Tracing the diversification history of a Neogene rodent invasion into South America

Abstract

We investigated spatial patterns of evolutionary relatedness and diversification rates to test hypotheses about the historical biogeographic processes underlying the radiation of Neotropical rats and mice (Sigmodontinae, ~400 species). A negative correlation between mean phylogenetic distance and diversification rates of rodent assemblages reveals a pattern of species co-occurrence in which assemblages of closely related species are also the fastest diversifying ones. Subregions of the Neotropics occupied by distantly related species that are on average more slowly diversifying include Central America, northern South America, and the Atlantic forest. In southern South America, recent species turnover appears to have been higher. Ancestral locations for the main tribes of sigmodontines were also estimated, suggesting eastern South America and the Amazonian lowlands were colonized before some central Andean regions, even though the latter are now centers of species richness for these rodents. Moreover, a past connection between the tropical Andes and the Atlantic Forest is suggested by our results, highlighting a role for a hypothetical arc connecting the two biomes, which would have impacted many other groups of organisms. Whether rapid, recent speciation in some regions is related to Quaternary climatic fluctuations and the young age of sigmodontines (~12.7 Ma crown age) or instead to intrinsic traits of these rodents remains an open question. If the former is true, we hypothesize that contrasting trends will characterize older Neotropical clades.

Evoregions: Mapping shifts in phylogenetic turnover across biogeographic regions

“…These biogeographically discrete units compose the so‐called biogeographical realms, regions, dominions or provinces (Costello et al., 2017; Holt et al., 2013; Morrone, 2014), named depending on the spatial scale of the study (see Morrone, 2015; Vilhena & Antonelli, 2015 for a discussion about terminology). Each monophyletic clade (taxa) is likely to have its unique set of important biogeographic regions (bioregions), reflecting major geological and climatological factors in action during the timing of diversification, and the particular organism's dispersal abilities (Edler et al., 2017; Maestri et al., 2019). Boundaries for different taxa that are found later to be in coincident position may help to infer global bioregions.…”

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

“…The timing of Atlantic Forest colonization by tree squirrels (around 1 Mya) is comparable to the timing of the entrance of some species of sigmodontine rodents (such as species in the genera Euryoryzomys, Hylaeamys and Oligoryzomys; Steppan and Schenk, 2017;Maestri et al, 2019). At least two main distinct spatiotemporal routes have been proposed between the Amazon and the Atlantic Forest (Costa, 2003;Batalha-Filho et al, 2013;Ledo and Colli, 2017): older (middle to late Miocene) connections between southeastern Atlantic Forest and western Amazonia (the SE-NW bridge), and younger (Pliocene and Pleistocene) connections across northeastern Brazil (the NE bridge).…”

“…Several Central American vertebrate lineages that originated along the Pliocene-Pleistocene boundary have been shown to exhibit their ancestral ranges in northern South America (Barrantes, 2009;Saldarriaga-Córdoba et al, 2017;Maestri et al, 2019). Savage (2002) proposed a two-step dispersal pulse hypothesis to explain amphibians and reptiles of South America inhabiting Middle America.…”

“…Moreover, among these species, E. variegatoides colonized back to the Pacific dominion through anagenetic dispersal. Some groups of sigmodontine rodents also had their origin estimated to be in the late Miocene or Pliocene in northern South America, suggesting that this region has played an important role on the origin and diversification of forest rodents (Maestri et al, 2019). In the mid-Pliocene, when several of the cladogenetic events of the Central American radiation have been estimated, important geological events such as the development of the Sierra Madre oriental and occidental and the volcanism of the Trans-Mexican Volcanic Belt were taking place (Sedlock et al, 1993).…”

Evoregions: Mapping Shifts in Phylogenetic Turnover Across Biogeographic Regions

“…These biogeographic discrete units compose the so-called biogeographical realms, regions, dominions, or provinces (Holt et al 2013; Morrone 2014; Costello et al 2017), named depending on the spatial scale of the study (see Morrone 2015 and Vilhena and Antonelli 2015 for a discussion about terminology). Each monophyletic clade (taxa) is likely to have its unique set of important biogeographic regions (bioregions), reflecting the principal geological and climatological factors in action during the timing of diversification, and the particular organism’s dispersal abilities (Edler et al 2017; Maestri et al 2019). Boundaries for different taxa that are found later to be in coincident position may help to infer global bioregions.…”