We used molecular approaches to study the status of speciation in coral reef fishes known as hamlets (Serranidae: Hypoplectrus). Several hamlet morphospecies coexist on Caribbean reefs, and mate assortatively with respect to their strikingly distinct colour patterns. We provide evidence that, genetically, the hamlets display characteristics common in species flocks on land and in freshwaters. Substitutions within two mitochondrial DNA (mtDNA) protein-coding genes place hamlets within a monophyletic group relative to members of two related genera (Serranus and Diplectrum), and establish that the hamlet radiation must have been very recent. mtDNA distances separating hamlet morphospecies were slight (0.6 ± 0.04%), yielding a coalescent estimate for the age of the hamlet flock of approximately 430 000 years. Morphospecies did not sort into distinct mtDNA haplotype phylogroups, and alíeles at five hypervariable microsatellite loci were shared broadly across species boundaries. None the less, molecular variation was not distributed at random. Analyses of mtDNA haplotype frequencies and nested clades in haplotype networks revealed significant genetic differences between geographical regions and among colour morphospecies. We also observed significant microsatellite differentiation between geographical regions and in Puerto Rico, among colour morphospecies; the latter providing evidence for reproductive isolation between colour morphospecies at this locale. In our Panama collection, however, colour morphospecies were mostly genetically indistinguishable. This mosaic pattern of DNA differentiation implies a complex interaction between population history, mating behaviour and geography and suggests that porous boundaries separate species in this flock of brilliantly coloured coral reef fishes.

No abstract

We isolated and characterized 11 microsatellite loci in the Mona Island iguana (Cyclura cornuta stejnegeri). Eleven loci exhibit moderate to high allelic diversity (two to 12 alleles, mean = 4.5) and polymorphism (mean observed heterozygosity, 0.56; range, 0.26 to 0.78) in 41 adults. This marker set has low probability of identity and high parentage exclusion power and will be suitable for studies of paternity, social organization and relatedness in this species.

We isolated and characterized 12 microsatellite loci from the hawksbill sea turtle (Eretmochelys imbricata). The loci exhibited a variable number of alleles that ranged from three to 14 with an average observed heterozygosity of 0.70 (SD 0.18) across 40 hawksbill turtles from the Caribbean. The polymorphism exhibited individually and in combination makes them suitable for fine-scale genetic studies. In particular, the low probability of identity and high paternity exclusion of these markers makes them highly useful for parentage and relatedness studies. These new markers greatly increase the power of genetic studies directed towards the conservation of this endangered species.

Reproduction of the fish Brotula clarkae (Pisces: Ophidiidae) in the Colombian Pacific. We studied the reproductive ecology of the fish Brotula clarkae based on 754 individuals obtained from the industrial and artisanal fisheries in the Colombian Pacific (March 1994 to December 1996. Histological sections (paraplast embedding and Harris's hematoxylin-eosin stain) were made from 151 females (26-100 cm total length). Additionally, mean diameter and particular features are described for oocyte phases and ovarian development stages. The mean size at initial sexual maturity of females was determined with two methods (graphic and statistic) in 61.3 cm and 62.3 cm respectively. The general sex ratio was 1:1.There are several spawn pulses between May and October. The mean fecundity by spawn pulse was 1 005 657 eggs. We recommend a fishing ban during the reproduction period and a minimal catch size above 62.3 cm.