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Warning coloration provides a textbook example of natural selection, but the frequent observation of polymorphism in aposematic species presents an evolutionary puzzle. We investigated biogeography and polymorphism of warning patterns in the widespread butterfly Danaus chrysippus using records from citizen science ( n = 5467), museums ( n = 8864) and fieldwork ( n = 2586). We find that polymorphism in three traits controlled by known mendelian loci is extensive. Broad allele frequency clines, hundreds of kilometres wide, suggest a balance between long-range dispersal and predation of unfamiliar morphs. Mismatched clines for the white hindwing and forewing tip in East Africa are consistent with a previous finding that the black wingtip allele has spread recently in the region through hitchhiking with a heritable endosymbiont. Light/dark background coloration shows more extensive polymorphism. The darker genotype is more common in cooler regions, possibly reflecting a trade-off between thermoregulation and predator warning. Overall, our findings show how studying local adaptation at the global scale provides a more complete picture of the evolutionary forces involved.

Spatial changes in natural selection patterns can give rise to local adaptation and genetic differentiation between populations. Local adaptation for phenological traits is pronounced in many forest tree species. The Swedish breeding program was established from ‘plus’ trees selected across the country and can therefore be a very good source of information on local adaptation. In the present thesis, we estimated the genetic basis of local adaptation in two Eurasian spruce species Norway spruce (P. abies) and Siberian species (P. obovata) using large-scale whole-exome data and Sanger sequences from samples taken from the Swedish breeding program and from natural populations. To detect signals of local adaptation in Norway spruce (P. abies), we started by studying population genetic clustering and inferring the demographic history of the species. In addition to the already known three main domains in Norway spruce, we also found four genetic clusters created by admixture events between the aforementioned three main clusters. Demographic inferences indicated two recolonizations directions in Scandinavia: east to west (from central Russia and Siberia) and south to north (from Alpine and Carpathian), but also revealed repeated hybridization between P. abies and P. obovata and gene flow among clusters. We next estimated the genetic basis of local adaptation of three phenotypic traits (height, diameter and bud-burst) by multivariate analyses and genome-wide association studies. The results showed that geographical origin is a strong predictor of growth and phenology and trees of southern origins outcompeted local provenances. We further revealed that growth traits were highly polygenic and bud-burst somewhat less. Population genetic structure largely affects the detection of local adaptation. Therefore we further visualized the fine-scale map of population genetic structure through dense sampling of trees from the Swedish breeding program. Trees of Swedish origins were assigned into two main clusters with an admixture zone in central Sweden and the genetic contribution from P. obovata was detected in northern Sweden. A large number of SNPs were found to be associated with environmental variables and exhibited a stronger pattern of isolation-by-distance than random SNPs. Finally we tested for local adaptation in two well-defined candidate genes (FTL2 and GI) of phenology in P. obovata. Clinal variation in FTL2 gene expression, growth cessation, and allele frequency of FLT2 and GI were revealed in populations along Ob River, paralleling the ones in Norway spruce populations in Scandinavia and in Siberian spruce populations along the Yenisei River.

New species form through the evolution of genetic barriers to gene flow between previously interbreeding populations. The understanding of how speciation proceeds is hampered by our inability to follow cases of incipient speciation through time. Comparative approaches examining different diverging taxa may offer limited inferences, unless they fulfill criteria that make the comparisons relevant. Here, we test for those criteria in a recent adaptive radiation of the Rhagoletis pomonella species group (RPSG) hypothesized to have diverged in sympatry via adaptation to different host fruits. We use a large-scale population genetic survey of 1568 flies across 33 populations to: (1) detect on-going hybridization, (2) determine whether the RPSG is derived from the same proximate ancestor, and (3) examine patterns of clustering and differentiation among sympatric populations. We find that divergence of each in-group RPSG taxon is occurring under current gene flow, that the derived members are nested within the large pool of genetic variation present in hawthorn-infesting populations of R. pomonella, and that sympatric population pairs differ markedly in their degree of genotypic clustering and differentiation across loci. We conclude that the RPSG provides a particularly robust opportunity to make direct comparisons to test hypotheses about how ecological speciation proceeds despite on-going gene flow.

Background Lodgepole pine (Pinus contorta) and interior spruce (Picea glauca, Picea engelmannii, and their hybrids) are distantly related conifer species. Previous studies identified 47 genes containing variants associated with environmental variables in both species, providing evidence of convergent local adaptation. However, if the intensity of purifying selection varies with the environment, clines in nucleotide diversity could evolve through linked (background) selection that would yield allele frequency-environment signatures resembling local adaptation. If similar geographic patterns in the strength of purifying selection occur in these species, this could result in the convergent signatures of local adaptation, especially if the landscape of recombination is conserved. In the present study, we investigated whether spatially/environmentally varying purifying selection could give rise to the convergent signatures of local adaptation that had previously reported. Results We analyzed 86 lodgepole pine and 50 interior spruce natural populations spanning heterogeneous environments in western Canada where previous analyses had found signatures of convergent local adaptation. We estimated nucleotide diversity and Tajima’s D for each gene within each population and calculated the strength of correlations between nucleotide diversity and environmental variables. Overall, these estimates in the genes with previously identified convergent local adaptation signatures had no similar pattern between pine and spruce. Clines in nucleotide diversity along environmental variables were found for interior spruce, but not for lodgepole pine. In spruce, genes with convergent adaption signatures showed a higher strength of correlations than genes without convergent adaption signatures, but there was no such disparity in pine, which suggests the pattern in spruce may have arisen due to a combination of selection and hybridization. Conclusions The results rule out purifying/background selection as a driver of convergent local adaption signatures in lodgepole pine and interior spruce. Electronic supplementary material The online version of this article (10.1186/s12862-019-1438-8) contains supplementary material, which is available to authorized users.

