| Popis: |
Normal tables of development intentionally ignore variation that results from both environmental and genetic sources. However, variation is important to consider when determining which characters most reliably indicate the stage of embryos. Our objective was to quantify variation in the relative time of the appearance and duration of character states for embryos of the lizard Uta stansburiana. The expression of the number of pharyngeal slits, development of optic capsule, eye pigmentation, and body size were highly variable, that is, these character states spanned multiple nominal stages. In general, the assessment of character variation in concert with the construction of normal tables would facilitate staging embryos for descriptive, experimental, and comparative studies. |
