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Evolution of Brooding in Sea Anemones: Patterns, Structures, and Taxonomy

Larson, Paul G
http://rave.ohiolink.edu/etdc/view?acc_num=osu1448278385

Abstract Details

2015, Doctor of Philosophy, Ohio State University, Evolution, Ecology and Organismal Biology.
Brooding is an unusual reproductive behavior among Actiniarians (sea anemones). Sea anemones commonly free-spawn gametes producing pelagic offspring that develop independently. In brooding, offspring are retained until the juveniles or adult stage. Brooding behaviors are diverse among sea anemones but some of this diversity is obscured by imprecise or inconsistent terminology. Brooding is taxonomically widespread, but most brooding species are found within Actiniidae. The actiniid genus Epiactis is particularly notable for its wide geographic distribution and diversity in characters associated with reproduction. Individuals of the Antarctic, hermaphroditic species E. georgiana brood offspring on the surface of the adult, whereas anemones in the gonochoric north Pacific species, E. handi, hold offspring within the gastrovascular cavity. Additional Epiactis species have been described from the Arctic and Atlantic oceans and include species which aren’t known to brood. This variation provides an unusual opportunity to investigate the evolutionary patterns in reproductive characters and ramifications of brooding modes, but also calls into question the monophyly of the genus. This uncertainty is manifested in the literature through taxonomic actions including the creation of Cnidopus for several Epiactis species and in dispute regarding the specific identity of certain Epiactis specimens. Here I employ morphological and molecular techniques to investigate taxonomic and systematic questions about the genus Epiactis, and to investigate patterns in the evolution of brooding in sea anemones. I address taxonomic issues by employing anatomical methods such as histological sectioning, tissue squash preparations and dissection. I make extensive use of museum materials and examine type specimens and other museum lots of the focal species, and collect new specimens from across the known range in order to identify geographic and taxonomic boundaries. I use DNA sequence data to assess relationships among species and investigate the evolutionary patterns in brooding modes and and other reproductive characteristics. Chapter 1 introduces the group and biological phenomena of interest. In chapter 2 the phenomenon of brooding is reviewed broadly across Actiniaria. Terminology used in discussion of brooding is defined. Epiactis fecunda is treated in chapter 3 and is reassigned to the genus Urtcina based on morphological examination of new specimens. In chapter 4, new collections and museum specimens determined to be Epiactis ritteri and Epiactis japonica are examined. Their specific destinctness is justified with morphological characters, as is the distinctness of the internally brooding individuals from lower latitudes previously identified as E. ritteri. The latter individuals are renamed Epiactis handi. The final chapter reports on phylogenetic analyses of Epiactis species and other actiniids based on nucleotide sequence data. In it, Epiactis is revealed to be a polyphyletic group in which North Pacific species and Southern hemisphere species form separate clusters, both with internal and externally brooding representatives. In the North Pacific, externaly brooding species have evolved from internally brooding ancestors.
Marymegan Daly (Advisor)
Freudenstein John (Committee Member)
Klompen Johannes (Committee Member)
167 p.
Biology; Evolution and Development
Evolution; Brooding; phylogenetics; taxonomy; sea anemone; invertebrate; marine;

Recommended Citations

Citations

  • Larson, P. G. (2015). Evolution of Brooding in Sea Anemones: Patterns, Structures, and Taxonomy [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448278385

    APA Style (7th edition)

  • Larson, Paul. Evolution of Brooding in Sea Anemones: Patterns, Structures, and Taxonomy. 2015. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1448278385.

    MLA Style (8th edition)

  • Larson, Paul. "Evolution of Brooding in Sea Anemones: Patterns, Structures, and Taxonomy." Doctoral dissertation, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448278385

    Chicago Manual of Style (17th edition)

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