ELAV Intron 8: a single-copy sequence marker for shallow to deep phylogeny in Eupulmonata Hasprunar & Huber, 1990 and Hygrophila Férussac, 1822 (Gastropoda: Mollusca).

Progress in eupulmonate gastropod taxonomy is limited by absence of single- or low-copy nuclear DNA markers that provide species-scale insights. We detail here the single-copy intron 8 of the embryonic lethality and abnormal visual system gene (ELAVI8). High sequence conservation within flanking exons 8 and 9 allowed design of non-redundant primers that enable PCR amplification across a broad phylogenetic extent. Across the Eupulmonata and Hygrophila ELAVI8 product ranged from 602 to 802 base pairs in length. A multiple sequence alignment across 62 taxa, representing 36 genera and 12 major clades, showed 1296 sites with 865 variable positions. Typically, 2–10 base pair differences were noted between closely related species within a genus, with 74–200 bases differing between major infra-order clades. ELAVI8 maximum-likelihood trees showed essentially identical topologies at high levels of support compared to those created from concatenated ITS1 + 2 (within a genus) or 28S (across Eupulmonata and Hygrophila). ELAVI8 is superior to these two phylogenetic marker regions, however, because it (1) resolves phylogenetic pattern from species- to sub-cohort scales in a single amplicon, (2) was better able to resolve family- and deeper-clades at high support, (3) allows for outgroup rooting between genera, and (4) possesses no intercopy haplotype variability. [ABSTRACT FROM AUTHOR]