Seed dormancy and germination behaviour in two Euphrasia species (Orobanchaceae) occurring in the Swiss Alps

The optimal time for germination of a seed depends on environmental conditions of its habitat, the life cycle of the germinating plant, and the conditions for successful establishment, growing and reproduction. We studied the germination behaviour of the alpine annual Euphrasia minima and an alpine ecotype of E. salisburgensis in a lowland garden experiment. Seeds of both species and their hybrids germinated at constant (5 °C) and at varying temperatures (3–10 °C), and never before spring after seed ripening. Germination was spread over 3 years, which suggests that the seeds formed a persistent seed bank. The two species together with E. minima and E. minima hybrids differed significantly in the germination rate in the first and second spring.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 649–656.     

Contrasting temporal dynamics and spatial patterns of population genetic structure correlate with differences in demography and habitat between two closely-related African freshwater snails

The relationship between habitat stability, demography, and population genetic structure was explored by comparing temporal microsatellite variability spanning a decade in two closely-related hermaphroditic freshwater snails from Cameroon, Bulinus forskalii and Bulinus camerunensis . Although both species show similar levels of preferential selfing, microsatellite analysis revealed significantly greater allelic richness and gene diversity in populations of the highly endemic B. camerunensis compared to those of the geographically-widespread B. forskalii . Additionally, B. camerunensis populations showed significantly lower spatial genetic differentiation, higher dispersal rates, and greater temporal stability compared to B. forskalii populations over a similar spatial scale. This suggests that a more stable demography and greater gene flow account for the elevated genetic diversity observed in this geographically-restricted snail. This contrasts sharply with a metapopulation model (which includes extinction/contraction, recolonization/expansion, and passive dispersal) invoked to account for population structuring in B. forskalii . As intermediate hosts for medically important schistosome parasites, these findings have ramifications for determining the scale at which local adaptation may occur in the coevolution of these snails and their parasites.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 747–760.     

Phylogenetic diversity of forest trees in the Usambara mountains of Tanzania: correlations with altitude

The relationship between diversity of large trees and altitude was investigated in a Tanzanian tropical rain forest. In total, 231 samples of 20 trees of ≥ 20 cm d.b.h. from the East and West Usambara mountains, covering an elevation range from 280 m to 2180 m a.s.l., were analysed. An ordination demonstrated a constant turnover of species, genera, family and orders with elevation. There were no obvious zones or discontinuities. There was no decline in plot richness with respect to altitude for species, genera or orders. Family richness was shown to increase with altitude. A measure of genetic diversity, the avalanche index, was calculated for each plot to investigate the effect of incorporating phylogenetic relatedness of individuals into the diversity measure. Distances between taxa were extracted from a recent molecular phylogeny of the angiosperms. Incorporation of phylogenetic diversity at family level enhanced the positive correlation between plot diversity and altitude.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 217–228.     

High levels of genetic diversity in populations of Iris aphylla L. (Iridaceae), an endangered species in Poland

We used RAPDs (Random Amplified Polymorphic DNAs) to investigate genetic diversity and its partition within and between three populations of Iris aphylla in Poland. Analysis of Molecular Variance (AMOVA) of 84 distinct RAPD multiband genotypes revealed higher variation within populations (77.2%) than genetic differentiation between them (22.8%, P  < 0.002). Values of genetic diversity indices ( H ) were similar in all three sites (0.21–0.24). The differentiation of the populations corresponded to low average gene flow ( Nm  = 0.81). Our results indicated that genetic diversity was independent of population size. We concluded that although sexual reproduction and gene flow between populations of I. aphylla were very limited, they preserved high levels of genetic diversity. Relatively large number of seeds, which migrated in the past to populations, as well as patterns of reproduction and life history of I. aphylla may explain this situation.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 65–72.     

Spatial genetic structure and clonal diversity in an alpine population of Salix herbacea (Salicaceae)

BACKGROUND AND AIMS: Many alpine plant species combine clonal and sexual reproduction to minimize the risks of flowering and seed production in high mountain regions. The spatial genetic structure and diversity of these alpine species is strongly affected by different clonal strategies (phalanx or guerrilla) and the proportion of generative and vegetative reproduction. METHODS: The clonal structure of the alpine plant species Salix herbacea was investigated in a 3 x 3 m plot of an alpine meadow using microsatellite (simple sequence repeat; SSR) analysis. The data obtained were compared with the results of a random amplified polymorphic DNA (RAPD) analysis. KEY RESULTS: SSR analysis, based on three loci and 16 alleles, revealed 24 different genotypes and a proportion of distinguishable genotypes of 0.18. Six SSR clones were found consisting of at least five samples, 17 clones consisting of more than two samples and seven single genotypes. Mean clone size comprising at least five samples was 0.96 m(2), and spatial autocorrelation analysis showed strong similarity of samples up to 130 cm. RAPD analysis revealed a higher level of clonal diversity but a comparable number of larger clones and a similar spatial structure. CONCLUSIONS: The spatial genetic structure as well as the occurrence of single genotypes revealed in this study suggests both clonal and sexual propagation and repeated seedling recruitment in established populations of S. herbacea and is thus suggestive of a relaxed phalanx strategy.     