International audience; Secondary contact zones are natural systems which can be efficiently used to measure genetic differentiation and gene flow and thus provide a good opportunity to assess the level of reproductive isolation between divergent evolutionary lineages. In this study, we used ten Z-linked and nine autosomal loci from seven chromosomes and twenty males to evaluate gene flow across a secondary contact zone between two mitochondrial lineages of the Eurasian Green Woodpecker (Picus viridis), that diverged around 1 million years ago. One lineage (Picus viridissharpei) is distributed throughout the Iberian Peninsula whereas the other one (Picus viridisviridis) is widespread across the Western Palearctic. These two lineages form a secondary contact zone in southern France. Formerly treated as two subspecies of Picus viridis, several authors have recently proposed assigning a specific rank to P. viridis sharpei and P. viridis viridis. Our results indicate no introgression of nuclear loci in allopatric populations located on both sides of the contact zone, which thus acts as an efficient barrier to gene flow. All males sampled within the contact zone and one male sampled near its eastern border were slightly admixed revealing that reproductive isolation between P. viridissharpei and P viridis viridis has not been completely achieved. In accordance with the geographical range of each lineage, the two admixed males sampled near the western border of the contact zone harboured a large proportion of P. viridissharpei alleles whereas admixed males sampled eastwardly near the Rhone Valley had a high proportion of P. viridis viridis alleles. Overall our results further support considering P. viridissharpei and P. viridisviridis as two biological species.

International audience; Environmental gradients can help us comprehend the range of adaptations or plasticity that a given species can exhibit in response to climatic change. In this study, we assessed the response in female body size, clutch size and egg volume to elevational gradients in closely related wolf spiders. We measured these traits in Pardosa glacialis, P. hyperborea, P. furcifera and P. palustris, collected along elevational gradients across six sites in Arctic and sub-Arctic regions (four sites in Greenland, one in Iceland and one in the Faroe Islands), although not all species were found at all sites. Body size and reproductive traits did not vary with elevation in a consistent manner among species although smaller species were more sensitive to the gradients. The positive relationship between body size and clutch size was most pronounced in the larger species, indicating that larger species are better able to translate favourable environmental conditions into a larger reproductive output. Our study illustrates that elevational gradients may not fully capture spatial variation in environmental conditions experienced by high-latitude wolf spider species.

La variación de características morfométricas de Apis mellifera fue estudiada en 4 estaciones a lo largo de un gradiente altitudinal (986 a 2621 m de elevación) en la Cordillera Oriental colombiana. Se analizó si las partes corporales seleccionadas siguen o no la regla de Bergmann, que indica una asociación positiva entre la masa corporal de especies y la latitud (altitud) en la que habitan. Pese al buen volumen de estudios al respecto, pocos analizan los cambios proporcionales entre las partes del cuerpo a lo largo de los gradientes o si las partes siguen una variación homogénea. La variación corporal de A. mellifera fue analizada mediante un análisis multivariado de varianza (MANOVA) y la relación entre cada medida morfométrica y la altitud mediante análisis de regresión. El MANOVA indicó diferencias significativas entre los sitios, donde al incrementar la altitud se observó un aumento en el tamaño de las partes corporales estudiadas, especialmente en las estructuras de vuelo: largo y ancho del ala delantera, ancho del ala trasera y el ancho del basitarsus. La vena cubital 1 mantuvo su tamaño al aumentar la altura, al igual que el número de hamuli, excepto para las abejas de la última estación (2621 m). El peso seco del cuerpo mostró un crecimiento a medida que aumentó la altitud hasta los 2014 m, pero a los 2621 m decreció significativamente. Se encontró una variación clinal positiva en la mayoría de las características morfométricas ligadas al vuelo y algunos apéndices. Sin embargo, el largo del cuerpo, ancho de la cabeza, índice cubital, vena cubital 2 y el largo del ala trasera se mantuvieron constantes en todas las altitudes, exceptuando un incremento significativo a los 2621 m de elevación. Los resultados se asociaron con que a una menor presión atmosférica y menor densidad del aire se puede reducir el potencial de vuelo, lo que puede dar como resultado una relación positiva en el tamaño de las alas y una relación negativa con el peso corporal en las abejas que viven en las partes altas de la montaña. Se concluye que estos insectos son afectados por más variables que las citadas en la regla de temperatura-tamaño de Bergmann y que los cambios morfométricos se podrían dar por razones más complejas. The variation of morphometric characteristics of Apis mellifera was studied in 4 stations along an altitudinal gradient (986 to 2621 m elevation) in the Colombian East Mountain Range. It was analyzed whether or not the selected body parts follow the Bergmann rule, which indicates a positive association between the body mass of species and the latitude (altitude) in which they inhabit. Despite the good volume of studies in this respect, few analyze the proportional changes between the parts of the body along the gradients or if the parts follow a homogeneous variation. The body variation of A. mellifera was analyzed by a multivariate analysis of variance (MANOVA) and the relationship between each morphometric measure and altitude by regression analysis. The MANOVA indicated significant differences between the sites, where increasing the altitude showed an increase in the size of the body parts studied, especially in the flight structures: length and width of the front wing, width of the rear wing and width of the basitarsus. The length of cubital vein 1 remained unchanged as the height increased, as did the number of hamuli, except for the bees of the last station (2621 m). The dry weight of the body showed a growth as the altitude increased until 2014 m, but at 2621 m it decreased significantly. A positive clinal variation was found in most of the morphometric characteristics linked to flight and some appendices. However, the length of the body, head width, cubital index, cubital vein 2 and the length of the hind wing remained constant at all altitudes, except for a significant increase at 2621 m elevation. The results were associated with the fact that at lower atmospheric pressure and air density, the flight potential can be reduced, which can result in an increase in the size of the wings and a reduction in body weight in the bees that live in the high mountain. In conclusion these insects are affected by more variables than those cited in the Bergmann temperature-size rule and that morphometric changes could occur for more complex reasons Magíster en Ciencias Biológicas Maestría

