Genome variation in tick infestation and cryptic divergence in Tunisian indigenous sheep

Abulgasim M. Ahbara, Médiha Khamassi Khbou, Rihab Rhomdhane, Limam Sassi, Mohamed Gharbi, Aynalem Haile, Mourad Rekik, Barbara Rischkowsky, Joram M. Mwacharo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
52 Downloads (Pure)


Background: Ticks are obligate haematophagous ectoparasites considered second to mosquitos as vectors and reservoirs of multiple pathogens of global concern. Individual variation in tick infestation has been reported in indigenous sheep, but its genetic control remains unknown. 

Results: Here, we report 397 genome-wide signatures of selection overlapping 991 genes from the analysis, using ROH, LR-GWAS, XP-EHH, and FST, of 600 K SNP genotype data from 165 Tunisian sheep showing high and low levels of tick infestations and piroplasm infections. We consider 45 signatures that are detected by consensus results of at least two methods as high-confidence selection regions. These spanned 104 genes which included immune system function genes, solute carriers and chemokine receptor. One region spanned STX5, that has been associated with tick resistance in cattle, implicating it as a prime candidate in sheep. We also observed RAB6B and TF in a high confidence candidate region that has been associated with growth traits suggesting natural selection is enhancing growth and developmental stability under tick challenge. The analysis also revealed fine-scale genome structure indicative of cryptic divergence in Tunisian sheep. Conclusions: Our findings provide a genomic reference that can enhance the understanding of the genetic architecture of tick resistance and cryptic divergence in indigenous African sheep.

Original languageEnglish
Article number167
JournalBMC Genomics
Issue number1
Early online date28 Feb 2022
Publication statusFirst published - 28 Feb 2022

Bibliographical note

© 2022. The Author(s).


  • Animals
  • Cattle
  • Genome
  • Genotype
  • Mosquito Vectors
  • Polymorphism, Single Nucleotide
  • Sheep/genetics
  • Tick Infestations/genetics


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