Date of Completion
Honors College Thesis
College of Arts and Science Honors, Honors College
Dr. Joseph J. Schall
Dr. Joseph Gorres
Dr. Nicholas Gotelli
Life history, Monocystis, Amynthas, genetic variation, life cycle, mating system
Monocystis is a parasites in the phylum Apicomplexa that infects nearly 100% of earthworms; however, the parasites have low survivorship, low production of transmissible gametocysts, and seemingly lack schizogony. The purpose of this study was to investigate the improbable lifecycle and life history traits of a Monocystis species of the invasive Asian earthworms, Amynthas agrestis and A. tokioensis in Vermont.
Preliminary data suggested that Monocystis sp. vary in life history traits between three sites sampled; therefore, it was necessary to investigate the genetic diversity and the mating system of its host, as the mating system is responsible for genetic variation. Random Amplified Polymorphic DNA (RAPD) markers revealed genetic variation within and among sites of both Amynthas spp. which appear to employ a mixed-mating system of both sexual and asexual reproduction demonstrated by the presence of both clonal and unique genotypes.
The life history and life cycle of Monocystis sp. in A. agrestis was described by using microscopy to measure phenology and parasite stages and numbers. Amynthas spp. at Audubon had a shorter season and the parasites produced gametocysts earlier than at the other two sites. The parasite success rate at Audubon, Hort Farm, and Centennial Woods were 113.8%, 73.6%, and 0%, repectively. Audubon worms had higher numbers of gametocyts but a lower mean number of sporocysts per gametocyst (127.0) than did hosts at Hort Farm (145.8). Monocystis sp. has different life history traits and schedules to compensate for the length of the season and the genetic variation of its host.
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Keller, Erin L., "Life history of Monocystis parasites and genetic diversity of their hosts, the invasive Amynthas earthworms" (2016). UVM Honors College Senior Theses. 218.