It has been widely suggested that invasion success along broad environmental gradients may be partially due to phenotypic plasticity, but rapid evolution could also be a relevant factor for invasions. Seed and fruit traits can be relevant for plant invasiveness since they are related to dispersal, germination, and fitness. Some seed traits vary along environmental gradients and can be heritable, with the potential to evolve by means of natural selection. Utilizing cross-latitude and reciprocal-transplant experiments, we evaluated the adaptive value of seed thickness as assessed by survival and biomass accumulation in Taraxacum officinale plants. In addition, thickness of a seed and Endosperm to Seed Coat Proportion (ESCP) in a second generation (F2) was measured to evaluate the heritability of this seed trait. On the other hand, we characterized the genetic variability of the sampled individuals with amplified fragment length polymorphism (AFLP) markers, analyzing its spatial distribution and population structure. Overall, thickness of seed coat (plus wall achene) decreases with latitude, indicating that individuals of T. officinale from northern populations have a thicker seed coat than those from southern populations. Germination increased with greater addition of water and seeds from southern localities germinated significantly more than those from the north. Additionally, reciprocal transplants showed significant differences in survival percentage and biomass accumulation among individuals from different localities and moreover, the high correlation between maternal plants and their offspring can be suggesting a high grade of heritability of this trait. Although genetic differentiation was found when was considered all populations, there was no significant differentiation when only was compared the northernmost populations which inhabit in the driest climate conditions. Our results suggest that climatic conditions could affect both, the ESCP and the genetic variability in the invasive T. officinale, suggesting that this seed trait could be indicative of adaptive selection. Thus, colonization along broad geographical gradients in many cases may be the result –in part- for the presence of functional traits as shown in invasive plant species with rapid adaptive capacity.

Common seals Phoca vitulina give birth in the Wadden Sea area during the summer months. We provide evidence that the pupping season has advanced in date in this region. Analysis of stranding dates of recently-born, orphaned pups admitted for rehabilitation, revealed a shift of, on average, 0.88 days per year over the period 1974–2008, yielding a total advance of 26 days. Although the pupping season has become progressively earlier, there were no indications of any negative impact on the weight of the pups, nor was there an increase in the proportion of seals with a lanugo coat. These observations suggest that the most likely explanation for the change in phenology of the pupping season is a corresponding change in the timing of cessation of the period of delayed implantation. It is suggested that shifts in phenology could reflect an adaptive response of the animals to altered local circumstances. The latter may in turn be induced by larger scale phenomena such as food availability or climate change.

Here we provide the first detailed description of the hybrid zone between the Cremona chromosomal race of house mouse (ICRE; 2n = 22) and the standard all-telocentric race (40ST; 2n = 40), with full karyotypes of 106 individuals from 17 localities along a transect between the 2 races to the west of Lake Garda in Northern Italy. The ICRE race is characterised by 9 pairs of metacentric chromosomes in a homozygous state and we use the metacentric frequency data along the transect to fit tanh metacentric clines. The clines are narrow (5–8 km, standardised width) suggesting low hybrid fitness. However, the lack of occurrence of ICRE × 40ST F1 hybrids and presence of other hybrid types suggests that the F1 hybrids initially produced in this hybrid zone were at least partially fertile, despite having 9 meiotic trivalent configurations. We apply the same cline-fitting methodology to 3 previously studied hybrid zones between metacentric races and the 40ST race. Taken together with published clinal data on 4 further metacentric-40ST hybrid zones, we are able to make objective generalisations on the characteristics of such zones in the house mouse. Zones involving 22-chromosome races are narrower, on average, than other metacentric-40ST hybrid zones and do not show a tendency towards the generation of new races as found with zones where the metacentric race has a higher 2n. It appears that metacentric-40ST zones are unlikely to be sites of speciation (even when a 22-chromosome race is involved), although a mosaic structure to the hybrid zone may enhance this possibility. We make a comparison between metacentric-40ST zones and contacts between 2 metacentric races, for a comprehensive perspective of chromosomal hybrid zones in the house mouse.

Variation among natural populations of Culex (Culex) quinquefasciatus Say is associated with different vectorial capacities. The species Cx. quinquefasciatus is present in the equatorial, tropical and subtropical zones in the Brazilian territory, with intermediate forms between Cx. quinquefasciatus and Culex pipiens occurring in regions of latitudes around 33°-35° S. Herein, we studied geographically distinct populations of Cx. quinquefasciatus by genetic characterization and analysis of intra-specific wing morphometrics. After morphological analysis, molecular characterization of Cx. quinquefasciatus and intermediate forms was performed by polymerase chain reaction of the polymorphic nuclear region of the second intron of the acetylcholinesterase locus. Additionally, the morphology of adult female wings collected from six locations was analyzed. Wing centroid sizes were significantly different between some geographical pairs. Mean values of R2/R2+3 differed significantly after pairwise comparisons. The overall wing shape represented by morphometric characters could be divided into two main groupings. Our data suggest that Brazilian samples are morphologically and genetically distinct from the Argentinean samples and also indicated a morphological distinction between northern and southern populations of Brazilian Cx. quinquefasciatus. We suggest that wing morphology may be used for preliminary assessment of population structure of Cx. quinquefasciatusin Brazil.

Chromosomal polymorphism for the third chromosome in Drosophila pseudoobscura has been widely studied for genetic variation in different environments or locations far apart. However, there is less information regarding sites geographically near one another. Targeting on possible micro-geographic variation in the species, a serial study was done on 12 Mexican populations grouped in four regions, including locations in Durango (DU), the border area of Guanajuato-San Luis Potosi states (GP), Chiapas (CH) and Saldilo (SA). Flies were trapped in their natural habitats using fermenting bananas as bait. They were individually cultivated in the laboratory for larvae production. In a given population sample several flies were cultivated together but only one larva per culture provided salivary tissue to observe polytene chromosomes. Gene arrangements or inversions were identified and frequencies were calculated. A total of 767 third chromosomes were studied and 11 different inversions detected. The type and relative frequencies of the arrangements varied among regions. From the 11 inversions observed, 10 were found in Durango, five in Guanajuato-San Luis Potosi and Chiapas, and eight in Saltillo. The inversion frequencies in the Durango locations varied in four cases, but only one in Chiapas, three cases in Guanajuato-San Luis Potosi, and five in Saltillo. It was also observed that there were geographical gradients for inversions within regions as follows: four arrangements in Saltillo and Durango, three in Guanajuato-San Luis Potos? and one in Chiapas. Moreover, all four regions studied showed evidences for micro-geographical variation. Nevertheless, more studies are needed to elucidate the relevance of the inversion frequencies changes in neighboring populations and also any seasonal-annual frequencies observed in the locations studied here.

