Titi monkey biogeography: Parallel Pleistocene spread by Plecturocebus and Cheracebus into a post‐Pebas Western Amazon

Abstract

Titi monkeys, subfamily Callicebinae, are a diverse, species‐rich group of Neotropical primates with an extensive range across South America. Their distribution in space and time makes them an interesting primate model for addressing questions of Neotropical historical biogeography. Our aim was to reconstruct the biogeographic history of Callicebinae to better understand their diversification patterns and the history of their colonisation of South America since the late Miocene. We reconstructed a time‐calibrated phylogeny of 19 titi species under Bayesian inference using two mitochondrial and 11 nuclear loci. Species were assigned across eight Neotropical areas of endemism, and statistical biogeographic methods implemented in BioGeoBEARS were employed to estimate ancestral areas using 12 biogeographic models. Our results indicate that the most recent common ancestor to extant titi monkeys was widespread from the present‐day Andean foothills in the Colombian Amazon, through the wet and dry savannas of Bolivia and Brazil, to the southern Atlantic forest of eastern Brazil. Genus‐level divergences were characterised by vicariance of ancestral range in the late Miocene. Species‐level diversification in Cheracebus and the Plecturocebus moloch group occurred as they spread across the Amazon in the Pleistocene and were largely characterised by a sequential, long‐distance “island‐hopping” dispersal model of speciation from a narrow area of origin through jump dispersal across rivers. This study comprises the first large‐scale investigation of the evolutionary history of titi monkeys in the context of Amazonian and South American historical biogeography and sheds light on the processes that generated the great diversity found among Callicebinae.

Ancient DNA of the extinct Jamaican monkey Xenothrix reveals extreme insular change within a morphologically conservative radiation

“…This estimated divergence considerably postdates the geological formation of the Greater Antilles as oceanictype islands, and also the hypothesized existence of a subaerial landspan connecting these islands to South America during the Eocene-Oligocene transition (46), indicating that primates must have arrived via over-water dispersal, in contrast to some other components of the Caribbean Neogene mammal fauna (13). This hypothesized colonization mechanism for Xenothrix is consistent with the present-day distribution of its extant sister genus Cheracebus, the northernmost callicebine genus, which occurs across northern South America into the Orinoco region of Venezuela (28,29).…”

“…In their description of new Xenothrix material, MacPhee and Horovitz (23) concluded that Xenothrix exhibited no derived characters in common with Aotus, but was instead closely allied with callicebines (titi monkeys) on the basis of several derived craniodental traits. All callicebines were then referred to the single genus Callicebus; however, recent molecular analysis recognizes three clades within Callicebus sensu lato which diverged during the Miocene, and which have been elevated to distinct genera (Callicebus, Cheracebus, Plecturocebus) (28,29). More recently, geometric morphometric analysis of extant and fossil platyrrhines suggested that Xenothrix could represent an ancient lineage that diverged before the radiation of crown platyrrhines (30).…”

“…Partition homogeneity analysis has demonstrated that phylogenetic analyses of platyrrhines, and specifically those including Caribbean primates, recover different results using craniodental versus postcranial data (31), suggesting that phylogenetic hypotheses based on restricted morphological character datasets available for extinct species are not robust and must be interpreted with care. Most previous morphological hypotheses have also relied upon taxonomy that is inconsistent with more recent platyrrhine molecular phylogenies (28,29). These considerations have obvious implications for the explanatory value of morphology-only data for Caribbean primates.…”

“…Two contrasting modes of speciation are likely to have driven evolution in Xenothrix and mainland Callicebinae. Barriers to gene flow created by river systems (38) and Pleistocene climate refugia (39) are considered primary factors responsible for generating the high primate species diversity found today in the Neotropics, including the diversity observed within Callicebus, Cheracebus, and Plecturocebus, which are thought to have diversified primarily through sequential "jump dispersal" across rivers (29). Although mainland callicebine populations are separated geographically, they inhabit relatively similar environments and occupy comparable niches, an ecological context likely to be associated with little morphological divergence over time.…”

Andean Tectonics and Mantle Dynamics as a Pervasive Influence on Amazonian Ecosystem

“…The connection between Amazonas and Orinoco drainage systems has long been investigated also for the aquatic fauna, with clear evidence of past connection and dynamic river capture events up to the present 30–32 . Other clades of terra firme forest birds and primates, on the other hand, seem to have diversified in Amazonia from the southwestern forests at the base of the Andes, occupying the Amazonian upland forests when they became available in central Amazonia after 3 Ma 33–36 .…”