Complete Mitochondrial Genome Sequences of Chinese Indigenous Sheep with Different Tail Types and an Analysis of Phylogenetic Evolution in Domestic Sheep

Convergent Evolution of Himalayan Marmot with Some High-Altitude Animals through ND3 Protein

The Himalayan marmot (Marmota himalayana) mainly lives on the Qinghai-Tibet Plateau and it adopts multiple strategies to adapt to high-altitude environments. According to the principle of convergent evolution as expressed in genes and traits, the Himalayan marmot might display similar changes to other local species at the molecular level. In this study, we obtained high-quality sequences of the CYTB gene, CYTB protein, ND3 gene, and ND3 protein of representative species (n = 20) from NCBI, and divided them into the marmot group (n = 11), the plateau group (n = 8), and the Himalayan marmot (n = 1). To explore whether plateau species have convergent evolution on the microscale level, we built a phylogenetic tree, calculated genetic distance, and analyzed the conservation and space structure of Himalayan marmot ND3 protein. The marmot group and Himalayan marmots were in the same branch of the phylogenetic tree for the CYTB gene and CYTB protein, and mean genetic distance was 0.106 and 0.055, respectively, which was significantly lower than the plateau group. However, the plateau group and the Himalayan marmot were in the same branch of the phylogenetic tree, and the genetic distance was only 10% of the marmot group for the ND3 protein, except Marmota flaviventris. In addition, some sites of the ND3 amino acid sequence of Himalayan marmots were conserved from the plateau group, but not the marmot group. This could lead to different structures and functional diversifications. These findings indicate that Himalayan marmots have adapted to the plateau environment partly through convergent evolution of the ND3 protein with other plateau animals, however, this protein is not the only strategy to adapt to high altitudes, as there may have other methods to adapt to this environment.

The genetic profiles and maternal origin of local sheep breeds on Java Island (Indonesia) based on complete mitochondrial DNA D-loop sequences

Background and Aim:

Java Island is one of the islands in Indonesia which has local sheep breeds with specific characteristics and native development geography in certain regions. This study aimed to determine the genetic profiles and maternal origin of six local sheep breeds on Java Island.

Materials and Methods:

This study was conducted by identifying the profiles of complete mitochondrial DNA (mtDNA) displacement loop (D-loop) region sequences on a total of 22 individual in six local sheep breeds on Java Island, including Javanese thin-tailed (JTT), Javanese Fat-Tailed (JFT), Batur (BTR), Wonosobo (WSB), Garut (GRT), and Priangan (PRG) sheep. The D-loop region was amplified using specific primers, and the polymerase chain reaction (PCR) was performed. The PCR products were purified and sequenced.

Results:

The mtDNA D-loop analysis identified 21 haplotypes in the analyzed 22 animals with 123 polymorphic sites (V) consisting of 60 singleton variable sites (S) and 63 parsimony informative sites (P). Within all breeds tested, the haplotype diversity, the average number of pairwise differences (K), and nucleotide diversity (Pi) were 0.99567, 25.36364, and 0.02153, respectively. The genetic distance (D) within groups and between groups was 0.001-0.006 and 0.004-0.036, respectively. The phylogeny resulted in the presence of two haplogroups (Hap), which are 5 Hap A and 16 Hap B. All JTT, JFT, BTR, and WSB breeds were in the same cluster in Hap B, whereas GRT and PRG breeds were in clusters in both Hap A and Hap B.

Conclusion:

The high genetic diversity in six local sheep breeds on Java Island suggests that they originated from different genetic sources. JTT sheep have closer genetic relationships to JFT, BTR, and WSB sheep, and they are close to European sheep, whereas GRT sheep have closer genetic relationships to PRG sheep. Both are closer to Asian sheep than to European sheep.