Phylogeography and postglacial colonization routes of Ips typographus L. (Coleoptera, Scolytidae)

Ips typographus populations were analysed by enzyme electrophoresis and by sequence analysis in order to quantify the degree of population differentiation. Enzyme electrophoresis showed a high gene flow among all European populations. Analysis of single loci showed that aspartate aminotransferase-2 ( Aat-2 ) clustered the Scandinavian populations apart from the other populations whereas other enzyme loci showed no significant pattern. Analysis of mitochondrial DNA revealed eight haplotypes. The populations from Italy, Croatia and Belgium were the most polymorphic. Two haplotypes (I and II) were found in the majority of Central European populations. In the northern populations only one haplotype (I) was found. The Russian and Lithuanian populations had a particular haplotype (IV) that was not found in any of the other populations. In view of these data it is suggested that the population structure of I. typographus has been influenced by events which took place during and after the last ice age. Populations were forced into refugial areas in the south and in the area north of Moscow along with the host tree, Picea abies . P. abies had four refugial areas: the Apennine Alps, the Dinaric Alps, the Carpathian Alps and Kostroma, an area north of Moscow. With amelioration of the temperature, beetles spread after P. abies . According to the data presented here, I. typographus migrated from the Apennine and/or Dinaric Alps to the north. Whilst there is evidence for high gene flow among populations, bottleneck effects can still be detected in the north and also in the east. Beetles from the refugial area north of Moscow did not spread to Scandinavia or to the west like the host tree.     

Chloroplast DNA phylogeography of European ashes, Fraxinus sp. (Oleaceae): roles of hybridization and life history traits

We investigated range-wide phylogeographic variation in three European ash species (Fraxinus sp., Oleaceae). Chloroplast DNA (cpDNA) microsatellites were typed in the thermophilous Fraxinus angustifolia and Fraxinus ornus and the observed haplotypes and the geographic distribution of diversity were compared to cpDNA data previously obtained in the more cold-tolerant Fraxinus excelsior. We found wide-ranging haplotype sharing between the phylogenetically close F. angustifolia and F. excelsior, suggesting hybridization (i) in common glacial refuges in the Iberian Peninsula, northern Italy, the eastern and/or Dinaric Alps and the Balkan Peninsula, and/or (ii) during postglacial recolonization. The data allowed us to propose additional glacial refuges for F. angustifolia in southern Italy and in Turkey, and populations from the latter region were particularly polymorphic. There was evidence for refuge areas in Italy, the Balkan Peninsula and Turkey for F. ornus, which did not share any single chloroplast haplotype with the other species. In both F. angustifolia and F. ornus, cpDNA diversity (h(S) = 0.027 and h(S) = 0.009, respectively) was lower and fixation levels (G(ST) = 0.964 and G(ST) = 0.983, respectively) higher than in sympatric F. excelsior (h(S) = 0.096, G(ST) = 0.870). These diversity patterns could be due to temperature tolerance or the demographic history.     

Range-wide phylogeography of the European temperate-montane herbaceous plant Meum athamanticum Jacq.: evidence for periglacial persistence

Aim  The aim of this study is to analyse the genetic population structure of Meum athamanticum Jacq. in order to explore the alternative hypotheses (1) that the central and northern highland populations are the result of post-glacial recolonization from southern refugia, and the disjunct distribution of M. athamanticum can be explained by modern ecological conditions, or (2) that extant populations north of the Alps and Pyrenees persisted in situ during glacial periods.
Location  Europe.
Methods  Variation of amplified fragment length polymorphisms (AFLPs) was analysed for 23 populations from the entire range of the species. We used band-based approaches and methods based on allele frequencies to measure genetic diversity and to identify population structure.
Results  Our analyses reveal a north–south differentiation within M. athamanticum . High levels of genetic diversity, as well as private fragments, are found in populations both north and south of the Alps. Differentiation among populations is lower in the northern than in the southern population group, and significant isolation-by-distance is found only in the latter group.
Main conclusions  Our results indicate that M. athamanticum survived the last ice age in multiple refugia throughout its contemporary range and did not expand into areas north of the Alps from southern refugia. We found evidence that regional-scale migration in northern, formerly periglacial, parts of the species range has resulted in the intermingling of populations. In contrast, southern populations are characterized by long-term isolation. The south-west Alps represent an area where immigration and mixing of populations from northern and southern refugia appears to have taken place.     

