1) Population genetic structure of marine organisms, phylogeography, phylogeny and conservation genetics

The analysis of the population structure is fundamental to apply adequate conservation measures. In marine environments one of the main problems in management is the presence of cryptic species, either endemic or of recent invasion that can be detected using a phylogeographic approach by phylogenetic reconstruction with multiple genes. We have observed cryptic species associated to different habitats, or morphotypes (Ascideans: Clavelina sp and Pseudodistoma sp) or different distribution areas (fishes: Tripterygion tartessicum). The use of microsatellites (isolated in our group) has enabled inter- (population differentiation and isolation by distance) and intrapopulation analyses (clonality, substructure, selfrecruitment) in sponges (Crambe, Scopalina), ascidenas (Microcosmus) crustaceans (Palinurus, Liocarcinus) and fishes (Tripterygion, Serranus). Combining mitochondrial genes and microsatellite loci has proved to be a useful methodology for studying population structure in the sponge Crambe crambe and the sea turtle Careta careta. Currently we are extending the studies to other marine invertebrates and vertebrates with different dispersal capabilities such as the European spiny lobster Palinurus elephas and the invasive ascidean Microcosmus squamiger.


Staff
Dr. Marta Pascual


Postdocs
Dr. Carles Carreras


Predocs
Ferran Palero
Marc Rius
Victor Hugo García


Collaborators
Dr. Xavier Turon (Biologia Animal, Universitat de Barcelona)
Dr. Enrique Macpherson (Centre d'Estudis Avançats de Blanes, CSIC)
Dr. Pere Abelló (Institut de Ciències del Mar, CSIC)
Dr. Iosune Uriz (Centre d'Estudis Avançats de Blanes, CSIC)
Dr. Alex Aguilar (Biologia Animal, Universitat de Barcelona)
Dr. Lluís Cardona (Biologia Animal, Universitat de Barcelona)
Dr. Arnaud Estoup (Centre de Biologie et de Gestion des Populations, INRA)
Dr. David Posada (Bioquímica, Genética e Inmunología, Universidad de Vigo)
Dr. Keith Crandall (Integrative Biology, Brigham Young University)




2) Genomic structure in Drosophila subobscura

Microsatellite loci can be used as molecular markers to study processes of genomic reorganization, rates of recombination in different genomic regions and for detecting areas under selection in processes of adaptation to the laboratory conditions and to nature. In order to carry out these studies we have localized by fluorescent in-situ hybridization on polytene chromosomes the microsatellite loci isolated from a genomic library of Drosophila subobscura. The cytological positions in D. subobscura have been compared with the whole genomic sequence of two other drosophilid species, D. pseudoobscura and D. Melanogaster, available in GenBank. The mapping has allowed the use of some loci in studies on laboratory adaptation analyzing the role of drift and selection in the change of allele frequencies through time. A genetic map is currently under construction and will be compared to the cytological map which will allow to empirically detect high and low recombination areas. The localized microsatellite loci are also being used to study the role of inversions in preventing recombination as well as to analyze the associations between these loci and chromosomal rearrangements that will allow inferring the effect of selection.

D. subobscura was introduced into both North and South America just over two decades ago and then spread rapidly. Just a few years after the introduction clines for chromosomal inversion frequencies were detected in both North and South America that almost always had the same sign with latitude as in the Old World, providing experimental support for the adaptive value of this polymorphism. Two decades after the introduction wing length clines had also evolved, which largely converged on the ancestral cline in Europe, showing that the rate of morphological evolution on a continental scale is very fast. Recessive lethal genes are not randomly distributed among the chromosomal arrangements in colonizing populations. The persistence of the allelism over several years suggests that some lethal-carrying chromosomes may be heterotic. Data on microsatellite variation are consistent with a rather strong founder effect and also with the two-phase microsatellite mutational model.


Staff
Lluís Serra
Francesc Mestres
Marta Pascual
Joan Balanyà


Predocs
Pedro Arauz
Héctor Ruiz


Collaborators
Dr. Raymond  B. Huey (University of Washington, Seattle, USA)
Dr. George W. Gilchrist ( College of William and Mary, USA)
Dr. Concepció Arenas (Estadística, Universitat de Barcelona)
Dr. Arnaud Estoup (Centre de Biologie et de Gestion des Populations, INRA, France)
Pedro Fernández Iriarte (Universidad Nacional de Mar del Plata, Argentina)