Clinal variation across replicated environmental gradients can reveal evidence of local adaptation, providing insight into the demographic and evolutionary processes that shape intraspecific diversity. Using 1773 genome-wide single nucleotide polymorphisms we evaluated latitudinal variation in allele frequency for 134 populations of North American and European Atlantic salmon (Salmo salar). We detected 84 (4.74%) and 195 (11%) loci showing clinal patterns in North America and Europe, respectively, with 12 clinal loci in common between continents. Clinal single nucleotide polymorphisms were evenly distributed across the salmon genome and logistic regression revealed significant associations with latitude and seasonal temperatures, particularly average spring temperature in both continents. Loci displaying parallel clines were associated with several metabolic and immune functions, suggesting a potential basis for climate-associated adaptive differentiation. These climate-based clines collectively suggest evidence of large-scale environmental associated differences on either side of the North Atlantic. Our results support patterns of parallel evolution on both sides of the North Atlantic, with evidence of both similar and divergent underlying genetic architecture. The identification of climate-associated genomic clines illuminates the role of selection and demographic processes on intraspecific diversity in this species and provides a context in which to evaluate the impacts of climate change.

The early period of genetics is closely associated with the study of chromosomal inversions. For almost a century, evolutionary biologists found evidence for the role of inversions in central processes such as adaptation and speciation. In spite of huge efforts, many questions remain about the evolutionary forces underlying the distribution and dynamics of inversions in natural populations. Fortunately, old problems can be solved with new tools. In this issue, Kapun et al. (2014) present a remarkable combination of resources and techniques, including publicly available data, karyotyping, statistical estimation of haplotypes, Pool-Seq data and experimental evolution, setting the ground for exciting developments in the field. © 2014 John Wiley & Sons Ltd.

International audience; Discriminating closely related species can become a taxonomical challenge if a clear morphological diagnosis is lacking. Two subspecies have been recognized in Pardosa agrestis (Westring, 1861); however, their validity is still debated. To resolve this dilemma, quantitative and qualitative traits were measured for 30 females and 30 males per site from ten localities throughout Western Europe (11 measurements on each individual) and compared between subspecies. Mean annual temperature and geographical coordinates from all sites were also included in the statistical models in order to test for variations in size over the distribution range of each subspecies. We found significant differences in body size and size of copulatory organs as well as accurate criteria of discrimination between P. a. agrestis and P. a. purbeckensis F.O.P. Cambridge, 1895, suggesting that these taxa are two valid morphological species, occurring sympatrically. We also showed that temperatures did not directly influence the size of individuals, but that one species had smaller individuals at higher latitudes (following the converse Bergmann's rule), and that both species had larger individuals in centrally sampled populations (fitting to the centre hypothesis). (C) 2014 The Linnean Society of London

This thesis deals with the invasion biology of the western corn rootworm, (WCR) in Europe. Multiple introductions of this pest in Europe from the United States and the 90’s, led to the formation of two main invasive outbreaks, genetically differentiated and located in Northwest Italy (NW Italy) and in Central and South-Eastern Europe (CSE Europe). Both outbreaks converged towards each other and came into contact in 2008, in the region of Veneto (Northern Italy). The main objective of these three years of research was to detect study and document a precise case of hybridization during a biological invasion. First of all, I showed that the contact zone detected in Veneto results in a hybrid zone. For that, several types of population genetics analyses were performed using microsatellite markers. In a second time, I exploited this hybrid zone and used the theory of neutral clines and the linkage disequilibrium to estimate dispersal (σ) of WCR in Northern Italy around 20 km.generation-1/2. Finally I showed the absence of impact of hybridization in the european invasion of WCR in natura, by measuring on hybrid and parental genotypes, numerous phenotypic traits positively associated to the fitness of individuals. Thus, a selection or a selection against hybrids is excluded in this particular case of hybridization and the invasion dynamics of WCR in Europe should not be affected in any way.; Cette thèse s’inscrit dans le contexte de la biologie de l’invasion de la chrysomèle des racines du maïs, Diabrotica virgifera virgifera (Dvv), en Europe. Les introductions multiples de cette peste sur le vieux continent à partir des années 1990 et en provenance des États-Unis ont conduit à la formation de plusieurs foyers envahissants dont deux principaux, différenciés génétiquement et situés en Italie du Nord-Ouest (Italie NO) et en Europe Centrale et du Sud-Est (Europe CSE). Ces deux foyers sont entrés en contact en 2008, en Italie du Nord, dans la région de la Vénétie. L’objectif principal de ces trois années de recherche était de détecter, d’étudier et de documenter un cas précis d’hybridation au cours d’une invasion biologique. Dans un premier temps, j'ai montré que la zone de contact détectée en Vénétie résultait bien en une zone hybride. Pour cela plusieurs types d’analyses de génétique des populations ont été réalisés à l’aide de marqueurs micro-satellites. Dans un second temps, j'ai exploité cette zone hybride et utilisé la théorie des clines neutres et le déséquilibre de liaison pour estimer la dispersion (σ) de Dvv en Italie du Nord aux alentours de 20 km.génération−1/2. Enfin j'ai montré l’absence d'impact de l’hybridation au cours de l’invasion européenne de Dvv in natura, en mesurant sur des génotypes hybrides et parentaux, de nombreux traits phénotypiques positivement liés à la fitness des individus. Ainsi, une sélection ou contre sélection des hybrides est à exclure dans ce cas précis d’hybridation et la dynamique de l’invasion de cette peste en Europe ne devrait être affectée en aucune façon.

