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Aim: The mutualistic relationship between anemones and anemonefishes is one of the most iconic examples of symbiosis. However, while anemonefishes have been extensively studied in terms of genetic connectivity, such information is lacking entirely for host sea anemones. Here, we provide the first information on the broad‐scale population structure and phylogeographical patterns of three species of host sea anemone, Heteractis magnifica, Stichodactyla mertensii and Entacmaea quadricolor. We evaluate if there is concordance in genetic structure across several distinct biogeographical areas within the Indo‐Pacific region and to what extent the observed patterns may concur with those found for anemonefishes. Location: Indo‐Pacific, including the Red Sea. Taxon: Heteractis magnifica, S. mertensii and E. quadricolor Methods: Microsatellite markers and a combination of statistical methods including Bayesian clustering, isolation by distance (IBD), analysis of molecular variance (AMOVA) and principal components analysis (PCA) were used to determine population structure. The congruence among distance matrices (CADM) method was used to assess similarity in spatial genetic patterns among species. Results: Significant population structure was identified in the three host anemone species. Each species is likely composed of at least two genetic clusters corresponding to two biogeographical regions, the Red Sea and the rest of the Indo‐Pacific. Two of the three anemone species seem to be experiencing admixture where the two main clusters overlap (the Maldives). IBD analyses in the Red Sea revealed differences in gene flow among species, suggesting more limited dispersal potential for E. quadricolor than for S. mertensii and H. magnifica. Clonality is documented in S. mertensii for the first time. Main conclusions: This research documents the genetic population structure for three ecologically important host sea anemones across the Indo‐Pacific and provides valuable insights regarding their biogeography and evolution. Specifically, we found high levels of genetic divergence between populations across different biogeographical regions, suggesting different evolutionary lineages within species. At the same time, common geographical overlap of population structures suggests similar evolutionary histories among all three species. Interestingly, the observed patterns are congruent to some extent with structure reported for several anemonefish species, reflecting their close ecological association. [ABSTRACT FROM AUTHOR]

Relatively few studies have investigated the genetic population structure of sea anemones. This is particularly true for sea anemones that host some of the most iconic fishes on coral reefs, the anemonefishes. One of the main reasons for this knowledge gap is the lack of appropriate genetic markers. We developed and characterized a total of 47 novel polymorphic microsatellite markers for four host sea anemone species from the Indo-Pacific: Entacmaea quadricolor (n = 16 microsatellite markers), Heteractis magnifica (n = 8), Stichodactyla mertensii (n = 13), and Stichodactyla gigantea (n = 10). Here, we report genetic diversity statistics from two different sampling locations for each anemone species. Overall, we found that most markers were highly polymorphic. On average, we found a mean of seven alleles per locus. Observed and expected heterozygosities displayed high variation among loci, ranging from 0.033 to 0.980 and from 0.038 to 0.927, respectively. Only four loci showed deviations of Hardy-Weinberg equilibrium in both populations and were identified as having null alleles. Additionally, two pairs of loci were identified to be in linkage disequilibrium in only one population. Host anemones are highly sought after in the marine aquarium trade and are susceptible to thermal bleaching. Although most studies focus on their obligate symbionts (the anemonefish), genetic analyses of host sea anemones can expand our understanding of the biology, connectivity, and population structure of these organisms and potentially help develop conservation strategies that will aid both the host and its symbionts. [ABSTRACT FROM AUTHOR]

Summary The degree to which offspring remain near their parents or disperse widely is critical for understanding population dynamics, evolution, and biogeography, and for designing conservation actions. In the ocean, most estimates suggesting short-distance dispersal are based on direct ecological observations of dispersing individuals, while indirect evolutionary estimates often suggest substantially greater homogeneity among populations. Reconciling these two approaches and their seemingly competing perspectives on dispersal has been a major challenge. Here we show for the first time that evolutionary and ecological measures of larval dispersal can closely agree by using both to estimate the distribution of dispersal distances. In orange clownfish ( Amphiprion percula ) populations in Kimbe Bay, Papua New Guinea, we found that evolutionary dispersal kernels were 17 km (95% confidence interval: 12–24 km) wide, while an exhaustive set of direct larval dispersal observations suggested kernel widths of 27 km (19–36 km) or 19 km (15–27 km) across two years. The similarity between these two approaches suggests that ecological and evolutionary dispersal kernels can be equivalent, and that the apparent disagreement between direct and indirect measurements can be overcome. Our results suggest that carefully applied evolutionary methods, which are often less expensive, can be broadly relevant for understanding ecological dispersal across the tree of life. [ABSTRACT FROM AUTHOR]

The relatively recent fields of terrestrial landscape and marine seascape genetics seek to identify the influence of biophysical habitat features on the spatial genetic structure of populations or individuals. Over the last few years, there has been accumulating evidence for the effect of environmental heterogeneity on patterns of gene flow and connectivity in marine systems. Here, we investigate the population genetic patterns of an anemonefish, Amphiprion bicinctus, along the Saudi Arabian coast of the Red Sea. We collected nearly one thousand samples from 19 locations, spanning approximately 1500 km, and genotyped them at 38 microsatellite loci. Patterns of gene flow appeared to follow a stepping-stone model along the northern and central Red Sea, which was disrupted by a distinct genetic break at a latitude of approximately 19°N. The Red Sea is characterized by pronounced environmental gradients along its axis, roughly separating the northern and central from the southern basin. Using mean chlorophyll-a concentrations as a proxy for this gradient, we ran tests of isolation by distance ( IBD, R2 = 0.52) and isolation by environment ( IBE, R2 = 0.64), as well as combined models using partial Mantel tests and multiple matrix regression with randomization ( MMRR). We found that genetic structure across our sampling sites may be best explained by a combined model of IBD and IBE (Mantel: R2 = 0.71, MMRR: R2 = 0.86). Our results highlight the potential key role of environmental patchiness in shaping patterns of gene flow in species with pelagic larval dispersal. We support growing calls for the integration of biophysical habitat characteristics into future studies of population genetic structure. [ABSTRACT FROM AUTHOR]

Connectivity, the demographic linking of local populations through the dispersal of individuals, is one of the most poorly understood processes in population dynamics, yet has profound implications for conservation and harvest strategies. For marine species with pelagic larvae, direct estimation of connectivity remains logistically challenging and has mostly been limited to single snapshots in time. Here, we document seasonal and interannual patterns of larval dispersal in a metapopulation of the coral reef fish Amphiprion polymnus. A 3-year record of larval trajectories within and among nine discrete local populations from an area of approximately 35 km was established by determining the natal origin of settled juveniles through DNA parentage analysis. We found that spatial patterns of both self-recruitment and connectivity were remarkably consistent over time, with a low level of self-recruitment at the scale of individual sites. Connectivity among sites was common and multidirectional in all years and was not significantly influenced by seasonal variability of predominant surface current directions. However, approximately 75% of the sampled juveniles could not be assigned to parents within the study area, indicating high levels of immigrations from sources outside the study area. The data support predictions that the magnitude and temporal stability of larval connectivity decreases significantly with increasing distance between subpopulations, but increases with the size of subpopulations. Given the considerable effort needed to directly measure larval exchange, the consistent patterns suggest snapshot parentage analyses can provide useful dispersal estimates to inform spatial management decisions. [ABSTRACT FROM AUTHOR]