Fig 1.
Colonization models proposed for seabirds in the literature: Mother-satellite, Stepping-stone and Island-metapopulation.
The diagrams show source (upper case) and newly founded (lower case) colonies with arrows indicating the flow of colonizers. The models support different predictions in terms of the genetic variability and private alleles (i.e. alleles that are not found in other sampled populations) of the founder populations as shown respectively in the lower section.
Fig 2.
Location and development of the newly established colonies of Cory’s shearwaters in Galicia.
The bar charts show the number of apparently occupied burrows (AOB’s; open bars) and the number of burrows containing eggs (dark grey bars) and chicks (closed bars), in each of the newly established breeding colonies of Cory’s shearwater in Galicia (Coelleira, Sisargas and Cíes) during 2008–2014. The closed circles represent the size of the largest raft observed assembling near the colony during the main breeding season (May-August).
Table 1.
Indices of genetic diversity in Cory’s shearwater populations from Galicia (new colonies), the Atlantic and the Mediterranean.
Fig 3.
Mean number of private alleles per locus (i.e. alleles that are not found in other sampled populations) as functions of standardized sample size (g). Private alleles were analyzed using: (a) individual Atlantic colonies and the Mediterranean group (Pantaleu, Aire and Habibas); (b) four combination of colonies, Galicia (Coelleira, Sisargas and Cíes), Atlantic (Azores, Desertas, Canarias and Berlengas), Selvagens and Mediterranean (see Fig 4 for rationale underlying this grouping); (c) private alleles of all pair combinations of the four major breeding areas. Private allelic richness for a pair combination estimates the number of distinct alleles private to a group of populations and found in all populations in the group, thus indicative of shared ancestry.
Table 2.
Pairwise FST values for microsatellites of Cory´s shearwaters (above diagonal) and distances in km (below diagonal) from 11 breeding localities in the Atlantic and the western Mediterranean.
Fig 4.
Population genetic structure of Cory’s shearwater.
(a) Factorial correspondence analysis performed on pairwise allele frequency differences using GENETIX v.4. (b) Population-level neighbour-joining tree based on FST across the 10 loci with per cent bootstrap support (10,000 replicates) shown at nodes. (c) Inferred ancestry (Q-matrix) of the two genetic clusters (red: Atlantic cluster; blue: Mediterranean cluster) for populations (upper panel) and individuals (lower panel) estimated by permutation from ten Structure analyses for individuals and populations, respectively, using Clumpp.
Fig 5.
Assignment of Galician individuals to potential source populations.
(a-c) Discriminant Analysis of Principal Components (DAPC in adegenet) on Cory’s shearwater populations using three main reference areas (Core Atlantic, Selvagens and Mediterranean): (a) Scatter plot of individuals used as reference and groups as inertia ellipses according with two discriminant functions, representing 93% of variance (x-axis: first discriminant function [DF1], 66% of variance, y-axis: second discriminant function [DF2], 27% of variance); (b) Scatter plot of individuals from the three Galician colonies; (c) Number of individuals assigned to the main reference areas; (d) Heat plot of assignment probabilities of Cory’s shearwaters captured at the newly established Galician colonies. Each column represents an individual (50 females and 53 males) and colour the probability to be assigned to a reference population as estimated by GeneClass2. Probability was calculated independently for each population by Monte-Carlo resampling.
Fig 6.
Morphometric comparison of Galician Cory´s shearwaters with those from populations elsewhere.
(a) Bivariate plot of wing length against tarsus length comparing the measurements of Cory’s shearwaters sampled in Galicia (Cíes, Sisargas and Coelleira) with the average values of Atlantic (red ovals) and Mediterranean (blue ovals) populations. Ovals are centered on the mean and the length of their axes is equal to one standard deviation. (b) Relationship between body size estimated as the first principal component (PC1) of a PCA analysis and the loadings in the first discriminant function (DF1) of the DAPC performed on microsatellite data (see Fig 5). Arrows indicate the two females assigned to the Mediterranean genetic cluster by the DAPC.
Table 3.
Tracking data collected during the breeding period (from pre-laying to chick-rearing) in different colonies of Cory’s shearwaters of the Atlantic Ocean and the Mediterranean Sea.
Fig 7.
Individual tracks of the 11 Cory´s shearwaters that visited Galician waters to forage during the breeding season.
White stars correspond to the main breeding colonies where tracking studies have been conducted. Telemetry data was collected on the islands of (1) Corvo, (2) Graciosa, (3) Faial, (4) Santa Maria, (5) Berlenga, (6) Porto Santo, (7) Deserta, (8) Selvagem Grande, (9) Alegranza, (10) La Palma, (11) El Hierro, (12) Gran Canaria and, (13) Chafarinas. Black stars represent the three newly established breeding areas of (14) Coelleira, (15) Sisargas and (16) Cíes in Galicia. Four individuals from Berlenga (black), three from Porto Santo (blue) and two from Deserta (red) and one from Santa Maria (green) foraged off Galicia. See Table 3 for further details.