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Trematodes in the limelight: Division of labour, life cycles and interactions with other symbionts
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- Author / Creator
- Ayala-Diaz, Monica
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Parasites that require multiple hosts to complete their life cycles can significantly affect the ecology of their hosts and ecosystems. Trematodes are obligatory parasites that use snails as first intermediate hosts and vertebrates as definitive hosts. There are four genera of freshwater snails in Alberta (Lymnaea, Physa, Planorbella and Stagnicola) whose trematode communities remain largely undocumented. Effects of these parasites on their snail hosts are also unknown. I surveyed multiple sites that varied in trematode prevalence and species richness. Through DNA barcoding, I reported for the first time in Alberta the presence of Ribeiroia ondatrae and Drepanocephalus spathans, two trematodes of importance for wildlife conservation. Using in-vitro techniques and behavioural analysis, I provided for the first time in Canada evidence for the existence of division of labour in freshwater trematodes, a strategy only documented in some marine species so far. I tested for effects of trematode infection on snail host survival and showed that survival differed among snail genera, influenced by location and intensity of infection. I studied symbiotic relationships among snails, trematodes, oligochaete worms (genus Chaetogaster) and leeches (genus Helobdella). Oligochaete worms are likely attracted to snails shedding cercariae, whereas leech presence did not seem to be related to trematode infection of their snail host. I also provided, for the first time in Alberta, plausible complete life cycles for 20 trematode species that use snails as first intermediate hosts, snails, leeches, fish and amphibians as second intermediate hosts, and birds and mammals as definitive hosts.
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- Subjects / Keywords
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- Graduation date
- Fall 2024
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.