Ecology matters: Atlantic-Mediterranean disjunction in the sand-dune shrub Armeria pungens (Plumbaginaceae)

Inferring the evolutionary history of Mediterranean plant lineages from current genetic, distributional and taxonomic patterns is complex because of a number of palaeoclimatic and geological interconnected factors together with landscape heterogeneity and human influence. Therefore, choosing spatially simplified systems as study groups is a suitable approach. An amplified fragment length polymorphism (AFLP) study using two restriction enzyme combinations (EcoRI/MseI and KpnI/MseI) was carried out to estimate the structure of genetic variation throughout the range of Armeria pungens. This species has a West Iberian-Corso/Sardinian disjunct distribution on coastal sand-dune ecosystems. Bayesian, amova and genetic distance analyses of the AFLP data revealed the same distinguishable genetic groups, which do not match the main geographical disjunction. Corso-Sardinian populations were found to be genetically closer to southwest Portuguese than to those from the Gulf of Cadiz (the closest geographically). Eastwards long-distance dispersal is therefore invoked to explain this geographical disjunction. A GIS analysis based on bioclimatic envelope modelling aiming to characterize the current locations of A. pungens found strong similarities between the Portugal and Corsica-Sardinia sites and less so between these areas and the Gulf of Cadiz. This coincident pattern between AFLP and climatic data suggests that the geographical disjunction is better explained by climatic factors than by the likeliness of a stochastic dispersal event. Such a combined phylogeographical-GIS modelling approach proves to be enlightening in reconstructing the evolutionary history of plant species.     

Phylogeography and genetic structure of disjunct Salix arbutifolia populations in Japan

Disjunct geographic distributions of boreal plant species at the southern edges of their ranges are expected to result in low genetic diversity and high genetic differentiation in the disjunct populations. This prediction was tested in a riparian willow, Salix arbutifolia, distributed in the northeastern Eurasian continent and the Sakhalin, Hokkaido, and Honshu Islands, using chloroplast DNA haplotypes and nuclear microsatellite genotypes. Hokkaido and Honshu populations shared a chloroplast haplotype identical to a closely related species, S. cardiophylla. This haplotype was divergent from haplotypes in the Eurasian continent (Primorsky) and the Sakhalin Island. In the nuclear microsatellites, most Hokkaido populations were genetically closer to Primorsky populations than to Sakhalin populations in spite of the geographical vicinity between Sakhalin and Hokkaido. The unexpected genetic divergence between Sakhalin and Hokkaido implies a complicated history of migration and colonization. The most peripheral populations in Honshu had the lowest genetic diversity and were most differentiated from the others. Thus, low genetic diversity and high genetic differentiation at the range periphery suggest substantial effects of genetic drift on genetic structure in the disjunct populations of Salix arbutifolia at the southern edge of its range.     

Importance of demographic history for phylogeographic inference on the arctic–alpine plant Phyllodoce caerulea in East Asia

Arctic–alpine plants have enormous ranges in the Northern Hemisphere. Phylogeographic studies have provided insights into their glacial survival as well as their postglacial colonization history. However, our understanding of the population dynamics of disjunct alpine populations in temperate regions remains limited. During Pleistocene cold periods, alpine populations of arctic–alpine species in East Asia were either connected to an ice-free Beringia refugium or they persisted with prolonged isolation after their establishment. To estimate which of these scenarios is more likely, we elucidated the genetic structure of Phyllodoce caerulea (Ericaceae) in Beringia and northern Japan, East Asia. Sequence variation in multiple nuclear loci revealed that P. caerulea can be distinguished into northern and southern groups. A demographic analysis demonstrated that the north–south divergence did not predate the last glacial period and detected introgression from Phyllodoce aleutica, relative widely distributed in East Asia, exclusively into the southern group. Therefore, although there has been genetic divergence between northern Japan and Beringia in P. caerulea, the divergence is unlikely to have resulted from their prolonged geographic separation throughout several cycles of glacial and interglacial periods. Instead, our study suggests that the introgression contributed to the genetic divergence of P. caerulea and that the range of P. caerulea was plausibly connected between northern Japan and Beringia during the last glacial period. Overall, our study not only provides a biogeographic insight into alpine populations of arctic–alpine plants in East Asia but also emphasizes the importance of careful interpretation of genetic structure for inferring phylogeographic history.     

