Biology of acanthocephalan Acanthocephalus anguillae in subterranean habitatsBenko, Grega (Avtor) Kostanjšek, Rok (Mentor) parasite infestationolmsubterranean environmentwaterliceecological flexibilitybehavioural manipulationhelminthsconservation biologyThe trophically transmitted acanthocephalan Acanthocephalus anguillae typically cycles between waterlice (Asellus aquaticus) and freshwater fishes. Its presence in the Postojna–Planina Cave System (PPCS), where it infests cave-dwelling waterlice and the olm (Proteus anguinus), provides an exceptional opportunity to explore the ecological flexibility of this parasite while simultaneously raising important conservation considerations. This thesis applied an integrative approach combining parasitological examination of olm collection specimens, assessment of parasite gravidity, molecular analyses, behavioural experiments, and histological examinations. Systematic examination of olms collected between 1968 and 2022 revealed A. anguillae only in PPCS, with records beginning in 1994. The survey also provided the first confirmation of Pomphorhynchus sp. in olms, which predominated prior to the emergence of A. anguillae. Gravidity assessment revealed contrasting evidence of host suitability: while many parasites were extraintestinal and degraded, gravid females were found in recent specimens, indicating that the olm is a partially compatible host capable of supporting parasite reproduction. Genetic analyses showed substantial gene flow between cave and nearby surface populations of A. anguillae, supporting ongoing connectivity rather than long-term isolation. Behavioural experiments detected no novel manipulation of waterlice by A. anguillae adapted to subterranean conditions, as the reduction in photophobia persisted. Histological analyses revealed typical acanthocephalan-induced intestinal lesions in olms, although their impact on host health remains uncertain. Overall, A. anguillae represents a new population in PPCS sustained by surface influx. It appears to have recently gained the ability to reproduce in a cave definitive host, while its manipulation strategies in the intermediate host remain unadapted to subterranean conditions. Severe inflammatory responses and potential sublethal effects highlight the need for continued health monitoring of olm populations and their parasites.[G. Benko]20252026-01-22 07:15:17Doktorsko delo/naloga178243UDK: 595.151:551.44(043.3)VisID: 278660COBISS_ID: 266027267sl