Genetic differentiation of Diplodus sargus (Pisces: Sparidae) populations in the south-west Mediterranean

Allozyme analysis of tissue samples of 1249 white sea bream Diplodus sargus from five localities of the south-west Mediterranean revealed a high degree of genetic polymorphism. The observed heterozygosity ranged from 0.4182 (Cape of Palos) to 0.3138 (Tabarca). Several populations were characterized by unique alleles. Examination of the spatial structure was performed using Nei's distances and F- statistics, and indicated genetic differences between groups. One group, which clustered Tabarca and Guardamar, could be explained by the small geographical distance between them. Mazarrón and Cape of Palos samples showed genetic divergence from other samples (Guardamar, Tabarca and Águilas) and this difference may be as a result of local current systems and larval dispersal.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 249–261.     

Clonality and recombination in the arctic plant Saxifraga cernua

The circumarctic clonal plant Saxifraga cernua reproduces efficiently via bulbils, largely depends on insects for pollination and appears to set seed very rarely. However, high levels of genotypic variation observed at small spatial scales in the arctic archipelago of Svalbard have been taken as evidence of occasional sexual reproduction. Here we assess the relative contributions of mutation and recombination to random amplified polymorphic DNA variation in four populations in East Greenland and re-analyse the Svalbard data. Greater variation due to recombination was predicted in Greenland than in Svalbard, because the higher summer temperatures and longer growing season likely increase the chances for sexual reproduction. Although we observed higher levels of genotypic diversity in Greenland than in Svalbard, matrix incompatibility and linkage disequilibrium measures provided no evidence of more sexuality, suggesting differences in glacial/postglacial history. The genetic structure and spatial distribution of clones suggest that clonal migration may increase variability in local populations, which is consistent with frequent large-scale migration in this species inferred from a circumarctic analysis of chloroplast DNA haplotypes. We conclude that a combination of somatic mutations and sexual reproduction has contributed to the observed patterns of genotypic diversity in the Greenland and Svalbard populations of S. cernua , and that sexual reproduction is important in maintaining genotypic diversity, despite the rarity of observations of seed setting.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 209–217.     

Sex and genetic structure across age groups in populations of the European marine invasive mollusc, Crepidula fornicata L. (Gastropoda)

In long-lived species, variance in allele frequencies over time may vary according to the number of generations contributing to progeny. Here, we investigate the temporal stability of genetic diversity and structure in relation to sex and age in introduced populations of Crepidula fornicata , an exotic gastropod that successfully invaded Europe . This protandrous species has the potential to change sex from male to female according not only to age, but also to local sex ratio (social environment). This mechanism may adjust the reproduction efficiency across different cohorts and thus decrease the likelihood of genetic drift in the following generations. Based on crude demographic structure analysis in two spatially closed introduced French populations, we demonstrate that recruitment is discontinuous. Although timing of sex change is different across populations, both populations have a similar age structure characterized by distributions of males and females changing across generations. Using five microsatellite loci, we show that both populations display a temporal genetic homogeneity and a stability in genetic diversity indices across age groups examined. Our results highlight that the social control of sex change in C. fornicata has strong implications to the maintenance of high genetic diversity by enhancing breeding across several generations at each reproductive season.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 365–374.     

Fine‐scale genetic structure overrides macro‐scale structure in a marine snail: nonrandom recruitment,demographic events or selection?

The planktotrophic littorinid species Littoraria flava occupies a continuous habitat on rocky shores close to brackish and freshwater sources. Previous studies of this species have shown a moderate genetic structure over a broad geographical scale, with high deviations from Hardy–Weinberg expectations in many allozymic loci. Local-scale subdivision in marine species with a long dispersal phase is unexpected, but occasionally found. Using a horizontal transect at three locations, we examined whether microscale and short-term subdivision also occurred in L. flava populations and, if so, whether this could explain the Hardy–Weinberg deviations. Littoraria flava showed even more structuring on a microgeographical scale (4–300 m) than on a large-scale (> 200 km). The Ewens–Watterson neutrality test showed that 18% of the tests deviated significantly from the neutrality model. A homogeneity test for each locus across samples within transects showed homogeneous and high F _IS values in many loci. These results and the apparent genetic patchiness within transects suggest that asynchronous spawning associated with recurrent colonizations in L. flava can explain the local differentiation without a recognizable pattern. In addition, there could be a balance between these factors and diversifying selection acting on different loci at different times and localities. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 23–36.     

