Experimental Hybridization Between Two Species of Subtropical Sea Urchins from Tampa Bay, Arbacia punctulata and Lytechinus variegatus: An Analysis of Skeletal Morphology Using the Scanning Electron Microscope
Date
2015
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College of Natural and Health Sciences, The University of Tampa
Abstract
Two genera of subtropical sea urchins, Arbacia punctulata and Lytechinus variegatus are common in the Tampa Bay area. A. punctulata is typically found in deeper coastal waters in the Gulf of Mexico, while L. variegatus typically inhabits the inshore sea grass beds of Tampa Bay. A. punctulata has recently expanded its range to include the shallow coastal waters near the mouth of Tampa Bay and now overlaps the range of L. variegatus. The two species broadcast spawn during overlapping seasons and hybrid embryos, from L. variegatus male with A. punctulata female and A. punctulata male with L. variegatus female, have been generated and raised in the laboratory up to the pluteus larval stage. In order to determine if the two genera are hybridizing in the field, specimens from Tampa Bay have been collected, acclimated to lab conditions, spawned, and the skeletal morphometrics of the larvae from four crosses, including two within species crosses used as controls and the two reciprocal hybrid crosses, have been examined at both the light and electron microscopy level. Mean percent fertilization was highest, 87%, in the L. variegatus control cross, 45% in the A. punctulata control cross, 37% in the L. variegatus female × A. punctulata male hybrid cross, and below 5% in the A. punctulata female × L. variegatus male hybrid cross. The prism stage of each control cross had minor differences so the focus of this study was on the four arm pluteus stage skeletal features at the Scanning Electron Microscopy (SEM) level.The pluteus larvae from each control cross for A. punctulata and L. variegatus had distinctive skeletal features. The skeletal features of the pluteus larvae from the hybrid cross were very similar to those of the maternal parent, but some variations were observed. In the A. punctulata control cross, the Anterolateral Rods (AR) of the larvae initially grew at day four and then shrank at day six while the Post-oral Rods (PR) continued to grow. Total Rod Length of A. punctulata control was generally always smaller than L. variegatus control. Also, the total rod length of L. variegatus female × A. punctulata male hybrids was about the same as L. variegatus control and sometimes larger. Growth patterns of all treatments, L. variegatus and A. punctulata controls as well as L. variegatus female × A. punctulata male hybrids, did not follow a clear trend as expected; as time proceeded total rod length shrunk, grew, and shrunk again. When live larval and skeletal measurements (SEM) were compared, skeletal measurements seemed to be more accurate.
Description
Recommended Citation: Meadows , Erin M. . “Experimental Hybridization Between Two Species of Subtropical Sea Urchins from Tampa Bay, Arbacia Punctulata and Lytechinus Variegatus: An Analysis of Skeletal Morphology Using the Scanning Electron Microscope.” Acta Spartae, 2015. https://doi.org/10.48497/DM68-4P43.
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Keywords
Experimental hybridization, Subtropical sea urchins, Arbacia punctulata, Lytechinus variegatus, Skeletal morphology, Scanning electron microscope, Department of Biology, Research Subject Categories::NATURAL SCIENCES, Research Subject Categories::NATURAL SCIENCES::Biology
Citation
Meadows , Erin M. . “Experimental Hybridization Between Two Species of Subtropical Sea Urchins from Tampa Bay, Arbacia Punctulata and Lytechinus Variegatus: An Analysis of Skeletal Morphology Using the Scanning Electron Microscope.” Acta Spartae, 2015. https://doi.org/10.48497/DM68-4P43.