Fig 1.
The coastal area of Cameroon indicating the studied estuaries and major dispersal corridor and barrier to gene flow.
Map generated from Hydrography shape files obtained from the World Resource Institute (WRI) Congo Basin Forest Atlases webpage: http://www.wri.org/our-work/project/congo-basin-forests/cameroon.
Fig 2.
The coastal area of Cameroon with the 11 sites as in Table 1 and the proportions of two inferred clusters of individuals for each population.
Proportions of inferred clusters (Q-values) per population are represented as bar charts at their respective geographical locations on the map.
Table 1.
Description of the studied R. racemosa populations from the coastline of Cameroon.
Table 2.
Descriptive statistics of genetic diversity based on 11 nuclear microsatellite loci for 11 populations of Rhizophora racemosa from the Coast of Cameroon.
Fig 3.
Principal Coordinate analysis (PCoA, above) and Neighbor-joining tree (NJ tree, below).
The grouping of 11 populations of Rhizophora racemosa along the entire coast of Cameroon into 3 groups with high admixtures of populations from the Rio Del Rey Estuary and the Cameroon Estuary complex and isolation of first group of populations of the Loukondje Estuary (Kribi, site 10) and the Ntem Estuary (Campo, site 11). The second group is made-up of 2 landward populations from the Rio Del Rey Estuary (MBO, site 2 and EKO, site 1) (>75% bootstrapping). A third large group consisting of one seaward population from the Rio Del Rey Estuary (BEK, site3) and 5 other populations from the Cameroon Estuary complex (sites 5–9). Bootstrap values ≥ 75 are indicated on each node of the NJ tree and site numbers (1–11) are indicated beside the pop ID’s.
Table 3.
Analysis of Molecular Variance (AMOVA-Fst) based on a pooling of populations (Hierarchical) into estuaries and non-pooling (non-hierarchical).
Table 4.
Pairwise population genetic differentiation.
Fig 4.
Pairwise contemporary migration rates between populations based on Bayesian estimates using individual multilocus genotypes.
Fig 5.
Strong isolation by distance (IBD) among Rhizophora racemosa populations along the coast of Cameroon.
The pairwise actual genetic differentiation (Dest) increases from 0 to 7% over a direct flight geographic distance of up to 300 km), p < 0.001.
Fig 6.
Box-whisker plot of mean population pairwise Fst values between “Within” ocean current population pairs group and ‘Between’ ocean current population pairs group.
Fig 7.
Location of virtual propagules (dots) after 3 months of floating.
Virtual propagules were released hourly during the months February, March, April, September and October 2012, since these months correspond with propagule release periods for Rhizophora racemosa in the study area (personal observation). Hence, in total, 3626 virtual propagules were released in each of the locations. Author-defined release locations correspond with the localities where samples for our genetic analyses were collected, which were subsequently shifted to the closest ocean point (rectangles) to ensure the possibility of particle movement. Site numbers (1–11) are indicated beside the corresponding point.
Fig 8.
Gene flow barriers (red lines) and hypothetical barriers (Black dotted lines).
The thickness of the red line indicates the importance of the barriers based on the 3 different distance matrices (pairwise Nei’s genetic distances between populations (S3 Table), pairwise Fst, Pairwise Dest) used in the analysis.
Table 5.
Descriptive statistics of comparative genetic diversity of different estuaries.