Biological evidence supports an early and complex emergence of the Isthmus of Panama

Abstract

SignificanceThe formation of the Isthmus of Panama, which linked North and South America, is key to understanding the biodiversity, oceanography, atmosphere, and climate in the region. Despite its importance across multiple disciplines, the timing of formation and emergence of the Isthmus and the biological patterns it created have been controversial. Here, we analyze molecular and fossil data, including terrestrial and marine organisms, to show that biotic migrations across the Isthmus of Panama began several million years earlier than commonly assumed. An earlier evolution of the Isthmus has broad implications for the mechanisms driving global climate (e.g., Pleistocene glaciations, thermohaline circulation) as well as the rich biodiversity of the Americas.

Reply to Lessios and Marko et al.: Early and progressive migration across the Isthmus of Panama is robust to missing data and biases

“…In summary, the analyses presented here indicate that the findings reported by Bacon et al (3) are robust to the issues raised (4,5). Recent efforts have shed light on the geological formation of the Isthmus of Panama and its impact on the region's biodiversity, climate, and oceanic circulation (9,10).…”

“…Similar patterns prevailed despite intrinsic differences among the taxonomic groups surveyed. This led Bacon et al (3) to reject the assumption of a single closure of the Isthmus at ca. 3.5 Ma in favor of an older, more complex model of land emergence and biotic interchange.…”

Five palaeobiological laws needed to understand the evolution of the living biota

“…While there has been a dramatic increase in the number of integrated palaeontological and neontological studies [1][2][3][4] , from a palaeobiological perspective, the field of biology has not yet fully assimilated the fundamental findings from the fossil record. Here I summarize these findings in the context of their relevance to our understanding of the living biota.…”

Tempo and mode of speciation in Holacanthus angelfishes based on RADseq markers

“…There, marine organisms, including about 40 species of fish, were separated by the closure of the Isthmus of Panama. The date of the closure itself has recently been debated, based on new geological and molecular data, arguing for an old closure time (Bacon et al, 2015a(Bacon et al, , 2015bCoates and Stallard, 2013;Jackson and O'Dea, 2013;Lessios, 2015;Marko et al, 2015), rather than the classically accepted 3.1-3.5 Mya (Coates and Obando, 1996;Collins, 1996;Craig et al, 2004;Knowlton, 1993;Lessios, 2008;Marko, 2002;Thomson et al, 2000). Genetic divergence between geminate species varies, and this variation is in part due to variability in substitution rates and in part due to ecological and evolutionary characteristics of specific taxa that determine the actual time of separation between geminates (Knowlton and Weigt, 1998;Lessios, 2008).…”