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Comparative phylogeography of a multi-level sea anemone symbiosis: effects of host specificity on patterns of co-diversification and genetic biodiversity

Titus, Benjamin M
http://orcid.org/0000-0002-0401-1570
http://rave.ohiolink.edu/etdc/view?acc_num=osu1511308921778638

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Evolution, Ecology and Organismal Biology.
Understanding the patterns and processes that generate and maintain biodiversity is the key pursuit of evolutionary biology. The field of phylogeography attempts to bridge the gap between phylogenetics and populations genetics, and reveal the underlying historical and biogeographic mechanisms of the divergence process itself. In a comparative framework, phylogeography seeks to identify the shared historical processes that promote population and species level diversification. Largely missing from the comparative phylogeographic literature are experimental frameworks that account for abiotic and biotic factors, as many taxa engage in highly specialized interactions that can have profound impacts on evolutionary history. Accounting for biological traits can thus identify the relative contributions of abiotic versus biotic process across ecosystems, the origin and maintenance of ecological communities, and increased power to evaluate top-down hypotheses about the generation of biodiversity. Tropical coral reefs are among the most biodiverse ecosystems on the planet, and inherently reliant on highly specialized symbioses that represent millions of years of evolutionary interactions. Long-term, stable, ecological associations generate an a priori hypothesis of concordant phylogeographic history among interacting species, yet the degree of specificity and fidelity within these associations should lead to varying degrees of shared biogeographical histories. Using a common sea anemone symbiosis on coral reefs from the Tropical Western Atlantic, I test the hypothesis that variation in host specificity, across five co-occurring crustacean species symbiotic with sea anemones, predicts levels of phylogeographic concordance with their shared host, the corkscrew anemone Bartholomea annulata. First, in Chapters 2-6, using DNA barcodes and high-throughput DNA sequencing, I demonstrate that three of the five nominally described, focal crustacean species, are actually cryptic species complexes with complex evolutionary histories diverging across allopatric boundaries, and resulting in patterns of isolation, introgression, long-distance colonization, and hybrid speciation. In Chapters 7 & 8, I focus on the evolutionary history of the sea anemone host B. annulata. I demonstrate that in addition to my focal crustacean species, the anemone host is a cryptic species complex as well and has diverged sympatrically throughout the Tropical Western Atlantic. Coalescent modeling suggests that this diversification occurred with continuous gene flow between putative species. In Chapter 8 I conduct the first range-wide phylogeographic study of any tropical sea anemone species worldwide. Bartholomea annulata exhibits subtle, but significant, population differentiation across the region. The most highly differentiated populations reside on the eastern and western side of the Florida Straits. Finally, in Chapter 9 I reconstruct the phylogeographic history for all co-occurring species throughout the Tropical Western Atlantic using mtDNA and single nucleotide polymorphisms (SNPs). Both datasets reveal discordant patterns of population subdivision across the entire region for the focal crustacean species, but two commonly shared phylogeographic breaks at the Mona Passage and Florida Straits. Coalescent simulation and model selection indicates some shared demographic processes across these breaks. However, extensive temporal variation around divergence time estimates across these breaks suggest that, these processes are acting on each species at different timescales. Thus, we recover no pattern that suggests host specificity predicts concordance with anemone host B. annulata.
Marymegan Daly (Advisor)
John Freudenstein (Committee Member)
Bryan Carstens (Committee Member)
411 p.
Biology
Symbiosis; phylogeography, species delimitation; co-evolution; coral reefs; Caribbean; sea anemone; crustacean

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Citations

  • Titus, B. M. (2017). Comparative phylogeography of a multi-level sea anemone symbiosis: effects of host specificity on patterns of co-diversification and genetic biodiversity [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511308921778638

    APA Style (7th edition)

  • Titus, Benjamin. Comparative phylogeography of a multi-level sea anemone symbiosis: effects of host specificity on patterns of co-diversification and genetic biodiversity. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1511308921778638.

    MLA Style (8th edition)

  • Titus, Benjamin. "Comparative phylogeography of a multi-level sea anemone symbiosis: effects of host specificity on patterns of co-diversification and genetic biodiversity." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511308921778638

    Chicago Manual of Style (17th edition)

osu1511308921778638
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This open access ETD is published by The Ohio State University and OhioLINK.