Ph.D., Evolution & Ecology, The Ohio State University, 2017
Postdoctoral research: American Museum of Natural History, 2018-2020
Postdoctoral research: University of Lausanne, Switzerland, 2020-2021
- Evolution & Ecology of Tropical Marine Mutualisms
- Systematics of Actiniaria (sea anemones)
Research in the Titus Lab uses the iconic mutualisms from tropical coral reefs to understand the evolutionary and ecological processes that generate biodiversity in these tightly linked interactions.
We combine field research, systematics, and genomic approaches to understand mutualisms at all levels of biological organization. Our lab is currently focused on three main projects involving sea anemones and the clownfish-sea anemone symbiosis.
Systematics and Species delimitation of the clownfish-hosting sea anemones:
The clownfish-sea anemone symbiosis has been used as a model mutualism for exploring fundamental biological processes. However, the 10 nominally described species of host anemones have only been described morphologically.
The presence of cryptic host anemone taxa thus holds the potential to transform our evolutionary understanding of this symbiosis and bear on the interpretation of dozens of studies that span scientific disciplines.
Using newly developed bait-capture probes targeting Ultra Conserved Elements we are using range-wide sampling and genomic species delimitation approaches to disentangle the true species-level diversity of the host anemones. This work is currently funded by the National Science Foundation
Origin of tropical sea anemone diversity:
Contrary to the generally observed pattern of hyperdiversity in the tropics, anemone diversity peaks in temperate ecosystems. As a result, tropical species have received a fraction of the scientific attention as temperate ones, with no major efforts in the systematics of tropical anemone diversity since the advent of modern DNA sequencing.
Compounding a lack of systematic effort in the tropics, anemones have few diagnostic morphological characters and slowly evolving mitochondrial DNA that is ineffective as a species-level marker. Thus, it is likely that tropical anemone diversity is vastly under-described, and a genomic approach is required to simultaneously delimit species, place them into broader phylogenomic context, and determine what morphological characters are informative at every hierarchical level.
Using newly developed bait-capture probes for Class Anthozoa, we are testing whether the tropics are a center of origin, or a center of accumulation, of tropical sea anemone diversity. This project will be the first major phylogenomic reconstruction within the Order Actiniaria and is funded by the National Science Foundation.
Genomic consequences and convergence in a model marine mutualism:
Mutualisms can radically shape the architecture of the genome, trigger adaptive radiations, lead to rapid population expansions, and impact rates of molecular evolution. Using the multiple origins of symbiosis with clownfishes as a research framework, our lab is conducting full genome sequencing of the clownfish-hosting sea anemones to test general evolutionary expectations of mutualism.
Specifically, we are testing:
- Whether mutualism with clownfishes has generated similar selective pressure and therefore resulted in convergent genome evolution and architecture among host anemones.
- The Red King Hypothesis, which states that the balance of mutually exploitative symbioses should lead constituent mutualistic lineages to have slower rates of molecular evolution than their free-living relatives.
- Whether the mutualistic benefits of hosting clownfishes led to the significant ecological opportunity for host anemones, and thus, signatures of demographic population expansion that coincide with the onset of the symbiosis.
- Glon, H., Quattrini, A., Rodriguez, E., Titus, B.M., Daly, M. Comparison of sequence-capture and ddRAD approaches in resolving species and populations in hexacorallian anthozoans. Molecular Phylogenetics and Evolution 163, 107233. https://doi.org/10.1016/j.ympev.2021.107233
- Titus, B.M., Gibbs, H.L., Simoes, N., Daly, M. . Topology testing and demographic modeling reveal a novel diversification pathway in the Caribbean Sea following the formation of the Isthmus of Panama. Biorxiv preprint. 427733. https://doi.org/10.1101/2021.01.22.427733
- Romain, J.J., Exton, D.A., Smith, D.J., Rose, A., Vondriska, C.V., Titus, B.M. Fine-scale patterns of cleaning activity by Pederson’s cleaner shrimp, (Ancylomenes pedersoni) across ecologically disjunct reef habitats. Journal of the Marine Biological Association of the United Kingdom. https://doi.org/10.1017/S0025315420000958
- Riginos, CR, Crandall, ED, Liggans, L, Gaither, MR, Ewing, RB, Meyer, C, Andres, KR, Euclide, PR, Titus, BM, Therkildsen, NO, Salces-Castellano, A, Stewart, LC, Toonen, RJ, Deck, J . Building a Global Genomics Observatory: using GEOME (the Genomic Observatories Metadatabase) to expedite and improve deposition and retrieval of genetic data and metadata for biodiversity research. Molecular Ecology Resources. https://doi.org/10.1111/1755-0998.13269