Phenotypical characterization of indigenous freshwater crayfish populations

The morphology of an animal is known to reflect both genetic variation and adaptation to the environment. Thus, phenotypic criteria have been used to characterize indigenous crayfish populations. Twenty-one morphometric parameters were measured on crayfish from 25 waterbodies in the Austrian and Italian parts of Tyrol. They were analysed with hierarchical cluster analysis to obtain the population structure based on morphological similarity between and within the freshwater crayfish species Astacus astacus (noble crayfish), Austropotamobius torrentium (stone crayfish) and Austropotamobius pallipes (white-clawed crayfish). Furthermore, a stepwise discriminant analysis was applied to the morphometric data to test their differentiating power between populations. Both analyses resulted in a clear differentiation of species and populations, and reflected geographic separations. Thus, the developed morphometric methods were shown to be applicable to characterize the phenotype in freshwater crayfish and seem appropriate to be used for stock identification and the effective characterization of management units in decapod crustaceans.     

Phylogeography of the threatened crayfish (genus Austropotamobius) in Italy: implications for its taxonomy and conservation

A nucleotide sequence analysis of a portion of the mitochondrial large ribosomal subunit was performed to define the phylogeography of the threatened crayfish Austropotamobius (Decapoda; Astacidae) in Italy. We collected 61 specimens from 31 localities across the Italian peninsula. For the phylogenetic inference, we combined the 61 Austropotamobius spp sequences obtained from this study with 18 sequences deposited in GenBank and corresponding to Italian, French, Irish, Swiss, and Slovenian locations. Among the analysed sequences, 34 distinct haplotypes were detected. Our results confirmed the presence of both A. pallipes and A. italicus in the Italian peninsula and the existence within the latter species of a strong intraspecific genetic variation, due to the occurrence of four subspecies with a well-defined geographic distribution. From a conservation viewpoint, Italy, with its high haplotype variability, may be considered a 'hot spot' for the genetic diversity of the European native crayfish Austropotamobius. We suggest that re-introduction programs should be conducted with extreme caution in Italy, since not only the two Austropotamobius species but also the four A. italicus subspecies are genetically and taxonomically separate units and require independent conservation plans.     

Geographical variation of mitochondrial DNA between populations of the white-clawed crayfish Austropotamobius pallipes

1. The white-clawed crayfish Austropotamobius pallipes has a widespread distribution in Europe, but since the last century its distribution has been severely affected by a combination of factors, particularly the disease crayfish plague, introduced by foreign crayfish species. At present A. pallipes is considered as vulnerable and endangered and measures are being taken in a number of countries to conserve it.
2. The application of genetics to conservation is of practical value particularly where restocking is being considered. This study assesses levels of genetic differentiation from an analysis of mitochondrial DNA (mtDNA) variation by restriction fragment length polymorphism of four populations sampled on a European scale. Six different composite haplotypes were detected among sixty-four crayfish representing the four populations. mtDNA nucleon diversity values within species ranged from 0.63% to 12.35%. A close genetic similarity was found between British and French populations of A. pallipes .
3. Results show that mtDNA can be as a suitable diagnostic marker for measuring genetic diversity between crayfish populations and that such information is of use in planning crayfish conservation strategies.     

