Fluctuating asymmetry in Ichthyophonus-sp. infected newts, Notophthalmus viridescens, from Vermont

Abstract

Measures of fluctuating asymmetry (FA) have been used to assess the significance of stress in amphibian populations. When animals with bilateral body plans are challenged by environmental stressors, departures from bilateral symmetry can emerge during development. The tendency for FA to develop has been linked to greater susceptibility to pathogens in many organisms. In our study, newts (Notophthalmus viridescens) infected with Ichthyophonus-sp. exhibited greater size-corrected FA of the hind limbs than uninfected animals from the same population. Among infected animals, however, the intensity of infection and the extent of hind limb asymmetry were not correlated, suggesting that asymmetry did not arise following infection, but rather that newts having greater FA may have been more susceptible to infection as a result of the same stresses that produced the increase in FA. There was no relationship between dorsal spot pattern FA and infection status or hind limb FA. We suggest that spot pattern may be less canalized than hind limb development. Newts are widely distributed and important components of freshwater communities in eastern North America and, thus, any change in their vitality may affect the composition of those communities. Analyses of hind limb FA may be a useful and non-invasive tool for identifying potentially vulnerable amphibian