Date of Completion

Spring 5-7-2014

Thesis Advisor(s)

Louise A. Lewis

Honors Major

Molecular and Cell Biology

Disciplines

Bioinformatics | Molecular Genetics | Other Ecology and Evolutionary Biology | Terrestrial and Aquatic Ecology

Abstract

In 1909, the species Oophila amblystomatis Lambert ex Wille was described for green algae that symbiose with salamanders in the egg stage (Wille). There are two hypotheses about the source of algae: 1) that algae enter from the surrounding water once the egg clutch is laid in a pond, and 2) that they are acquired from the maternal reproductive tract. We developed a third hypothesis developed to account for the salamander reproductive cycle. Male salamanders lay spermatophores, which are protein-filled capsules, on plant matter in and around ponds. Spermatophores are exposed to the environment before use by females in internal fertilization. Thus, we investigated possible sources of the algae in Quarry pond in Connecticut, U.S.A., by comparing rbcL chloroplast sequences of algae cultured from spermatophores, cloacal swabs of male and female salamanders, egg jelly samples, and multiple eggs across clutches.

Sequences of algae from eggs were distributed into five phylogenetic lineages; those from jelly, cloacal swabs, and spermatophores were found in three lineages, two of which were shared with those from eggs. In addition, all sequences from cloacal swabs aligned with sequences of free-living algae from the class Trebouxiophyceae. Most sequences from eggs aligned with free-living algae from class Chlorophyceae, order Volvocales, which was previously shown to symbiose with eggs of the Northwestern salamander Ambystoma gracile (Goff & Stein 1978). We cannot exclude either the environmental acquisition or the maternal transmission hypothesis, suggesting that both sources may contribute to the presence of algae in salamander eggs.

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