Microsatellites reveal high population viscosity and limited dispersal in the ant Formica paralugubris

We used microsatellites to study the fine-scale genetic structure of a highly polygynous and largely uni-colonial population of the ant Formica paralugubris. Genetic data indicate that long-distance gene flow between established nests is limited and new queens are primarily recruited from within their natal nest. Most matings occur between nestmates and are random at this level. In the center of the study area, budding and permanent connections between nests result in strong population viscosity, with close nests being more similar generically than distant nests. In contrast, nests located outside of this supercolony show no isolation by distance, suggesting that they have been initiated by queens that participated in mating flights rather than by budding from nearby nests in our sample population. Recruitment of nestmates as new reproductive individuals and population viscosity in the supercolony increase genetic differentiation between nests. This in turn inflates relatedness estimates among worker nestmates (r = 0.17) above what is due to close pedigree links. Local spatial genetic differentiation may favor the maintenance of altruism when workers raise queens that will disperse on foot and compete with less related queens from neighboring nests or disperse on the wing and compete with unrelated queens.

Genetic variability of a population of Aedes aegypti from Paraná, Brazil, using the mitochondrial ND4 gene

Genetic variability of a population of Aedes aegypti from Paraná, Brazil, using the mitochondrial ND4 gene. To analyze the genetic variability of populations of Aedes aegypti, 156 samples were collected from 10 municipalities in the state of Paraná, Brazil. A 311 base pairs (bp) region of the NADH dehydrogenase subunit 4 (ND4) mitochondrial gene was examined. An analysis of this fragment identified eight distinct haplotypes. The mean genetic diversity was high (h = 0.702; p = 0.01556). AMOVA analysis indicated that most of the variation (67%) occurred within populations and the F ST value (0.32996) was highly significant. F ST values were significant in most comparisons among cities. The isolation by distance was not significant (r = -0.1216 and p = 0, 7550), indicating that genetic distance is not related to geographic distance. Neighbor-joining analysis showed two genetically distinct groups within Paraná. The DNA polymorphism and AMOVA data indicate a decreased gene flow in populations from Paraná, which can result in increased vectorial competence.

Inbreeding and sex-biased gene flow in the ant Formica exsecta.

The objective of this study was to assess breeding and dispersal patterns of both males and females in a monogyne (a single queen per colony) population of ants. Monogyny is commonly associated with extensive nuptial flights, presumably leading to considerable gene flow over large areas. Opposite to these expectations we found evidence of both inbreeding and sex-biased gene flow in a monogyne population of Formica exsecta. We found a significant degree of population subdivision at a local scale (within islands) for queens (females heading established colonies) and workers, but not for colony fathers (the males mated to the colony queens). However, we found little evidence of population subdivision at a larger scale (among islands). More conclusive support for sex-biased gene flow comes from the analysis of isolation by distance on the largest island, and from assignment tests revealing differences in female and male philopatry. The genetic similarity between pairs of queens decreased significantly when geographical distance increased, demonstrating limited dispersal and isolation by distance in queens. By contrast, we found no such pattern for colony fathers. Furthermore, a significantly greater fraction of colony queens were assigned as having originated from the population of residence, as compared to colony fathers. Inbreeding coefficients were significantly positive for workers, but not for mother queens. The queen-male relatedness coefficient of 0.23 (regression relatedness) indicates that mating occurs between fairly close relatives. These results suggest that some monogyne species of ants have complex dispersal and mating systems that can result in genetic isolation by distance over small geographical scales. More generally, this study also highlights the importance of identifying the relevant scale in analyses of population structure and dispersal.

