Abstract
Aim
Comparative phylogeographic studies ask the question “do ecological communities co-
diversify?” Symbioses generate a priori expectations for phylogeographic concordance, yet few
empirical comparative phylogeographic studies use symbiotic communities to interrogate this
question. Here we conduct a comparative phylogeographic study spanning the entire geographic
ranges of six co-occurring species that form a complex symbiosis on coral reefs in the Tropical
Western Atlantic. We further test the hypothesis that similar demographic processes are
responsible for structuring this symbiosis where members share common phylogeographic
barriers, both spatially and temporally.
Location
Coral reefs in the Tropical Western Atlantic Ocean
Taxa
Corkscrew sea anemone, Bartholomea annulata, and its symbiotic crustacean community
including Alpheus immaculatus, Ancylomenes pedersoni, Periclimenes yucatanicus,
Stenorhynchus seticornis, and Thor dicaprio.
Methods
We collected >1300 individuals from 13 localities and generated a phylogeographic
dataset using mtDNA barcodes and double digest restriction site associated DNA sequencing
(ddRADseq). We used genetic clustering analyses and phylogeographic concordance factors to
identify shared barriers to dispersal. We conducted modeling in fastsimcoal2 to test the
demographic processes structuring communities across shared phylogeographic barriers.
Results
We find that no symbionts are spatially, temporally, or demographically concordant
with their host anemone. This indicates that symbiotic association has a minimal role in
generating concordant phylogeographic histories for these taxa. However, some members of this
system share phylogeographic barriers at the Mona Passage and Florida Straits. Where co-
occurring taxa do share phylogeographic barriers, modeling in fastsimcoal2 implicates similar
demographic processes in generating concordant structure, yet on different timescales.
Main Conclusions
Taken together, our analyses highlight the variable evolutionary outcomes
within a single multi-level symbiosis- a complicated collection of phylogeographic histories
where both concordance and discordance prevail.
Purpose
Formatted data files, models, and input files used to conduct all molecular and
demographic analyses for the following project:
DOI: 10.57778/38BS-HM62
Suggested Citation
Titus, B., & Daly, M. (2026). Concordance and discordance: variable phylogeographic outcomes in a multi-species symbiosis from the Tropical Western Atlantic [Data set]. Dauphin Island Sea Lab. https://doi.org/10.57778/38BS-HM62
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