DOI: 10.5061/dryad.18931zd45
title: Batesian mimicry converges towards inaccuracy in myrmecomorphic spiders

description: Batesian mimicry is an impressive example of convergent evolution driven
 by predation. However, the observation that many mimics only superficially
 resemble their models despite strong selective pressures is an apparent
 paradox. Here, we tested the ‘perfecting hypothesis’, that posits that
 inaccurate mimicry may represent a transitional stage at the
 macro-evolutionary scale by performing the hereto largest phylogenetic
 analysis (in terms of the number of taxa and genetic data) of
 ant-mimicking spiders across two speciose, but independent clades, the
 jumping spider tribe Myrmarachnini (Salticidae) and the sac spider
 sub-family Castianeirinae (Corinnidae). We found that accurate ant mimicry
 evolved in a gradual process in both clades, by an integration of compound
 traits contributing to the ant-like habitus with each trait evolving at
 different speeds. Accurate states were highly unstable at the
 macro-evolutionary scale likely because strong expression of some of these
 traits comes with high fitness costs. Instead, the inferred global optimum
 of mimicry expression was at an inaccurate state. This result reverses the
 onus of explanation from inaccurate mimicry to explaining the exceptional
 evolution and maintenance of accurate mimicry and highlights that the
 evolution of Batesian mimicry is ruled by multiple conflicting selective
 pressures.
description: # Batesian mimicry converges towards inaccuracy in myrmecomorphic spiders
 [https://doi.org/10.5061/dryad.18931zd45](https://doi.org/10.5061/dryad.18931zd45) ## Summary This dataset is comprised of Ultra-conserved element (UCE) sequence data, supplemental metadata about each specimen used, and morphometric measurements used to infer physical traits that exhibit ant-mimetic characteristics. Ultra-conserved elements are short regions of a genome that retain highly similar structure across even distantly-related taxonomic groups. The "centre" of these elements is the most conserved, with increasing variation in the UCE as you move away from the centre. Because of this characteristic, UCEs produce an excellent phylogenetic signal at both deep and shallow nodes of a phylogeny. We used UCEs to construct both Maximum Likelihood and Bayesian inferences of phylogeny for two separate spider clades. ## Description of the data and file structure ### Ultra-conserved element (UCE) final alignments Each taxonomic group (Corinnidae, Salticidae) has its own separate UCE dataset. Each dataset comprises 3 formats: BEAST (.xml), FASTA (.fasta), and NEXUS (.nex). There is no difference between the FASTA and NEXUS alignments apart from the format; the Maximum Likelihood analyses used the FASTA alignments, but the NEXUS format are also included to facilitate data compatibility. The BEAST alignments are a slightly modified set of the previous alignments in XML format, which includes priors and other model parameters used to compute Bayesian phylogenetic inferences. ``` Corinnidae.fasta Corinnidae.nex Corinnidae.xml Salticidae.fasta Salticidae.nex Salticidae.xml ``` #### FASTA Format The data for each individual spans two lines within the file. The first line is always prefixed by a "&gt;" and lists the individual's identifier, usually the taxon name. The next line contains the full concatenated DNA sequence. Each UCE locus was aligned separately prior to concatenation. DNA nucleotides are represented by "A", "T", "C", and "G", with gaps coded as "-". #### NEXUS Format The NEXUS format is more versatile than FASTA, as it separates data into separate "blocks", which can have various attributes and contributions depending on the program reading/writing the data. The data file starts with "#NEXUS"; each block is defined by the "begin" operator, followed by a description of the block type and closed with a semicolon, e.g., "begin taxa;". The data section follows, with an extra line at the end containing only a semicolon to designate the end of the section. The block is completed with "end;". Our data files include two blocks: a taxa block and a characters block. The taxa block contains the name of each taxon in the dataset, and the character block contains the DNA alignments for each specimen. DNA nucleotides are represented by "A", "T", "C", and "G", with missing data coded as "?", and with gaps coded as "-". #### BEAST Format The BEAST format is even more versatile than the NEXUS format, with a similar structure of separate "blocks" to represent different data types or to encode model parameters. Unlike FASTA and NEXUS, it is not meant to be edited manually; rather, data in the file is manipulated using BEAUTi, a graphical interface used to prepare data to be run using BEAST. The same format is used with BEAST and BEAST 2 (and their respective versions of BEAUTi), but XML files produced in one version often have compatibility problems with the other version. Our files are compatible with BEAST 2. ### Supplemental information files #### Appendix\_2\_\_Dataset\_S1\_-\_sample\_information.xlsx This is a Microsoft Excel spreadsheet that lists various metadata associated with each specimen used in this study. There are two tabs, one for Corinnidae, and one for Salticidae. The types of metadata are: ``` Sample name / Unique I.D. Author Sex Identified by Voucher Institution Voucher Collection Identifier / Reg # CAT # / Tissue.ID Preparation SRA # Higher Taxon FAMILY SUBFAMILY Country State Prov Region County Specific Locality Decimal lat Decimal long Collection Date Preservative DNA extraction method Approximate total extracted DNA (ng) Reads Pass QC Contigs UCE loci (50% from PHYLUCE; after QC) Notes Name used in early phylogenetic work and comparative analyses ``` #### Appendix\_3\_\_Dataset\_S2\_-\_biometric\_measurements.xlsx This is a Microsoft Excel spreadsheet that lists biometric/morphometric measurements for each each specimen used in this study. There are four tabs: Castianeirinae trait indices, Castianeirinae raw measurements, Myrmarachnini trait indices, and Myrmarachnini raw measurements. The trait indices are: ``` Sample name / Unique I.D. Thin_legs Elong_ceph. Elong_abdomen Elong_pedicel Ill_by_colour Lat_ceph._const Dor_ceph._const Lat_abdominal_const Dor_abdominal_const Mimic_accuracy Level of mimetic accuracy Extrapolated data (values in red colour font) #Castianeirinae only ``` The raw measurements are: ``` Sample name / Unique I.D. Leg III Femur: width Leg III Femur: length Leg III Femur: ratio (width/length) 1 - Leg III Femur ratio Cephalothorax: width Cephalothorax: length Cephalothorax: ratio (width/length) 1 - Cephalothorax ratio Abdomen: width Abdomen: length Abdomen: ratio (width/length) 1 - Abdomen ratio Pedicel: length Body length Pedicel length/body length Note on illusion by colouration Illusion by colouration score Constriction height Cephalothorax height Constriction height/Cephalothorax height: ratio 1 - Constriction height/Cephalothorax height: ratio Constriction width Cephalothorax width Constriction width/Cephalothorax width: ratio 1 - Constriction width/Cephalothorax width: ratio Constriction height Abdomen height Constriction height/Abdomen height: ratio 1 - Constriction height/Abdomen height: ratio Constriction width Abdomen width Constriction width/Abdomen width: ratio 1 - Constriction width/Abdomen width: ratio Mimic Accuracy ```