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Extensive Population Structure Highlights an Apparent Paradox of Stasis in the Impala (Aepyceros melampus)

Garcia-Erill, Genís ; Wang, Xi ; Rasmussen, Malthe S ; Quinn, Liam ; Khan, Anubhab ; Bertola, Laura D ; Santander, Cindy G ; Balboa, Renzo F ; Ogutu, Joseph O and Pečnerová, Patrícia LU orcid , et al. (2024) In Molecular Ecology 33(22).
Abstract

Impalas are unusual among bovids because they have remained morphologically similar over millions of years-a phenomenon referred to as evolutionary stasis. Here, we sequenced 119 whole genomes from the two extant subspecies of impala, the common (Aepyceros melampus melampus) and black-faced (A. m. petersi) impala. We investigated the evolutionary forces working within the species to explore how they might be associated with its evolutionary stasis as a taxon. Despite being one of the most abundant bovid species, we found low genetic diversity overall, and a phylogeographic signal of spatial expansion from southern to eastern Africa. Contrary to expectations under a scenario of evolutionary stasis, we found pronounced genetic structure... (More)

Impalas are unusual among bovids because they have remained morphologically similar over millions of years-a phenomenon referred to as evolutionary stasis. Here, we sequenced 119 whole genomes from the two extant subspecies of impala, the common (Aepyceros melampus melampus) and black-faced (A. m. petersi) impala. We investigated the evolutionary forces working within the species to explore how they might be associated with its evolutionary stasis as a taxon. Despite being one of the most abundant bovid species, we found low genetic diversity overall, and a phylogeographic signal of spatial expansion from southern to eastern Africa. Contrary to expectations under a scenario of evolutionary stasis, we found pronounced genetic structure between and within the two subspecies with indications of ancient, but not recent, gene flow. Black-faced impala and eastern African common impala populations had more runs of homozygosity than common impala in southern Africa, and, using a proxy for genetic load, we found that natural selection is working less efficiently in these populations compared to the southern African populations. Together with the fossil record, our results are consistent with a fixed-optimum model of evolutionary stasis, in which impalas in the southern African core of the range are able to stay near their evolutionary fitness optimum as a generalist ecotone species, whereas eastern African impalas may struggle to do so due to the effects of genetic drift and reduced adaptation to the local habitat, leading to recurrent local extinction in eastern Africa and re-colonisation from the South.

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publishing date
type
Contribution to journal
publication status
published
in
Molecular Ecology
volume
33
issue
22
publisher
Wiley-Blackwell
external identifiers
  • pmid:39373069
  • scopus:85205938993
ISSN
0962-1083
DOI
10.1111/mec.17539
language
English
LU publication?
no
additional info
© 2024 The Author(s). Molecular Ecology published by John Wiley & Sons Ltd.
id
51129029-56b6-4c6e-abf7-15eeb07de69c
date added to LUP
2024-10-10 15:52:39
date last changed
2025-07-09 11:20:03
@article{51129029-56b6-4c6e-abf7-15eeb07de69c,
  abstract     = {{<p>Impalas are unusual among bovids because they have remained morphologically similar over millions of years-a phenomenon referred to as evolutionary stasis. Here, we sequenced 119 whole genomes from the two extant subspecies of impala, the common (Aepyceros melampus melampus) and black-faced (A. m. petersi) impala. We investigated the evolutionary forces working within the species to explore how they might be associated with its evolutionary stasis as a taxon. Despite being one of the most abundant bovid species, we found low genetic diversity overall, and a phylogeographic signal of spatial expansion from southern to eastern Africa. Contrary to expectations under a scenario of evolutionary stasis, we found pronounced genetic structure between and within the two subspecies with indications of ancient, but not recent, gene flow. Black-faced impala and eastern African common impala populations had more runs of homozygosity than common impala in southern Africa, and, using a proxy for genetic load, we found that natural selection is working less efficiently in these populations compared to the southern African populations. Together with the fossil record, our results are consistent with a fixed-optimum model of evolutionary stasis, in which impalas in the southern African core of the range are able to stay near their evolutionary fitness optimum as a generalist ecotone species, whereas eastern African impalas may struggle to do so due to the effects of genetic drift and reduced adaptation to the local habitat, leading to recurrent local extinction in eastern Africa and re-colonisation from the South.</p>}},
  author       = {{Garcia-Erill, Genís and Wang, Xi and Rasmussen, Malthe S and Quinn, Liam and Khan, Anubhab and Bertola, Laura D and Santander, Cindy G and Balboa, Renzo F and Ogutu, Joseph O and Pečnerová, Patrícia and Hanghøj, Kristian and Kuja, Josiah and Nursyifa, Casia and Masembe, Charles and Muwanika, Vincent and Bibi, Faysal and Moltke, Ida and Siegismund, Hans R and Albrechtsen, Anders and Heller, Rasmus}},
  issn         = {{0962-1083}},
  language     = {{eng}},
  month        = {{10}},
  number       = {{22}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Molecular Ecology}},
  title        = {{Extensive Population Structure Highlights an Apparent Paradox of Stasis in the Impala (Aepyceros melampus)}},
  url          = {{http://dx.doi.org/10.1111/mec.17539}},
  doi          = {{10.1111/mec.17539}},
  volume       = {{33}},
  year         = {{2024}},
}