Chondrocranial shape is bilaterally symmetric in juvenile Astyanax mexicanus.
Representative juvenile (8 dpf) specimens from surface fish (A), Tinaja (B) and Pachón (C) cavefish populations stained with Alcian blue and imaged at 80x magnification (scale bar = 1mm). Eight homologous landmarks (yellow; A-C) were placed on the ethmoid (e; green), trabecula (tr; orange), hyosymplectic (hs; red), and palatoquadrate (pq; blue; D-F). A Principal Components Analysis was used to compare the average shape of each individual on the right (blue) and left (red) sides for surface fish (G), Tinaja (H) and Pachón (I) cavefish. Confidence ellipses set to a significance threshold of p<0.05 overlap between the right (blue) and the left (red) shape for each population suggests shape quantification based on these landmarks is bilaterally symmetric. A student’s t-test revealed no significant differences in Procrustes distance between right and left sides for surface fish (p = 0.1598), Tinaja (p = 0.1645) and Pachón (p = 0.3532) cavefish.
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