This thesis deals with the invasion biology of the western corn rootworm, (WCR) in Europe. Multiple introductions of this pest in Europe from the United States and the 90’s, led to the formation of two main invasive outbreaks, genetically differentiated and located in Northwest Italy (NW Italy) and in Central and South-Eastern Europe (CSE Europe). Both outbreaks converged towards each other and came into contact in 2008, in the region of Veneto (Northern Italy). The main objective of these three years of research was to detect study and document a precise case of hybridization during a biological invasion. First of all, I showed that the contact zone detected in Veneto results in a hybrid zone. For that, several types of population genetics analyses were performed using microsatellite markers. In a second time, I exploited this hybrid zone and used the theory of neutral clines and the linkage disequilibrium to estimate dispersal (σ) of WCR in Northern Italy around 20 km.generation-1/2. Finally I showed the absence of impact of hybridization in the european invasion of WCR in natura, by measuring on hybrid and parental genotypes, numerous phenotypic traits positively associated to the fitness of individuals. Thus, a selection or a selection against hybrids is excluded in this particular case of hybridization and the invasion dynamics of WCR in Europe should not be affected in any way.; Cette thèse s’inscrit dans le contexte de la biologie de l’invasion de la chrysomèle des racines du maïs, Diabrotica virgifera virgifera (Dvv), en Europe. Les introductions multiples de cette peste sur le vieux continent à partir des années 1990 et en provenance des États-Unis ont conduit à la formation de plusieurs foyers envahissants dont deux principaux, différenciés génétiquement et situés en Italie du Nord-Ouest (Italie NO) et en Europe Centrale et du Sud-Est (Europe CSE). Ces deux foyers sont entrés en contact en 2008, en Italie du Nord, dans la région de la Vénétie. L’objectif principal de ces trois années de recherche était de détecter, d’étudier et de documenter un cas précis d’hybridation au cours d’une invasion biologique. Dans un premier temps, j'ai montré que la zone de contact détectée en Vénétie résultait bien en une zone hybride. Pour cela plusieurs types d’analyses de génétique des populations ont été réalisés à l’aide de marqueurs micro-satellites. Dans un second temps, j'ai exploité cette zone hybride et utilisé la théorie des clines neutres et le déséquilibre de liaison pour estimer la dispersion (σ) de Dvv en Italie du Nord aux alentours de 20 km.génération−1/2. Enfin j'ai montré l’absence d'impact de l’hybridation au cours de l’invasion européenne de Dvv in natura, en mesurant sur des génotypes hybrides et parentaux, de nombreux traits phénotypiques positivement liés à la fitness des individus. Ainsi, une sélection ou contre sélection des hybrides est à exclure dans ce cas précis d’hybridation et la dynamique de l’invasion de cette peste en Europe ne devrait être affectée en aucune façon.

All species demonstrate intraspecific anatomical variation. While generalisations such as Bergman's and Allen's rules have attempted to explain the geographic structuring of variation with some success, recent work has demonstrated limited support for these in certain Old World monkeys. This study extends this research to the baboon: a species that is widely distributed across sub-Saharan Africa and exhibits clinal variation across an environmentally disparate range. This study uses trend surface analysis to map the pattern of skull variation in size and shape in order to visualise the main axes of morphological variation. Patterns of shape and size-controlled shape are compared to highlight morphological variation that is underpinned by allometry alone. Partial regression is used to dissociate the effects of environmental terms, such as rainfall, temperature and spatial position. The diminutive Kinda baboon is outlying in size, so analyses were carried out with and without this taxon. Skull size variation demonstrates an east–west pattern, with small animals at the two extremes and large animals in Central and Southern Africa. Shape variation demonstrates the same geographical pattern as skull size, with small-sized animals exhibiting classic paedomorphic morphology. However, an additional north–south axis of variation emerges. After controlling for skull size, the diminutive Kinda baboon is no longer an outlier for size and shape. Also, the east–west component is no longer evident and discriminant function analysis shows an increased misclassification of adjacent taxa previously differentiated by size. This demonstrates the east–west component of shape variation is underpinned by skull size, while the north–south axis is not. The latter axis is explicable in phylogenetic terms: baboons arose in Southern Africa and colonised East and West Africa to the north, diverging in the process, aided by climate-mediated isolating mechanisms. Environmental terms appear poorly correlated with shape variation compared with geography. This might indicate that there is no simple environment–morphology association, but certainly demonstrates that phylogenetic history is an overbearing factor in baboon morphological variation.

Stress resistance characters are valuable tools for the study of acclimation potential, adaptive strategies and biogeographic patterns in species exposed to environmental variability. Water stress is a challenge to terrestrial arthropods because of their small size and relatively high area: volume ratio. Fruit flies have been investigated to record adaptive morphological and physiological traits, as well as to test their responses to stressful factors. In this study, we investigate the ability to cope with water stress, by examining variation in desiccation resistance in a species that lives mainly in desert lands. Specifically, we explored the genetic and ecological basis of desiccation resistance in populations of Drosophila buzzatii from Northern Argentina. We used a common garden experiment with desiccation treatments on a number of isofemale lines from four populations along an aridity gradient. Our results revealed significant among-population differentiation and substantial amounts of genetic variation for desiccation resistance. We also detected significant genotype-by-environment and genotype-by-sex interactions indicative that desiccation resistance responses of the lines assayed were environment- and sex-specific. In addition, we observed clinal variation in female desiccation resistance along gradients of altitude, temperature and humidity; that desiccation resistance is a sexually dimorphic trait, and that sexual dimorphism increased along the aridity and altitudinal gradients. Based on current evidence, we propose that the observed sex-specific responses may reflect different life history traits, and survival and reproductive strategies in different ecological scenarios. Fil: Sassi, Paola Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentina Fil: Hasson, Esteban Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina

Introduced species frequently show geographic differentiation, and when differentiation mirrors the ancestral range, it is often taken as evidence of adaptive evolution. The mouse-ear cress (Arabidopsis thaliana) was introduced to North America from Eurasia 150–200 years ago, providing an opportunity to study parallel adaptation in a genetic model organism. Here, we test for clinal variation in flowering time using 199 North American (NA) accessions of A. thaliana, and evaluate the contributions of major flowering time genes FRI, FLC, and PHYC as well as potential ecological mechanisms underlying differentiation. We find evidence for substantial within population genetic variation in quantitative traits and flowering time, and putatively adaptive longitudinal differentiation, despite low levels of variation at FRI, FLC, and PHYC and genome-wide reductions in population structure relative to Eurasian (EA) samples. The observed longitudinal cline in flowering time in North America is parallel to an EA cline, robust to the effects of population structure, and associated with geographic variation in winter precipitation and temperature. We detected major effects of FRI on quantitative traits associated with reproductive fitness, although the haplotype associated with higher fitness remains rare in North America. Collectively, our results suggest the evolution of parallel flowering time clines through novel genetic mechanisms.

