A practical method for staging metamorphosis in the tiger salamander Ambystoma tigrinum

Abstract

The aim of this study was to develop a set of practical metamorphic stages for the tiger salamander Ambystoma tigrinum that would 1) provide an early and quantifiable marker of the onset of metamorphosis and 2) not be dependent on knowledge of maximal values of gill length or tail height. Twenty morphological parameters were obtained from Ambystoma tigrinum larvae as they progressed through laboratory-induced metamorphosis (21 degrees C, continuous light). These parameters included measures of body weight, gill length, and tail height. Initiation or duration of metamorphosis could not be predicted when parameters were expressed relative to the number of days larvae were held in laboratory conditions. Early phases of metamorphosis were characterized by regression of the lower tail fin. Selected morphological parameters were expressed relative to the day on which each subject exhibited complete regression of the lower fin. This technique made it possible to order these parameters into a progressive series of metamorphic phases. Seven stages of metamorphosis were derived from this series, ranging from larvae (stage I) to complete regression of the gills (stage VII). Application of these stages does not require prior knowledge of maximal (initial) values of gill length or tail height.

Ontogeny of escape swimming performance in the spotted salamander

“…This observed pattern of relatively high escape performance in metamorphosing salamanders suggests that evolutionary pressure from predators to decrease the duration of salamander metamorphosis may be less than in most anurans. Data on metamorphic duration of salamanders are scarce, but it is generally thought to last longer than the more dramatic transformation of frogs (Norman 1985; Downie, Bryce & Smith 2004). If this relationship is valid, then high metamorphic escape performance relative to that in anurans may contribute to relaxing selection on the duration of salamander metamorphosis.…”

A model of transcriptional and morphological changes during thyroid hormone-induced metamorphosis of the axolotl

“…Comparisons of staging series based on these gross morphological events suggest that the pattern exhibited by TH-induced axolotls (Cano-Martinez, 1994) qualitatively resembles the pattern exhibited by naturally metamorphosing tiger salamanders ( Ambystoma tigrinum ; Norman, 1985; also see Rosenkilde and Ussing, 1996). Thus the axolotl represents a convenient and informative model system for examining metamorphic gene expression in the tiger salamander complex.…”

“…While the endocrinology ( e.g., Leloup and Buscaglia, 1977; Buchholz and Hayes, 2005; Larras-Regard et al, 1981; Alberch et al, 1986), histology ( e.g., Heady and Kollros, 1964; Nieuwkoop and Faber, 1967; Fahrmann, 1971a,b,c; Alberch et al, 1985; Ohmura and Wakahara, 1998), and morphology ( e.g., Taylor and Kollros, 1946; Nieuwkoop and Faber, 1967; Norman, 1985; Cano-Martinez et al, 1994; Rose, 1995a,b,c) of metamorphosis have been examined in anurans and urodeles, the vast majority of our knowledge about metamorphic gene expression comes from studies of anurans and Xenopus in particular (reviewed by Shi, 2000; Buchholz et al, 2006). This has enabled the conceptualization of models of Xenopus , and, to a lesser extent, Rana metamorphosis that integrate changes in morphology, histology, and gene expression (for examples see Ishizuya-Oka and Shi, 2007; Yoshizato, 2007).…”

Embryonic Staging Table for a Direct‐Developing Salamander, Plethodon cinereus (Plethodontidae)

“…These tables often focus on either embryonic and larval development (Oyama, 1930;Glü ckson, 1931;Anderson, 1943;Harrison, 1969;Hara and Boterenbrood, 1977;Bordzilovskaya et al, 1989;Collazo and Marks, 1994;Nye et al, 2003;Wong and Liversage, 2005;Ringia and Lips, 2007) or metamorphosis (Wilder, 1925;Grant, 1930Grant, , 1931Norman, 1985;Watson and Russell, 2000). The developmental criteria of metamorphic tables often rely on features not found in direct-developing plethodontids, such as tail fin height (Norman, 1985) or the presence of balancers and larval pigment patterns (Glü ckson, 1931), which makes explicit comparisons with Plethodon cinereus impossible.…”