Spatiotemporal Diversification of Tree Squirrels: Is the South American Invasion and Speciation Really That Recent and Fast?

Author(s)

de Abreu-Jr, Edson Fiedler ; Pavan, Silvia E. ^{[1, 2]} ; Tsuchiya, Mirian T. N. ^{[3, 2]} ; Wilson, Don E. ^[4] ; Percequillo, Alexandre R. ^[5] ; Maldonado, Jesus E. ^{[6, 7, 2]}

Affiliation

^[1] Museu Paraense Emilio Goeldi, Coordenacao Zool, Belem, Para - Brazil

^[2] de Abreu-Jr, Jr., Edson Fiedler, Natl Zool Pk, Smithsonian Conservat Biol Inst, Ctr Conservat Genom, Washington, DC 20008 - USA

^[3] Smithsonian Inst, Data Sci Lab, Off Chief Informat Officer, Washington, DC 20560 - USA

^[4] Smithsonian Inst, Div Mammals, Natl Museum Nat Hist, Washington, DC 20560 - USA

^[5] de Abreu-Jr, Jr., Edson Fiedler, Univ Sao Paulo, Escola Super Agr Luiz de Queiroz, Dept Ciencias Biol, Lab Mamiferos, Piracicaba - Brazil

^[6] George Mason Univ, Dept Environm Sci & Policy, Fairfax, VA 22030 - USA

^[7] George Mason Univ, Dept Biol, Fairfax, VA 22030 - USA

• Document type: Journal article
• Source: FRONTIERS IN ECOLOGY AND EVOLUTION; v. 8, JUL 23 2020.
• Web of Science Citations: 0

Abstract

Tree squirrels (Sciurinae, Sciurini) represent a diverse radiation that successfully colonized Europe, Asia and the Americas during the Miocene-Pliocene, but information on their evolutionary history remains unclear. In the Neotropics, they have been shown to exhibit the highest rate of diversification amongst all arboreal squirrels, with strikingly high species accumulation rates in the past 3 Mya. In this study, we investigated the tempo and mode of diversification of tree squirrels using a mitogenome dataset that includes 43 Sciurini species. Our results corroborate the date of origin of the tribe Sciurini around 14 Mya (13.4-15.5) but suggest that their ancestral area was most likely in North America. This is in contrast to previous findings that suggested that the ancestors of this tribe occupied Eurasia. We estimated that cladogenetic events leading to the Eurasian lineages occurred twice at 10.5 and 9.7 Mya. Current North American genera originated in a temporal window from 6.2-2.3 Mya, and the origin of the Neotropical radiation was estimated to have occurred around 6 Mya in northwestern South America, in the Pacific dominion. Remarkably, our results indicate that tree squirrels entered South America at an earlier date than previously estimated. This could have happened either through a land corridor connecting the Caribbean islands or through the Panamanian land bridge. Most cladogenetic events in Eurasia and North America appear to have occurred either late in the Miocene or in the Pleistocene, while the majority of Neotropical cladogenetic events occurred along the Pliocene-right after the South American invasion. We found a fairly constant speciation rate for tree squirrels (averaging 0.29), which contrasts with the peak of lineage accumulation observed in the Pliocene. The absence of fluctuations in the diversification rate may be the result of several extinction events that were responsible for equalizing the number of lineages maintained over time. Finally, we conclude that the South American invasion was not as recent as previously inferred, but the diversification there was indeed very fast. (AU)

• FAPESP's process: 09/16009-1 - Systematics, evolution and diversification of the subfamily Sigmodontinae in South America: the tribe Oryzomyini
• Grantee: Alexandre Reis Percequillo
• Support Opportunities: Research Grants - Young Investigators Grants