Genetic differentiation in Silene dioica metapopulations: estimation of spatiotemporal effects in a successional plant species

Silene dioica is a diploid, dioecious, perennial, insect-pollinated herb and part of the deciduous phase of primary succession in Skeppsvik Archipelago, Gulf of Bothnia, Sweden. These islands are composed of material deposited and left underwater by melting ice at the end of the last ice age. A rapid and relatively constant rate of land uplift of 0.9 cm per year continually creates new islands available for colonization by plants. Because the higher deposits appear first, islands differ in age. Because it is possible to estimate the ages of islands and populations of plant species belonging to early stages of succession, the genetic dynamics occurring within an age-structured metapopulation can be investigated in this archipelago. Fifty-two island populations of S. dioica of known ages, sizes, and distances from each other were studied through electrophoretic data. A number of factors increase the degree of genetic differentiation among these island populations relative to an island model at equilibrium. Newly founded populations were more differentiated than those of intermediate age, which suggests that colonization dynamics increase genetic variance among populations. The very old populations, which decrease in size as they approach extinction, were more differentiated than intermediate-aged populations. Isolation by distance occurs in this system. Colonizers are likely to come from more than one source, and the migrant pool model best explains colonization events in the archipelago. Degree of environmental exposure also affects population differentiation.

Natural selection in a postglacial range expansion: the case of the colour cline in the European barn owl.

Gradients of variation-or clines-have always intrigued biologists. Classically, they have been interpreted as the outcomes of antagonistic interactions between selection and gene flow. Alternatively, clines may also establish neutrally with isolation by distance (IBD) or secondary contact between previously isolated populations. The relative importance of natural selection and these two neutral processes in the establishment of clinal variation can be tested by comparing genetic differentiation at neutral genetic markers and at the studied trait. A third neutral process, surfing of a newly arisen mutation during the colonization of a new habitat, is more difficult to test. Here, we designed a spatially explicit approximate Bayesian computation (ABC) simulation framework to evaluate whether the strong cline in the genetically based reddish coloration observed in the European barn owl (Tyto alba) arose as a by-product of a range expansion or whether selection has to be invoked to explain this colour cline, for which we have previously ruled out the actions of IBD or secondary contact. Using ABC simulations and genetic data on 390 individuals from 20 locations genotyped at 22 microsatellites loci, we first determined how barn owls colonized Europe after the last glaciation. Using these results in new simulations on the evolution of the colour phenotype, and assuming various genetic architectures for the colour trait, we demonstrate that the observed colour cline cannot be due to the surfing of a neutral mutation. Taking advantage of spatially explicit ABC, which proved to be a powerful method to disentangle the respective roles of selection and drift in range expansions, we conclude that the formation of the colour cline observed in the barn owl must be due to natural selection.

Origin and expansion of the allotetraploid Aegilops geniculata, a wild relative of wheat.

*This study reconstructs the phylogeography of Aegilops geniculata, an allotetraploid relative of wheat, to discuss the impact of past climate changes and recent human activities (e.g. the early expansion of agriculture) on the genetic diversity of ruderal plant species. *We combined chloroplast DNA (cpDNA) sequencing, analysed using statistical parsimony network, with nonhierarchical K-means clustering of amplified fragment length polymorphism (AFLP) genotyping, to unravel patterns of genetic structure across the native range of Ae. geniculata. The AFLP dataset was further explored by measurement of the regional genetic diversity and the detection of isolation by distance patterns. *Both cpDNA and AFLP suggest an eastern Mediterranean origin of Ae. geniculata. Two lineages have spread independently over northern and southern Mediterranean areas. Northern populations show low genetic diversity but strong phylogeographical structure among the main peninsulas, indicating a major influence of glacial cycles. By contrast, low genetic structuring and a high genetic diversity are detected in southern Mediterranean populations. Finally, we highlight human-mediated dispersal resulting in substantial introgression between resident and migrant populations. *We have shown that the evolutionary trajectories of ruderal plants can be similar to those of wild species, but are interfered by human activities, promoting range expansions through increased long-distance dispersal and the creation of suitable habitats.

