Article

Population genetic analyses of Hypoplectrus coral reef fishes provide evidence that local processes are operating during the early stages of marine adaptive radiations.

Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Balboa, Ancon, Panama.
Molecular Ecology (Impact Factor: 6.28). 04/2008; 17(6):1405-15. DOI: 10.1111/j.1365-294X.2007.03654.x
Source: PubMed

ABSTRACT Large-scale, spatially explicit models of adaptive radiation suggest that the spatial genetic structure within a species sampled early in the evolutionary history of an adaptive radiation might be higher than the genetic differentiation between different species formed during the same radiation over all locations. Here we test this hypothesis with a spatial population genetic analysis of Hypoplectrus coral reef fishes (Serranidae), one of the few potential cases of a recent adaptive radiation documented in the marine realm. Microsatellite analyses of Hypoplectrus puella (barred hamlet) and Hypoplectrus nigricans (black hamlet) from Belize, Panama and Barbados validate the population genetic predictions at the regional scale for H. nigricans despite the potential for high levels of gene flow between populations resulting from the 3-week planktonic larval phase of Hypoplectrus. The results are different for H. puella, which is characterized by significantly lower levels of spatial genetic structure than H. nigricans. An extensive field survey of Hypoplectrus population densities complemented by individual-based simulations shows that the higher abundance and more continuous distribution of H. puella could account for the reduced spatial genetic structure within this species. The genetic and demographic data are also consistent with the hypothesis that H. puella might represent the ancestral form of the Hypoplectrus radiation, and that H. nigricans might have evolved repeatedly from H. puella through ecological speciation. Altogether, spatial genetic analysis within and between Hypoplectrus species indicate that local processes can operate at a regional scale within recent marine adaptive radiations.

0 Bookmarks
 · 
60 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Marine biologists have gone through a paradigm shift, from the assumption that marine populations are largely 'open' owing to extensive larval dispersal to the realization that marine dispersal is 'more restricted than previously thought'. Yet, population genetic studies often reveal low levels of genetic structure across large geographic areas. On the other side, more direct approaches such as mark-recapture provide evidence of localized dispersal. To what extent can direct and indirect studies of marine dispersal be reconciled? One approach consists in applying genetic methods that have been validated with direct estimates of dispersal. Here, we use such an approach-genetic isolation by distance between individuals in continuous populations-to estimate the spatial scale of dispersal in five species of coral reef fish presenting low levels of genetic structure across the Caribbean. Individuals were sampled continuously along a 220-km transect following the Mesoamerican Barrier Reef, population densities were estimated from surveys covering 17 200 m(2) of reef, and samples were genotyped at a total of 58 microsatellite loci. A small but positive isolation-by-distance slope was observed in the five species, providing mean parent-offspring dispersal estimates ranging between 7 and 42 km (CI 1-113 km) and suggesting that there might be a correlation between minimum/maximum pelagic larval duration and dispersal in coral reef fishes. Coalescent-based simulations indicate that these results are robust to a variety of dispersal distributions and sampling designs. We conclude that low levels of genetic structure across large geographic areas are not necessarily indicative of extensive dispersal at ecological timescales.
    Molecular Ecology 09/2012; · 6.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The delineation of reef fish species by colora-tion is problematic, particularly for the pygmy angelfishes (genus Centropyge), whose vivid colors are sometimes the only characters available for taxonomic classification. The Lemonpeel Angelfish (Centropyge flavissima) has Pacific and Indian Ocean forms separated by approximately 3,000 km and slight differences in coloration. These disjunct populations hybridize with Eibl's Angelfish (Centropyge eibli) in the eastern Indian Ocean and the Pearl-Scaled Angelfish (Centropyge vrolikii) in the western Pacific. To resolve the evolutionary history of these species and color morphs, we employed mitochondrial DNA (mtDNA) cytochrome b and three nuclear introns (TMO, RAG2, and S7). Phylogenetic analyses reveal three deep mtDNA lineages (d = 7.0–8.3 %) that conform not to species designation or color morph but to geographic region: (1) most Pacific C. flavissima plus C. vrolikii, (2) C. flavissima from the Society Islands in French Polynesia, and (3) Indian Ocean C. flavissima plus C. eibli. In con-trast, the nuclear introns each show a cluster of closely related alleles, with frequency differences between the three geographic groups. Hence, the mtDNA phylogeny reveals a period of isolation (ca. 3.5–4.2 million years) typical of congeneric species, whereas the within-lineage mtDNA U ST values and the nuclear DNA data reveal recent or ongoing gene flow between species. We conclude that an ancient divergence of C. flavissima, recorded in the non-recombining mtDNA, was subsequently swamped by introgression and hybridization in two of the three regions, with only the Society Islands retaining the original C. flavissima haplotypes among our sample locations. Alternatively, the yellow color pattern of C. flavissima may have appeared independently in the central Pacific Ocean and eastern Indian Ocean. Regardless of how the pattern arose, C. flavissima seems to be retaining species identity where it interbreeds with C. vrolikii and C. eibli, and sexual or natural selection may help to maintain color differences despite apparent gene flow.
    Coral Reefs 01/2012; 31:839-851. · 3.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Genetic connectivity among populations is of crucial importance in conservation and management of commercial threatened species. Here, we explored genetic connectivity and diversity from 490 queen conch Strombus gigas from nine oceanic atolls within the San Andres archipelago and three coastal islands closer to the colombian continental shelf (separated by more than 600 kilometers from the Archipelago), in the Southwestern Caribbean. Genetic differentiation was analyzed using the statistic ΦST provided by an analysis of molecular variance (AMOVA) and by a spatial analysis of molecular variance (SAMOVA). Correlation between genetic and geographic distance was explored by using Mantel test. All loci were polymorphic with high number of alleles per locus and showed deficit of heterozygosity departing from Hardy-Weinberg equilibrium. We found evidence for up to four different genetic stocks without indication of isolation by distance. Based on these results, the recovery of S. gigas in the Southwest- ern Caribbean should require management considerations that address local and regional actions.
    65thConference Of The Gulf And Caribbean Fisheries Institute; 11/2012

Full-text (3 Sources)

View
16 Downloads
Available from
May 17, 2014