Interactions between cryptic species of freshwater shrimp belonging to the genus paratya (Atyidae)

Paratya australiensis has been shown to consist of a complex of cryptic species, with as many as 16 species within the complex.  The species complex occurs throughout eastern and south-eastern Australian rivers.  This paper will present data to examine interactions between some of these species and will show an experimental approach to identifying the mechanisms that may be responsible for limiting gene flow between them.

In 1993, two of the species were mixed in a translocation event.  Subsequently the introduced species resulted in almost total extinction of the resident species.  Subsequent monitoring of the translocation site has shown that a small population of the resident species remains, and numbers have not reduced further since 2002.  In this paper, we present data on timing of reproduction of each of the species and propose a mechanism to explain how the residents have managed to ‘hang on’.

We also examine other river systems to test the hypothesis that such mechanisms may also operate in other parts of the range of this species complex, where two or more species overlap.