White rhino relatedness

Poaching during the 1800’s left as few as 50 southern white rhinos remaining in the wild by the beginning of the 20th century, and it is likely that genetic diversity was reduced during that population bottleneck. Today, white rhinos are once again threatened by heavy poaching pressure and can only survive in fenced parks and reserves. The movement of genes between isolated groups can be accomplished by moving the rhinos, but decisions about which rhinos to move are based on inexact pedigrees or considerations for population age and sex structure rather than true estimates of genetic relatedness. A third “layer” of genetic bottlenecking occurs when rhinos are translocated to the United States. During this process, they are often collected from a particular area for important land management or safety reasons, but this can result in the collection of individuals that are closely related. To counter these bottlenecks and maximize population sustainability, decisions about which white rhinos to pair for breeding in managed care need to consider accurate estimates of genetic relatedness. Furthermore, only ~50% of all the captive female white rhinos in the current U.S. population have reproduced, and we know that in many species there is an inverse relationship between relatedness and mating success, and a positive correlation between genetic diversity and mate preference or offspring survival. Mating animals whose genes are optimally different from each other reduces the chances that offspring will inherit harmful genes. By characterizing the current genetic relatedness and diversity of the white rhinos in the U.S. and using that data to inform management decisions, we hope one of the outcomes of this study will be the ability to achieve maximum reproductive success in the white rhino population moving into the future.