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The Effects of Salinity and Phytoplankton Food on Larval Cloning and Regeneration in the Sea Star Asterias forbesi
Fink, Elisabeth
Fink, Elisabeth
Abstract
Larvae of the sea star Asterias forbesi, a keystone species of the North American Atlantic coast, are able to clone by fissioning perpendicular to the anterior-posterior axis. Both anterior and posterior pieces have the capacity to regenerate, forming two genetically identical larvae. In other species of sea stars, the frequency of larval cloning has been shown to vary in response to environmental conditions, such as the abundance of phytoplankton, which serves as a food resource for larvae. Phytoplankton abundance and salinity fluctuate in the intertidal habitat of A. forbesi, as transient algal blooms often form when freshwater from land runoff inputs nutrients into coastal waters. In my thesis I examine the effects that salinity, food quantity, and food type have on cloning frequency and the effects that temperature and food have on regeneration success after fissioning. High food levels led to increased cloning frequency, and larvae fed Rhodomonas lens cloned more than those fed other species of algae, although the latter difference was not statistically significant. Salinity had no effect on clone production over the entire larval period, but larvae cultured at low salinity cloned earlier in the larval period than those cultured in normal salinity seawater. No environmental factors were shown to affect the frequency of regeneration success after cloning, but posterior clones regenerated three times more often than anterior clones, a result in line with prior research. My results therefore demonstrate that environmental factors affect cloning frequency, which could indicate that cloning is an adaptive trait in A. forbesi under particular environmental conditions. However, differential regeneration success likely results primarily from as yet unidentified internal mechanisms in the larva and not from environmental factors.
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2026-05-08
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Fink_Thesis_7v26-wcover.pdf
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- Embargoed until 2028-05-02
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http://creativecommons.org/licenses/by-nc-nd/4.0/
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2028-05-08
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Biology