The evolution of unicoloniality in ant societies : recognition, dispersal and population genetic structure

Introduction Societies of ants, bees, wasps and termites dominate many terrestrial ecosystems (Wilson 1971). Their evolutionary and ecological success is based upon the regulation of internal conflicts (e.g. Ratnieks et al. 2006), control of diseases (e.g. Schmid-Hempel 1998) and individual skills and collective intelligence in resource acquisition, nest building and defence (e.g. Camazine 2001). Individuals in social species can pass on their genes not only directly trough their own offspring, but also indirectly by favouring the reproduction of relatives. The inclusive fitness theory of Hamilton (1963; 1964) provides a powerful explanation for the evolution of reproductive altruism and cooperation in groups with related individuals. The same theory also led to the realization that insect societies are subject to internal conflicts over reproduction. Relatedness of less-than-one is not sufficient to eliminate all incentive for individual selfishness. This would indeed require a relatedness of one, as found among cells of an organism (Hardin 1968; Keller 1999). The challenge for evolutionary biology is to understand how groups can prevent or reduce the selfish exploitation of resources by group members, and how societies with low relatedness are maintained. In social insects the evolutionary shift from single- to multiple queens colonies modified the relatedness structure, the dispersal, and the mode of colony founding (e.g. (Crozier & Pamilo 1996). In ants, the most common, and presumably ancestral mode of reproduction is the emission of winged males and females, which found a new colony independently after mating and dispersal flights (Hölldobler & Wilson 1990). The alternative reproductive tactic for ant queens in multiple-queen colonies (polygyne) is to seek to be re-accepted in their natal colonies, where they may remain as additional reproductives or subsequently disperse on foot with part of the colony (budding) (Bourke & Franks 1995; Crozier & Pamilo 1996; Hölldobler & Wilson 1990). Such ant colonies can contain up to several hundred reproductive queens with an even more numerous workforce (Cherix 1980; Cherix 1983). As a consequence in polygynous ants the relatedness among nestmates is very low, and workers raise brood of queens to which they are only distantly related (Crozier & Pamilo 1996; Queller & Strassmann 1998). Therefore workers could increase their inclusive fitness by preferentially caring for their closest relatives and discriminate against less related or foreign individuals (Keller 1997; Queller & Strassmann 2002; Tarpy et al. 2004). However, the bulk of the evidence suggests that social insects do not behave nepotistically, probably because of the costs entailed by decreased colony efficiency or discrimination errors (Keller 1997). Recently, the consensus that nepotistic behaviour does not occur in insect colonies was challenged by a study in the ant Formica fusca (Hannonen & Sundström 2003b) showing that the reproductive share of queens more closely related to workers increases during brood development. However, this pattern can be explained either by nepotism with workers preferentially rearing the brood of more closely related queens or intrinsic differences in the viability of eggs laid by queens. In the first chapter, we designed an experiment to disentangle nepotism and differences in brood viability. We tested if workers prefer to rear their kin when given the choice between highly related and unrelated brood in the ant F. exsecta. We also looked for differences in egg viability among queens and simulated if such differences in egg viability may mistakenly lead to the conclusion that workers behave nepotistically. The acceptance of queens in polygnous ants raises the question whether the varying degree of relatedness affects their share in reproduction. In such colonies workers should favour nestmate queens over foreign queens. Numerous studies have investigated reproductive skew and partitioning of reproduction among queens (Bourke et al. 1997; Fournier et al. 2004; Fournier & Keller 2001; Hammond et al. 2006; Hannonen & Sundström 2003a; Heinze et al. 2001; Kümmerli & Keller 2007; Langer et al. 2004; Pamilo & Seppä 1994; Ross 1988; Ross 1993; Rüppell et al. 2002), yet almost no information is available on whether differences among queens in their relatedness to other colony members affects their share in reproduction. Such data are necessary to compare the relative reproductive success of dispersing and non-dispersing individuals. Moreover, information on whether there is a difference in reproductive success between resident and dispersing queens is also important for our understanding of the genetic structure of ant colonies and the dynamics of within group conflicts. In chapter two, we created single-queen colonies and then introduced a foreign queens originating from another colony kept under similar conditions in order to estimate the rate of queen acceptance into foreign established colonies, and to quantify the reproductive share of resident and introduced queens. An increasing number of studies have investigated the discrimination ability between ant workers (e.g. Holzer et al. 2006; Pedersen et al. 2006), but few have addressed the recognition and discrimination behaviour of workers towards reproductive individuals entering colonies (Bennett 1988; Brown et al. 2003; Evans 1996; Fortelius et al. 1993; Kikuchi et al. 2007; Rosengren & Pamilo 1986; Stuart et al. 1993; Sundström 1997; Vásquez & Silverman in press). These studies are important, because accepting new queens will generally have a large impact on colony kin structure and inclusive fitness of workers (Heinze & Keller 2000). In chapter three, we examined whether resident workers reject young foreign queens that enter into their nest. We introduced mated queens into their natal nest, a foreign-female producing nest, or a foreign male-producing nest and measured their survival. In addition, we also introduced young virgin and mated queens into their natal nest to examine whether the mating status of the queens influences their survival and acceptance by workers. On top of polgyny, some ant species have evolved an extraordinary social organization called 'unicoloniality' (Hölldobler & Wilson 1977; Pedersen et al. 2006). In unicolonial ants, intercolony borders are absent and workers and queens mix among the physically separated nests, such that nests form one large supercolony. Super-colonies can become very large, so that direct cooperative interactions are impossible between individuals of distant nests. Unicoloniality is an evolutionary paradox and a potential problem for kin selection theory because the mixing of queens and workers between nests leads to extremely low relatedness among nestmates (Bourke & Franks 1995; Crozier & Pamilo 1996; Keller 1995). A better understanding of the evolution and maintenance of unicoloniality requests detailed information on the discrimination behavior, dispersal, population structure, and the scale of competition. Cryptic genetic population structure may provide important information on the relevant scale to be considered when measuring relatedness and the role of kin selection. Theoretical studies have shown that relatedness should be measured at the level of the `economic neighborhood', which is the scale at which intraspecific competition generally takes place (Griffin & West 2002; Kelly 1994; Queller 1994; Taylor 1992). In chapter four, we conducted alarge-scale study to determine whether the unicolonial ant Formica paralugubris forms populations that are organised in discrete supercolonies or whether there is a continuous gradation in the level of aggression that may correlate with genetic isolation by distance and/or spatial distance between nests. In chapter five, we investigated the fine-scale population structure in three populations of F. paralugubris. We have developed mitochondria) markers, which together with the nuclear markers allowed us to detect cryptic genetic clusters of nests, to obtain more precise information on the genetic differentiation within populations, and to separate male and female gene flow. These new data provide important information on the scale to be considered when measuring relatedness in native unicolonial populations.