Genetic structure and differentiation of Gentiana atuntsiensis W. W. Smith and G. striolata T. N. Ho (Gentianaceae) as revealed by ISSR markers

The Hengduan Mountains are the core region of the Himalaya hotspot, and are renowned for their high levels of endemism. Gentiana atuntsiensis and G. striolata are two closely related and morphologically similar species endemic to this region. In this study, inter-simple sequence repeat (ISSR) markers were used to investigate the genetic structure within these two species, as well as the differentiation between them. An analysis of molecular variance-derived estimate demonstrated only 13.5% of genetic differentiation between the two species. Considering their adjacent distribution patterns, low genetic divergence, and clear clustering into two groups, it is hypothesized that the two species arose from a rapid and recent speciation event induced mainly by geographical isolation. A relatively high level of genetic diversity was revealed in each species (Shannon's index of diversity: H _sp = 0.324 and 0.391; H _pop = 0.225 and 0.274; for G. atuntsiensis and G. striolata , respectively). Most of the genetic variation was partitioned within populations ( Ø _ST = 0.232 and 0.226 in G. atuntsiensis and G. striolata , respectively). The large population sizes, outcrossing breeding system, and small, light seeds that disperse widely may explain the genetic structure in both species.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 225–232.     

An evaluation of the taxonomic distinctness of two Geonoma macrostachys (Arecaceae) varieties based on intersimple sequence repeat (ISSR) variation

The latest taxonomic account for the palms of the Amazon recognizes two common and widespread varieties of Geonoma macrostachys (Arecaceae) in western Amazonia: acaulis and macrostachys . These varieties are joined by intermediates, which obscure their taxonomic boundaries. An evaluation of the genetic distinctness between G. macrostachys varieties at a local and regional scale is presented. Thirty-one G. macrostachys individuals were randomly sampled from four Peruvian tropical moist forests. Twenty-seven intersimple sequence repeat (ISSR) primers were used, and all clear and reproducible bands were scored and analysed. Of the 99 ISSR bands produced, 51.52% were polymorphic. Nei's gene diversity value ( H ) was 0.2274 and Shannon's information index ( I ) was 0.3237. Clustering, ordination, and analyses of molecular variance (AMOVAs) suggested a lack of genetic distinctness between varieties at the regional level. Individuals clustered by geographical provenance, and two main groups were identified. A significant genetic differentiation between sympatric varieties occurred only in the northern locality (Φ_ST = 0.359, P  = 0.000). A hierarchical AMOVA revealed that the genetic diversity in G. macrostachys mainly lies between localities (76.58%). Mantel's test revealed no significant correlation between the geographical and genetic distances between individuals. We do not support the recognition of the two taxonomic varieties studied.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 381–392.     

Muscari turcicum (Liliaceae/Hyacinthaceae), a new species from south Anatolia, Turkey

Muscari turcicum Uysal, Ertugrul & Dural (Liliaceae/Hyacinthaceae) is described and illustrated from south Anatolia, Turkey. This species grows on alpine steppe in the Middle Taurus (C4 Konya Province). Muscari turcicum , an endemic confined to the Middle Taurus, is closely related to M. discolor Boiss. & Hausskn. and M. anatolicum Cowley & Özhatay. Diagnostic morphological characters are discussed and compared with those of closely related taxa.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 233–236.     

High mountains of the Japanese archipelago as refugia for arctic–alpine plants: phylogeography of Loiseleuria procumbens (L.) Desvaux (Ericaceae)

According to previous phylogeographic studies, high mountains at low latitudes are important areas for the study of the evolutionary history of arctic–alpine plants in surviving the Pleistocene climatic oscillations. To evaluate this hypothesis, we elucidated the genetic structure of the arctic–alpine plant, Loiseleuria procumbens , in the Japanese archipelago, which corresponds to one of the southernmost limits of its distribution, using 152 individuals from 17 populations that covered the entire distribution of the Japanese archipelago and Sakhalin, in addition to samples from Sweden. Based on 854 bp of chloroplast DNA, we detected eight haplotypes. Along with haplotype distribution, strong genetic differentiation between populations in central and northern Japan was elucidated by a neighbour-joining tree (100%) and spatial analysis of molecular variance (79%), which is consistent with other alpine plants in Japan, regardless of the species' range. In addition, the southernmost populations from northern Japan showed specific genetic structure, although the remaining areas of northern Japan and Sakhalin harboured an homogenous genetic structure. Our results suggest that the populations in central Japan persisted for a long time during the Pleistocene climatic oscillation and that genetic divergence occurred in situ , supporting our hypothesis in conjunction with a previous study of another arctic–alpine plant, Diapensia lapponica subsp. obovata .  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 403–412.     

