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Diversity in the Monogenea and Digenea: does lifestyle matter?
Thomas H Cribb1, Leslie A Chisholm, Rodney A Bray
1Department of Microbiology and Parasitology, School of Molecular and Microbial Sciences, The University of Queensland, 4072, Brisbane, Qld, Australia. t.cribb@mailbox.uq.edu.au
International Journal for Parasitology
|February 12, 2002
Summary
Parasitic flatworms (Monogenea and Digenea) in fish show similar species richness but differ in diversity drivers. Monogenean diversity stems from host specificity and morphology, while Digenean diversity arises from host/habitat shifts and tetrapod associations.
Area of Science:
- * Comparative Parasitology
- * Fish Health and Disease
- * Evolutionary Biology
Background:
- * Parasitic platyhelminths of fishes are broadly categorized into external Monogenea and internal Digenea.
- * Both groups exhibit long-term coevolutionary relationships with fish hosts, demonstrating high success in their respective ecological niches.
- * Current estimates suggest comparable species richness between Monogenea and Digenea.
Purpose of the Study:
- * To analyze the diversity patterns of Monogenea and Digenea in fishes, focusing on species and higher taxonomic richness.
- * To identify the evolutionary and ecological processes driving the observed differences in diversity between these two parasitic groups.
- * To compare the factors contributing to the richness of higher taxa (families) within Monogenea and Digenea.
Main Methods:
- * Comparative analysis of taxonomic richness at species and family levels for Monogenea and Digenea infecting fishes.
- * Evaluation of potential drivers of diversity, including host specificity, generation time, host-switching, and habitat adaptation.
- * Examination of evolutionary history and ecological factors influencing diversification in both parasitic groups.
Main Results:
- * While overall species richness may be similar, Monogenea exhibit high species richness within specific genera (e.g., Dactylogyrus, Gyrodactylus) not paralleled in Digenea.
- * Monogenean family richness is comparable to Digenea, but the nature of these families differs significantly.
- * Digenean family richness is explained by factors like tetrapod-associated taxa recolonization, niche expansion within hosts, and exploitation of specific mollusc lineages, which are less prominent in Monogenea.
- * Monogenean higher-level diversity is primarily linked to morphological adaptations of the haptor for host attachment.
Conclusions:
- * Despite similar species counts, the evolutionary pathways and diversification mechanisms of Monogenea and Digenea in fishes are distinct.
- * Monogenean diversity is largely driven by host specificity and specialized attachment structures, whereas Digenean diversity is shaped by broader ecological and host-related shifts.
- * Understanding these differing processes is crucial for comprehending the evolutionary ecology of fish parasites.