Deep mitochondrial DNA phylogeographic divergence in the threatened aoudad Ammotragus lervia (Bovidae, Caprini)

Abstract

The aoudad or Barbary sheep (Ammotragus lervia) is a threatened ungulate emblematic of North Africa, whose population structure and subspecific taxonomy have not been examined genetically. This knowledge is essential and urgently needed to inform ongoing conservation and management efforts. We analysed the mitochondrial cytochrome b gene and four nuclear genes (casein kappa, spectrin beta nonerythrocytic 1, thyroglobulin, thyrotropin subunit beta) for the first phylogeographic survey of the aoudad, and uncovered a deep Mediterranean-Saharan mitochondrial split separating two highly distinct evolutionary lineages. Their level of divergence is greater than or comparable to those observed between several pairs of congeneric species of different caprine genera. The split was estimated to have occurred in the Early Pleistocene, about 1.3 million years ago. None of the four nuclear genes surveyed, chosen because they have been used in phylogeographic and species-level phylogenetic studies of bovids, allowed us to detect, likely due to their slow evolutionary rate, the substantial and geographically coherent subdivision revealed by mitochondrial DNA. This study is evidence and testament to the ability of mitochondrial DNA, probably unrivalled by any other single-locus marker, as an exploratory tool for investigating population genealogy and history and identifying potential evolutionarily significant units for conservation in animals.

Population structure and genetic diversity of non-native aoudad populations

“…In its native range in North Africa, six aoudad subspecies have been described, based on their distribution and morphological differences in coat color and horns 27 . Derouiche et al 22 aimed to further evaluate the validity of the subspecies and determine the geographical limits of the valid ones using mitochondrial cytochrome b gene. Based on the haplotypes obtained, their results indicated a deep Mediterranean-Saharan genetic break in the species, suggesting the presence of two highly distinct evolutionary lineages.…”

“…Since scientific literature about the genetic structure of European aoudad populations is scarce, it is thus important to study genetic diversity and structure of those populations to assess their sustainability. Unfortunately, no comprehensive genetic analyzes have yet been carried out on original aoudad populations from their native range, except for a few studies of specific populations (e.g., Derouiche et al 22 ). In addition, insight into the genetic structure and origin of European aoudad populations might contribute to the ex-situ conservation of the species that is threatened in its native range.…”

Presence of the Barbary Sheep (Ammotragus lervia) in the region of Illizi (Southeast Algeria)

“…According to Cassinello (2013), Algeria hosts two subspecies of Barbary sheep: A. lervia Lervia in the north and west and A. lervia sahariensis in the south. A recent genetic study confirmed the old divergence of two lines corresponding to these two subspecies (Derouiche et al, 2020). A. Lervia Lervia is still present in very low numbers in four places in the mountains of the northeast, south of Tebessa, Batna, M'Sila and northeast of Biskra, and west to south of Tiaret and in the Bechar region (Kowalski & Rzebik-Kowalska, 1991;Bounaceur et al, 2016).…”

Distinct mtDNA lineages in free‐ranging Ammotragus(aoudad) from the United States indicate multiple introductions from northern Africa

“…Additional sequence data for both mitochondrial markers (cytb: n = 17, D loop: n = 3) and the nuclear gene ( PRNP : n = 1) datasets were obtained from NCBI GenBank and included samples examined in Derouiche et al ( 2020 ), Stipoljev et al ( 2021 ), as well as from unpublished studies. Inclusion of these samples broadened the sampling scheme to include individuals from the native range of aoudad as well as samples with a documented history (captive, semi‐captive, introduced, and zoo animals).…”

“…In reviewing the taxonomy of Caprini, Groves and Grubb ( 2011 ) questioned whether A. lervia was a single species. The sole genetic study (Derouiche et al, 2020 ) included wild‐caught individuals from the Algerian provinces of Béchar, Illizi, and Tamanrasset; as well as semi‐captive individuals obtained from several preserves and zoos in Algeria. Their results based on mitochondrial DNA sequences, reflected a Mediterranean and Saharan divergence which seems to correspond to the two subspecies ( A. l. sahariensis and A. l. lervia ).…”