Parentage of endemic Sorbus L. (Rosaceae) species in the British Isles: evidence from plastid DNA

The parentage of polyploid Sorbus species in the British Isles was investigated using plastid DNA microsatellites. Four hundred and fifty-three samples from 30 taxa were screened using six microsatellite fragments, which gave 28 haplotypes. The haplotypes formed groups clearly related to the ancestral diploids Sorbus aria , Sorbus aucuparia , and Sorbus torminalis . Species in the Sorbus aria group all had Aria haplotypes (with the exception of one English S. aria ), species in the Sorbus anglica group had an Aucuparia haplotype, and species in the Sorbus latifolia group had a Torminalis haplotype. Sorbus intermedia had an Aucuparia haplotype. This indicated that the hybridization events that led to the formation of species in the S. anglica and S. latifolia groups usually did so with S. aria s.l . as the pollen-donating (paternal) parent. The polyploids S. anglica , Sorbus bristoliensis , Sorbus croceocarpa , Sorbus decipiens , Sorbus devoniensis , Sorbus hibernica , Sorbus lancastriensis , Sorbus leptophylla , Sorbus leyana , Sorbus minima , Sorbus rupicola , Sorbus subcuneata , Sorbus vexans , Sorbus whiteana , Sorbus wilmottiana , and three unnamed taxa may each be derived from a single maternal lineage. The polyploids Sorbus eminens , Sorbus porrigentiformis , and S. latifolia have multiple maternal lineages. The two primary diploid hybrids S . ×  thuringiaca and S . ×  vagensis have arisen many times independently.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 291–304.     

Phylogeography of a host-specific insect: genetic structure of Ips typographus in Europe does not reflect past fragmentation of its host

The phylogeography of the bark beetle Ips typographus was assessed using five microsatellite markers. Twenty-eight populations were sampled throughout Europe on the host tree Picea abies . I. typographus showed very low levels of genetic diversity, and the study revealed a lack of genetic structure across Europe. No significant barrier to gene flow was found, even though P. abies has a fragmented distribution. A weak but significant effect of isolation by distance was found. These results suggest a high dispersal capacity of I. typographus , which leads to low genetic differentiation between populations. Its high dispersal capacity is likely to have prevented I. typographus from developing important local adaptations to its host, which would have influenced its genetic structure. The nuclear data was compared to previously published mitochondrial data that showed strong differentiation between Central–Northern European populations and Russian–Baltic populations, and a founder effect in Scandinavia, probably reflecting the postglacial history of I. typographus . Discrepancies between nuclear and mitochondrial markers could be due to the maternal inheritance of mitochondrial DNA, and to sex-biased dispersal in I. typographus . The overall low genetic diversity observed on both markers on a large geographical scale is discussed. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 239–246.     

Genetic variation in Femeniasia (Compositae, Cardueae), an endemic and endangered monotypic genus from the Balearic Islands (Spain)

Femeniasia balearica is the only representative of its genus and is endemic to a small area on the northern coast of Minorca (Balearic Islands, Spain). The entire range of the species covers only 18 km of coastline. It is extremely rare and classified as endangered in the National Catalogue of Threatened Species and as a priority species in the EU Habitats Directive. We carried out a census of current population size and estimated genetic diversity based on AFLP markers to facilitate conservation of this unique species. In the 66 individuals analysed (∼10% of population), 225 bands were scored and the level of diversity was relatively high. Three divergent population groups corresponding to geographical areas (Western, Central and Eastern) were identified. In AMOVA and Bayesian analyses, most of the diversity was found within populations but there was strong differentiation between the three population groups. Genetic and geographical distances between the populations were strongly correlated. Our results show that the populations of F. balearica are not genetically depauperate, in spite of their small sizes. Unexpectedly, our results suggest that as many as three MUs (management units) should be recognized in this very small area, because the low levels of gene flow among them indicate contemporary demographic independence.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 97–107.     

