title: Uncovering cryptic diversity and refugial persistence among small mammal lineages across the Eastern Afromontane biodiversity hotspot.
abstract: The Eastern Afromontane region of Africa is characterized by striking levels of endemism and species richness accompanied by significant conservation threat, a pattern typical across biodiversity hotspots. Using multi-locus molecular data under a coalescent species tree framework we identify major cryptic biogeographic patterns within and between two endemic montane small mammal species complexes, Hylomyscus mice and Sylvisorex shrews, co-distributed across the Albertine Rift and Kenya Highlands of the Eastern Afromontane Biodiversity Hotspot (EABH). Hypotheses put forward to account for the high diversity of the region include retention of older palaeo-endemic lineages across major regions in climatically stable refugia, as well as the accumulation of lineages associated with more recent differentiation between allopatric populations separated by unsuitable habitat during periods of Pleistocene aridification. Sympatric pairs of sister lineages were found to have significantly older divergence times than allopatric pairs. Genetic analyses and historical distribution modeling suggest that regional meta-populations have persisted since the Pliocene to mid-Pleistocene across a climatic gradient from the Albertine Rift in the west to the Kenya Highlands in the east for both focal taxa. Differing patterns of regional sub-division and demographic expansion were detected and are consistent with differing life histories as well as shared responses to regional variation in stability of suitable habitat. There is also strong support in both mice and shrew species for Late Miocene divergence with subsequent range expansion into sympatry in previously unidentified cryptic species pairs. These results highlight the broad temporal scale at which climatic and geological changes may have facilitated rare dispersal events between montane habitats as well as the long-term persistence of populations in both the Albertine Rift and the Kenyan Highlands that together contributed to the high species diversity and endemism in the EABH.
authors.affiliation: Biology Department, City College of New York - CUNY, 160 Convent Avenue, New York, NY 10031, USA; Biology Doctoral Program, The Graduate Center - CUNY, 365 Fifth Avenue, New York, NY 10016, USA; College of Professional Studies, Roosevelt University, 430 S. Michigan Avenue, Chicago, IL 60605, USA. Electronic address: terrencedemos@gmail.com.
authors.forename: Terrence C
authors.initials: TC
authors.lastname: Demos
authors.affiliation: College of Professional Studies, Roosevelt University, 430 S. Michigan Avenue, Chicago, IL 60605, USA; Mammals Division, Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, IL 60605, USA.
authors.forename: Julian C
authors.initials: JC
authors.lastname: Kerbis Peterhans
authors.affiliation: Mammalogy Section, National Museums of Kenya, P.O. Box 40658, Nairobi, Kenya.
authors.forename: Bernard
authors.initials: B
authors.lastname: Agwanda
authors.affiliation: Biology Department, City College of New York - CUNY, 160 Convent Avenue, New York, NY 10031, USA; Biology Doctoral Program, The Graduate Center - CUNY, 365 Fifth Avenue, New York, NY 10016, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hickerson
mesh_terms: D000351:Africa, Eastern; D000818:Animals; D044822:Biodiversity; D051189:Murinae / Q000235:genetics*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012788:Shrews / Q000235:genetics*
keywords: Albertine Rift; Biogeography; Forest refugia; Small mammals; Species delimitation; Species tree