Geographical variation of mitochondrial DNA between populations of the white-clawed crayfish Austropotamobius pallipes

1. The white-clawed crayfish Austropotamobius pallipes has a widespread distribution in Europe, but since the last century its distribution has been severely affected by a combination of factors, particularly the disease crayfish plague, introduced by foreign crayfish species. At present A. pallipes is considered as vulnerable and endangered and measures are being taken in a number of countries to conserve it.
2. The application of genetics to conservation is of practical value particularly where restocking is being considered. This study assesses levels of genetic differentiation from an analysis of mitochondrial DNA (mtDNA) variation by restriction fragment length polymorphism of four populations sampled on a European scale. Six different composite haplotypes were detected among sixty-four crayfish representing the four populations. mtDNA nucleon diversity values within species ranged from 0.63% to 12.35%. A close genetic similarity was found between British and French populations of A. pallipes .
3. Results show that mtDNA can be as a suitable diagnostic marker for measuring genetic diversity between crayfish populations and that such information is of use in planning crayfish conservation strategies.     

Role of the Dinaric Karst (western Balkans) in shaping the phylogeographic structure of the threatened crayfish Austropotamobius torrentium

1. This study examines phylogeography and phylogeny of the threatened stone crayfish, Austropotamobius torrentium, in order to elucidate the role of the Dinaric Karst geology in shaping the evolutionary history and genetic diversity of aquatic fauna in the western Balkans. Mitochondrial 16S rRNA and COI genes were partially sequenced from 188 and 159 crayfish, respectively, sampled from 70 localities. Phylogenetic relationships were reconstructed using four methods of phylogenetic inference. Divergence times between phylogroups were estimated in a Bayesian framework, and their demographic history was examined using neutrality tests and mismatch distribution analysis. 2. Seven geographically localised phylogroups separated by pronounced genetic gaps were found. Five of them have a distribution range within the northern‐central Dinaric (NCD) region, while the remaining two include populations from the southern Balkans (SB) and central and south‐eastern Europe (CSE). The oldest divergence event separated two NCD lineages from the rest of populations in the Late Miocene or Early Pliocene. Divergences amongst the five NCD phylogroups and SB + CSE occurred in the Pliocene. The most recent split separated SB and CSE phylogroups during the Late Pliocene. For both genes, uncorrected pairwise divergences between most of the phylogroups (4.1–8.7% for COI and 1.6–4.8% for 16S rRNA) were of the same range as, or higher than, some of the interspecific distances previously reported for the genus Austropotamobius. 3. Geographically isolated and deeply divergent cryptic monophyletic phylogroups within A. torrentium in the NCD region arose in the course of intensification of Neotectonic movements during the Pliocene and the beginning of the Pleistocene and the development of karstification that has heavily fragmented the palaeohydrography of the area. The results confirm a gradual north–south expansion of stone crayfish during the pre‐Pleistocene that preceded the rapid northward post‐glacial re/colonisation of central Europe (CSE phylogroup) through the Danube drainage. 4. Austropotamobius torrentium comprises morphologically cryptic but molecularly distinct taxa. Considering the relatively small geographical areas they inhabit, the NCD phylogroups of stone crayfish should be given the highest conservation priority.     

Haplotype richness in refugial areas: phylogeographical structure of <Emphasis Type="Italic">Saxifraga callosa</Emphasis>

This paper illustrates the phylogeographical structure of Saxifraga callosa in order to describe its genetic richness in refugial areas and to reconstruct its glacial history. S. callosa is a species spread throughout south-east France and Italy with a high distribution in the Maritime Alps. Four chloroplast microsatellite and AFLP markers were analyzed in populations of S. callosa. The size variants of all tested loci amount to 11 different haplotypes. Intrapopulational haplotype variation was found in two of the populations analyzed: on the Mt. Toraggio in the Maritime Alps, and in the Apuan Alps. On the other hand, no intrapopulational variation was found in 25 populations, most of which were sampled from isolated areas. Analysis of the haplotype distribution showed that population subdivision across all populations was high (G _ST = 0.899). Moreover, its genetic structure was studied using AMOVA and STRUCTURE analysis. The study legitimated inferred conclusions about the phylogeographical structure of the species and identified centers of diversity. Considerations concerning genetic structure and divergence among three major clades (Maritime Alps, Apuan Alps and Apennines), the patchy distribution of haplotypes, and the high number of private haplotypes support the proposal that S. callosa survived in some refugia within the Italian Peninsula refugium, and that mainly northern populations of refugia were involved in postglacial recolonization.     

