Parasite Distribution and Specificity in Anuran Host Complexes.
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This study was based on the parasite fauna of three anuran systems. In two of
the systems; the spadefoot toads, Scaphiopus bombifrons and S.multiplicatus and
the fire and yellow-bellied toads, Bombina bombina and B.variegata, inter-species
hybridisation occurs. In the third system an autopolyploid species complex
involves the Gray treefrogs, Hyla chrysoscelis and H.versicolor. The status of the
Scaphiopus hybrid zone in Arizona was re-assessed by cellulose-acetate gel
electrophoresis. Genotypic frequencies were comparable to those previously
documented, indicating that a region of 'balanced introgression' may exist.
Specimens were collected in areas of host sympatry and the distribution of
helminths within hosts of different genetic constitution investigated. From
extensive surveys of all three systems, parasite frequency distributions were
typically aggregated with no evidence of any change in host genetic predisposition
to infection. In addition, the surveys have documented a number of new host
and/or parasite locality records for each system. Of particular interest was the
discovery of the digenean Clinostomum complanatum in a desert environment, an
introduction related to human management of the ecosystem.
Particular reference was made to the specificity of the polystomatid
monogeneans, Polystoma nearcticum infecting members of the H.chrysoscelis-
H.versicolor complex and Neodiplorchis scaphiopodis infecting S.bombifrons and
S.multiplicatus. For Polystoma, worms from H.chlysoscelis and H.versicolor could
not be separated by morphology, which was supported by preliminary crossinfections.
This suggests that P.nearcticum infects both members of this complex.
For Neodiplorchis, morphological similarity was confirmed by cross-infections
which revealed that N.scaphiopodis can reach sexual maturity and produce fully
developed larvae in heterospecific hosts.
The neotenic development of P. nearcticum and the initial post-oncomiracidial
stages of N.scaphiopodis were documented. Furthermore, certain aspects of
transmission dynamics were examined by the experimental infection of
H. versicolor tadpoles with P. nearcticum .
Authors
Crosswaite, Matthew JohnCollections
- Theses [4098]