- Titus, BM, Laroche, R., Rodriguez, E., Wirshing, H., Meyer, C.P. Host identity and symbiotic association affects the taxonomic and functional diversity of the clownfish-hosting sea anemone microbiome. Biology Letters 16, 1-8. https://doi.org/10.1098/rsbl.2019.0738
- Rose, A., Titus, B.M., Romain, J.J., Vondriska, C.V. Exton, D.A. Multiple cleaner species provide simultaneous services to reef fish clients. Biology Letters. 16, 1-5. https://doi.org/10.1098/rsbl.2020.0723
- Titus, B.M., Blishak, P., Daly, M . Genomic signatures of sympatric speciation with historical and contemporary gene flow in a tropical anthozoan (Hexacorallia: Actiniaria). Molecular Ecology. https://doi.org/10.1111/mec.15157
- Titus, BM, Benedict, C., Laroche, R. Gusmao, LC, Van Deusen, V., Chiodo, T., Meyer, CP, Berumen, ML, Bartholomew, A., Yanagi, K., Reimer, JD, Fujii, T., Daly, M., Rodriguez, E. Phylogenetic relationships of the clownfish-hosting sea anemones. Molecular Phylogenetics & Evolution. https://doi.org/10.1016/j.ympev.2019.106526
- Titus, B.M, Daly, M., Vondriska, C., Hamilton, I., Exton D.A. Lack of strategic service provisioning by Pederson’s cleaner shrimp (Ancylomenes pedersoni) highlights independent evolution of cleaning behaviors between ocean basins. Scientific Reports. 9:629. https://doi.org/10.1038/s41598-018-37418-5
- O’Reilly, E. , Titus, B.M. Nelsen, M.W., Ratchford, S., Chadwick, N.E. Giant ephemeral anemones? Rapid growth and high mortality in the corkscrew sea anemone Bartholomea annulata under variable conditions. Journal of Experimental Marine Biology and Ecology. 509: 44-53. https://doi.org/10.1016/j.jembe.2018.08.013
- Titus, B.M., Daly, M, Hamilton, N., Berumen, M., Baeza, J.A. Global species delimitation and phylogeography of the circumtropical “sexy shrimp” Thor amboinensis reveals a cryptic species complex and secondary contact in the Indo-West Pacific. Journal of Biogeography. 45, 1275-1287. https://doi.org/10.1111/jbi.13231
- Titus, B.M. and M., Daly. Phylogeographic reconstruction reveals extensive cryptic diversity in a common symbiosis from the Tropical Western Atlantic. Reef Encounter. 32: 20-24. https://coralreefs.org/wp-content/uploads/2019/01/Reef-Encounter-August-2017-FINAL-Lo-Res.pdf
- Titus, B.M., Palombit, S, Daly, M. Endemic diversification in an isolated archipelago with few endemics: an example from a cleaner shrimp species complex in the Tropical Western Atlantic. Biological Journal of the Linnaean Society. 122: 98-112. https://doi.org/10.1093/biolinnean/blx039
- Titus, B.M. Vondriska, C., Daly, M. Comparative behavioral observations demonstrate the spotted “cleaner” shrimp Periclimenes yucatanicus engages in true symbiotic cleaning interactions. Royal Society Open Science. 4:170078. https://doi.org/10.1098/rsos.170078
- Titus, B.M., Daly, M, Macrander, J., Del Rio, A., Santos, S.R., Chadwick, N.E. Contrasting abundance and contribution of clonal proliferation to the population structure of the corkscrew sea anemone Bartholomea annulata in the tropical Western Atlantic. Invertebrate Biology. 136: 62-74. https://doi.org/10.1111/ivb.12162
- Titus, B.M. and M., Daly. Specialist and generalist symbionts show counterintuitive levels of genetic diversity and discordant demographic histories along the Florida Reef Tract. Coral Reefs. 36: 339-354. https://doi.org/10.1007/s00338-016-1515-z
- Titus, B.M. Daly, M., Exton, DA. Temporal patterns of Pederson shrimp (Ancylomenes pedersoni Chace 1958) cleaning interactions on Caribbean coral reefs. Marine Biology. 162: 1651-1664.
- Titus, B.M. Daly, M., Exton, DA. Do reef fish habituate to diver presence? Evidence from two reef sites with contrasting historical levels of SCUBA intensity in the Bay Islands, Honduras. PLOS ONE. 10(3): e0119645. https://doi.org/10.1007/s00227-015-2703-z
- Titus, B.M. and M. Daly . Fine-scale phylogeography reveals cryptic biodiversity in Pederson’s cleaner shrimp, Ancylomenes pedersoni (Crustacea: Caridea: Palaemonidae), along the Florida Reef Tract. Marine Ecology. 36: 1379-1390. https://doi.org/10.1111/maec.12237
- Huebner, L.K., Dailey, B., Titus, B.M., Khalaf, M., Chadwick, N.E. Host preference and habitat segregation among Red Sea anemonefish: effects of sea anemone traits and fish life stages. Marine Ecology Progress Series. 464: 1-15. Feature cover article. https://doi.org/10.3354/meps09964
- Lescinsky, H., Titus, B.M., Hubbard, D. Live coral cover in the fossil record: an example from Holocene reefs of the Dominican Republic. Coral Reefs. 31 (2): 335-346. https://doi.org/10.1007/s00338-011-0863-y
- Titus, B.M. and M. Daly . Population genomics for symbiotic anthozoans: can reduced representation approaches be used for taxa without reference genomes? Biorxiv preprint. 440289. https://doi.org/10.1101/440289