Evidence of horizontal gene transfer between land plant plastids has surprising conservation implications

Background and AimsHorizontal gene transfer (HGT) is an important evolutionary mechanism because it transfers genetic material that may code for traits or functions between species or genomes. It is frequent in mitochondrial and nuclear genomes but has not been demonstrated between plastid genomes of different green land plant species.MethodsWe Sanger-sequenced the nuclear internal transcribed spacers (ITS1 and 2) and the plastid rpl16 G2 intron (rpl16). In five individuals with foreign rpl16 we also sequenced atpB-rbcL and trnL_UAA-trnF_GAA.Key ResultsWe discovered 14 individuals of a moss species with typical nuclear ITSs but foreign plastid rpl16 from a species of a distant lineage. None of the individuals with three plastid markers sequenced contained all foreign markers, demonstrating the transfer of plastid fragments rather than the entire plastid genome, i.e. entire plastids were not transferred. The two lineages diverged 165–185 Myr BP. The extended time interval since lineage divergence suggests that the foreign rpl16 is more likely explained by HGT than by hybridization or incomplete lineage sorting.ConclusionsWe provide the first conclusive evidence of interspecific plastid-to-plastid HGT among land plants. Two aspects are critical: it occurred at several localities during the massive colonization of recently disturbed open habitats that were created by large-scale liming as a freshwater biodiversity conservation measure; and it involved mosses whose unique life cycle includes spores that first develop a filamentous protonema phase. We hypothesize that gene transfer is facilitated when protonema filaments of different species intermix intimately when colonizing disturbed early succession habitats.     

Dissimilar molecular and morphological patterns in an introgressed peripheral population of a sand dune species (Armeria pungens,Plumbaginaceae)

• Introgression is a poorly understood evolutionary outcome of hybridisation because it may remain largely undetected whenever it involves the transfer of small parts of the genome from one species to another. Aiming to understand the early stages of this process, a putative case from the southernmost border of the Armeria pungens range from its congener A. macrophylla is revisited following the discovery of a subpopulation that does not show phenotypic signs of introgression and resembles typical A. pungens.
• We analysed morphometrics, nuclear ribosomal DNA ITS and plastid DNA (trnL‐trnF) sequences, genome size, 45S and 5S rDNA loci‐FISH data and nrDNA IGS sequences.
• Within the study site, most individuals match morphologies of either of the two hybridising species, particularly the new subpopulation, with intermediate phenotypes being scarce. This pattern does not fully fit molecular evidence revealing two ITS ribotypes co‐occurring intragenomically in most plants from the study site and one single plastid haplotype. Genome size and structural features of the IGS sequences both indicate that A. pungens from the study site is genetically more similar to its sympatric congener than to the remainder of its conspecifics.
• Introgression of A. macrophylla into A. pungens and plastid capture explain all the evidence analysed. However, important features to understand the origin and fate of the introgressed population, such as the degree and direction of introgression, which are important for understanding early stages of hybridisation in plants with low reproductive barriers, should be addressed with new data.

     

Exon primed intron-crossing (EPIC) markers reveal natural hybridization and introgression in Actinidia (Actinidiaceae) with sympatric distribution

Interspecific hybridization is widespread among plants. Understanding the phylogenetic relationships among species is necessary for revealing the potential hybridization events. Actinidia, best known as kiwifruit genus found throughout a wide range in eastern Asian from Indonesia to Siberia. In this study, phylogenetic relationships of Actinidia species with sympatric distributions were investigated using three chloroplast introns (trnL-F, atpB-rbcL and rpl32-trnL) and three Exon primed intron-crossing (EPIC) markers. Chloroplast phylogeny supports non-monophyly of the five species studied excluding Actinidia fulvicoma var. lanata. The non-monophyly was also revealed by EPIC markers. Our results showed EPIC markers are more variable and informative for phylogenetic inference than that of chloroplast markers. The incongruences between loci from the plastid and nuclear DNA phylogenic trees may stem from incomplete lineage sorting or historical introgression hybridization. Incomplete lineage sorting may explain the non-monophyly between Actinidia chrysantha (section Maculatae) and other four species (section Stellatae), and introgression hybridization and high level of interspecific gene flow may explain the non-monophyly among the species of sect. Stellatae. Thus, natural hybridization and introgression may be common in Actinidia with sympatric distribution.     

