DOI: 10.5061/dryad.hm202
title: Data from: Phylogeny of mental glands, revisited

description: Mental glands and their associated delivery behaviors during courtship are
 unique to the plethodontid salamanders. Because previous interpretations
 of the evolution of these features were conducted using older phylogenetic
 hypotheses, we reanalyzed these traits with newer courtship descriptions
 and contemporary phylogenetic methods. Using Bayesian ancestral state
 reconstruction methods that have been developed since the first
 phylogenetic analyses were conducted in the mid-1990s, we reconstructed
 mental gland and courtship behavior evolution on a novel molecular (Rag1)
 topology of plethodontids. The most probable ancestral condition for
 plethodontids was resolved as presence of a mental gland. Loss of a mental
 gland occurred in each subfamily and was recovered as the most probable
 ancestral condition for the Spelerpinae. In contrast, parsimony
 reconstruction recovered the presence of a mental gland in the ancestor to
 Spelerpinae with multiple secondary losses. We hypothesize that that
 absence of a mental gland is possibly ancestral in some clades (i.e.,
 Spelerpinae), and secondary in others (e.g., paedomorphic Eurycea). The
 most probable ancestral form of the mental gland is likely to be the large
 pad-type distributed extensively in Plethodontinae and Bolitoglossinae.
 Desmognathans have the most unique mental glands, occurring in an anterior
 protrusion or bifurcated form (in Desmognathus wright). Fan-shaped mental
 glands evolved independently in Eurycea and Oedipina. Small pads arose
 independently in Bolitoglossinae, Plethodontinae, and Spelerpinae.
 Head-rubbing behavior for mental gland delivery mode was recovered as the
 most probable and parsimonious ancestral state for the Plethodontidae,
 with independent losses of this behavior in Plethodontinae and
 Spelerpinae. Because head-rubbing was observed in outgroups, we
 hypothesize that head-rubbing behavior predated mental gland evolution.
 Pulling, snapping, slapping, and biting behaviors evolved independently in
 the Plethodontinae and Spelerpinae and are not homologous with head
 rubbing. All hypotheses of mental gland and courtship evolution invoke
 homoplasy.
description: Supplementary table
 1Species and GenBank
 accession numbers for rag1 sequences used in this
 study.Supplementary figure
 1Unconstrained topology
 for selected taxa in the salamander family Plethodontidae using Rag1
 sequence obtained from GenBank.Supplementary figure
 2Topology for selected
 taxa in the salamander family Plethodontidae using Rag1 sequence obtained
 from GenBank. This topology is constrained to form a monophyletic unit for
 Pseudotrition, Gyrinophilus, and Stereochilus.Supp. Fig. 3 - Gland
 presence parsimonyParsimony reconstruction
 of mental glands within Plethodontidae. Two states were considered: absent
 (white) and present (black). Pie charts at each node provide the most
 parsimonious reconstruction for each node. The phylogeny was reconstructed
 using a Bayesian analysis of Rag1 sequences (see Materials and
 Methods).Supp. Fig. 4 - Gland
 morphology parsimonyParsimony reconstruction
 of mental gland morphology within Plethodontidae. Six unordered states
 were considered: absent (white), small pad (black), large pad (red),
 anterior protrusion (yellow), bifurcated (green), and fan-shaped (blue).
 Pie charts at each node provide the most parsimonious reconstruction for
 each node. The phylogeny was reconstructed using a Bayesian analysis of
 Rag1 sequences (see Materials and Methods).Supp. Fig. 5 - Head
 rubbing parsimonyParsimony reconstruction
 of heading rubbing within Plethodontidae. Two states were considered:
 absent (white) and present (black). Pie charts at each node provide the
 most parsimonious reconstruction for each node. The phylogeny was
 reconstructed using a Bayesian analysis of Rag1 sequences (see Materials
 and Methods).Supp. Fig. 6 - Pulling
 parsimonyParsimony reconstruction
 of pulling behavior within Plethodontidae. Two states were considered:
 absent (white) and present (black). Pie charts at each node provide the
 most parsimonious reconstruction for each node. The phylogeny was
 reconstructed using a Bayesian analysis of Rag1 sequences (see Materials
 and Methods).Supp. Fig. 7 - Snapping
 parsimonyParsimony reconstruction
 of snapping behavior within Plethodontidae. Two states were considered:
 absent (white) and present (black). Pie charts at each node provide the
 most parsimonious reconstruction for each node. The phylogeny was
 reconstructed using a Bayesian analysis of Rag1 sequences (see Materials
 and Methods).Supp. Fig. 8 - Slapping
 parsimonyParsimony reconstruction
 of slapping behavior within Plethodontidae. Two states were considered:
 absent (white) and present (black). Pie charts at each node provide the
 most parsimonious reconstruction for each node. The phylogeny was
 reconstructed using a Bayesian analysis of Rag1 sequences (see Materials
 and MethodsSupp. Fig. 9 - Biting
 restraint parsimonyParsimony reconstruction
 of biting/restraint behavior within Plethodontidae. Two states were
 considered: absent (white) and present (black). Pie charts at each node
 provide the most parsimonious reconstruction for each node. The phylogeny
 was reconstructed using a Bayesian analysis of Rag1 sequences (see
 Materials and Methods).