Genetic structure and phylogeography of Juniperus phoenicea complex throughout Mediterranean and Macaronesian regions: different stories in one

Abstract

The genetic structure of Juniperus phoenicea in the Mediterranean Basin is inferred using amplified fragment length polymorphism markers (AFLP) markers. As other Mediterranean conifers, J. phoenicea populations show moderate levels of genetic diversity and interpopulational differentiation. The pattern of distribution of genetic diversity seems highly influenced by the climatic fluctuations which occurred in the Pleistocene. It has been stated that the genetic structure of Mediterranean conifers is mediated by the historical climatic changes and the geological rearrangements which occurred in the Mediterranean Basin. J. phoenicea provides an excellent example to test how its genetic structure is influenced by these events. In this work, we study the amount and distribution of genetic diversity of J. phoenicea complex, in order to evaluate its taxonomic status and to reveal underlying phylogeographic patterns. The molecular diversity was analyzed for 805 individuals from 46 populations throughout its distribution range using AFLP markers. Principal coordinate analysis, analysis of molecular variance (AMOVA), and Bayesian-based analysis were applied to examine the population structure. AFLP markers revealed moderate levels of intrapopulation genetic diversity, pairwise genetic differentiation, and a clear pattern of isolation by distance. Bayesian analysis of population structure showed five clusters related to the taxonomic status of J. phoenicea and J. turbinata, and a geographic pattern of genetic structure in J. turbinata. All the analysis separate J. phoenicea from J. turbinata. For J. turbinata, up to four groups can be distinguished from a phylogeographic point of view. The genetic structure of J. turbinata seems highly influenced by climatic and geologic fluctuations occurring since the Oligocene.