Conservation genetics and geographic patterns of genetic variation of endangered shrub <Emphasis Type="Italic">Ammopiptanthus</Emphasis> (Fabaceae) in northwestern China

Phylogeographic patterns of Ammopiptanthus in northwestern China were examined with internal transcribed spacer (ITS) and three chloroplast intergenic spacers (trnH–psbA, trnL–trnF, and trnS–trnG). Two ITS genotypes (a–b) and 8 chloroplast haplotypes (A–H) were detected. Both ITS genotypes and chloroplast lineages were split in two geographic regions: western Xinjiang and the Alxa Desert. This lineage split was also supported by AMOVA analysis and the Mantel test. AMOVA showed that 89.81 % of variance in Ammopiptanthus occurred between the two geographic regions, and correlation between genetic distances and geographical distances was significant (r = 0.757, p < 0.0001). All populations in western Xinjiang shared haplotype A with high frequency, and range expansion was strongly supported by negative Fu’s F_S value, and mismatch distribution analysis, whereas populations in the Alxa Desert had higher genetic diversity and structure. We speculate that the cold and dry climate during the early Quaternary fragmented habitats of the species, limiting gene flow between regions, and interglacial periods most likely led to the range expansion in western Xinjiang. The low genetic diversity of Ammopiptanthus indicate a significant extinction risk, and protective measures should be taken immediately.     

The colonization history of the Mediterranean dwarf palm (<Emphasis Type="Italic">Chamaerops humilis</Emphasis> L., Palmae)

Chamaerops humilis L. (Mediterranean dwarf palm) is an important floristic element of the western Mediterranean region because it is the only palm species naturally distributed in both Europe and Africa. The combination of a time-calibrated phylogeny, a haplotype network and genetic diversity analyses based on plastid sequences, together with previous nuclear DNA fingerprint results, helped reconstruct the colonization history of the dwarf palm. Based on a sample of 218 individuals taken from 29 geographical areas that cover the current distribution of Chamaerops, we detected four plastid DNA (petA-psbJ) haplotypes distributed in two haplotype groups (lineage 1: haplotypes A/B; lineage 2: haplotypes C/D). Haplotypes A, B, and C showed a widespread geographical distribution in both Africa and Europe, whereas haplotype D was restricted to two African localities. Paleobotanical data, species distribution modeling and divergence time estimates suggest that Chamaerops diverged from Trachycarpus in the Miocene (27.05–6.05 Ma), followed by a split of the two C. humilis lineages that remained isolated during the Miocene-Pliocene. Divergence estimates also support a derived split into two haplotypes (A/B) in the Pleistocene, when the Mediterranean Sea barrier was in existence. This, together with geographical distribution of haplotypes A and B, strongly suggests that the disjunct distribution of C. humilis haplotypes in Europe and Africa is the result of long-distance dispersal (LDD) events rather than vicariance. In agreement with recurrent gene flow (events of LDD colonization), AMOVA revealed that most of the genetic variance was found among populations (61.52%). Irrespective of predominant plant translocations by humans or seed dispersal by natural means, our results support that current populations are the result of relatively recent contacts between Africa and Europe in the Quaternary.     

Evaluating species nonmonophyly as a trait affecting genetic diversity: a case study of three endangered species of Antirrhinum L. (Scrophulariaceae)

Molecular markers are routinely used to assess levels of diversity within and among populations, particularly with regard to species of conservation concern. However, when interpreting the level and partitioning of diversity observed, an implicit assumption is often made that the populations of the species in question form a monophyletic group. We tested this assumption in three endemics of Antirrhinum (A. charidemi, A. subbaeticum, and A. valentinum) using 79 nuclear [internal transcribed spacer (ITS)] and 85 plastid (psbA-trnH, trnT-trnL, trnK-matK, trnS-trnG) sequences representing multiple accessions of each of 24 Antirrhinum species (single accession of A. cirrhigerum). These species share six life history traits implicated in levels of genetic diversity, and have been the subject of previous population genetic studies. Populations of all three species formed monophyletic groups on ITS analysis. In contrast, none of the three species formed monophyletic groups on plastid sequence analysis: populations of A. charidemi fall in a monophyletic group including one accession of A. mollissimum, populations of A. subbaeticum form a polyphyletic group with plastid sequences shared with A. pulverulentum, and populations of A. valentinum are unresolved within a clade containing six other species. Lack of monophyly using plastid sequences is interpreted as a combination of shared ancestral polymorphism and hybridization in a reticulate evolutionary history of these species. Monophyly in the ITS tree may reflect a more recent sequence homogenization. We draw attention to the evaluation of species monophyly alongside the contribution of other life history traits in the historical interpretation of the level and partitioning of genetic diversity, and its use in recommendations for species conservation programs.     

