Juniperus phoenicea - EUFORGEN European forest genetic resources programme

Genetic summary

Genetic diversity and variation

Phoenician juniper shows moderate to high genetic diversity within populations despite severe fragmentation, with most genetic variation within populations – a pattern typical of outcrossing, wind-pollinated trees (Działuk et al., 2011). High intrapopulation variability in some populations is the result of long-term persistence in multiple refugia through the Pleistocene (Boratyński et al., 2009; Sánchez-Gómez et al., 2018).

Genetic differentiation between populations is high compared with many conifers worldwide because Mediterranean conifers, including Phoenician juniper, have experienced strong historical fragmentation and isolation (Boratyński et al., 2009). Genetic differentiation in Phoenician juniper is like that in other wind-pollinated conifers, indicating effective pollen-mediated gene flow (Działuk et al., 2011). Phoenician juniper has not been extensively translocated or mass-planted, so long-distance seed movement and cultivar introgression have had little effect on the species’ genetic diversity (Boratyński et al., 2009).

Genetic distribution and clustering

Phoenician juniper is split into clear genetic clusters that reflect long-term isolation and regional differentiation. One cluster exists in the eastern Iberian Peninsula and southern France (subsp. phoenicea), and a second cluster exists on the Atlantic shores and in the Atlas Mountains (subsp. turbinata). The high genetic divergence between these two populations implies isolation persisting through the Pleistocene (Boratyński et al., 2009). Populations from the Aegean shore are also genetically distinct, further indicating spatial isolation along Mediterranean coasts during glacial cycles (Boratyński et al., 2009).

European populations of Phoenician juniper are different from African populations, a pattern possibly caused by early divergence, with low gene flow or differing mutation rates between continents (Działuk et al., 2011). The Iberian Peninsula harbours the greatest taxonomic, morphological, biochemical, and genetic diversity (Działuk et al., 2011). Some studies show significant isolation by distance (up to ~400 km) in Phoenician juniper populations, indicating spatial genetic structuring (Sánchez-Gómez et al., 2018).

Gene flow

Phoenician juniper is wind-pollinated and can have both male and female parts (Boratyński et al., 2009). While long-distance gene flow is possible, the discontinuous, very large, and fragmented range of Phoenician juniper makes gene flow infrequent between some populations and contributes to genetic differentiation (Boratyński et al., 2009; Działuk et al., 2011; Sánchez-Gómez et al., 2018).

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Further relevant genetic traits

Interspecific taxa dynamics

Phoenician juniper comprises two genetically distinguishable subspecies, subsp. phoenicea in the Iberian Peninsula, southern France, and north-western Italy, and maritime subsp. turbinata, which is widespread around the Mediterranean. Their clear genetic difference reflects long-term isolation, which has resulted in distinct coastal versus inland genetic pools across Europe (Boratyński et al., 2009; Działuk et al., 2011; Sánchez-Gómez et al., 2018).

Glacial biogeography evolution

Repeated contractions into refugia followed by postglacial recolonization, westward colonization through the Mediterranean, fragmentation during glacial maxima, and limited recolonization from isolated refugia has heavily influenced the genetic structure and genetic diversity of Phoenician juniper. Populations of the species survived in multiple, long-isolated refugia (at least two on the Iberian Peninsula and maritime mountain areas), where prolonged isolation during Pliocene/Pleistocene cooling promoted genetic divergence and created distinct morphological, biochemical, and genetic lineages (Boratyński et al., 2009; Sánchez-Gómez et al., 2018). This history explains high between-population differentiation in Phoenician juniper and the concentration of genetic diversity in the Iberian Peninsula (Boratyński et al., 2009; Sánchez-Gómez et al., 2018).

Despite fragmentation and isolation, many Phoenician juniper populations retained substantial intrapopulation diversity because refugial populations were large enough to avoid severe bottlenecks. Wind pollination and bird-mediated dispersal of seed also allowed the maintenance of genetic diversity. Genetic diversity of Phoenician juniper decreases from east to west, reflecting harsher western Quaternary climates and survival/recolonization dynamics (Działuk et al., 2011; Sánchez-Gómez et al., 2018).

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Genetic conservation

Threats

Long-term fragmentation and geographic isolation of Phoenician juniper populations have restricted gene flow and created distinct, locally adapted populations. However, recent land-use change (rural abandonment) and increasing aridity have driven expansion of juniper woodlands, enlarging population size and range in many areas. This expansion helps stabilize local populations and environments, but historical damage from rural activities and ongoing pressures (overharvesting, habitat change) remain threats to some local gene pools. (Boratyński et al., 2009; Działuk et al., 2011; García, Guichoux, and Hampe, 2018; Boratyński et al., 2009; Działuk et al., 2011).

Management

Management efforts should be aimed at protecting remnant and refugial populations, maintaining or restoring connectivity to reduce genetic isolation, monitoring genetic structure across expanding and relict stands, and reducing overharvesting and land-use conversion. Where expansion occurs on abandoned farmland or in protected areas, managers should recognize the conservation value of juniper stands while balancing landscape-scale biodiversity objectives. Ex situ collections and targeted genetic studies can support conservation-aware restoration and inform adaptive management (Boratyński et al., 2009; Działuk et al., 2011; García, Guichoux, and Hampe, 2018; Boratyński et al., 2009; Działuk et al., 2011).

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Juniperus phoenicea
Phoenician juniper

Environmental zones

Genetic summary

Genetic diversity and variation

Genetic distribution and clustering

Gene flow

Further relevant genetic traits

Interspecific taxa dynamics

Glacial biogeography evolution

Genetic conservation

Threats

Management

Further reading

References

Juniperus phoeniceaPhoenician juniper

Environmental zones

Genetic summary

Genetic diversity and variation

Genetic distribution and clustering

Gene flow

Further relevant genetic traits

Interspecific taxa dynamics

Glacial biogeography evolution

Genetic conservation

Threats

Management

Further reading

References

Juniperus phoenicea
Phoenician juniper