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چکیده
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This study was conducted to investigate the effect of non-native species, Hirudo verbana, on native Iranian species, Hirudo orientalis. Due to the increasing demand for leech therapy and declines in populations of Iranian medicinal leech in nature, H. verbana has been imported into Iran; therefore, there is a possibility of entering this non-native species into natural habitats. Previous studies have shown that H. verbana and H. orientalis can produce hybrid offspring in laboratory. In this study the possibility of hybrid production between these species was investigated in semi-natural condition. Four experimental groups were determined as follows: interbreeding in laboratory (obligatory condition), inbreeding of H. verbana, inbreeding of H. orientalis, and interbreeding in semi-natural condition (optional hybridization). Fifty conspecific leeches were allocated in each inbreeding group while 25 leeches of each species were allocated in both interbreeding groups. After breeding period, fertility rate and viability of offspring were examined in different groups. Five different morphotypes of hybrids were produced in laboratory condition, but in semi-natural condition the fertility rate of both species was reduced and only H. orientalis was able to produce offspring in low fertility rate. Hybrid morphotypes were different from each other based on dorsal morphology. Dorsal morphology of hybrid morphotypes was similar to their maternal morphology. In all morphotypes, the ventral side of body was more similar to H. verbana. The hybrids were bigger than the purebreds. As a result, although H. verbana and H. orientalis produce hybrids in laboratory condition, but the possibility of producing hybrids in a natural environment could be considered unlikely.
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