Map showing sample locations (red dots) of <i>Sprattus fuegensis</i>.

<p>Small map shows places named in the main text. The Tic-Toc MPA is shown in the green area.</p

Genetic Structure in a Small Pelagic Fish Coincides with a Marine Protected Area: Seascape Genetics in Patagonian Fjords

<div><p>Marine environmental variables can play an important role in promoting population genetic differentiation in marine organisms. Although fjord ecosystems have attracted much attention due to the great oscillation of environmental variables that produce heterogeneous habitats, species inhabiting this kind of ecosystem have received less attention. In this study, we used <i>Sprattus fuegensis</i>, a small pelagic species that populates the inner waters of the continental shelf, channels and fjords of Chilean Patagonia and Argentina, as a model species to test whether environmental variables of fjords relate to population genetic structure. A total of 282 individuals were analyzed from Chilean Patagonia with eight microsatellite loci. Bayesian and non-Bayesian analyses were conducted to describe the genetic variability of <i>S</i>. <i>fuegensis</i> and whether it shows spatial genetic structure. Results showed two well-differentiated genetic clusters along the Chilean Patagonia distribution (i.e. inside the embayment area called TicToc, and the rest of the fjords), but no spatial isolation by distance (IBD) pattern was found with a Mantel test analysis. Temperature and nitrate were correlated to the expected heterozygosities and explained the allelic frequency variation of data in the redundancy analyses. These results suggest that the singular genetic differences found in <i>S</i>. <i>fuegensis</i> from inside TicToc Bay (East of the Corcovado Gulf) are the result of larvae retention bya combination of oceanographic mesoscale processes (i.e. the west wind drift current reaches the continental shelf exactly in this zone), and the local geographical configuration (i.e. embayment area, islands, archipelagos). We propose that these features generated an isolated area in the Patagonian fjords that promoted genetic differentiation by drift and a singular biodiversity, adding support to the existence of the largest marine protected area (MPA) of continental Chile, which is the Tic-Toc MPA.</p></div

Bayesian clustering results from STRUCTURE and GENELAND.

<p>A) Plot shows the most likely number of clusters for the dataset. GENELAND analyses with posterior probability isoclines denoting the extent of genetic landscapes. Clusters indicated by GENELAND: B) Largest Cluster (LC) and C) Smallest Cluster (SC). Black dots represent localities analyzed in this study (represented by its respective letter) and regions with the greatest probability of inclusion are shown in white, whereas diminishing probabilities of inclusion are proportional to the degree of coloring.</p

Pairwise F_ST and R_ST indices between sampling locations.

<p>Pairwise F_ST and R_ST indices between sampling locations.</p

Redundancy analyses based on factors that show less Akaike value from ordistep analyses.

<p>P-value was 0.039 (p<0.05). Open circles correspond to each zone, which are represented with its respective letter. Red crosses represent the allelic variability in the dataset, blue arrows point in the direction of maximum correlation, and the length of the arrow varies according to the strength of the correlation. RDA axis corresponds to an ordination constraint which represents a linear combination of these variables.</p

Genetic diversity parameters per sampling location and genetic cluster in microsatellite loci of <i>Sprattus fuegensis</i>.

<p>Genetic diversity parameters per sampling location and genetic cluster in microsatellite loci of <i>Sprattus fuegensis</i>.</p

Posterior probabilities of the three most probable models for the analyses including all the factors tested.

<p>Posterior probabilities of the three most probable models for the analyses including all the factors tested.</p

Descriptive statistics of genetic variation and Fu-<i>Fs</i>, Tajima's D and Ramos-Onsis & Rozas' R₂ neutrality tests of <i>O. longicaudatus</i> sequences in Chile and Argentina.

<p><i>N</i>: Number of individuals; S: Number of segregating sites; Hd: Haplotype diversity; pi: Nucleotide diversity; Θ_G = a compound parameter representing the effective population size and substitution rate estimated under the model of growing population; g: Growth parameter (<i>t</i> = 1/μ); SD: Standard deviation.</p

GENELAND analyses with posterior probability isoclines denoting the extent of genetic landscapes.

<p>The Mediterranean (2a), the Temperate Forests (2b) and Patagonia (2c) ecoregions are recovered in the figure. To facilitate interpretation, GENELAND output has been cropped, re-scaled and superimposed over the map of Chile and Argentina where <i>O. longicaudatus</i> ranges. Black dots represent localities analyzed in this study and the limit of the LGM is also shown. Regions with the greatest probability of inclusion are indicated by white, whereas diminishing probabilities of inclusion are proportional to the degree of coloring.</p

Bayesian Skyline Plots (BSP) for each GENELAND cluster.

<p>The historical demographic trends of mitochondrial lineages in <i>Oligoryzomys longicaudatus</i> are represented. The x axis is the time in 10³ years before present; the y axis is the estimated female effective population size. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032206#pone-0032206-g004" target="_blank">Fig. 4a</a> shows the BSP for Cluster 1 Mediterranean ecoregion, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032206#pone-0032206-g004" target="_blank">Fig. 4b</a> for Cluster 2 Temperate Forests, and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032206#pone-0032206-g004" target="_blank">Fig. 4c</a> for Cluster 3 Patagonia ecoregions. The grey areas shows the Last Glacial Maximum (LGM) between 26,000 and 13,000 years <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032206#pone.0032206-Holling1" target="_blank">[20]</a>.</p