DOI: 10.5061/dryad.s502854
title: Data from: Exploring the visual world of fossilized and modern fungus gnat eyes (Diptera: Keroplatidae) with X-ray microtomography

description: Animal eyes typically possess specialised regions for guiding different
 behavioural tasks within their specific visual habitat. These
 specializations, and evolutionary changes to them, can be crucial for
 understanding an animal’s ecology. Here, we explore how the visual systems
 of some of the smallest flying insects, fungus gnats, have adapted to
 different types of forest habitat over time (~30 mya to today).
 Unravelling how behavioural, environmental and phylogenetic factors
 influence the evolution of visual specialisations is difficult, however,
 because standard quantitative techniques often require fresh tissue and/or
 provide data in eye-centric coordinates that prevent reliable comparisons
 between species with different eye morphologies. Here, we quantify the
 visual world of three gnats from different time periods and habitats using
 X-ray microtomography to create high resolution 3D models of the compound
 eyes of specimens in different preservation states – fossilized in amber,
 dried or stored in ethanol. We present a method for analysing the
 geometric details of individual corneal facets and for estimating and
 comparing the sensitivity, spatial resolution, and field of view of
 species across geographical space and evolutionary time. Our results
 indicate that, despite their miniature size, fungus gnats do have
 variations in visual properties across their eyes. We also find some
 indication that these visual specializations vary across species and may
 represent adaptations to their different forest habitats. Overall, the
 findings demonstrate how such investigations can be used to study the
 evolution of visual specializations – and sensory ecology in general –
 across a range of insect taxa from different geographical locations and
 across time.
description: This dataset was collected using microCT imaging at the 4D
 Imaging Lab at Lund University. The data was then manually processed in
 Amira and further calculations were then performed in Matlab. See the
 Methods and Supplemental Methods sections of Taylor et al. for further
 information.
description: Amira Demo An example of the Amira analysis
 procedure described by Talyor et al. Opening the .hx file in Amira will
 open an Amira project in which all of the described analysis steps have
 been completed. Amira_demo.zip
   <strong>Gnat Eye
 Data</strong> The data require for and resulting
 from the computational analysis described by Taylor et al. The Zip archive
 contains a folder for each gnat (Ancient, Tropical, Temperate) which each
 contain the eye surface (in .stl format), one or more pairs of lines and
 path files (in .am format) and required transformations (in .txt format)
 to run the analysis scripts. The lends diameter, inter-facet angle and eye
 parameter calculated for each facter are included in .csv and .mat
 format. Gnat_eye_data.zip 
 <br> Gnat Compound Eyes and Labels Raw volumes
 and label volumes for eyes and heads. These data are archived at
 MorphoSource project ID 699.   
 Github gavinscode/museum-sample-eye-analysis.git
 Matlab scripts required for analysis and plotting.