The colonization history of the Mediterranean dwarf palm (Chamaerops humilis L., Palmae)

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• 作者：Beatriz Guzmán ; José M. Fedriani ; Miguel Delibes ; Pablo Vargas
• 关键词：Dispersal barrier ; Haplotype ; Long ; distance dispersal ; Mediterranean region ; ptDNA ; Vicariance
• 刊名：Tree Genetics & Genomes
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：13
• 期：1
• 全文大小：
• 刊物主题：Forestry; Plant Genetics & Genomics; Plant Breeding/Biotechnology; Tree Biology; Biotechnology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1614-2950
• 卷排序：13

文摘

Chamaerops humilis L. (Mediterranean dwarf palm) is an important floristic element of the western Mediterranean region because it is the only palm species naturally distributed in both Europe and Africa. The combination of a time-calibrated phylogeny, a haplotype network and genetic diversity analyses based on plastid sequences, together with previous nuclear DNA fingerprint results, helped reconstruct the colonization history of the dwarf palm. Based on a sample of 218 individuals taken from 29 geographical areas that cover the current distribution of Chamaerops, we detected four plastid DNA (petA-psbJ) haplotypes distributed in two haplotype groups (lineage 1: haplotypes A/B; lineage 2: haplotypes C/D). Haplotypes A, B, and C showed a widespread geographical distribution in both Africa and Europe, whereas haplotype D was restricted to two African localities. Paleobotanical data, species distribution modeling and divergence time estimates suggest that Chamaerops diverged from Trachycarpus in the Miocene (27.05–6.05 Ma), followed by a split of the two C. humilis lineages that remained isolated during the Miocene-Pliocene. Divergence estimates also support a derived split into two haplotypes (A/B) in the Pleistocene, when the Mediterranean Sea barrier was in existence. This, together with geographical distribution of haplotypes A and B, strongly suggests that the disjunct distribution of C. humilis haplotypes in Europe and Africa is the result of long-distance dispersal (LDD) events rather than vicariance. In agreement with recurrent gene flow (events of LDD colonization), AMOVA revealed that most of the genetic variance was found among populations (61.52%). Irrespective of predominant plant translocations by humans or seed dispersal by natural means, our results support that current populations are the result of relatively recent contacts between Africa and Europe in the Quaternary.