Made available in DSpace on 2022-04-28T19:53:56Z (GMT). No. of bitstreams: 0 Previous issue date: 1993-01-01 Spatial patterns of morphometric variation in Apis cerana indica were analysed. Factor and spatial autocorrelation analyses were applied to 29 characters, measured in 17 populations in India. Correlograms showed that 15 characters are patterned geographically, and 13 of them are related to overall size. These characters are distributed as a north-south cline, probably reflecting adaptations to environmental conditions. However, the great number of characteristics without geographical pattern suggests that part of the morphometric variability is due to local stochastic divergences. © 1993 International Bee Research Association. Departamento de Biologia Institute de Biociências-UNESP, CR 199, Rio Clara, Sao Paulo, CEP: 13506-900 Departamento de Biologia Institute de Biociências-UNESP, CR 199, Rio Clara, Sao Paulo, CEP: 13506-900

The inversion polymorphisms of the cactophilic Drosophila buzzatti Patterson and Wheeler (Diptera: Drosophilidae) were studied in new areas of its distribution in Argentina. A total of thirty-eight natural populations, including 29 from previous studies, were analyzed using multiple regression analyses. The results showed that about 23% of total variation was accounted for by a multiple regression model in which only altitude contributed significantly to population variation, despite the fact that latitude and longitude were also included in the model. Also, inversion frequencies exhibited significant associations with mean annual temperature, precipitation, and atmospheric pressure. In addition, expected heterozygosity exhibited a negative association with temperature and precipitation and a positive association with atmospheric pressure. The close similarity of the patterns detected in this larger dataset to previous reports is an indication of the stability of the clines. Also, the concurrence of the clines detected in Argentina with those reported for colonizing populations of Australia suggests the involvement of natural selection as the main mechanism shaping inversion frequencies in D. buzzatii. Fil: Soto, Ignacio Maria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Soto, Eduardo Maria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Carreira, Valeria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina Fil: Hurtado, Juan Pablo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Fanara, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina Fil: Hasson, Esteban Ruben. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Hauffe, Heidi Christine C/0000-0003-3098-8964; Foerster, Daniel/0000-0002-6934-0404; Searle, Jeremy/0000-0001-7710-5204; Gunduz, Islam/0000-0002-6436-5397 WOS: 000209241700003 PubMed: 24710041 In the house mouse there are numerous chromosomal races distinguished by different combinations of metacentric chromosomes. These may come into contact with each other and with the ancestral all-acrocentric race, and form hybrid zones. The chromosomal clines that make up these hybrid zones may be coincident or separated from each other (staggered). Such staggered hybrid zones are interesting because they may include populations of individuals homozygous for a mix of features of the hybridising races. We review the characteristics of four staggered hybrid zones in the house mouse and discuss whether they are examples of primary or secondary contact and whether they represent reticulate evolution or not. However, the most important aspect of staggered hybrid zones is that the homozygous populations within the zones have the potential to expand their distributions and become new races (a process termed 'zonal raciation'). In this way they can add to the total 'stock' of chromosomal races in the species concerned. Speciation is an infrequent phenomenon that may involve an unusual set of circumstances. Each one of the products of zonal raciation has the potential to become a new species and by having more races increases the chance of a speciation event. Turkish governmentTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); Natural Environment Research Council, UKNERC Natural Environment Research Council; Programme Alssan of the European UnionEuropean Union (EU); British Council; Spanish Ministerio de Ciencia y TecnologiaSpanish Government We are grateful to J. Pialek, C. Bidau, T. Panithanarak, J. Britton-Davidian, M.L. Mathias, A.C. Nunes and G. Ganem for collaborative work reported in this review. The work reported here was funded by the Turkish government (to I.G.), the Natural Environment Research Council, UK (to C.L.P., M.D.G., D.W.F., H.C.H. and J.B.S.), the Programme Alssan of the European Union (to M.D.G.), the British Council (to J.V., M.J.L.-F. and J.B.S.) and the Spanish Ministerio de Ciencia y Tecnologia (to M.A.S.-F.).

The work reported here was funded by the Turkish government (to İ.G.), the Natural Environment Research Council, UK (to C.L.P., M.D.G., D.W.F., H.C.H. and J.B.S.), the Programme Alßan of the European Union (to M.D.G.), the British Council (to J.V., M.J.L.-F. and J.B.S.) and the Spanish Ministerio de Ciencia y Tecnología (to M.A.S.-F.). In the house mouse there are numerous chromosomal races distinguished by different combinations of metacentric chromosomes. These may come into contact with each other and with the ancestral all-acrocentric race, and form hybrid zones. The chromosomal clines that make up these hybrid zones may be coincident or separated from each other (staggered). Such staggered hybrid zones are interesting because they may include populations of individuals homozygous for a mix of features of the hybridising races. We review the characteristics of four staggered hybrid zones in the house mouse and discuss whether they are examples of primary or secondary contact and whether they represent reticulate evolution or not. However, the most important aspect of staggered hybrid zones is that the homozygous populations within the zones have the potential to expand their distributions and become new races (a process termed 'zonal raciation'). In this way they can add to the total 'stock' of chromosomal races in the species concerned. Speciation is an infrequent phenomenon that may involve an unusual set of circumstances. Each one of the products of zonal raciation has the potential to become a new species and by having more races increases the chance of a speciation event.

