Abstract Detail

Biogeography

Del Valle, Jose Carlos [1], Casimiro-Soriguer, Ines [1], Buide, M. Luisa [2], Narbona, Eduardo [3], Whittall, Justen Bryant [4].

Phylogeographic Evidence from Three Genomes and Genetic Structure in Iberian Silene: A Special Case of Speciation by Small Sea Barrier.

The Mediterranean Basin is commonly described as one of the most important hotspots of biodiversity. Geological and climate events during the Quaternary have influenced the distribution of many species, making this region the perfectly situated to examine recent biogeographic and evolutionary processes. The genus Silene Section Psammophilae includes five very morphologically similar species: S. littorea, S. adscendens, S. cambessedesii, S. stockenii, and S. psammitis. These annual species are endemic to the Iberian Peninsula and Balearic Islands (Ibiza and Formentera), yet occupy distinct edaphic habitats (e.g. maritime sands, calcareous sandstones). We investigated the phylogeographic relationships of these species using a genome skimming approach from genomic DNA sequences of 26 populations representing the range of each species’ distribution. Reference-guided assembly of primarily 250-bp paired-end Illumina reads produced the complete plastid genome (cpDNA; 156 kbp), partial mitochondrial genome (mtDNA; 74 kbp), and the nuclear ribosomal cistron (nrDNA, 6.4 kbp). Selected variable regions of the cpDNA and mtDNA assemblies were confirmed by Sanger sequencing. Geographic structure in the distribution of genetic variation was assessed with an isolation-by-distance analysis. Genetic population structuring was determined with Bayesian Analysis (Structure and Geneland) and Discriminant Analysis of Principal Components, using the genotype data from 738 single nucleotide polymorphisms distributed in the cpDNA genome. Silene cambessedesii, distributed in the Balearic Islands, is the only species that forms a monophyletic clade and shows strong genetic differentiation with respect to the remaining taxa of the Iberian Peninsula. These results contrast with those obtained for the mainland populations. In addition to incongruence among the three genomes, phylogenetic analyses are also largely incongruent with current taxonomical and ecogeographical characteristics. Only a well-supported clade of S. littorea and S. stockenii emerges from the southern region of the Iberian Peninsula. In the same way, no clear geographic clustering was revealed from these analyses. The widespread incongruence between taxonomy and phylogeographic results may arise from gene flow among species or incomplete lineage sorting, where only a speciation event like isolation to the Balearic Islands is necessary to produce agreement between taxonomy and phylogeography. Lineages that are rife with either hybridization or incomplete lineage sorting will have histories that may be difficult to resolve, even with massive amounts of data.

1 - Universidad Pablo de Olavide, Biologí­a Molecular e Ingenierí­a Bioquí­mica, Ctra. de Utrera, km 1, 41013, Sevilla, Spain, Seville, Seville, 41013, Spain
2 - University Pablo De Olavide, Ctra. De Utrera, Km 1, Sevilla, N/A, 41013, Spain
3 - Universidad Pablo De Olavide, Biología Molecular E Ingeniería Bioquímica, Carretera De Utrera Km 1, Seville, N/A, 41013, Spain
4 - Santa Clara University, Department Of Biology, 500 El Camino Real, Santa Clara, CA, 95053, USA

Keywords:
Phylogeography
speciation
Isolation by distance
Next generation sequencing
Reference-guided assembly
Silene
Sea barrier
Incomplete lineage sorting
hybridization.

Presentation Type: Oral Paper
Session: 37, Biogeography II
Location: 103/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 9:30 AM
Number: 37007
Abstract ID:607
Candidate for Awards:None