Fixation and preservation contribute to distortion in vertebrate museum specimens: a ten-year study with the lizard Anolis sagrei

Preservation of museum specimens depends on chemical fixation and preservation, processes that might distort the original material. Relatively few studies have examined preservation effects in potentially susceptible soft-bodied taxa like herpetofauna, and those that have rarely extend over more than a few months. We collected six common morphological measurements from the same set of radiographed specimens of the Neotropical lizard Anolis sagrei over nearly ten years to investigate whether morphometric changes result from fixation in formalin and/or subsequent long-term preservation in ethanol. Snout-vent length (SVL) declined 3.5% on average over 10 years, starting almost immediately with fixation and continuing to decline during fluid preservation, eventually leveling off at 40 weeks and beyond. The mostly-ossified component of SVL, spine length, declined 2% on average, but the decline did not begin until fluid preservation commenced and continued throughout the duration of the study...