Ontogenetic transition from unicuspid to multicuspid oral dentition in a teleost fish: Astyanax mexicanus, the Mexican tetra (Ostariophysi: Characidae)

Abstract

Teleost fishes display a remarkable diversity of adult dentitions; this diversity is all the more remarkable in light of the uniformity of first-generation dentitions. Few studies have quantitatively documented the transition between generalized first-generation dentitions and specialized adult dentitions in teleosts. We investigated this transition in the Mexican tetra, Astyanax mexicanus (Characidae), by measuring aspects of the dentition in an ontogenetic series of individuals from embryos to 160 days old, in addition to adults of unknown age. The first-generation dentition and its immediate successors consist of small, unicuspid teeth that develop extraosseously. Multicuspid teeth first appear during the second tooth replacement event, and are derived from single tooth germs, rather than from the fusion of multiple conical tooth germs. We document that the transition from unicuspid to multicuspid teeth corresponds to a change in the location of developing tooth germs (from extraosseous to intraosseous) and in patterns of tooth replacement (from haphazard to simultaneous within a jaw quadrant). In addition, while the size of the largest teeth scales with positive allometry to fish size, the transition to multicuspid teeth is accompanied by an exceptionally large increase in tooth size. Yamamoto Y, Espinasa L, Stock DW, Jeffery WR. 2003. Development and evolution of craniofacial patterning is mediated by eye-dependent and -independent processes in the cavefish Astyanax. Evolution and Development 5: 435-446. Yamamoto Y, Stock DW, Jeffery WR. 2004. Hedgehog signaling controls eye degeneration in blind cavefish. Nature 431: 844-847.

A new species of the genus <i>Yuriria</i> Jordan & Evermann, 1896 (Actinopterygii, Cyprinidae) from the Ameca basin of the Central Mexican Plateau

“…3A). Despite morphology having been largely used as the basis for species descriptions, many species show a high degree of phenotypic plasticity depending on habitat conditions, and the influence of allometry in morphometric measurements has been widely recognized (Hood & Heins, 2000;Trapani et al, 2005). We conclude that morphologic measurements alone are not appropriate diagnostic characters for the identification of Yuriria species.…”

Developmental genetic mechanisms of evolutionary tooth loss in cypriniform fishes

“…1A). Trapani et al (Trapani et al, 2005) identified the first teeth to appear in larvae as one attached to each premaxillary bone and one on each side of the dentary bone midline (Fig. 1B,C).…”

Zebrafish dentition in comparative context

“…The location of developing replacement teeth in ray-finned fishes may be either extraosseous (in the soft tissue outside of the bone to which they attach) or intraosseous (in sockets within the bone) (Trapani, 2001). The zebrafish and other cypriniforms share the ancestral condition of extraosseous replacement tooth formation, with their closest relatives exhibiting intraosseous development occurring within the Characiformes (Trapani, 2001;Trapani et al, 2005).…”