SREL Reprint #2034

Mating and oviposition in paedomorphic Ambystoma talpoideum precedes the arrival of terrestrial males

John D. Krenz1,2 and David M. Sever3

1Institute of Ecology, University of Georgia, Athens, GA 30602, USA
2Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA
3Department of Biology, Saint Mary's College, Notre Dame, IN 46556, USA

Abstract: A comparison between the onset of mating and oviposition in facultatively paedomorphic (aquatic) Ambystoma talpoideum and the migration dates of metamorphic (terrestrial) males into the same breeding site revealed a mechanism of partial reproductive isolation. Most paedomorphic females captured in early November 1993 already were inseminated; the onset of oviposition was observed soon thereafter. Most metamorphic males did not arrive at the pond until mid-December or early January, and these migration dates are consistent with data from previous years. The path of development (paedomorphosis or metamorphosis) of an individual is incompletely plastic; heritable differences between individuals exist in their propensity to metamorphose. A partial reproductive partition between paedomorphic females and metamorphic males may favor a gradual reduction in the propensity to metamorphose in the offspring of paedomorphic females. This mechanism, coupled with antagonistic agents such as pond-drying, may promote this life history dichotomy.

Keywords: Caudata; Ambystoma talpoideum; Paedomorphosis; Natural selection; Onset of mating; Phenotypic plasticity; Reproductive isolation

SREL Reprint #2034

Krenz, J.D. and D.M. Sever. 1995. Mating and oviposition in paedomorphic Ambystoma talpoideum precedes the arrival of terrestrial males. Herpetologica 51:387-393.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).