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espanolEl coral Porites sverdrupi es el unico coral escleractinio endemico del golfo de California. En las ultimas 2 decadas sus poblaciones se han restringido a 3 areas, bahia de La Paz, bahia de Loreto y bahia Concepcion. Debido a que esta especie enfrenta un elevado riesgo de extincion, existe una urgente necesidad de generar informacion biologica, ecologica y genetica que guie los esfuerzos de conservacion de la especie. Este es el primer trabajo sobre la diversidad y la conectividad genetica en la especie, para lo cual analizamos las colonias coralinas de bahia de Loreto y bahia Concepcion. Nuestros resultados muestran alta diversidad genetica en ambas poblaciones de P. sverdrupi, con una estructura genetica significativa entre ellas. Esta condicion es causada por el tiempo de duracion larval corto, el potencial de dispersion bajo entre las poblaciones y la adaptacion local. Nuestros resultados enfatizan la necesidad de realizar mas investigacion para establecer estrategias adecuadas de conservacion. EnglishThe coral Porites sverdrupi is the only scleractinian endemic to the Gulf of California. Over the last 2 decades its populations have been restricted to 3 areas, La Paz Bay, Loreto Bay, and Concepcion Bay. As this species faces a high risk of extinction, there is an urgent need for biological, ecological, and genetic information for the guidance of conservation efforts. This is the first study on genetic diversity and connectivity in the species. For this, we analyzed coral colonies from Loreto Bay and Concepcion Bay. Our results show that there is high genetic diversity in P. sverdrupi at both sites, with significant genetic structure between them. This condition is caused by a combination of short pelagic larval duration, low dispersal potential between the populations, and local adaptation. Our results emphasize the need for more research in order to establish adequate conservation strategies.

Los patrones de estructura genetica en las poblaciones marinas estan asociados a una variedad de mecanismos de dispersion y de escalas espaciales. Las especies pelagicas migratorias, como el dorado Coryphaena hippurus, reafirman la nocion de un medio ambiente marino abierto y continuo. Muchos estudios han mostrado que las especies pelagicas oceanicas tienden a ser homogeneas geneticamente a grandes escalas geograficas, solo existiendo diferenciacion entre sus limites de distribucion o entre cuencas oceanicas. En este trabajo presentamos resultados que indican heterogeneidad genetica del dorado a escalas geograficas menores a las predichas por las generalizaciones anteriores. Patrones de restriccion (RFLPs) del gen mitocondrial NADH1 produjeron niveles de estructura genetica altamente significativos (ΦST = 0.029, P = 0.004, AMOVA) entre peces de Baja California Sur (BCS), Sinaloa y Hawai, consistentes con frecuencias haplotipicas heterogeneas (P = 0.014, prueba exacta de diferenciacion genetica) y con una menor diversidad molecular en los peces muestreados en BCS Patterns of genetic structure among marine populations involve a variety of dispersal mechanisms and spatial scales. Pelagic species, such as the dolphinfish Coryphaena hippurus, epitomize the open and continuous nature of the marine environment due to their extensive migrations. Many studies have revealed that oceanic pelagic species tend to be genetically homogeneous over local and often extended geographic scales and only show levels of differentiation among extreme localities or ocean basins. Here we present genetic data suggesting genetic heterogeneity in the dolphinfish at geographic scales much smaller than those predicted by those generalizations. Mitochondrial NADH1 gene RFLPs revealed a highly significant (ΦST = 0.029, P = 0.004, AMOVA) molecular genetic structure among fish from Baja California Sur (BCS), Sinaloa and Hawaii, consistent with heterogeneous haplotype frequencies (P = 0.014, exact test of genetic differentiation) and a depressed molecular diversity in fish sampled off BCS.

We analyzed the genetic diversity and structure of three allopatric populations of the Pacific red snapper Lutjanus peru (Nichols and Murphy, 1922) by means of restriction fragment length polymorphisms of the entire mitochondrial control region (1350 bp). We found high levels of haplotype (h = 0.966) and nucleotide (π = 3.23%) diversities among the 100 organisms analyzed from Baja California Sur, Sinaloa and Jalisco (Mexico). Most of the molecular variability was detected with only one of the five restriction enzymes used (MseI). Heterogeneity analysis of haplotype frequencies was not significant (χ2 = 125.1, P > 0.25); neither were Wright's fixation index (FST = 0.0062, P = 0.140) nor its molecular analogue (ΦST = 0.0194, P = 0.056). An analysis of molecular variance (AMOVA) confirmed the absence of differentiation between peninsular and continental populations, even though it produced a marginally significant ΦST (ΦST = 0.0116, P = 0.048). No phylogeographic pattern was detected in a Neighbor-Joining gene tree. We argue that high molecular diversity levels are consistent with a large population size and that the absence of an apparent genetic structure, in the extreme north of the species distribution, suggests the action of mechanisms favoring passive larval transport among allopatric populations; although active adult migration cannot be ruled out.