The inversion polymorphisms of the cactophilic Drosophila buzzatti Patterson and Wheeler (Diptera: Drosophilidae) were studied in new areas of its distribution in Argentina. A total of thirty-eight natural populations, including 29 from previous studies, were analyzed using multiple regression analyses. The results showed that about 23% of total variation was accounted for by a multiple regression model in which only altitude contributed significantly to population variation, despite the fact that latitude and longitude were also included in the model. Also, inversion frequencies exhibited significant associations with mean annual temperature, precipitation, and atmospheric pressure. In addition, expected heterozygosity exhibited a negative association with temperature and precipitation and a positive association with atmospheric pressure. The close similarity of the patterns detected in this larger dataset to previous reports is an indication of the stability of the clines. Also, the concurrence of the clines detected in Argentina with those reported for colonizing populations of Australia suggests the involvement of natural selection as the main mechanism shaping inversion frequencies in D. buzzatii. Fil:Soto, I.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Soto, E.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Carreira, V.P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Hurtado, J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Fanara, J.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Hasson, E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

A number of (sub)species of Ephippiger ephippiger are analysed for geographical variation in morphological characters and allozyme frequencies. About 700 specimens from 33 sites, mainly from the southern part of France, are studied. Genetic distances are very low. All characters show clinical variation, but most clines differ from each other. It is concluded that within the material studied no species nor subspecies can be distinguished: there are only a great number of local forms without taxonomic status. The taxa E. cruciger, E. cunii and E. ephippiger moralesagacinoi have to be suppressed. Instead there is only one very polymorphic species. Traditionally this taxon should be called E. ephippiger vitium complex, but according to KRUSEMAN (1988) the name E. ephippiger diurnus Dufour 1841 should be used.

Two eucalypt clines were examined using morphological, ecophysiological and molecular analyses. The species complexes examined were an ironbark complex (Eucalyptus melanophloia x E. whitei) and a box complex (E. brownii x E. populnea). Both of these complexes demonstrate continuous morphological variation across their clines. The origin of these morphological clines has previously been interpreted as the product of secondary contact between allopatric species. In this study, an analysis of morphological variation across the clines did not identify an increase in trait variance in the intermediate populations, which suggests that previous theories concerning the origin of these clines may not be valid. Genetic structuring in nuclear and chloroplast DNA was examined across the clines to investigate whether the morphological clines were the product of secondary contact between two independent evolutionary lineages, or whether the clines represent a single evolutionary lineage that has undergone primary differentiation. The microsatellite analyses indicated that there was little genetic structuring across either cline, and that there were only low levels of population differentiation. The lack of hierarchical structuring in the distribution of nuclear genetic variation suggests that these clines are unlikely to be the product of recent gene flow between two formerly allopatric species/populations. A nested clade analysis of the JLA+ region of the cpDNA provides additional evidence to reject the null hypothesis that the morphospecies classifications represent distinct evolutionary lineages. Instead the analyses indicate that each cline represents a single cohesion species and a single evolutionary lineage. The phylogeographic distribution of cpDNA haplotypes is likely to have resulted from restricted seed mediated gene flow with isolation by distance. A more cogent explanation for the clines, based on the genetic data, is that they have arisen through the process of continuous morphological diversification that has been promoted by a directional selection gradient. Drought experiments were conducted in the glasshouse to investigate whether differences in physiological performance under water stress helps to explain the maintenance of the ironbark cline. Under increasing water stress, the morphotypes showed differences in their ability to maintain water status and photosynthetic rates, yet there was no obvious pattern to these differences across the cline. Physiological differences are therefore inadequate to explain the maintenance of the ironbark cline and highlight the compensatory role that morphological variation may play in alleviating water stress. The value of adopting the cohesion species concept and a hypothesis-testing framework to assess species status is demonstrated in this study. This framework provided a statistical approach to distinguish independent evolutionary lineages from interspecific populations and provides evidence to refute the current species status of the species complexes studied. Eucalypt classification is predominantly based on morphology, which results in taxonomic classification that may not reflect genealogical relationships. This is due to the disparity between morphological and phylogenetic relationships. I therefore suggest that current presumptions regarding the prevalence and importance of hybridisation within the genus may reflect taxonomic classification. An accurate assessment of the prevalence and importance of hybridisation requires species classification to be based on genealogical relationships.

8 páginas, 3 tablas, 3 figuras, The Atlantic Ocean-Mediterranean Sea junction has been proposed as an important phylogeographical area on the basis of concordance in genetic patterns observed at allozyme, mtDNA and microsatellite DNA markers in several marine species. This study presents microsatellite DNA data for a mobile invertebrate species in this area, the cuttlefish Sepia officinalis, allowing comparison of this relatively new class of DNA marker with previous allozyme results, and examination of the relative effects on gene flow of the Strait of Gibraltar and the Almerı´a-Oran oceanographic front. Genetic variation at seven microsatellite loci screened in six samples from NE Atlantic and Mediterranean coasts of the Iberian Peninsula was high (mean Na = 9.6, mean He = 0.725). Microsatellites detected highly significant subpopulation structuring (FST = 0.061; RST = 0.104), consistent with an isolation-by-distance model of low levels of gene flow. Distinct and significant clinal changes in allele frequencies between Atlantic and Mediterranean samples found at five out of seven loci, however indicate these results might be also consistent with an alternative model of secondary contact and introgression between previously isolated and divergent populations, as previously proposed for other marine species from the Atlantic-Mediterranean area. A pronounced ‘step’ change between SW Mediterranean samples associated with the Almerı´a-Oran front suggests this oceanographic feature may represent a contemporary barrier to gene flow., This research was partially supported by project AMB94-0371 (CICYT, Spain). MP-L was supported by a fellowship from University of Vigo (Spain).

The nature and extent of morphological variation within populations of Gammarus duebeni are examined. The exceptional tolerance of G. duebeni to salinities that encompass three orders of magnitude was known in the 19th Century, and has attracted considerable attention from physiologists and ecologists in the 20th Century, including the likelihood that populations in freshwater are distinct from those living in more saline environments. It is concluded that gradual evolution into discrete and readily distinguished subspecies is currently underway, eventually producing several new species in freshwater and saline habitats.

The Ukrainian brook lamprey Eudontomyzon mariae was collected in two streams belonging to the Sava river basin in Croatia. The great variation in morphological characters of this species is emphasized and its description is augmented. Clinal variation in the trunk myomeres, total length and the oral disc dentition is detected.

