Date of Award

8-2018

Document Type

Thesis

College

College of Arts and Sciences

Degree Program

Biology

Degree Name

Master of Science

Thesis Advisor

Julian Smith

Committee Member

Cynthia Tant

Committee Member

Dwight Dimaculangan

Keywords

Meiofauna Flatworms, Platyhelminthes, Proseriata, Rhabdocoela, Cryptic speciation, Internal transcribed spacer

Abstract

Meiofauna are unusual in that they typically have widespread distribution, despite being small-bodied and unable to swim. This is known as the meiofaunal paradox; cryptic speciation has been suggested as a possible explanation for the meiofaunal paradox. In order to determine whether cryptic speciation and genetic differentiation across populations of meiofaunal flatworms could be detected along the eastern coast of North America, I collected specimens of two different morphospecies of meiofaunal flatworms (Paramonotus sp. and Proschizorhynchella sp.) from different locations in North Carolina and Florida. Specimens were sequenced for four different genetic markers: 18S gene, 28S gene, ITS region, and cox-1 gene. For Proschizorhynchella sp. I found evidence that Proschizorhynchella sp. consisted of two cryptic species: one in Onslow Bay, NC and one in Florida. For Paramonotus sp. I found that all populations consisted of the same biological species (all populations of Paramonotus sp. were found in Onslow Bay). I also found that 18S and 28S showed no variation across populations for both morphospecies and that the ITS region showed no genetic variation across populations for Paramonotus sp. There was, however, variation across the different populations of Proschizorhynchella sp. for both the ITS region and the cox-1 gene. For Paramonotus sp. there was some genetic variation across populations for the cox-1 gene. For the two sites where both morphospecies were present, there was a numerical difference in the amount of genetic variation across these two sites for these two morphospecies, wherein the variation across sites was numerically higher for Proschizorhynchella sp. than it was for Paramonotus sp.

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