Photo of unisexual Ambystoma vs. smallmouth salamander

The photo below shows two female Ambystoma salamanders from Cuyahoga County, Ohio. The salamander on the left is a unisexual hybrid, based on head and body shape. The salamander on the right appears to be a pure smallmouth salamander (Ambystoma texanum), but it is possible that it is also a hybrid. Without directly genotyping her, it is impossible to be certain that she is a pure smallmouth salamander.

This group of salamanders is incredibly interesting. Thousands of years ago, hybridization between several species (primarily Jefferson’s salamander and the blue-spotted salamander) resulted in offspring that contained the nuclear genomes of both parental species. The descendants of these initial hybrid offspring are entirely female, and reproduce clonally. However, the hybrid females need to use the sperm of male salamanders to initiate egg development. In most cases, the male genome is discarded after the sperm is used to initiate egg development.

You can find biologists researching this interesting genus at

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