Developmental system drift in the patterning of the arthropod tarsus

The current understanding of proximodistal axis patterning in arthropod legs is grounded in insect models. The paradigm for appendage evolution in this phylum is that the gene regulatory network responsible for leg subdivision and patterning is broadly conserved. Recent surveys of these genes have suggested that chelicerate exemplars exhibit divergent appendage patterning dynamics, though functional data remain limited. One salient mismatch in expression occurs in homologs of the homeobox gene clawless. In insects, clawless is expressed in the distalmost leg territory, specifying the claw-bearing pretarsus. In the harvestman Phalangium opilio, clawless occupies a broad tarsal domain early in development, localizing later to the metatarsus-tarsus boundary, suggestive of a tarsal patterning function. Here, we tested the function of harvestman clawless using RNAi. Unlike insects, we show that clawless knockdown results in disrupted tarsal growth and patterning of its proximal segmental bou..., , # Data from: Developmental system drift in the patterning of the arthropod tarsus

Dataset DOI: [10.5061/dryad.95x69p8zs](https://doi.org/10.5061/dryad.95x69p8zs)

## Description of the data and file structure

The collected data consist of hyperstacks of confocal laser scanning microscopy images, in raw format. Each stack contains some or all of the following channels: 405 nm (blue); 488 nm (green); 546 nm (red); 594 nm (red); 647 nm (far red). The numbering of the files corresponds the numbering of the figures in the associated paper.

### Files and variables

#### File: FigureS6e.Plit_InsVI_03_le1WL_40x_Dapi.AF.al-647_Cll-594_TDE.lif

**Description:** Confocal microscopy hyperstack corresponding to Figure S6e. Distal podomeres of leg 1 in the sea spider *Pycnogonum litorale* (instar VI) with expression of *clawless* and *aristaless*. Following complete separation of tarsus and propodus, only a small region of co-expression remains in the dorsal tarsus joint. The claw retains non-over...,