Reviewing the Great American Biotic Interchange: climate change as a trigger for biodiversity dispersal

Abstract

The Great American Biotic Interchange (GABI), during which an intense biodiversity interchange occurred between South and North America (SA and NA), strongly affected the biodiversity of the Americas. Despite its importance, there are still knowledge gaps regarding the factors triggering species dispersion, the taxonomic groups that first dispersed, the age at which dispersions began and intensified, and whether there was a main dispersal direction through the continent (from NA to SA or vice versa). To fill these gaps, we conducted a scientific literature review of the GABI, searching for studies with information regarding dispersal age, taxonomic groups (invertebrates, amphibians, non-avian reptiles, birds, mammals and plants), dispersion direction (towards SA or NA) and the type of data used as the source of evidence (fossil, molecular or extant species). We also investigated the effect of the climatic dynamic on the biodiversity dispersal through the relationships between oxygen-isotope levels (δ¹⁸O, as a proxy of past temperatures) and the number and geological age of dispersal records. Only 41.8% (87 publications) of the studies included information on biodiversity dispersion during GABI. We found evidence of GABI starting at 23 million years ago (Ma) and becoming a continuous process from approximately 15 Ma. Cooling periods after the Miocene Climate Optimum favoured continuous dispersals, which have since intensified. Studies based on molecular data recovered more closely related to the intermediate ages of dispersal records. In addition, birds, plants and mammals were displaced first, whereas amphibians were displaced last.

Keywords: GABI; asymmetry hypothesis; biodiversity dispersion; cooling; neotropical region.

Figure 1.

(A) Geographical context of North and South America isolation—indicated by dashed line—with representative fauna that evolved in isolation during this period; and (B) the Great American Biotic Interchange, denoting the end of the gap following the establishment of the Panama Isthmus land bridge—dashed line—and the faunal dispersion between North and South America. Brown silhouettes represent taxa from North America, while green silhouettes represent those from South America. The taxa silhouettes were obtained from PhyloPic (https://www.phylopic.org/): Mammuthus columbi by U.S. National Park Service (vectorized by William Gearty); Titanis walleri by Steven Traver; Glyptodon by Celest Luna; Washingtonia robusta by Guillaume Dera; Boa constrictor by Becky Barnes; Bison by Tracy A. Heath; Craugastos augusti by Jose Carlos Arena-Monroy; Smilodon by Margot Michaud; Megachilidae by Thomas Hegna; Priodontes maximus by Celeste luna and uploaded by Fabio Machado; Tremarctos ornatus by Andy Wilson; Macrauchenia patachonica by Steven Traver; Vultur gryphus by Kai Caspar; Dicotyles tajacu by Steven Traver; Arminiheringia auceta by Steven Traver. All silhouettes are under the Creative Commons CC0 1.0, Universal Public Domain Dedication license (https://creativecommons.org/publicdomain/zero/1.0/).

Figure 2.

Number of dispersal events through the last 23 Myr of the GABI for (A) mammals, (B) birds, (C) plants, (D) invertebrates, (E) reptiles, and (F) general (all groups). The δ¹⁸O levels over time shown in (F) indicate heating (red) or cooling (blue) periods. The taxon silhouettes were obtained from PhyloPic (https://www.phylopic.org/): Smilodon by Margot Michaud; Titanis walleri by Steven Traver; Acanthaceae by Saneesh; Megachilidae by Thomas Hegna; Boa constrictor by Becky Barnes. All silhouettes are under the Creative Commons CC0 1.0, Universal Public Domain Dedication license (https://creativecommons.org/publicdomain/zero/1.0/).

Figure 3.

Segmented regression analysis showing the breaks (thresholds) for (A) δ¹⁸O levels over time (colours indicate the frequency of the dispersal events), (B) number of dispersal events over time (colours indicate the δ¹⁸O levels), and (C) number of dispersal events versus δ¹⁸O levels (colours indicate the age). The grey vertical lines represent the thresholds, and the * indicates the selected model (i.e. model with ΔAIC<4).

Figure 4.

Principal component analysis relating the number of dispersal events with: (A) ages (Ma) and type of evidence source (molecular, fossil and extant species); (B) type of evidence source and taxonomic group (amphibians, birds, invertebrates, mammals, plants and reptiles); and (C) taxonomic group and dispersal directions (NA to SA, SA to NA, or both). The taxa silhouettes were obtained from PhyloPic (https://www.phylopic.org/): Smilodon by Margot Michaud; Titanis walleri by Steven Traver; Acanthaceae by Saneesh; Megachilidae by Thomas Hegna; Boa constrictor by Becky Barnes; Craugastos augusti by Jose Carlos Arena-Monroy. All silhouettes are under the Creative Commons CC0 1.0, Universal Public Domain Dedication license (https://creativecommons.org/publicdomain/zero/1.0/).