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Introgression in peripheral populations and colonization shape the genetic structure of the coastal shrub Armeria pungens.

ABSTRACT: The coastal shrub Armeria pungens has a disjunct Atlantic-Mediterranean distribution. The historic range expansion underlying this distribution was investigated using the nuclear internal transcribed spacer region, three plastid regions (namely trnL-F, trnS-fM and matK) and morphometric data. A highly diverse ancestral lineage was identified in southwest Portugal. More recently, two areas have been colonized: (1) Corsica and Sardinia, where disjunct Mediterranean populations have been established as a result of the long-distance dispersal of Portuguese genotypes, and (2) the southern part of the Atlantic range, Gulf of Cadiz, where a distinct lineage showing no genetic differentiation among populations occurs. Genetic consequences of colonization seem to have been more severe in the Gulf of Cadiz than in Corsica-Sardinia. Although significant genetic divergence is associated with low plastid diversity in the Gulf of Cadiz, in Corsica-Sardinia, the loss of plastid haplotypes was not accompanied by divergence from disjunct Portuguese source populations. In addition, in its northernmost and southernmost populations, A. pungens exhibited evidence for ancient or ongoing introgression from sympatric congeners. Introgression might have created novel genotypes able to expand beyond the latitudinal margins of the species or, alternatively, these genotypes may be the result of surfing of alleles from other species in demographic equilibrium into peripheral populations of A. pungens. Our results highlight the evolutionary significance of genetic drift following the colonization of new areas and the key role of introgression in range expansion.

SUBMITTER: Pineiro R

PROVIDER: S-EPMC3183879 | biostudies-other | 2011 Feb

REPOSITORIES: biostudies-other

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Introgression in peripheral populations and colonization shape the genetic structure of the coastal shrub Armeria pungens.

Piñeiro R R Widmer A A Aguilar J Fuertes JF Nieto Feliner G G

Heredity 20100428 2

The coastal shrub Armeria pungens has a disjunct Atlantic-Mediterranean distribution. The historic range expansion underlying this distribution was investigated using the nuclear internal transcribed spacer region, three plastid regions (namely trnL-F, trnS-fM and matK) and morphometric data. A highly diverse ancestral lineage was identified in southwest Portugal. More recently, two areas have been colonized: (1) Corsica and Sardinia, where disjunct Mediterranean populations have been establishe ...[more]

PMID: 20424642

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Project description:BACKGROUND:Apocynum venetum L. is an important medicinal plant that is mainly distributed in the coastal areas and northwest of China. In addition to its high medical and economic value, its adaptation to saline-alkali and coastal saline lands makes A. venetum an ideal candidate for use in vegetation restoration. To date, the study of A. venetum has been limited in the northwest region of China, little attention has been paid to the genetic diversity and population structure of A. venetum populations in the coastal region. Here, we performed transcriptome sequencing of total RNA from A. venetum leaves and developed efficient expressed sequence tag-simple sequence repeat (EST-SSR) markers for analyzing the genetic diversity and population structure of A. venetum in the coastal region. RESULTS:A total of 86,890 unigenes were generated after de novo assembly, and 68,751 of which were successfully annotated by searching against seven protein databases. Furthermore, 14,072 EST-SSR loci were detected and 10,243 primer pairs were successfully designed from these loci. One hundred primer pairs were randomly selected and synthesized, twelve primer pairs were identified as highly polymorphic and further used for population genetic analysis. Population genetic analyses showed that A. venetum exhibited low level of genetic diversity (mean alleles per locus, NA?=?3.3; mean expected heterozygosity, HE?=?0.342) and moderate level of genetic differentiation among the populations (genetic differentiation index, FST?=?0.032-0.220) in the coastal region. Although the contemporary (mean mc?=?0.056) and historical (mean mh?=?0.106) migration rates among the six A. venetum populations were moderate, a decreasing trend over the last few generations was detected. Bayesian structure analysis clustered six populations into two major groups, and genetic bottlenecks were found to have occurred in two populations (QG, BH). CONCLUSIONS:Using novel EST-SSR markers, we evaluated the genetic variation of A. venetum in the coastal region and determined conservation priorities based on these findings. The large dataset of unigenes and SSRs identified in our study, combining samples from a broader range, will support further research on the conservation and evolution of this important coastal plant and its related species.

Dataset Information

Introgression in peripheral populations and colonization shape the genetic structure of the coastal shrub Armeria pungens.

Publications

Introgression in peripheral populations and colonization shape the genetic structure of the coastal shrub Armeria pungens.

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