Patterns of genetic diversity in North Africa: Moroccan-Algerian genetic split in Juniperus thurifera subsp. africana

Asma Taib,Abdelkader Morsli,Àngel Romo,Katarzyna Sękiewicz,Łukasz Walas,Adam Boratyński,Aleksandra Chojnacka,Monika Dering

doi:10.1038/s41598-020-61525-x

Abstract

Juniperus thurifera is a key element of the forest communities in arid and semi-arid areas of the western Mediterranean. Previous genetic and morphological investigations suggested that Algerian populations are genetically more similar to European than to Moroccan populations and advocated their recognition at the variety rank. We aimed to investigate the spatial genetic structure in J. thurifera to verify the distinct character of the Algerian population in terms of the genetic breaks reported among several North African taxa. We also modelled species distributions since the Eemian to recognise the impact of past climatic changes on the current pattern of diversity and predict possible changes in species distribution in the future. Species-specific microsatellites were used in the analysis of 11 populations from Algeria, Morocco and Europe. We revealed the significant genetic distinctiveness of the Algerian populations from the Moroccan and European stands that may have important taxonomic and conservation implications. The diversity pattern revealed for J. thurifera reflects the east-west genetic splits reported among some North African plant and animal taxa and suggests an impact of shared historical processes. Additionally, modelling of the distribution allowed us to identify possible glacial refugia and their impact on the modern pattern of differentiation in J. thurifera. Reduction of species occurrence, especially in the European domain, is likely according to the future projections of the species distribution.

Highlights

Compared to the northern Mediterranean, the genetic diversity and differentiation patterns of woody species in the southern part of the region that comprises North Africa is rather poorly explored[1,2]
A comparison between the European part of the J. thurifera range and the African populations indicated that the population from Algeria had the highest significant average value of within-population diversity (Hs = 0.808; P = 0.133), but this value was not significantly higher than the other values (Table 1)
We demonstrated that Algerian populations of J. thurifera are a genetically distinct lineage (Figs. 1 and 2) and could be classified as J. thurifera var. aurasiaca, as previously suggested[35]

Summary

Introduction

Compared to the northern Mediterranean, the genetic diversity and differentiation patterns of woody species in the southern part of the region that comprises North Africa is rather poorly explored[1,2]. In some studies that were focused on the evolutionary history of the North African tree species, the distinctiveness between Moroccan and Algerian/Tunisian populations emerges recurrently. Moroccan stands of Cedrus atlantica and Alnus glutinosa are genetically distinct from the Algerian populations[7,8]. (thuriferous juniper) occurs in Europe and North Africa but the species range is greatly fragmented[13,14,15,16,17]. The morphological and genetic distinctiveness of populations from Europe and North Africa led to the recognition of the two subspecies: J. thurifera subsp. A suggestion to separate the Algerian relict populations under the name J. thurifera var. In North Africa, species exhibits population fragmentation, reduced regeneration and strong decline in Algeria[39]. Genetic responses to climate-driven environmental changes will likely be based on standing genetic diversity, which requires the maintenance of high within-population variability[41]

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Discussion

Conclusion