Data and code from: Alternative pathways into the deep sea: Patterns in Bivalvia

Relatively few clades have colonized the deep sea. Here, we analyze evolutionary pathways into this harsh environment, as a continuum defined by two potential end-members—a \"piecemeal model\", with exclusively deep-sea species (deep-sea endemics herein) derived from multiple, independent entries, and an “in-situ diversification model” with one entry followed by species proliferation. We focus first on two ancient, distantly related subclades in Class Bivalvia, Mytilidae and Lucinidae, each with hundreds of species occurring globally from the intertidal to abyssal plains. Placing bathymetric ranges into newly inferred molecular phylogenies, we find that the deep-sea endemics within Lucinidae derive in piecemeal fashion, estimating up to 16 phylogenetically isolated entries and one modest in-situ diversification. Mytilidae entered the deep sea just four times, with most endemics stemming from the prolific in-situ diversification of Bathymodiolinae. We suggest that the contrasting phylogene..., The following text is derived from the Methods found in the associated paper's main text and supplementary materials. References (some of which pertain to justifying methods) have been removed, but may be found in their respective texts. 
Database of marine bivalve taxa and bathymetries
We used a comprehensive dataset of 8402 extant marine bivalve species compiled from Huber 2015 and the subsequent literature (Supplementary Dataset S1). For this dataset, subgenera were elevated to \"operational genera\" to increase sampling of hypothesized monophyletic groups that can be analyzed for their differences in bathymetric occurrences. Owing to local topological uncertainties, we classified bivalve taxa into 86 operational families for the 100 taxonomic families represented in the initial Crouch et al. (2019) dataset, as follows: Neilonellidae, Tindariidae, Sareptidae and Yoldiidae were treated as Malletiidae sensu lato; Bathyspinulidae, Lametilidae, Phaseolidae, and Siliculidae were treate..., # Data and code from: Alternative pathways into the deep sea: Patterns in Bivalvia

Dataset DOI: [10.5061/dryad.8931zcs4m](https://doi.org/10.5061/dryad.8931zcs4m)

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**SupplementaryDataset_S1.xlsx**

All data used in this study, to the exclusion of the molecular data, can be found in this file. The first sheet contains a field key that explains the contents of all other sheets. The second and third sheets present the taxonomic information, bathymetric depths, depth categories, and depth references for all species in Mytilidae and Lucinidae, respectively. The third sheet also includes the biogeographic provinces (according to Huber 2015) that lucinid species occur in, the corresponding climatic categories (tropical vs extratropical vs both), and whether each species was classified as a close relative of a deep-sea taxon under our strict and broad schemes (see Methods). The fourth sheet provides binary depth categories for all bivalve species. The fifth sheet includes the climatic ..., , **Changes after Nov 4, 2025:**&nbsp;One mytilid taxon (*D. pelseneeri*) reassigned from shallow to deep. All relevant tables were updated accordingly.