Aggression and competition for shelter between a native and an introduced crayfish in Europe

1. The introduced North American crayfish, Pacifastacus leniusculus Dana, is expanding its range in Europe and locally often replaces two native crayfish species, Astacus astacus L. and Austropotamobius pallipes Lereboullet. Pacifastacus leniusculus is also expected to invade the habitat of a third native crayfish, the endangered Austropotamobius torrentium Schrank. Interspecific aggressive interactions and competition for shelter were experimentally studied in the laboratory to assess the potential impact of P. leniusculus on A. torrentium .
2. Neither species was inherently dominant in aggressive interactions, but dominance was strongly size-dependent, favouring the larger and faster growing species, P. leniusculus .
3. Access to limited shelter was generally determined by aggressive dominance, although species-specific preference also influenced the outcome of competition for shelter. Austropotamobius torrentium had a higher preference for experimental shelters and often defended these even against larger P. leniusculus .
4. In accordance with theoretical models of animal conflicts, agonistic interactions between equally sized contestants were more severe than between animals of different size.
5. The P. leniusculus used in the present experiment were infected with the crayfish plague, Aphanomyces astaci , to which the animals are resistant. The crayfish transmitted the disease to non-resistant A. torrentium which died ≈ 2 weeks after contact with P. leniusculus .     

The molecular population structure of the tall forb Cicerbita alpina (Asteraceae) supports the idea of cryptic glacial refugia in central Europe

There is an ongoing debate about the glacial history of non‐arctic species in central and northern Europe. The two main hypotheses are: (1) postglacial colonization from refugia outside this region; (2) glacial survival in microclimatically favourable sites within the periglacial areas. In order to clarify the glacial history of a boreo‐montane tall forb, we analysed AFLPs from populations of Cicerbita alpina through most of its range (Scandinavia, the mountains of central Europe, the Alps, the Pyrenees and the Balkan Peninsula). We found a major differentiation between the Pyrenean population and all others, supported by principal coordinate, neighbour joining and STRUCTURE analyses. Furthermore, three populations from the central and north‐eastern Alps were genetically distinct from the bulk of populations from Scandinavia, central Europe, the Alps and the Balkan Peninsula. Most populations, including those from central and northern Europe, had moderate to high levels of genetic diversity (mean Shannon index H_Sh = 0.292, mean percentage of polymorphic loci P = 54.1%, mean Nei's gene diversity H = 0.195). The results indicate separate glacial refugia in the Pyrenean region and the Italian Alps. Furthermore, they provide evidence of glacial persistence in cryptic refugia north of the Alps, from where Scandinavia and most of the Alps are likely to have been colonized following deglaciation. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 142–154.     

European wildcat populations are subdivided into five main biogeographic groups: consequences of Pleistocene climate changes or recent anthropogenic fragmentation?

