Species Displacement Between an Introduced and A ‘vulnerable’ Crayfish: The Role of Aggressive Interactions and Shelter Competition

摘要: In eastern Hokkaido, Japan, the native crayfish Cambaroides japonicus de Haan has been declining rapidly while exotic Pacifastacus leniusculus Dana expanding its range. We speculated that observed displacement of by is partly due to an interference interaction for shelter between two species. studied impacts on testing experimentally whether intensity interference, outcome dominance order and occupancy differed single- mixed-species combinations showed less defensive behaviours towards than conspecifics. contrast, exhibited more Pairwise comparison agonistic in mixed species groups revealed exhibiting frequently aggressive attacks Camaboides showing their respective counterparts. Dominance encounter generally dictated pairs but not pairs. Because utilization, when these are limited supply, was much frequent Pacifastacus, suffered from both conspecifics heterospecifics they competed a single shelter. however, did show any change presence or absence conspecics heterospecifics. Inferiority interactions can therefore be critical disadvantage if shelters natural situations.