Phylogenetic Analysis of Snow Sheep (Ovis nivicola) and Closely Related Taxa

Abstract

Based on mitochondrial cytochrome b gene sequence analysis, the history of true sheep (Ovis) began approximately 3.12 million years ago (MYA). The evolution of Ovis resulted in three generally accepted genetic groups: Argaliforms, Moufloniforms, and Pachyceriforms. The Pachyceriforms of the subgenus Pachyceros comprise the thin-horn sheep Ovis nivicola (snow sheep), Ovis dalli (Dall and Stone sheep), and Ovis canadensis (Rocky Mountain and desert bighorn). North America wild sheep (O. canadensis and O. dalli) evolved separately from Eurasian wild sheep and diverged from each other about 1.41 MYA. Ancestral stock that gave rise to snow sheep, Moufloniforms, and Argaliforms occurred 2.3 MYA, which then gave rise to two different extant lines of snow sheep that diverged from each other about 1.96 MYA. The more recent nivicola line is genetically closer to the North American wild sheep and may represent a close association during the refugium when Alaska and Siberia were connected by the Bering land bridge. The earlier period of evolution of the Pachyceriforms suggests they may have first evolved in Eurasia, the oldest ancestor then giving rise to North American wild sheep, and that a canadensis-like ancestor most likely gave rise to nivicola. Cytogenetic analysis further validates that the standard diploid number for modern nivicola is 52.

Haplogroup relationships between domestic and wild sheep resolved using a mitogenome panel

“…In addition, Figure 1 revealed Argali sheep to be more closely related to domestic animals when compared with Urial sheep. This is inconsistent with a previous mtDNA-based analysis (Bunch et al, 2006), but concordant with a classification system based on chromosome number, which indicates that the Urial sheep (2n ¼ 58) is more distantly related to domestic sheep (2n ¼ 54) than the wild Argali (2n ¼ 56) (Nadler et al, 1973). The mitogenome of the European mouflon (O. musimon) grouped with other haplogroup HB sequences in line with previous findings that indicate it should not be considered a truly wild sheep (Hiendleder et al, 2002;Pedrosa et al, 2005;Meadows and Kijas, 2008).…”

“…In previous studies, partial mtDNA sequences have been used to show the Urial and Argali are highly unlikely to be the progenitor of domestic sheep (Hiendleder et al, 1998(Hiendleder et al, , 2002Wu et al, 2003;Chen et al, 2006;Tapio et al, 2006;Meadows et al, 2007), however the relationship between wild and domestic sheep was revisited in this study for three reasons. First, the relationship between wild species remains unresolved, as a number of different phylogenies have been reported (Hiendleder et al, 2002;Bunch et al, 2006;Meadows et al, 2007). Second, candidate wild species have been discounted as the progenitor of modern sheep using short fragments of mtDNA.…”

QTL mapping for sexually dimorphic fitness-related traits in wild bighorn sheep

“…In bighorn sheep, data interpretation could be facilitated by previous research in domestic sheep (Ovis aries, B3 million years divergence, Bunch et al, 2006). Indeed, one QTL has already been mapped for horn size in domestic sheep (that is, on chromosome 10 near the horns locus, Johnston et al 2010).…”

CYTOGENETIC CHARACTERISTIC OF Ovis ammon ammon, O. nivicola borealis AND THEIR HYBRIDS

“…The third pair of biarmed chromosomes evolved through centric fusion between the 5 th and the 11 th chromosomes, which has led to species with 2n = 54. This metacentric chromosome also was found in snow sheep whose karyotype is 2n = 52; such reduction of karyotype in O. nivicola was caused by the fusion between the 9 th and 19 th chromosomes (31). The study of available literature shows the lack of e cytogenetic data about wild sheep subspecies.…”