Genetic,Ecological and Morphological Divergence between Populations of the Endangered Mexican Sheartail Hummingbird (Doricha eliza)

The Mexican Sheartail (Doricha eliza), an endangered hummingbird, is endemic to Mexico where two populations have a disjunct distribution. One population is distributed along the northern tip of the Yucatan Peninsula whereas the other is mostly restricted to central Veracruz. Despite their disjunct distribution, previous work has failed to detect morphological or behavioral differences between these populations. Here we use variation in morphology, mtDNA and nuDNA sequences to determine the degree of morphological and molecular divergence between populations, their divergence time, and historical demography. We use species distribution modeling and niche divergence tests to infer the relative roles of vicariance and dispersal in driving divergence in the genus. Our Bayesian and maximum likelihood phylogenetic analyses revealed that Doricha eliza populations form a monophyletic clade and support their sister relationship with D. enicura. We found marked genetic differentiation, with reciprocal monophyly of haplotypes and highly restricted gene flow, supporting a history of isolation over the last 120,000 years. Genetic divergence between populations is consistent with the lack of overlap in environmental space and slight morphological differences between males. Our findings indicate that the divergence of the Veracruz and Yucatan populations is best explained by a combination of a short period of isolation exacerbated by subsequent divergence in climate conditions, and that rather than vicariance, the two isolated ranges of D. eliza are the product of recent colonization and divergence in isolation.     

Temperate origin and diversification via southward colonization in Fatsia (Araliaceae), an insular endemic genus of the West Pacific Rim

Islands isolated by oceans that act as a geographical barrier for plant migration often possess high species endemism and have been deemed as a natural laboratory for studying species divergence. Fatsia Decne. & Planch. (Araliaceae), with three species, is one of the few plant genera absent in continents while exclusively spanning continental and oceanic islands. The nuclear ribosomal internal transcribed spacer (nrITS) phylogeny uncovered a pattern with reciprocal monophyly of Fatsia oligocarpella Koidz. (Bonin) and Fatsia polycarpa Hayata (Taiwan) vs. paraphyly of Fatsia japonica (Thunb.) Decne. & Planch. (Japan and Ryukyus), suggesting ancestry of the species in Japan and a likely temperate origin; whereas, lack of monophyly of all three allopatrically distributed species at chloroplast DNA (cpDNA) trnL–trnF spacer likely resulted from lineage sorting. In spite of the limited habitats for F. oligocarpella, unexpectedly high genetic variations in this species of oceanic islands were likely attributable to multiple colonizations and recurrent gene introgression. Biogeographical analyses suggested that Fatsia likely diverged via southward colonization in Bonin Islands and Taiwan during the late Pliocene to Pleistocene. Besides, Fatsia species with an allopatric distribution provide a perfect model for testing speciation modes of insular endemics. Nonzero gene flow between species was detected based on MIGRATE and STRUCTURE analyses of DNA sequences and microsatellite fingerprints, suggesting that allopatric speciation is less likely.     

Molecular evidence for the origin and evolutionary history of the rare American desert monotypic family Setchellanthaceae

Setchellanthus caeruleus, which has disjunct populations in the north of the Chihuahuan Desert and in the Tehuacán-Cuicatlán valley, was selected to understand the evolutionary history of plants in this desert and its southerly relicts. This species constitutes the monotypic family Setchellanthaceae, which forms part of a group of plants that produce mustard-oil glucosides or glucosinolates. Molecular phylogenetic analyses based on DNA plastid sequences of plants of S. caeruleus from both areas, including representative taxa of the order Brassicales, were carried out to estimate the time of origin of the family (based on matK?+?rcbL) and divergence of populations (based on psbI-K, trnh-psbA, trnL-trnF). In addition, comparative ecological niche modelling was performed to detect if climate variables vary significantly in northern and southern populations. Analyses revealed that Setchellanthaceae is an ancient lineage that originated between 78 and 112 Mya during the mid-late Cretaceous—much earlier than the formation of the Chihuahuan Desert. The molecular data matrix displayed a few indel events as the only differences of plastid DNA sequences between northern and southern populations. It is suggested that due to climate changes in this desert in the Pliocene, populations of Setchellanthus remained in the Sierra de Jimulco and in Cuicatlán, in climatically stable locations. Ecological niche models of northern populations predict niches of southern populations and identity niche tests indicate that there are no differences in their ecological niches.     