Extreme population differentiation in vulnerable slavemaking ant with fragmented distribution

Understanding levels of population differentiation and inbreeding are important issues in conservation biology, especially for social Hymenoptera with fragmented and small population sizes. Isolated populations are more vulnerable to genetic loss and extinction than those with extended continuous distributions. However, small populations are not always a consequence of a recent reduction of their habitat. Thus, determining the history of population isolation and current patterns of genetic variation of a species is crucial for its conservation. Rossomyrmex minuchae is a slave-making ant with patchy distribution in South Eastern Spain and is classified as vulnerable by the IUCN. In contrast, the other three known species of the genus are presumed to show more uniform distributions. Here we investigate the genetic diversity and population structure of R. minuchae and compare it with that found in two other species of the genus: R. anatolicus and R. quandratinodum. We conclude that although genetic diversity of R. minuchae is low, there is no evidence of a recent bottleneck, suggesting a gradual and natural fragmentation process. We also show extreme population differentiation at nuclear and mitochondrial markers, and isolation by distance at a local scale. Despite some evidence for inbreeding and low genetic variation within populations, we found almost no diploid males, a finding which contrasts with that expected in inbred Hymenoptera with single locus complementary sex determination. This could mean that sex is determined by another mechanism. We argue that continued low population size means that detrimental effects of inbreeding and low genetic variation are likely in the future. We suggest that a policy of artificial gene flow aimed at increasing within population variation is considered as a management option.

