Reproductive ability of hybrids between Japanese pond turtle (Mauremys japonica) and Reeves’ pond turtle (Mauremys reevesii)

3.	Ueno S, Kamezaki N, Mine K, Suzuki D, Hosoya S, Kikuchi K, Okamoto K, Torii M, Kadowaki K, Okamoto K, and Sano M

Hybridization  induced  by  human  activities,  such  as  crossbreeding  between  invasive  and  native   species, can adversely affect the natural biodiversity of an ecosystem. In Japan, the endemic turtle  species Mauremys japonica  is  known  to  hybridize  with  the  alien  species  Mauremys  reevesii,  and   putative hybrids have been encountered in the wild. If M. japonica ×M. reevesii hybrids can readily  crossbreed with M. japonica, the hybridization with M. reevesii could lead to the extinction of pure  M.  japonica populations.  However,  information  on  the  reproductive  ability  of  M.  japonica ×M.  reevesii  hybrids  is  limited.  In  this  study,  we  collected  wild-caught  hybrids  from  across  western   Japan to assess their reproductive ability. We investigated the nesting season timing, clutch size,  embryonic  development,  hatching  success,  and  sperm  viability.  The  results  showed  that  female   hybrids nested during the same months as the parental species and had similar clutch sizes and  hatching  success.  No  embryonic  development  abnormalities  were  detected,  and  viable  sperm   were observed in all hybrid male semen samples. In conclusion, the fertility of M. japonica ×M.  reevesii hybrids appears to be similar to the fertilities of the parental species, posing a potential  challenge for M. japonica conservation.

Zoological science

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doi:10.2108/zs210047