Data from: New evidence for hybrid zones of forest and savanna elephants in Central and West Africa

The African elephant is made up of forest and savanna subspecies. Both subspecies are highly endangered due to severe poaching and habitat loss, and knowledge of their population structure is vital to their conservation. Previous studies demonstrated marked genetic and morphological differences between forest and savanna elephants and despite extensive sampling, genetic evidence of hybridization between them has been restricted largely to a few hybrids in the Garamba region of northeastern Democratic Republic of Congo. Here we present new genetic data on hybridization from previously unsampled areas of Africa. Novel statistical methods applied to these data identify 46 hybrid samples - many more than have been previously identified - only two of which are from the Garamba region. The remaining 44 are from three other geographically-distinct locations: a major hybrid zone along the border of the DRC and Uganda, a second potential hybrid zone in Central African Republic, and a smaller fraction of hybrids in the Pendjari-Arli complex West Africa. Most of the hybrids show evidence of interbreeding over more than one generation, demonstrating that they are fertile. Mitochondrial and Y chromosome data demonstrate that the hybridization is bidirectional, involving males and females from both subspecies. We hypothesize that the hybrid zones may have been facilitated by poaching and habitat loss. This, combined with geographically localized hybrid zones and high divergence and genetic distinctness throughout their ranges, are consistent with calls to reclassify forest and savanna elephants as separate species.非洲象包含森林亚种与稀树草原亚种（forest and savanna subspecies）。由于猖獗的偷猎与栖息地丧失，这两个亚种均处于极度濒危状态，而明确其种群结构对其保护工作至关重要。此前的研究已证实森林象与稀树草原象之间存在显著的遗传与形态学差异；尽管已开展广泛采样，但二者间的杂交遗传证据此前仅局限于刚果民主共和国（Democratic Republic of Congo，简称DRC）东北部加兰巴地区（Garamba region）的少数杂交个体。本研究整合了非洲此前未被采样区域的杂交相关遗传新数据，并通过全新的统计方法对这些数据进行分析，共鉴定出46个杂交个体样本——这一数量远多于此前已发现的杂交个体总数，其中仅2个样本来自加兰巴地区。其余44个杂交样本则来自另外3个地理分布迥异的区域：一是刚果民主共和国与乌干达边境沿线的大型杂交带，二是中非共和国境内的一处潜在杂交带，三是西非彭贾里-阿尔利复合区域（Pendjari-Arli complex）内的少量杂交个体。绝大多数杂交个体均呈现出多代混血的遗传特征，证实其具备生育能力。线粒体（mitochondrial）与Y染色体（Y chromosome）数据显示，二者间的杂交为双向性过程，涉及两个亚种的雌雄个体。研究团队推测，偷猎与栖息地丧失可能助推了这些杂交带的形成。结合上述发现——包括地理上局限分布的杂交带、以及两个类群在各自分布范围内呈现的高度遗传分化与遗传独特性——本研究结果与将森林象与稀树草原象重新分类为独立物种的呼吁相一致。