Variable queen number in ant colonies: no impact on queen turnover, inbreeding, and population genetic differentiation in the ant Formica selysi.

Variation in queen number alters the genetic structure of social insect colonies, which in turn affects patterns of kin-selected conflict and cooperation. Theory suggests that shifts from single- to multiple-queen colonies are often associated with other changes in the breeding system, such as higher queen turnover, more local mating, and restricted dispersal. These changes may restrict gene flow between the two types of colonies and it has been suggested that this might ultimately lead to sympatric speciation. We performed a detailed microsatellite analysis of a large population of the ant Formica selysi, which revealed extensive variation in social structure, with 71 colonies headed by a single queen and 41 by multiple queens. This polymorphism in social structure appeared stable over time, since little change in the number of queens per colony was detected over a five-year period. Apart from queen number, single- and multiple-queen colonies had very similar breeding systems. Queen turnover was absent or very low in both types of colonies. Single- and multiple-queen colonies exhibited very small but significant levels of inbreeding, which indicates a slight deviation from random mating at a local scale and suggests that a small proportion of queens mate with related males. For both types of colonies, there was very little genetic structuring above the level of the nest, with no sign of isolation by distance. These similarities in the breeding systems were associated with a complete lack of genetic differentiation between single- and multiple-queen colonies, which provides no support for the hypothesis that change in queen number leads to restricted gene flow between social forms. Overall, this study suggests that the higher rates of queen turnover, local mating, and population structuring that are often associated with multiple-queen colonies do not appear when single- and multiple-queen colonies still coexist within the same population, but build up over time in populations consisting mostly of multiple-queen colonies.

How a haemosporidian parasite of bats gets around: the genetic structure of a parasite, vector and host compared.

Parasite population structure is often thought to be largely shaped by that of its host. In the case of a parasite with a complex life cycle, two host species, each with their own patterns of demography and migration, spread the parasite. However, the population structure of the parasite is predicted to resemble only that of the most vagile host species. In this study, we tested this prediction in the context of a vector-transmitted parasite. We sampled the haemosporidian parasite Polychromophilus melanipherus across its European range, together with its bat fly vector Nycteribia schmidlii and its host, the bent-winged bat Miniopterus schreibersii. Based on microsatellite analyses, the wingless vector, and not the bat host, was identified as the least structured population and should therefore be considered the most vagile host. Genetic distance matrices were compared for all three species based on a mitochondrial DNA fragment. Both host and vector populations followed an isolation-by-distance pattern across the Mediterranean, but not the parasite. Mantel tests found no correlation between the parasite and either the host or vector populations. We therefore found no support for our hypothesis; the parasite population structure matched neither vector nor host. Instead, we propose a model where the parasite's gene flow is represented by the added effects of host and vector dispersal patterns.

The role of geography and ecology in shaping repeated patterns of morphological and genetic differentiation between European minnows (Phoxinus phoxinus) from the Pyrenees and the Alps

