Shedding Light on the Origin of Egyptian Sheep Breeds by Evolutionary Comparison of Mitochondrial D-Loop

Abstract

(1) Background: It has been recognized that the origin of fat-tailed sheep occurred within coarse wool breeds and that this character was introgressed several times into thin-tailed populations. However, no study has investigated this idea for Egyptian breeds using mtDNA analyses. (2) Methods: Using new sequences of the control region, we constructed a database of 467 sequences representing 37 breeds including fat- and thin-tailed ones with 80 Egyptian individuals belonging to six local breeds (Barki, Fallahi, Ossimi, Rahmani, Saidi, Sohagi). The phylogenetic tree obtained with the maximum likelihood method was submitted to the Newick Extra program to count the direct and indirect links between the individuals of each breed. (3) Results: Several Egyptian breeds were strongly connected to "primitive" thin-tailed breeds from Europe, indicating a clear genetic background of the "thin tail" breed type that supports the view of archeologists. In several cases, we suspected Western Asian breeds to be involved in the introgression of the fat tail character. In contrast, the Ossimi breed showed a high affinity to a fat-tailed breed of Western Asia, suggesting a direct migration and no thin tail ancestors. The Saidi is unique as our analyses revealed its strong connection with thin-tailed Sudanese breeds.

Keywords: Egyptian breed; fat-tail introgression; mitochondrial control region; phylogenetic analysis.

Figure 1

The NMDS position of the breeds based on their Fst. The envelopes gathering the domestic Ovis aries breeds were drawn according to the six regions defined in Table 1. The Asian Mouflon Ovis gmelini anatolica was treated separately.

Figure 2

Cluster analysis from the phylogenetic analysis using Newick Extra according to the geographical distribution and tail phenotype. Wide circle: rumped tail; red circle: fat tail; green circle: fat deposit at the base of the tail; no circle: thin tail. Background color of characters: yellow: Egypt; orange: East Tropical Africa; blue: Europe; red: Western Asia; violet: Central Asia; green: Eastern Asia; white: O. gemlini anatolica and O. gmelini ophion. The breeds are noted according to the four-letter code in Table 1. The Tuj animal does not appear because it has no connection to any breed.

Figure 3

Type-2 connections between Egyptian and other breeds (77% of the total links were retained). The results are given in percentages but the sum of links for each breed is written at the top of each bar. The four-letter code of each breed is the same as in Table 1.

Figure 4

Type-2 connections between East Tropical African breeds and other breeds (around 70% of the total links were retained). The full data are presented in Supplementary Table S4. The values are given in percentages but the real sums are indicated at the top of each bar. The four-letter code of each breed is the same as in Table 1.