A comprehensive phylogeny of extinct and extant Rhizomyinae (Rodentia): evidence for multiple intercontinental dispersals

Abstract

The subfamily Rhizomyinae is known from the Late Oligocene up to the present. Today this group comprises six species, which live in southern Asia and eastern Africa. Despite the current moderate diversity of the rhizomyines, they had a greater diversification and wider distribution in the past: from Asia, their land of origin, to Africa, which they entered during the Early Miocene. So far 33 fossil species can be referred to this group. A cladistic analysis involving fossil and living species has been carried out. Prokanisamys spp. turned out to be the most basal taxa of the ingroup. This analysis calls into question the monophyly of several genera, and allows the proposal of a phylogenetic definition of the tribes Tachyoryctini and Rhizomyini. It also provides information about the origin of the African rhizomyines and allows inferring multiple dispersal phenomena from Asia to Africa in Early and Late Miocene times.

Phylogenetic position of the endemic Mount Oku rat,Lamottemys okuensis(Rodentia: Muridae), based on molecular and morphological data

“…In addition, the intensification of Pliocene volcanic activities in Central East Africa, which led to the formation of the Rift Valley (Baker, Mohr & Williams, ; Logatchev, Belossov & Milanovsky, ), and in the CVL (Wright et al ., ), inhibited exchange between the CVL and Ethiopian mountains and thus promoted the differentiation of Lamottemys following the montane forest refuge model (Rietkerk, Ketner & de Wilde, ; Robbrecht, ; Plana, ). Our divergence time estimate is congruent with the pulse of morphospecies diversification observed at about 4.1 Mya for the Afroalpine fossorial rodent Tachyoryctes in the Ethiopian Plateau (López‐Antonanzasa, Flynn & Knoll, ). Pliocene palaeontological data from Central Africa are needed for a better understanding of the evolutionary scenarios that promoted the diversification of CVL endemics.…”

Are the Rhizomyinae and the Spalacinae closely related? Contradistinctive conclusions between genetics and palaeontology

“…The rather poor fossil record of the African rhizomyines-there is no record of the group between the early Miocene Prokanisamys sp. from Libya and the late middle Miocene Pronakalimys from Kenya-does not confirm hypothesised explanations for the multiple migrations of Rhizomyinae from Asia to Africa as interpreted in López-Antoňanzas et al (2012). From a biological point of view, a long-distance migration of fossorial, territorial rodents is unlikely (Kryštufek and Griffiths 2002), so our working hypothesis is that the non-fossorial Prokanisamys migrated from Asia to Africa where it developed a fully fossorial mode of life independent of its Asian counterparts.…”

Molecular and morphological evidence for a Pleistocene radiation of laminate-toothed rats (Otomys: Rodentia) across a volcanic archipelago in equatorial Africa

“…These younger dates are interesting, given that the first known fossils of the Afroalpine fossorial rodent Tachyoryctes are constrained to the Late Miocene with a pulse of morpho‐species diversification at ∼4.1 Ma. These events were all confined to the Ethiopian Plateau (López‐Antonãnzasa, Flynn & Knoll, ). Complementary phylogeographic studies of Lobelia, Tachyoryctes and other representative Afroalpine endemics can be expected to refine these insights revealed by Otomys across the volcanic archipelago of equatorial Africa.…”