Rick Jessica A, Junker Julian, Lewanski Alexander L, Swope Brittany, McGlue Michael M, Sweke Emmanuel A, Kimirei Ismael A, Seehausen Ole, Wagner Catherine E
School of Natural Resources and the Environment, The University of Arizona, Tucson, AZ 85721, USA.
Center for Ecology, Evolution, and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, CH-6047 Kastanienbaum, Switzerland.
bioRxiv. 2025 Jan 18:2025.01.14.633002. doi: 10.1101/2025.01.14.633002.
Top predators have oversized impacts on food webs and ecosystem dynamics, and introducing a novel predator to a naive environment can have dramatic consequences for endemic biodiversity. Lake Tanganyika is unique among African lakes in the diversity of the pelagic top predators in the genus , where four species are endemic to the lake. Using a combination of reduced-representation and whole genome resequencing data, and pairing these with phylogenetic and demographic modeling approaches, we find that colonization of Lake Tanganyika was much more recent (1-2 Mya) than other major and diverse clades within the lake. Demographic modeling suggests that diversification among species within the lake occurred during a time period of dramatic changes in lake levels driven by glacial-interglacial cycles, supporting a role of these fluctuations as a "species pump" for lacustrine taxa. We further find that these lake level fluctuations likely contributed to multiple bouts of admixture among species during the mid- to late-Pleistocene (90-500 Kya). Together, our findings suggest a dynamic and environmentally linked evolutionary history of the radiation with the potential for dramatic ecosystem consequences for the taxa already present in Lake Tanganyika prior to colonization and diversification.
When introduced to novel ecosystems, top predators can cause major alterations to biodiversity and food webs. Species introductions to novel habitats can also provide invading taxa with ecological opportunities that facilitate evolutionary diversification. Here, we find evidence that the radiation of endemic top predators in East Africa's Lake Tanganyika originated surprisingly recently, and that these species have experienced periods of hybridization with a widespread riverine relative throughout their history. These findings have major implications for the history of the lake and suggest that the introduction of Nile perch into Lake Victoria, which caused dramatic ecosystem and food web changes, may be a contemporary analog to the historical events in Lake Tanganyika.
顶级捕食者对食物网和生态系统动态有着巨大影响，将一种新的捕食者引入一个未受影响的环境可能会对当地生物多样性产生巨大影响。坦噶尼喀湖在非洲湖泊中独一无二，其浮游顶级捕食者属具有多样性，其中有四个物种是该湖特有的。通过结合简化基因组和全基因组重测序数据，并将这些数据与系统发育和种群动态建模方法相结合，我们发现坦噶尼喀湖的[某属物种]定殖比该湖内其他主要且多样的进化枝要近得多（约100 - 200万年前）。种群动态建模表明，该湖内[某属物种]的分化发生在由冰期 - 间冰期循环驱动的湖泊水位剧烈变化时期，这支持了这些波动作为湖泊生物分类群“物种泵”的作用。我们进一步发现，这些湖泊水位波动可能在更新世中期至晚期（约9万 - 50万年前）促成了[某属物种]之间的多次混合。总之，我们的研究结果表明，[某属物种]辐射具有动态且与环境相关的进化历史，对于在[某属物种]定殖和分化之前就已存在于坦噶尼喀湖的生物分类群可能产生巨大的生态系统后果。
当引入新的生态系统时，顶级捕食者会对生物多样性和食物网造成重大改变。向新栖息地引入物种也能为入侵分类群提供促进进化多样化的生态机会。在这里，我们发现证据表明东非坦噶尼喀湖的特有顶级捕食者辐射起源惊人地晚近，并且这些物种在其整个历史中都经历了与一种广泛分布的河流亲缘物种杂交的时期。这些发现对该湖的历史具有重大意义，并表明尼罗河鲈鱼引入维多利亚湖导致了巨大的生态系统和食物网变化，这可能是坦噶尼喀湖历史事件的当代类似情况。
