinal leech Hirudo medicinalis has been thought to comprise a single species with several different color morphs, but recently some of these color morphs have been assigned to separate species based on morphology, geographical distribution, and molecular sequence data. This research was aimed at testing the ability of three of these species, H. medicinalis, Hirudo verbana, and Hirudo orientalis, to interbreed. We found that in the laboratory, all three species were able to mate with each other and produce hybrid offspring. This suggests that the reproductive isolation is not strong among these species of the genus Hirudo. However, fewer offspring were produced from interspecific crosses compared with intraspecific crosses. This decrease of fecundity (and in some cases, offspring viability) indicates some degree of reproductive isolation between H. medicinalis, H. verbana, and H. orientalis. [ABSTRACT FROM AUTHOR]