Ploidy and genetic diversity in Ontario salamanders of the Ambystoma jeffersonianum complex revealed through an electrophoretic examination of larvae

Abstract

Salamander larvae from 13 breeding ponds were subjected to chromosomal and electrophoretic analyses. Both triploid and diploid members of the Ambystoma jeffersonianum complex were polymorphic for a malate dehydrogenase locus (MDH-3) and a lactate dehydrogenase locus (LDH-2). Sympatric A. maculatum larvae were electrophoretically distinctive from A. jeffersonianum complex larvae at both loci. Two genetically distinctive triploid clones were fixed heterozygotes. Most diploid larvae were homozygous, but a few diploid heterozygotes were found for both polymorphic loci. All the offspring of a sperm-carrying single triploid female which produced eggs in the laboratory were genetically identical to each other and to the mother but the tadpoles from some naturally occurring egg masses from one pond contained both diploid and triploid individuals. Tadpoles from two different egg masses contained representatives of both triploid genetic clones. Two different triploid genotypes were found to occur in a pond in Parry Sound District. This provides evidence for a northern extention of the known range for Ontario triploids. The genetic information derived from A. jeffersonianum complex triploids suggests that there exists genetic interaction among certain members of this complex.