近日，美国加州大学伯克利分校Z. Jack Tseng团队揭示了一个长达千万年的生物地理学中转区为美洲大生物交换奠定了基础。2026年7月30日出版的《科学》杂志发表了这项成果。

南北美洲之间通过巴拿马陆桥的物种迁移，即著名的“美洲大生物交换”（GABI），塑造了当今美洲的哺乳动物群落，标志着南美动物群所谓“辉煌孤立”的决定性终结。由于缺乏实质性的低纬度记录，以往关于这一格局的研究依赖南美和温带北美化石，得出结论认为脉冲式交换始于约280万年前。

基于来自墨西哥的新低纬度化石数据，研究组发现了证据，表明存在一个持续的三阶段交换过程。第一阶段始于1000万年前，较高纬度北方哺乳动物最初在墨西哥“中转区”中积累。扩散开始于第二阶段，呈现强烈的南北梯度并伴随生物地理联系的增强（700万至300万年前）。最终阶段即为早已被详尽描述的分类群脉冲（约280万年前至今）。

附：英文原文

Title: A 10-million-year biogeographic holding pen primed the Great American Biotic Interchange

Author: Z. Jack Tseng, Leah X. Kahn, Adolfo Pacheco-Castro, Oscar Carranza-Castaeda, José Jorge Aranda-Gomez, Yang Wang, Julio César Chávez-Ambriz, Chance Hannold, H. Gregory McDonald, Xiaoming Wang

Issue&Volume: 2026-07-30

Abstract: The movement of taxa between North and South America across the Panamanian land bridge, known as the Great American Biotic Interchange (GABI), established modern-day mammal assemblages in the Americas, heralding the decisive end of what has been called the “splendid isolation” of the South American fauna. Lacking substantive low-latitude records, previous work on this pattern relied on South American and temperate North American fossils to conclude that pulsed interchanges began about 2.8 million years ago (mya). Based on new low-latitude fossil data from México, we found evidence for a prolonged, triphasic interchange. Phase 1 consisted of the initial accumulation of northern higher-latitude mammals in a Mexican “holding pen” beginning 10 mya. Dispersal began in phase 2, with a strong north-south gradient and increasing biogeographic connections (7 to 3 mya). The final phase consisted of the already well-described taxonomic pulses (from ~2.8 mya).

DOI: aef2893

Source: https://www.science.org/doi/10.1126/science.aef2893