Comparative Study of the Phenotypic and Molecular Genetic Diversity of “Tergui” Camel Population in the Hoggar Region (South Algeria) ^†

Abstract

In the framework of the sustainable management of the genetic diversity (morphometric and molecular) of the “Tergui” camel population represented by the phenotypes (Abahou, Amelal, Alemlagh, Atelagh, and Azerghaf), surveys in the Hoggar area of 87 individuals from 11 localities were conducted in order to estimate the variability of the inter-intra-population. The morphological results provide full information about the structure of this population and demonstrate an important polymorphism. The results of the genotyping of the DNA with 20 microsatellite markers made it possible to demonstrate inter- and intra-population genetic variability characterized by a high rate of heterozygosity (Hnb) and effective alleles. The rate of heterozygosity in our phenotypes varied from 0.56 to 0.63, which is higher than that observed in foreign populations ranging from 0.537 to 0.629. A total of 169 alleles of 20 microsatellite loci were detected. The mean number of alleles per locus was 7.15, 6.15, 3.10, 4.45, and 3.25 for Abahou, Amelal, Alemlagh, Atelagh, and Azerghaf, respectively. The loci evaluation showed higher PIC values greater than 0.5, which are considered very instructive. The heterozygous values observed for all the loci analyzed were lower than expected, which could be attributed to inbreeding in the population or subdivision of the studied population into distinct breeds and phenotypes. On the other hand, the number of observed alleles is higher and has shown a frequency that exceeds 7.3%. The genetic differentiation values between the phenotypes analyzed were much lower and the level of differences accounted for 1.1% of the total genetic variation. All loci contributed to this differentiation with FST values being moderately low and similar but very significant (p < 0.001). The overall FST value was similar but slightly higher than that of 0.9%. The genetic similarity between the phenotypes and the classification methods (AFC and DACP) gave results similar to the phenotypic characteristics, and showed that they appear to be genetically very similar, thereby supporting the decision to consider them only mildly differentiated.

Published: 30 March 2023

1. Introduction

Genetic resources are the most valuable and strategically important commodity because many indigenous populations, races, and ecotypes contribute to human needs and could generate much more than they currently do. In order to ensure the sustainability of species and avoid their extinction, the study and management of biodiversity allows us to accumulate knowledge and orient towards their economic value on the genetic level and to qualify biodiversity as a potential source of permanent income on a global scale [1].

An effort has been made to determine, through the analysis of genetic diversity, the different phenotypes (ecotypes) of the “Tergui” population that have until now only been differentiated based on phenotypic appearance, geographical location, or tribal property. It was agreed that variations in the main morphological criteria, genotype, and performance that make up populations were not sufficient to describe them as “races”. This study deals with the camel’s genetic variability; its main objective is to characterize the genetic diversity of the “Tergui” camel population in the Hoggar region based on the phenotypic and molecular criteria, to analyze it within and between ecotypes, and to highlight the prospects of its exploitation in systems of sustainable livestock.

2. Material and Methods

The study was carried out throughout the Hoggar region. Initially, a pre-survey in order to select the localities, range, and degree of diversity of the phenotypes encountered with maximum representativeness was conducted [2], covering 11 localities and a part of Tamanrasset: Tamanrasset, Izernene, Asskrem, Tin-Amzi, Tarahnent, Izerzi, In-Amguel, Hirafok, Silet, and Abalessa. The morphologic methodology was based on dimensionless dimensional space, and then sampling the DNA extraction of the blood samples of 87 animals.

3. Results and Discussion

The usefulness of microsatellite and phenotypic observed in all the ecotypes (Abahou, Amellal, Alemlagh, Atelagh, and Azzerghaf) had high heterozygosity values (0.62, 0.63, 0.62, 0.59, and 0.62, respectively). The number of alleles observed is higher, and most of private alleles (55) were at very low frequencies (below 3%), although two alleles unique to Abahou population CVRL7 (292) and CMS9 (237) showed a frequency that exceeded 7.3%. Genetic differentiation values among the five analyzed camel populations are much lower, and the level of differences explained 1.1% of the total genetic variation. All loci contribute to this differentiation, with F_ST values being moderately low and similar for all of the studied systems, and yet still very significant (p < 0.001). Our overall F_ST value was similar to but slightly higher than the 0.9%. However, it was smaller than those previously found between Indian camel breeds (F_ST = 8.2%, [3] and Tunisian camel populations (F_ST = 9%), [4]. The genetic similarity between the Algerian Tergui populations was further illustrated using genetic distances, correspondence analysis, and clustering methods (DAPC). These three classical estimates are based on genetic relationships, and gave similar results. The neighbor-joining tree (DR) showed a clear subdivision of the breeds into tree main groups, each divided into subgroups, and the Azerghaf population was more closely related to Abahou–Amelal group than the Alemlagh–Atelagh group. Our estimates for the relationship of the indigenous population is similar to the one reported by the phenotypic, where it has been pointed out using characteristics (color). Furthermore, the genetic similarity of the Tergui populations was also demonstrated using the FCA and the DAPC clustering approaches. These results could be explained by the two populations being common ancestors, with an extensive gene flow between the five Tergui populations.

4. Conclusions

This study on the genetic diversity of the camel’s “Tergui” through the five phenotypes revealed great phenotypic diversity, which is due to the presence of a number of mutations with a visible effect. The genetic polymorphism was studied morphologically and molecularly. It appears the population that is geographically neighboring is genetically close, and there seems to be a significant divergence between geographically distant populations (cases of the Abahou and Azerghaf phenotypes). Moreover, the analysis as well as the genetic distances show that they appear to have a genetic kinship. The use of microsatellite markers made it possible to confirm the genetic diversity observed at the morphological level. The genotyping results presented, even though the number of loci studied is quite large, and provided an initial estimate of camel gene diversity. In addition, it shares a large genetic base, despite the appearance of regional differences with a fairly high inbreeding rate of 15%. Indeed, the population seems threatened by the lack of management of genealogies in the herds and by crossbreeding, which could lead to a change in its genetic structure towards homozygosity. It appears, then, that the lack of a livestock management program for a given type of production and the importance of the uncontrolled migration of individuals among the herds both cause a continuous flow of genes between the phenotypes.