International audience; Evolution of a new gene function is a fundamental process of adaptation. Gene duplication followed by divergence due to relaxed selection on redundant copies has been viewed as the predominant mechanism involved in this process. At a macroevolutionary scale, evidence for this scenario came from the analysis of sequences of genes families. However, even if several genetic models have described the different potential microevolutionary scenario for a new function to evolve, little is really known about the initial evolutionary dynamics of such processes. We analyze such early dynamics in natural populations of the mosquito Culex pipiens polymorphic for a duplication at Ace. 1, a locus involved in insecticide resistance. The date of occurrence and the selective advantages of the duplication were estimated using frequency data. We propose a scenario where the spread of a duplication is driven, from the very beginning, by selection due to insecticide treatment.

Some characteristics of the song of a number of Ephippiger (sub) species are compared, in particular the number of syllables in the chirp. Syllable duration appears comparable in all forms studied.In E. terrestris (with E. t. bormansi and E. t. caprai included) all chirps are monosyllabic, in E. discoidalis 3-(2/5)-syllabic, in E. perforatus 5/6-syllabic and in E. provincialis the chirps are predominantly 3/5-syllabic.In the E. ephippiger diurmus complex a clinal variation exists: in northern locations monosyllabic chirps prevail, in the south of France (Pyr. orient., Aude, Herault) polysyllabic ones (Fig. 3). Just as in morphometric and allozymic characters, there are continuous transitions between populations from 1/2-syllabic to 5/6/7-syllabic chirps. None of these characters, however, vary along the same geographical lines. Therefore, neither the song structure nor other known parameters can be used to distinguish taxa within the E. ephippiger diurnus complex.E. e. vicheti generally produces polysyllabic chirps, but in this case no clinical variation is apparent.The available data are discussed in the perspective of the function and the phylogeny of the song in the Ephippigerinae.

The semilinear parabolic system that describes the evolution of the gene frequencies in the diffusion approximation for migration and selection at a multiallelic locus without dominance is investigated. The population occupies a finite habitat of arbitrary dimensionality and shape (i.e., a bounded, open domain in Rd). The selection coefficients depend on position; the drift and diffusion coefficients may depend on position. The primary focus of this paper is the dependence of the evolution of the gene frequencies on λ, the strength of selection relative to that of migration. It is proved that if migration is sufficiently strong (i.e., λ is sufficiently small) and the migration operator is in divergence form, then the allele with the greatest spatially averaged selection coefficient is ultimately fixed. The stability of each vertex (i.e., an equilibrium with exactly one allele present) is completely specified. The stability of each edge equilibrium (i.e., one with exactly two alleles present) is fully described when either (i) migration is sufficiently weak (i.e., λ is sufficiently large) or (ii) the equilibrium has just appeared as λ increases. The existence of unexpected, complex phenomena is established: even if there are only three alleles and migration is homogeneous and isotropic (corresponding to the Laplacian), (i) as λ increases, arbitrarily many changes of stability of the edge equilibria and corresponding appearance of an internal equilibrium can occur and (ii) the conditions for protection or loss of an allele can both depend nonmonotonically on λ. Neither of these phenomena can occur in the diallelic case.

The semilinear parabolic system that describes the evolution of the gene frequencies in the diffusion approximation for migration and selection at a multiallelic locus is investigated. The population occupies a finite habitat of arbitrary dimensionality and shape (i.e., a bounded, open domain in Rd). The selection coefficients depend on position and may depend on the gene frequencies; the drift and diffusion coefficients may depend on position. Sufficient conditions are given for the global loss of an allele and for its protection from loss. A sufficient condition for the existence of at least one internal equilibrium is also offered, and the profile of any internal equilibrium in the zero-migration limit is obtained.

Directional gene flow between genetically differentiated populations leads to parallel gene-frequency gradients at various loci; processes of differential selection are not expected to result in equally oriented patterns of gene frequencies. Therefore, inferences on the mechanisms maintaining genetic diversity can be drawn by comparing the directions of clines at different loci. An approach to quantifying the orientation of a cline is put forward here. The method is based on description of gene-frequency variance as a function of distance between populations, by means of directional variograms. The mean axis of the cline is then computed by averaging the directional components of variation; it can be regarded as the axis along which the frequencies of an allele vary showing the maximum degree of order. The significance of the mean axis can be tested, and the directions of two clines can be compared, using techniques developed in circular statistics. An example of application of this method to human gene frequencies is presented. Discordant clines are observed at six electrophoretically polymorphic loci in Eurasian populations. Only a fraction of such clines can be accounted for by the Neolithic radiation of early farmers in the Middle East and Europe.

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Human-mediated transport creates secondary contacts between genetically differentiated lineages, bringing new opportunities for gene exchange. When similar introductions occur in different places, they provide informally replicated experiments for studying hybridisation. We here examined 4,279 Mytilus mussels, sampled in Europe and genotyped with 77 ancestry-informative markers. We identified a type of introduced mussels, called "dock mussels," associated with port habitats and displaying a particular genetic signal of admixture between M. edulis and the Mediterranean lineage of M. galloprovincialis. These mussels exhibit similarities in their ancestry compositions, regardless of the local native genetic backgrounds and the distance separating colonised ports. We observed fine-scale genetic shifts at the port entrance, at scales below natural dispersal distance. Such sharp clines do not fit with migration-selection tension zone models, and instead suggest habitat choice and early-stage adaptation to the port environment, possibly coupled with connectivity barriers. Variations in the spread and admixture patterns of dock mussels seem to be influenced by the local native genetic backgrounds encountered. We next examined departures from the average admixture rate at different loci, and compared human-mediated admixture events, to naturally admixed populations and experimental crosses. When the same M. galloprovincialis background was involved, positive correlations in the departures of loci across locations were found; but when different backgrounds were involved, no or negative correlations were observed. While some observed positive correlations might be best explained by a shared history and saltatory colonisation, others are likely produced by parallel selective events. Altogether, genome-wide effect of admixture seems repeatable and more dependent on genetic background than environmental context. Our results pave the way towards further genomic analyses of admixture, and monitoring of the spread of dock mussels both at large and at fine spacial scales.