Population genetics, environmental tolerances, and natural variation in infection frequency of the parasitic anemone, Edwardsiella lineata
Embargo Date
2027-02-10
OA Version
Citation
Abstract
Mnemiopsis leidyi, the sea walnut, is one of the most destructive invasive species in the world. The ctenophore has broad environmental tolerances, a high rate of zooplankton consumption, extensive regeneration capabilities, and extraordinary fecundity. While there is a substantial body of research on M. leidyi’s role as a predator of zooplankton and as prey to the ctenophore Beroe ovata, only a few studies have examined M. leidyi’s relationship with its parasite, the lined sea anemone, Edwardsiella lineata. Previous research has shown that E. lineata may be exerting top-down control on the ctenophore in areas where present along the Northwestern Atlantic; the parasite has not established a population in M. leidyi’s invasive range. While a handful of studies have examined the ecological relationship between host and parasite, all studies have taken place at the same site, Woods Hole, and some failed to report key parameters such as host size and parasite number. More detailed examinations of this relationship are necessary to understand the parasite’s potential for controlling host populations in both native and European waters and how this control may be affected under various abiotic conditions. In my dissertation I performed three studies exploring the ecological relationship between M. leidyi and E. lineata. First, I profiled the variation in infection frequency in populations in Massachusetts and Rhode Island and examined the relationship between host size, parasite load, and seasonality. My results show that in natural populations, infected ctenophores are larger than non-infected conspecifics. The pattern of infection was also highly variable across sites and time. Second, I tested the temperature and salinity tolerances of E. lineata larvae to determine if certain conditions, such as those found in the invasive range of M. leidyi are refuges for the host from parasitism. My data indicate that temperature and salinity conditions alone will not prevent E. lineata from establishing a population in Europe. However, developmental outcomes and survival are both reduced at lower salinities and higher temperatures. Finally, using a RAD-seq approach I profiled population connectivity between juvenile parasite and adult polyp populations of E. lineata in Massachusetts and Rhode Island. E. lineata populations were found to be panmictic like host M. leidyi, though some structuring appeared between parasite and polyp populations. While asexual reproduction was seen in polyp mats, none was found within hosts.These data help contribute to the wider body of research on the M. leidyi-E. lineata system and also provide data on sea anemone genetic structure, which is currently understudied. I suggest that future studies examine cues for asexual reproduction in both the parasite and host and profile infection frequency and genetic structure in populations further south.
Description
2024
License
Attribution 4.0 International