Firasat, S. | Search bioRxiv

bioRxiv2020

Genetic analysis confirms the presence of Dicrocoelium dendriticum in the Himalaya ranges of Pakistan.

Lancet liver flukes of the genus Dicrocoelium (Trematoda: Digenea) are recognised parasites of domestic and wild herbivores. The aim of the present study was to address a lack of knowledge of lancet flukes in the Himalaya ranges of Pakistan by characterising Dicrocoelium species collected from the Chitral valley. The morphology of 48 flukes belonging to eight host populations was examined in detail and according to published keys, they were identified as either D. dendriticum or Dicrocoelium chinensis. PCR and sequencing of fragments of ribosomal cistron DNA, and cytochrome oxidase-1 (COX-1) and NADH dehydrogenase-1 (ND-1) mitochondrial DNA from 34, 14 and 3 flukes revealed 10, 4 and 1 unique haplotypes, respectively. Single nucleotide polymorphisms in these haplotypes were used to differentiate between D. chinensis and D. dendriticum, and confirm the molecular species identity of each of the lancet flukes as D. dendriticum. Phylogenetic comparison of the D. dendriticum rDNA, COX-1 and ND-1 sequences with those from D. chinensis, Fasciola hepatica and Fasciola gigantica species was performed to assess within and between species variation and validate the use of species-specific markers for D. dendriticum. Genetic variations between D. dendriticum populations derived from different locations in the Himalaya ranges of Pakistan illustrate the potential impact of animal movements on gene flow. This work provides a proof of concept for the validation of species-specific D. dendriticum markers and is the first molecular confirmation of this parasite species from the Himalaya ranges of Pakistan. The characterisation of this parasite will allow research questions to be addressed on its ecology, biological diversity, and epidemiology.

genetics↗

bioRxiv2017

Like Sugar in Milk: Reconstructing the genetic history of the Parsi population

BackgroundThe Parsis, one of the smallest religious community in the world, reside in South Asia. Previous genetic studies on them, although based on low resolution markers, reported both Iranian and Indian ancestries. To understand the population structure and demographic history of this group in more detail, we analyzed Indian and Pakistani Parsi populations using high-resolution autosomal and uniparental (Y-chromosomal and mitochondrial DNA) markers. Additionally, we also assayed 108 mitochondrial DNA markers among 21 ancient Parsi DNA samples excavated from Sanjan, in present day Gujarat, the place of their original settlement in India.\n\nResultsOur extensive analyses indicated that among present-day populations, the Parsis are genetically closest to Middle Eastern (Iranian and the Caucasus) populations rather than their South Asian neighbors. They also share the highest number of haplotypes with present-day Iranians and we estimate that the admixture of the Parsis with Indian populations occurred [~]1,200 years ago. Enriched homozygosity in the Parsi reflects their recent isolation and inbreeding. We also observed 48% South-Asian-specific mitochondrial lineages among the ancient samples, which might have resulted from the assimilation of local females during the initial settlement.\n\nConclusionsWe show that the Parsis are genetically closest to the Neolithic Iranians, followed by present-day Middle Eastern populations rather than those in South Asia and provide evidence of sex-specific admixture from South Asians to the Parsis. Our results are consistent with the historically-recorded migration of the Parsi populations to South Asia in the 7thcentury and in agreement with their assimilation into the Indian sub-continents population and cultural milieu \"like sugar in milk\". Moreover, in a wider context our results suggest a major demographic transition in West Asia due to Islamic-conquest.

evolutionary biology↗