Gene Flow in Hellbenders

Over the past few decades, the hellbender population (Cryptobranchus alleganiensis) has decreased dramatically and the species has been deemed endangered. In an effort to preserve this species, the Missouri Department of Conservation and the Saint Louis Zoo started a captive breeding program. The members of this program were then studied to better understand the population dynamics and gene flow in order to implement new strategies of how to preserve hellbenders in the wild. The scientists involved in this study attempted to answer 1) whether Missouri hellbenders exhibit fine-scale genetic structuring and 2) whether or not levels of diversity differ between habitat patches within a single stream. A number of hellbenders were tagged and their age, sex, and habitat were recorded and their DNA was analyzed. The genotype frequencies were recorded, looking for deviations in the Hardy-Weinburg equation which would indicate if genetic drift and gene flow were factors in the sampled populations. Feist et al. came to the conclusion that hellbender movement between populations is more complex than previously thought due to inconsistencies in observational data and genetic data gathered from the multiple populations. Because this study focused on all hellbender caught and not just sedentary adults, it is assumed that significant amounts of movement occurred at larval and juvenile life stages. The streams in which hellbender also resides are subject to changes in the flow rate due to floods and changes in velocity, stream depth, and discharge from upstream also serve a factor in hellbender larval distribution that is hard to account for, explaining why previous studies have underestimated the gene flow in adult populations of hellbenders. In addition to these findings, it was concluded that inbreeding depression and nonrandom mating have not yet become big problems in these populations. Knowing these results are useful for hellbender population management in captivity and for release into the wild. However, it is only a temporary measure until environmental factors that have contributed to the decline of hellbenders can also be rectified. Until then, they are forced to rely on human intervention and restorative release programs for the flourishing of this species.

Feist SM, Briggler JT, Koppelman JB, Eggert LS. "Within-River Gene Flow in the Hellbender (Cryptobranchus alleganiensis) and Implications for Restorative Release." (2014) Conservation Genetics 15(4) - 953-966. http://download-v2.springer.com/static/pdf/207/art%253A10.1007%252Fs10592-014-0591-2.pdf?token2=exp=1429895949~acl=%2Fstatic%2Fpdf%2F207%2Fart%25253A10.1007%25252Fs10592-014-0591-2.pdf*~hmac=b49f11387a8a97d0b666ec8040a235daf3b08b56d8f75a8f8b2f2b8d4f6ff41b.