San Bernardino kangaroo rat (Dipodomys merriami parvus; SBKR), an endangered subspecies, faces ongoing anthropogenic threats such as habitat loss. Their habitat has undergone strong human-mediated fragmentation, resulting in extinction of some local populations and dramatic size reduction of the remaining populations. We examined the genetic diversity, population structure, and phylogeography of this subspecies using partial mitochrondrial DNA sequencing and microsatellite genotyping. Our study indicates that currently, the three remaining populations seem to be highly fragmented. Clear population structure and low level of haplotype sharing suggests that there has been no recent gene flow among populations, except in the case of human mediated gene flow as a result of a single translocation event. Diversity levels are on par with other species with fragmented distributions. Further, shallow phylogenetic divergence suggests the populations have not been diverged long enough to detect phylogenetic structure and separation is likely recent. Given the limited gene flow, low numbers of SBKR as evident by low return on trapping efforts, and low effective population size, habitat restoration and translocations may be warranted to maintain levels of diversity in a declining metapopulation.

圣贝纳迪诺袋鼠大鼠（Dipodomys merriami parvus; SBKR）是一种濒临灭绝的亚种，面临着持续的人为威胁，例如栖息地丧失。他们的栖息地经历了强烈的人类介导的分裂，导致一些当地人口灭绝，剩余人口急剧减少。我们使用部分线粒体DNA测序和微卫星基因分型研究了该亚种的遗传多样性，种群结构和种系。我们的研究表明，目前，剩余的三个人口似乎高度分散。清晰的种群结构和低水平的单倍型共享表明，除了由于单次易位事件导致的人类介导的基因流以外，种群之间没有新的基因流。多样性水平与其他零散的物种同等。进一步，较浅的系统发育差异表明种群之间的分化时间还不够长，无法检测出系统发育结构，因此分离很可能是近期进行的。鉴于基因流量有限，诱捕工作回报率低，有效种群规模低，栖息地恢复和易位性低可证明SBKR数量少，以保持种群数量下降的多样性水平。