Neutral and selective processes c an drive repeated patterns of evolu tion in dif ferent groups of populationsexp eriencing similar ecol ogica l gradients. In this paper, we used a combinat ion of nucl ear and mitochondrialDNA markers, as well as geometric morphometrics, to investigate repeated patterns of morphological andgenetic divergence of E uropean minnows in two mountain ranges : the Pyrenees and the Al ps. Europeanminnows (Phoxinus phoxinus) are cyprinid fish i nha bitin g most freshwater bodies in Europe, including those indifferent mountain r anges that could act as major geographical barriers to gene flow. We explored patterns ofP. phoxinus phenotypic and genetic di versi fication along a gradi ent of alti tude common to the two mountainranges, and tested for isolation by distance (IBD), isolation by environment (IBE) and isolation by adaptation(IBA). The results indicated that populations from the Pyr enees a nd the Alps bel ong to two well differentiated,reciprocally monophyletic mt DNA lineages. Substantial genetic differentiation due to geographical isolationwithin and between populations from the Pyrenees and the Alps was also found using rapidly evolving AFLPsmarkers (isolation by distance or IBD), as well as morphological differences between mountain ranges. Als o,morphology varied strong ly with elevation and so did genetic differentiation to a lower extent. Despitemoderate evidence for IBE and IBA, and therefore of repeated evolution, substantial population heterogeneitywas found at the genetic level, suggesting that selection and population specific genetic drift act in concert toaffect genetic divergence.

Increased diversity of egg-associated bacteria on brown trout (Salmo trutta) at elevated temperatures.

The taxonomic composition of egg-associated microbial communities can play a crucial role in the development of fish embryos. In response, hosts increasingly influence the composition of their associated microbial communities during embryogenesis, as concluded from recent field studies and laboratory experiments. However, little is known about the taxonomic composition and the diversity of egg-associated microbial communities within ecosystems; e.g., river networks. We sampled late embryonic stages of naturally spawned brown trout at nine locations within two different river networks and applied 16S rRNA pyrosequencing to describe their bacterial communities. We found no evidence for a significant isolation-by-distance effect on the composition of bacterial communities, and no association between neutral genetic divergence of fish host (based on 11 microsatellites) and phylogenetic distances of the composition of their associated bacterial communities. We characterized core bacterial communities on brown trout eggs and compared them to corresponding water samples with regard to bacterial composition and its presumptive function. Bacterial diversity was positively correlated with water temperature at the spawning locations. We discuss this finding in the context of the increased water temperatures that have been recorded during the last 25 years in the study area.

Combining genetic and demographic data for the conservation of a Mediterranean habitat-forming species

The integration of ecological and evolutionary data is highly valuable for conservation planning. However, it has been rarely used in the marine realm, where the adequate design of marine protected areas (MPAs) is urgently needed. Here, we examined the interacting processes underlying the patterns of genetic structure and demographic strucuture of a highly vulnerable Mediterranean habitat-forming species (i.e. Paramuricea clavata (Risso, 1826)), with particular emphasis on the processes of contemporary dispersal, genetic drift, and colonization of a new population. Isolation by distance and genetic discontinuities were found, and three genetic clusters were detected; each submitted to variations in the relative impact of drift and gene flow. No founder effect was found in the new population. The interplay of ecology and evolution revealed that drift is strongly impacting the smallest, most isolated populations, where partial mortality of individuals was highest. Moreover, the eco-evolutionary analyses entailed important conservation implications for P. clavata. Our study supports the inclusion of habitat-forming organisms in the design of MPAs and highlights the need to account for genetic drift in the development of MPAs. Moreover, it reinforces the importance of integrating genetic and demographic data in marine conservation.

Phylogeographie und Populationsgenetik der Arten der Gattung Fosterella (Bromeliaceae) in den südamerikanischen Anden