Glacial history of high alpine Ranunculus glacialis (Ranunculaceae) in the European Alps in a comparative phylogeographical context

There is considerable controversy concerning the fate of Alpine plants during Pleistocene glaciations. While some studies have found evidence for nunatak survival, others have explained the present genetic patterns by survival only in peripheral refugia. We investigated 75 populations of high alpine Ranunculus glacialis from its entire Alpine distribution. Phylogeographical analyses of AFLP data revealed four groups of populations. Two of them, located in the western Alps, were genetically isolated from each other and from the eastern groups, whereas the two eastern Alpine groups were genetically more similar to each other. This suggests longer isolation and/or lower levels of gene flow in the two western groups. As all groups are close to, or overlap with, presumed glacial refugia, invoking glacial survival on nunataks is unnecessary to explain the present genetic pattern. Similar to the phylogeographical patterns of R. glacialis , the previously investigated alpine Phyteuma globulariifolium and Androsace alpina , which are also confined to siliceous bedrock, showed strong geographical affinities to peripheral refugial areas and there were large-scale congruencies in the location of these refugia for all three species.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 183–195.     

Glacial history of Saxifraga paniculata (Saxifragaceae): molecular biogeography of a disjunct arctic-alpine species from Europe and North America

The molecular biogeography of the disjunctly distributed and morphologically highly variable species Saxifraga paniculata Mill. was analysed using amplified fragment length polymorphism (AFLP) and chloroplast microsatellites. The study comprised 77 samples from mountain regions in Europe and North America throughout the complete range of distribution. AFLP data revealed clear genetic differentiation between samples from the Arctic, the Caucasus, and the eastern European mountains. Samples from the Alps were divided into two groups. One group clustered with the samples from central Europe and the Pyrenees, whereas another group with individuals from southern Norway. AFLP diversity was lowest in the Arctic and highest in the Alps. Chloroplast microsatellite analysis revealed eight haplotypes but no unequivocal phylogeographical pattern. However, haplotype diversity was highest in the Alps and central Europe whereas, in the Arctic, only few widespread haplotypes could be found. The results indicate in situ survival of S. paniculata in the Caucasus, the eastern European mountains, and the Alps. The Arctic has presumably been colonized postglacially from North American refugia south of the ice shield. Southern Norway and the Pyrenees have most likely been colonized from two phylogeographically different groups in the Alps. The origin of the central European samples remains ambiguous. In situ survival seems to be as possible as several postglacial recolonization events from the Alps. The obtained molecular data clearly support the subdivision of S. paniculata into three subspecies: ssp. cartilaginea from the Caucasus, ssp. laestadii from northern Norway, Iceland, and North America, and ssp. paniculata from the other geographical regions.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 385–398.     

The genus Pholcus (Araneae, Pholcidae) in the Canary Islands

This paper offers a detailed taxonomic revision of all Canarian Pholcus species described before 2003, all of which are newly described and newly illustrated. Pholcus guadarfia sp. nov. is described, while a neotype for Pholcus malpaisensis Wunderlich, 1992 is also provided. In addition, we propose Pholcus gomerae Wunderlich, 1980 as a senior synonym for Pholcus gomeroides Wunderlich, 1987. More importantly, cladistic analysis based on the morphological characters of the Macaronesian Pholcus species was conducted for the first time. Parsimony analyses of 73 morphological characters revealed the close relationships between those species from the Canary Islands, Madeira and the Macaronesian enclave in Africa (between Agadir and Nouadhibou).  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 151 , 59–114.     

Evolutionary radiation of the cicada genus Maoricicada Dugdale (Hemiptera: Cicadoidea) and the origins of the New Zealand alpine biota

We have used ancestral character state reconstruction and molecular dating to test hypotheses on the evolution of New Zealand alpine cicadas of the genus Maoricicada Dugdale. Gene trees were estimated from mitochondrial DNA and the nuclear loci elongation factor 1-α, period, and calmodulin and species-level relationships were reconstructed using gene tree parsimony. These analyses suggest that the alpine habitat character state had a single origin and that the ancestral Maoricicada lived in low to mid-elevation habitats. Our reconstructions also strongly support the hypothesis that this ancestor was darkly coloured and had increased pubescence, classic adaptations of alpine insects. Using relaxed-clock Bayesian dating methods, we estimated that the radiation of the alpine Maoricicada species was coincident with the late Miocene acceleration in the rate of uplift of the Southern Alps rather than uplift in the early Miocene. These dates are very similar to those of other alpine taxa, indicating that the New Zealand alpine biota is very young. Our reconstructions suggest that the ancestral Maoricicada may have been preadapted to the alpine environment because it existed before the origin of high mountainous habitats, dwelt at mid-to-low altitudes, and yet possessed the classic alpine insect adaptations of heavy pubescence and dark coloration.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 419–435.