Molecular phylogenetics of shrews (Mammalia: Soricidae) reveal timing of transcontinental colonizations

Abstract

We sequenced 2167 base pairs (bp) of mitochondrial DNA cytochrome b and 16S, and 1390 bp of nuclear genes BRCA1 and ApoB in shrews taxa (Eulipotyphla, family Soricidae). The aim was to study the relationships at higher taxonomic levels within this family, and in particular the position of difficult clades such as Anourosorex and Myosorex. The data confirmed two monophyletic subfamilies, Soricinae and Crocidurinae. In the former, the tribes Anourosoricini, Blarinini, Nectogalini, Notiosoricini, and Soricini were supported. The latter was formed by the tribes Myosoricini and Crocidurini. The genus Suncus appeared to be paraphyletic and included Sylvisorex. We further suggest a biogeographical hypothesis, which shows that North America was colonized by three independent lineages of Soricinae during middle Miocene. Our hypothesis is congruent with the first fossil records for these taxa. Using molecular dating, the first exchanges between Africa and Eurasia occurred during the middle Miocene. The last one took place in the Late Miocene, with the dispersion of the genus Crocidura through the old world.

Phylogeny and biogeography of bees of the tribe Osmiini (Hymenoptera: Megachilidae)

“…In contrast to the boreal osmiine lineages, many North American osmiine taxa are restricted to or have their center of distribution in arid regions of the southwestern USA, especially the Madrean Region (Michener, 2007), e. g., Chelostoma (Foveosmia), Xeroheriades, Hoplitis (Proteriades), Atoposmia and Ashmeadiella. This distribution pattern might indicate older dispersal events from the eastern hemisphere, e. g., during the Middle Miocene as observed in two clades of less cold-adapted bumblebees (10-15 Myr and 12-18 Myr, respectively; Hines 2008) and in shrews ($14-12 Myr; Dubey et al, 2007), or even around the Oligocene-Miocene boundary ($23-20 Myr;Hunt, 2004).…”

“…The use of character models to infer ancestral geographic ranges suffers from some limitations, especially because state transitions often have immediate effects on speciation if states are geographic ranges (Ronquist, 1997;Ree et al, 2005;Ree and Smith, 2008). However, the use of character models is widely applied for biogeography reconstruction (Nepokroeff et al, 2003;Dubey et al, 2007;McGuire et al, 2007;Pereira et al, 2007;Pereira and Baker, 2008) as it presents many advantages over parsimony-based methods. Character models take phylogenetic uncertainty and branch lengths into account and allow distinct rates between different states.…”

“…We explored two models of character evolution applying the maximum likelihood approach implemented in BayesTraits. First, rates were all constrained to be equal, corresponding to the simple model Mk1 (Lewis, 2001) usually used in biogeography reconstruction (Dubey et al, 2007;McGuire et al, 2007). Second, we allowed three free rates of biogeographic exchange: Afrotropical versus Palearctic, Palearctic versus Nearctic, Afrotropical versus Nearctic.…”

Expanded Host Diversity and Geographic Distribution of Hantaviruses in Sub-Saharan Africa

“…On the basis of albeit meager fossil records and assuming equally probable and bidirectional exchanges between Eurasia and Africa, the family Soricidae likely originated in Eurasia (18). Shrews of the Myosorex genus are believed to have originated in the tropical forests of central Africa during the Middle Miocene, approximately 12 to 15 million years before the present (16,18).…”

“…Shrews of the Myosorex genus are believed to have originated in the tropical forests of central Africa during the Middle Miocene, approximately 12 to 15 million years before the present (16,18). In reconstructing the biogeographic history of the Soricidae, Dubey and colleagues proposed three equally parsimonious scenarios, based on the premise of two independent origins of the Crocidura genus (18).…”