Developmental Asymmetry in Growing Japanese Quail (Coturnix japonica)

STARCK, M.J.*; HELM, B.; SALZER, U.: Developmental Asymmetry in Growing Japanese Quail (Coturnix japonica)

Measures of fluctuating asymmetry (FA) may by used as a gauge of developmental stability of various traits in growing animals; i.e., a high level of FA indicates labile development while low levels of FA stand for stabile development. In this study, we asked (1) whether levels of FA change during development, and (2) whether interactions between environment and organism affect FA. In detail, we asked whether coefficients of variation (CV) of morphometric measurements as well as their FAs change during ontogeny. Further, we addressed the question whether interactions between the environment and the growing organism affected FAs and patterns of morphological development. We studied developing tarsometatarsus of Japanese quail (Coturnix japonica) from its first occurrence on embryonic day 5 to adulthood. Coefficients of variation of tarsal length were high during early and mid embryogenesis. Coefficients of Variation and level of FA began to decline briefly before hatching. A sudden and distinct drop of measured FA occurred immediately after hatching. During posthatching development, measures of FA continued to decline to low adult values. If signed asymmetry was recorded for each day post-hatching, we observed a clear pattern of alternating asymmetry. Conclusions from our study are that (1) degree of developmental stabilization (canalization) increases during ontogeny. (2) The steep decline of FA immediately after hatching suggests that organism environment interactions are an important contribution to shaping the phenotype, i.e., reduce asymmetry, and (3) time series of alternating asymmetry suggest compensatory growth and left-right signaling during growth of tarsus.

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