extent and meaning of hybridization and introgression between Siberian spruce (Picea obovata) and Norway spruce (Picea abies): cryptic refugia as stepping stones to the west?
Boreal species were repeatedly exposed to ice ages and went through cycles of contraction and expansion while sister species alternated periods of contact and isolation. The resulting genetic structure is consequently complex, and demographic inferences are intrinsically challenging. The range of No...
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| Published in: | Molecular ecology Vol. 25; no. 12; pp. 2773 - 2789 |
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| Main Authors: | , , , , , , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
England
John Wiley & Sons, Ltd
01-06-2016
Blackwell Publishing Ltd |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Boreal species were repeatedly exposed to ice ages and went through cycles of contraction and expansion while sister species alternated periods of contact and isolation. The resulting genetic structure is consequently complex, and demographic inferences are intrinsically challenging. The range of Norway spruce (Picea abies) and Siberian spruce (Picea obovata) covers most of northern Eurasia; yet their geographical limits and histories remain poorly understood. To delineate the hybrid zone between the two species and reconstruct their joint demographic history, we analysed variation at nuclear SSR and mitochondrial DNA in 102 and 88 populations, respectively. The dynamics of the hybrid zone was analysed with approximate Bayesian computation (ABC) followed by posterior predictive structure plot reconstruction and the presence of barriers across the range tested with estimated effective migration surfaces. To estimate the divergence time between the two species, nuclear sequences from two wellâseparated populations of each species were analysed with ABC. Two main barriers divide the range of the two species: one corresponds to the hybrid zone between them, and the other separates the southern and northern domains of Norway spruce. The hybrid zone is centred on the Urals, but the genetic impact of Siberian spruce extends further west. The joint distribution of mitochondrial and nuclear variation indicates an introgression of mitochondrial DNA from Norway spruce into Siberian spruce. Overall, our data reveal a demographic history where the two species interacted frequently and where migrants originating from the Urals and the West Siberian Plain recolonized northern Russia and Scandinavia using scattered refugial populations of Norway spruce as stepping stones towards the west. |
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| Bibliography: | http://dx.doi.org/10.1111/mec.13654 Academy of Finland Japan Society for the Promotion of Science (JSPS) Appendix S1 Methods and results. Fig. S1 The correlation of summary statistics and sample sizes using the rarefaction test. Fig. S2 The tests of the most likely number of clusters in the structure analysis using SSR loci based on ∆K (Evanno et al. ) or Ln P(D) (Pritchard et al. ). Fig. S3 The posterior prediction of summary statistics based on the IA model. Fig. S4 The posterior prediction of summary statistics based on the AM model. Fig. S5 The proportion of each inferred genetic cluster for four subpopulation groups based on structure analysis (K = 4) using simulated dataset under the IA model. Fig. S6 The proportion of each inferred genetic cluster for four subpopulation groups based on structure analysis (K = 5) using simulated dataset under the IA model. Fig. S7 The proportion of each inferred genetic cluster for four subpopulation groups based on structure analysis (K = 4) using simulated dataset under the AM model. Fig. S8 The proportion of each inferred genetic cluster for four subpopulation groups based on structure analysis (K = 5) using simulated dataset under the AM model. Fig. S9 Posterior distributions for parameters estimated under the Isolation model (A) and the Isolation-with-migration model (B). Table S2 SSR loci polymorphism for all four subpopulations: ALP (pop. 1-22), NOR (pop. 23-64), HYZ (pop. 65-81), and OBR (pop. 82-102). Table S3 The mode and 95% confident interval of marginal posterior distribution for parameters estimated under the IA and AM models using 10 SSR loci. Table S4 Observed summary statistics for the total number of segregating sites (S) and confidence intervals (2.5%, 97.5%) and means for Watterson's theta (thetaW), the average number of pairwise nucleotide differences (thetaPi) and Tajima's D calculated both within Picea abies and Picea obovata and across both species. Table S5 Median parameter estimates and confidence intervals (2.5%, 97.5%) for the neural network ABC analysis on sequence data.Table S1 Summary for references of datasets of nuclear and mitochondrial (mt) DNA variation of 102 populations examined in this study. FORMAS istex:3972ACA22F3E02E552E0F7404DAF75608908C12E ark:/67375/WNG-5XKMN4JX-N BioDiversa projects Linktree and Tiptree ArticleID:MEC13654 European Commission FP7-project FORGER - No. KBBE-289119 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0962-1083 1365-294X 1365-294X |
| DOI: | 10.1111/mec.13654 |