A Literature Review of Unisexual Ambystoma and Related Polyploid Hybrid Survival and Development


The Ambystoma laterale-jeffersonianum complex is a collection of salamander populations inhabiting a significant portion of New England, including western Massachusetts. This complex consists of two groups, sexuals and unisexuals. Sexual A. laterale and A. jeffersonianum are diploid and reproduce sexually. Unisexuals, conversely, range from haploid to pentaploid, and are simply classified as Ambystoma, having no true species identity. This population of unisexual salamanders consists entirely of females which can reproduce both sexually and asexually (Bogart et al, 2007). Within this complex, unisexuals can sexually reproduce only with sexual males, often resulting in hybrid offspring (Charney et al., 2014). Due to the incongruence of ploidy between sexuals and unisexuals, hybrid offspring range in ploidy from haploid to pentaploid as well. While hybrids can develop into completely healthy, phenotypically normal adults, they face an extremely high mortality rate as embryos prior to the first cleavage event (Avis, 2019; Charney et al., 2019). Throughout my research, I have amassed information regarding the Ambystoma complex’s embryogenesis, genetics, and environment in an attempt to consolidate much of what is currently known about them in the literature. In addition, I here propose multiple experiments that could be completed by future thesis students and other researchers in order to determine what factors play a role in causing this high mortality rate in early hybrid embryos.



Biology, Ambystoma, Developmental Biology, Genetics, Habitat Conservation, Herpetology