Extant populations of the European wildcat are fragmented across the continent, the likely consequence of recent extirpations due to habitat loss and over‐hunting. However, their underlying phylogeographic history has never been reconstructed. For testing the hypothesis that the European wildcat survived the Ice Age fragmented in Mediterranean refuges, we assayed the genetic variation at 31 microsatellites in 668 presumptive European wildcats sampled in 15 European countries. Moreover, to evaluate the extent of subspecies/population divergence and identify eventual wild × domestic cat hybrids, we genotyped 26 African wildcats from Sardinia and North Africa and 294 random‐bred domestic cats. Results of multivariate analyses and Bayesian clustering confirmed that the European wild and the domestic cats (plus the African wildcats) belong to two well‐differentiated clusters (average Ф_ST = 0.159, R_st  = 0.392, P > 0.001; Analysis of molecular variance [AMOVA]). We identified from c. 5% to 10% cryptic hybrids in southern and central European populations. In contrast, wild‐living cats in Hungary and Scotland showed deep signatures of genetic admixture and introgression with domestic cats. The European wildcats are subdivided into five main genetic clusters (average Ф_ST = 0.103, R_st  = 0.143, P > 0.001; AMOVA) corresponding to five biogeographic groups, respectively, distributed in the Iberian Peninsula, central Europe, central Germany, Italian Peninsula and the island of Sicily, and in north‐eastern Italy and northern Balkan regions (Dinaric Alps). Approximate Bayesian Computation simulations supported late Pleistocene–early Holocene population splittings (from c. 60 k to 10 k years ago), contemporary to the last Ice Age climatic changes. These results provide evidences for wildcat Mediterranean refuges in southwestern Europe, but the evolution history of eastern wildcat populations remains to be clarified. Historical genetic subdivisions suggest conservation strategies aimed at enhancing gene flow through the restoration of ecological corridors within each biogeographic units. Concomitantly, the risk of hybridization with free‐ranging domestic cats along corridor edges should be carefully monitored.     

Phylogeny and species composition of five European species of Branchiobdella (Annelida: Clitellata: Branchiobdellida) reflect the biogeographic history of three endangered crayfish species

Branchiobdellid annelids are usually found as commensal symbionts associated with crayfish populations, but knowledge of their dispersion and ecology in Europe is generally scarce. We hypothesized that their geographic extension of species and populations may mirror the distribution history of their hosts. We analysed potential host specificities and the geographic distribution of species from the Italian and Austrian Tyrol and Carinthia by characterizing the morphological and genetic features. On the three indigenous crayfish species Astacus astacus, Austropotamobius pallipes and Austropotamobius torrentium , we identified four branchiobdellid species based on morphological characteristics: Branchiobdella hexodonta, Branchiobdella pentodonta, Branchiobdella balcanica and Branchiobdella parasita . In contrast to the morphological classification, phylogenetic analysis using mitochondrial cytochrome c oxidase I (CO-I) sequences identified five main lineages: B. balcanica, B. hexodonta, Branchiobdella italica, B. parasita and B. pentodonta . The arrangement of branchiobdellid species corresponded generally to the geographical distribution of their crayfish hosts' locations but also confirmed previous assumptions of crayfish translocations. Our study provides the first application of ideas on the association of freshwater crayfish and their ectosymbionts to be used for discussing the biogeography of crayfish populations. The phenotypical and genotypical analysis also demonstrated so far ignored effects of human activities at both macro-ecological and micro-ecological levels.     

Genetic divergence of Connecticut Melanoplus femurrubrum populations

We surveyed Melanoplus femurrubrum populations within the state of Connecticut for genetic diversity at multiple genetic markers, including three mitochondrial [cytochrome oxidase subunit 1 (COI), reduced form of nicotinamide adenine dinucleotide dehydrogenase subunit 2 (ND2), and AT rich] and one nuclear [internal transcribed spacers of the ribosomal DNA cluster (ITS1)] gene regions. All markers were variable, and the AT-rich gene showed the highest sequence divergence. Analysis of molecular variance (AMOVA), fixation index (Fst) analysis, and phylogeographic patterns showed little divergence between northern and southern regions. Estimates of genetic diversity (pi) showed higher mitochondrial diversity in the northern region but nearly equal diversity for the ITS1 gene. This study shows for the first time in Melanoplus genetic variation for the ND2, AT rich, and ITS genes within a small geographic area. Our methods and results should be useful for other researchers interested in conducting population-level studies on closely related species.     

