The impact of fossil record spatial heterogeneity on inferring the asymmetry of the Great American Biotic interchange

• Grant number: 25/21858-0
• Support Opportunities: Scholarships in Brazil - Master
• Start date: November 01, 2025
• End date: September 30, 2026
• Field of knowledge: Biological Sciences - Ecology
• Principal Investigator: Tiago Bosisio Quental
• Grantee: Thaís Gomes Piazza Faria
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/06780-4 - The deep time drivers of biodiversity at the local, regional and global scales, AP.BTA.JP2

Abstract

The Great American Biotic Interchange (GABI) has been described in the literature as one of the greatest known biological experiments in the recent history of the Earth. It consists of migration pulses between the north and south american biotas, mainly following the formation of the Panama Isthmus in the last 2 million years. One striking feature of this biotic exchange is an asymmetrical result on past and present day biotas, with South America harboring more migrant lineages from the North than vice-versa. Several hypotheses regarding differential rates of immigration, extinction and speciation have been proposed to explain such asymmetrical patterns. Those hypotheses have been recently tested using fossil occurrences and very sophisticated quantitative methods specially developed to take into account different aspects of the fossil record incompleteness, with a particular focus on the temporal heterogeneity of the occurrences. However, recent concerns over the impact of the spatial heterogeneity of fossil occurrences have yet to be addressed. Specifically, there are major differences in sampled area between South and North America, and different sampled areas of fossil occurrences can impact inferences of speciation and extinction rates due to the species-area effect. Furthermore, a recent study suggests that North and South American native lineages show an asymmetry in their travelled distances from the Panama Isthmus into their respective foreign continents., which could also influence our ability to properly estimate migration rates. We will use mammal fossil occurrence data and cutting edge methods that explicitly take into account the spatial biases of the fossil record to re-evaluate the different hypotheses that have been proposed to explain the migration asymmetry we see today in the Americas.