The Great Rift Valley is a more pronounced biogeographic barrier than the Blue Nile Valley for six Ethiopian Highland passerines in the eastern Afromontane biodiversity hotspot

Abstract

The Ethiopian Highlands are divided by lowland biogeographic barriers, including the Blue Nile Valley (BNV) and Great Rift Valley (GRV). We show that the GRV is a more pronounced phylogeographic break than the BNV for 6 focal passerines. Previous research suggests that the BNV greatly shaped phylogeographic patterns in relatively sedentary montane taxa such as frogs and rodents, whereas the GRV shaped phylogeographic patterns in volant taxa such as birds. However, no previous research simultaneously compares the impact of each valley on phylogeographic patterns in birds, and as these barriers vary in geographic extent and topography, the relative extent of their effects on gene flow is unclear. Using whole-genome resequencing, we quantified genetic variation in 6 montane forest passerines in the Ethiopian Highlands and found that their phylogeographic patterns varied, with general trends distinct from those of taxa that were previously studied across the same barriers. Genetic variation was assessed by estimating genome-wide genetic diversity (HO), demographic history, phylogeographic structure, and phylogeographic concordance among taxa. Population pairs flanking the GRV showed higher FST and more distinct population clusters in principal component analysis than those separated by the BNV. HO was broadly consistent across populations, excluding noticeable reductions in 2 populations (1 population each in 2 separate species). The overall phylogenetic signature and concordance across study taxa supported populations separated by the BNV as sister and populations southeast of the GRV as most distinct.center dot The Ethiopian Highlands are exceptionally biodiverse in species and community diversity.center dot Highland landscape features can isolate species' populations, causing distinct populations or new species to form over time, impacting biodiversity patterns.center dot Different species may be affected by landscape features to varying degrees based on their attributes. Studies characterizing evolutionary responses to landscape features in Ethiopia are mostly limited to sedentary organisms like frogs and rodents.center dot We characterized genetic variation-a component of biodiversity-in 6 Ethiopian Highland songbirds that are thought to be highly mobile.center dot In these songbirds, we found genetic structure between populations separated by the Great Rift Valley and the Blue Nile Valley, showing that these valleys dissecting the Ethiopian Highlands isolate some songbird populations.center dot Evolutionary relationships between populations of our focal species and between populations of all highland species studied to date differed in how genetically distinct they were in relation to each dividing barrier.

Keywords

biodiversity hotspots; Ethiopia; genetic diversity; genomics; passeriformes; phylogeography

Published in

Ornithology
2024, volume: 141, number: 4, article number: ukae030
Publisher: OXFORD UNIV PRESS INC

SLU Authors

• Meheretu, Yonas

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    
  • Mekelle University

UKÄ Subject classification

Evolutionary Biology

Publication identifier

• DOI: https://doi.org/10.1093/ornithology/ukae030

Permanent link to this page (URI)

https://res.slu.se/id/publ/131708