Genetic differentiation of the Western Capercaillie highlights the importance of South-eastern Europe for understanding the species phylogeography

The Western Capercaillie (Tetrao urogallus L.) is a grouse species of open boreal or high altitude forests of Eurasia. It is endangered throughout most mountain range habitat areas in Europe. Two major genetically identifiable lineages of Western Capercaillie have been described to date: the southern lineage at the species' southernmost range of distribution in Europe, and the boreal lineage. We address the question of genetic differentiation of capercaillie populations from the Rhodope and Rila Mountains in Bulgaria, across the Dinaric Mountains to the Slovenian Alps. The two lineages' contact zone and resulting conservation strategies in this so-far understudied area of distribution have not been previously determined. The results of analysis of mitochondrial DNA control region sequences of 319 samples from the studied populations show that Alpine populations were composed exclusively of boreal lineage; Dinaric populations of both, but predominantly (96%) of boreal lineage; and Rhodope-Rila populations predominantly (>90%) of southern lineage individuals. The Bulgarian mountains were identified as the core area of the southern lineage, and the Dinaric Mountains as the western contact zone between both lineages in the Balkans. Bulgarian populations appeared genetically distinct from Alpine and Dinaric populations and exhibited characteristics of a long-term stationary population, suggesting that they should be considered as a glacial relict and probably a distinct subspecies. Although all of the studied populations suffered a decline in the past, the significantly lower level of genetic diversity when compared with the neighbouring Alpine and Bulgarian populations suggests that the isolated Dinaric capercaillie is particularly vulnerable to continuing population decline. The results are discussed in the context of conservation of the species in the Balkans, its principal threats and legal protection status. Potential conservation strategies should consider the existence of the two lineages and their vulnerable Dinaric contact zone and support the specificities of the populations.     

Population genetic structure of the endangered crayfish Austropotamobius pallipes in France based on microsatellite variation: biogeographical inferences and conservation implications

1. One important goal in conservation biology is to characterise evolutionary lineages within endangered species before management decisions are taken. Here, we assess population differentiation in the freshwater crayfish Austropotamobius pallipes, an endangered species endemic to western Europe and provide valuable information for the conservation of French populations. 2. Analysis of five microsatellite loci in 44 populations revealed very different within population levels of genetic diversity (0.000 < H₀ < 0.564). Two groups, corresponding to northern and southern French populations, showed a high degree of genetic differentiation in both allele frequencies and allele sizes. Comparison of these results with previous studies of A. pallipes strongly suggests that the divergence between northern and southern populations could have occurred during the last glaciation period of the Pleistocene from one Atlantic and one Mediterranean refuge. 3. Evidence for genetic admixture between these two lineages was revealed by correspondence analyses in southern populations, probably as the result of artificial translocations. 4. French populations appeared significantly differentiated among the different river drainages and were highly structured within rivers. The impact of population size, population bottlenecks and founder events on the population genetic differentiation are discussed. 5. Based on these results, we propose the designation of two evolutionarily significant units for A. pallipes in France. Our data also support the maintenance of separate demographic management strategies for crayfish inhabiting different river systems. However, genetic analyses will have to be combined with demographic and ecological data for sustainable conservation programmes.     

Genetic differentiation among populations of Cicerbita alpina (L.) Wallroth (asteraceae) in the western Alps

In this study we analyzed the genetic population structure of the hygrophilous tall-herb Cicerbita alpina in the western Alps because this group of mountain plants is underrepresented in the biogeographical literature. AFLP (amplified fragment length polymorphism) fingerprints of 40 samples were analyzed from four populations situated in a transect from the southwestern Alps to the eastern part of the western Alps and one population from the Black Forest outside the Alps. Two genetic groups can be distinguished. The first group (A) comprises the populations from the northern and eastern parts of the western Alps, and the second group (B) comprises the populations from the southwestern Alps and the Black Forest. Group A originates most likely from at least one refugium in the southern piedmont regions of the Alps. This result provides molecular evidence for a humid climate at the southern margin of the Alps during the Würm glaciation. Group B originates presumably from western or northern direction and we discuss two possible scenarios for the colonization of the Alps, i.e. (1) long-distance dispersal from southwestern refugia and (2) colonization from nearby refugia in the western and/or northern Alpine forelands. The study demonstrates that the target species harbours considerable genetic diversity, even on a regional scale, and therefore is a suitable model for phylogeographic research.     