Die tropischen Anden sind eines der artenreichsten Gebiete der Erde. Fast die Hälfte der 45.000 in diesem Gebiet vorkommenden Gefäßpflanzenarten sind in den Anden endemisch (Myers et al. 2000). Die Gattung Fosterella (Bromeliaceae) ist eine den Anden zugeordnete Pflanzengruppe, denn die meisten ihrer 31 Arten kommen in den Anden vor. Achtzehn Arten sind kleinräumige Endemiten. Fosterella hat damit Modellcharakter für diese Region. In der vorliegenden Arbeit wurde die Evolution der Gattung in Raum und Zeit mithilfe der vergleichenden Sequenzierung von sechs plastidären Loci (atpB-rbcL, matK, psbB-psbH, rpl32-trnL, rps16-trnK, rps16-Intron) und einem nukleären Marker (PHYC) untersucht. Es wurden über 90 Akzessionen von 24 Fosterella-Arten untersucht. Mit 5,6 % informativer Merkmale innerhalb der Gattung war rpl32-trnL der informativste Chloroplastenmarker. Es wurden mit den kombinierten Sequenzdaten eine Maximum Parsimony-, eine Maximum Likelihood- und eine Bayes´sche Analyse berechnet. Weiterhin wurden biogeographische und ultrametrische Untersuchungen durchgeführt. Die 6-Locus-Phylogenie zeigt eine Aufteilung der monophyletischen Gattung Fosterella in sechs Gruppen, von denen vier – die penduliflora-, weddelliana-, weberbaueri- und micrantha-Gruppe - klar monophyletisch und gut gestützt sind. Die albicans- und die rusbyi-Gruppe bilden hingegen einen Komplex. Ultrametrische Analysen legen ein Alter der Gattung von ca. 9,6 Mio. Jahren nahe. Der geographische Ursprung von Fosterella befindet sich nach den vorliegenden biogeographischen Analysen in den Anden und nach der Biom-Analyse zu gleicher Wahrscheinlichkeit entweder in andinen Trockenwäldern (seasonally dry tropical forests, SDTFs) oder in azonalen Standorten des amazonischen Tieflands östlich der Anden. Es gab mehrere Ausbreitungsereignisse, von denen die beiden Fernausbreitungsereignisse nach Mittelamerika (F. micrantha) und in das zentrale Amazonasgebiet (F. batistana) die auffälligsten sind. Die feuchten Bergregenwälder (Yungas) der Anden wurden offenbar mehrfach unabhängig von Fosterella-Arten besiedelt. Insgesamt wurden elf nukleäre Marker (XDH, GS, RPB2, MS, ADH, MS, GLO/PI, CHS, FLO/LFY, NIAi3 und PHYC) auf ihre Anwendbarkeit für molekularsystematische Studien in Fosterella getestet. Davon konnten acht Marker erfolgreich mithilfe einer PCR amplifiziert werden. Die Fragmentgrößen lagen zwischen 350 bp und 1.500 bp. Nur für drei Loci (FLO/LFY, NIAi3 und PHYC) konnten lesbare DNA-Sequenzen in Fosterella erzeugt werden. FLO/LFY zeigte nur 1,5 % Variabilität innerhalb der Gattung. Der NIA-Locus erzeugte bei der Amplifikation mehrere Fragmente, die separat voneinander sequenziert wurden. Der Locus PHYC konnte hingegen aufgrund der guten Amplifizier- und Sequenzierbarkeit für das gesamte Probenset sequenziert werden. Dieser Marker zeigte eine Variabilität innerhalb der Gattung von 10,2 %, davon waren 6,8 % informativ. In der Phylogenie basierend auf PHYC ist Fosterella klar monophyletisch, innerhalb der Gattung zeigt sich jedoch an der Basis eine unaufgelöste Polytomie. Es lassen sich neun mehr oder weniger gut gestützte Artengruppen definieren – rusbyi-, villosula-, albicans-, weddelliana-, penduliflora-, weberbaueri-, micrantha-, robertreadii- und spectabilis-Gruppe - die sich in ihrer Zusammensetzung mit Ausnahme der weddelliana-Gruppe von den nach Chloroplastendaten definierten Gruppen unterscheiden. Viele Arten sind para- oder polyphyletisch, so z. B. F. albicans, F. penduliflora und F. rusbyi. Bei den beiden erstgenannten Arten weisen die unterschiedlichen Stellungen in Chloroplasten- und Kernphylogenie auf Hybridisierungsereignisse hin.