Randomly Amplified Polymorphic DNA Variation in Populations of Eastern Australian Koalas, Phascolarctos cinereus

Randomly amplified polymorphic DNA (RAPD) variation in populations of the koala, Phascolarctos cinereus, was investigated, revealing significant differences in the level of diversity between southern and northern regions of eastern Australia. Of the 20 polymorphic RAPD markers identified in koalas, 4-7 were polymorphic in southern populations, while 12-17 were polymorphic in northern populations. Analysis of molecular variance revealed a significant difference in the estimated variance between koalas from northern and those from southern regions (P < 0.001), where populations from the north were greater than twice as variable as their southern cousins. The total genetic diversity observed was attributed to regional differences (30.91%), population differences within a region (11.77%), and differences among individuals within a population (57.32%). For the within-region analyses, a large proportion of the genetic diversity was attributable to individual differences within a population, 80.34% for the north and 91.23% for the south. These results demonstrate that RAPD markers are useful for determining population structure among koalas.     

Genetic diversity and the mating system of a rare Mexican pinon, Pinus pinceana, and a comparison with Pinus maximartinezii (Pinaceae)

Weeping pi?on (Pinus pinceana) has a restricted and fragmented range, trees are widely scattered within populations, and reproduction is limited. Nevertheless, genetic diversity was high; based on 27 isozyme loci in 18 enzyme systems, unbiased expected heterozygosity averaged 0.174. Differentiation also was high (F(ST) = 0.152), reflecting isolation between southern, central, and northern fragments of the range. Among populations in the northern fragment, F(ST) was only 0.056, and the number of migrants per generation (Nm) was 4.21, which should preclude fixation. Nm between central and southern populations or between them and populations in the northern fragment was lower, 0.99-1.66, indicating a degree of genetic isolation. Multilocus outcrossing rates (t(m)) ranged from 0.836 in the south to 0.897 in the north. Therefore, selfing is low but statistically significant. The equilibrium inbreeding coefficient (F(e)) calculated from t(m) was in good agreement with observed inbreeding coefficients, suggesting that weeping pi?on may be near equilibrium with respect to inbreeding and selection against selfed trees. Weeping pi?on was variable at all loci polymorphic in maxipi?on (Pinus maximartinezii) and, therefore, qualifies as a possible progenitor of maxipi?on. Because of the high level of diversity, reasonable levels of gene flow within the northern fragment of weeping pi?on's range, high rates of outcrossing, and, perhaps, only weak selection against inbred trees, protection in reserves would be a viable option for conservation.     

Origin and colonization history of the white-clawed crayfish,Austropotamobius pallipes,in Ireland

The presence of the white-clawed crayfish Austropotamobius pallipes complex in Ireland is suspected to be a result of human translocations. Two hypotheses have been formulated about the origin of the crayfish: from British populations or from western French populations. In order to resolve this question, nine Irish crayfish populations (a total of 124 individuals) were sampled along a south-north cline and investigated by combining two molecular markers: mtDNA and RAPDs. The mtDNA marker, analysed by RFLP on the entire molecule, showed an absence of polymorphism within and among Irish populations. The RFLP haplotype found in Irish populations was only recorded in western French populations and was different from those found in English populations. This result may be explained by a human introduction of crayfish to Ireland from western French populations. RAPD analysis showed a clinal reduction of genetic variability within Irish populations from south to north, associated with an increase in their genetic differentiation. A stepwise model of translocation from the south to the north of Ireland is proposed and discussed.