Estudio de las variaciones espaciales y temporales de la diversidad genética de la trucha común, Salmo trutta, en ríos de la Península Ibérica

Se ha analizado las causas de la distribución espacial de la variabilidad genética del ADN mitocondrial en poblaciones de trucha común de la cuenca del Duero y de los Pirineos Orientales. En total se han analizado de novo 49 localidades, 13 en la cuenca del río Duero y 36 en los principales ríos del Pirineo oriental. Además se analizaron las fluctuaciones temporales en 14 de las localidades del Pirineo Oriental. Estudios previos indican un marcado contraste de los patrones de diversidad entre ambos territorios. En la cuenca del río Duero los análisis confirmaron la presencia de los dos linajes matriarcales descritos previamente, el linaje Atlántico (AT) y el linaje Duero (DU). Los análisis de la varianza molecular (AMOVA) siguiendo una jerarquía hidrográfica sugirieron una alta estructuración de las poblaciones coincidente con los patrones ictiológicos observados en la cuenca. El linaje DU parece haber estado presente permanentemente en la cuenca interior del Duero, mientras que las zonas más próximas a la desembocadura han padecido diversas colonizaciones de trucha del linaje AT, que reflejarían los cambios climáticos ocurridos en el Cuaternario. Se ha detectado una discrepancia en el límite entre ambos grupos definidos por genes nucleares (alozimas) y el ADN mitocondrial. Estas discrepancias pueden ser debidas a un efecto más severo de la deriva genética en el ADN mitocondrial que en los marcadores nucleares. Sin embargo, en este trabajo se han observado evidencias a favor de selección en el ADN mitocondrial del linaje DU que también explicaría estas discrepancias. El análisis más exhaustivo en las cuencas de los Pirineos orientales, permitió detectar nuevos haplotipos mitocondriales de los linajes Adriático (AD) y Mediterráneo (ME). En esta región, los AMOVAs confirmaron que las diferencias entre poblaciones dentro de río son más importantes que las diferencias entre ríos. No obstante se observó un patrón de aislamiento por distancia en toda la zona, reflejo de la estructuración de las poblaciones en la cuenca del río Ebro. Además, aunque los AMOVAs mostraron que el componente temporal de la variación es inferior al espacial, las fluctuaciones temporales en la comparación matriarcal de las poblaciones resultaron estadísticamente significativas. Estas fluctuaciones están asociadas tanto a la deriva genética como a procesos de flujo génico entre poblaciones próximas. Dentro de las cuencas, los componentes de diferenciación entre afluentes son, en general, superiores a los obtenidos dentro de cada afluente, patrón que parece estar extendido en la trucha común. Los estudios a escala microgeográfica en la Noguera Vallferrera y Noguera Cardós (afluentes del Noguera Pallaresa) reprodujeron este patrón de diferenciación. Los tamaños efectivos y la tasa de migración entre ambos ríos fueron similares a los descritos en poblaciones noratlánticas. Los tamaños efectivos de las hembras (Nef), calculados a partir del ADN mitocondrial fueron menos de la mitad del tamaño efectivo total tanto en la Noguera Vallferrera como en el resto de localidades pirenaicas estudiadas. Estos bajos tamaños efectivos de las hembras serían también responsables de las fluctuaciones temporales observadas. Los ejemplares repoblados parecen hibridar poco con los nativos, pero su presencia podría intensificar indirectamente los procesos de deriva genética y complicar la conservación de los patrimonios genéticos nativos. Con la salvedad de la existencia de selección que favorece a los haplotipos del linaje DU, los procesos poblacionales que regulan la distribución de la variabilidad genética en la cuenca del Duero y en los Pirineos Orientales podrían ser parecidos y caracterizados por la existencia de múltiples demes interconectados a lo largo del curso fluvial.