Phylogeography and population genetics of Acanthophyllum squarrosum complex (Caryophyllaceae) in the Irano-Turanian region

Acanthophyllum squarrosum and two closely related species, A. heratense and A. laxiusculum (Caryophyllaceae), form a complex that covers parts of subalpine steppes of the Irano-Turanian (IT) region. In this study, we explored the genetic structure and phylogeography of this complex based on partial sequences of two chloroplasts (psbA–trnH and rpl32–trnL (UAG)) and two nuclear (EST24 and nrITS) DNA regions. We analysed 80 individuals from eight populations and detected 12 chloroplast haplotypes, 16 and eight nuclear alleles in EST24 and nrITS sequences, respectively. Phylogenetic trees and haplotype networks did not show distinct genetic groups in the complex and this could be explained by incomplete lineage sorting or introgression between species. Divergence time analysis revealed a Quaternary origin for A. squarrosum complex at approximately 1.8 million years ago (Mya) and the neutrality test results indicated that this complex experienced a recent population expansion. AMOVA analysis of the chloroplast regions showed a significant genetic differentiation among populations and low genetic differentiation within populations, but opposite results were found with nuclear markers, implying introgression between A. squarrosum complex populations.     

Refugia and phylogeography of Taiwania in East Asia

Aim The East Asia endemic Taiwania cryptomerioides Hayata is an iconic and relictual monotypic conifer whose main extant populations are now restricted to the Yunnan–Myanmar border, northern Vietnam and Taiwan. It has also been reported from several localities in Guizhou, Hubei and Fujian Provinces, China. Its fossil record indicates that, while it was more widely distributed in the Northern Hemisphere and grew under a range of different ecological conditions, it has remained almost unchanged in its morphology for over 100 Myr. We investigate whether these remaining extant, disjunct populations have diverged genetically; when such a divergence may have occurred; and which, if any, of the extant populations exhibit refugial characteristics. Location East Asia. Methods Sequences of five chloroplast DNA markers (petG–trnP, trnH–psbA, trnV–trnM, trnC–ycf6 and trnL–trnF) from all extant populations of T. cryptomerioides were analysed to reveal their phylogeography. Molecular clock models with fossil calibrations were used to estimate divergence times between extant populations. Results Extremely low nucleotide diversity was found in the overall population (π = 0.00077) with only nine haplotypes distinguished. The mainland Asia populations share one major ancestral haplotype. The insular populations in Taiwan all possess a unique haplotype with at least an eight‐mutational‐step difference to the mainland Asia haplotype. Molecular clock estimations demonstrated that the mean divergence time between the predominant insular population haplotype and the mainland Asia haplotype occurred at c. 3.23–3.41 Ma, followed by a split into Vietnamese and Yunnan–Myanmar populations (c. 1.0–1.39 Ma). Main conclusions Strong genetic differentiation exists between insular (Taiwan) and mainland Asia populations. The split between insular and mainland haplotypes can be dated back to the end of the Pliocene. The Yunnan–Myanmar border area, northern Vietnam and Taiwan are identified here as potential refugia for T. cryptomerioides. Other populations in mainland China are unlikely to be the result of historical fragmentation and their origins require further investigation.     

Gene flow between alien and native races of the holoparasitic angiosperm Orobanche minor (Orobanchaceae)

The holoparasitic angiosperm Orobanche minor parasitizes a diverse range of flowering plants from at least 16 orders in both the monocots and eudicots. However, populations of O. minor show host specificity at a local level. Our previous work identified the potential for host specificity to act as a catalyst for genetic divergence among populations of O. minor. Here we have extended this investigation by sampling populations from multiple hosts, across a broad geographic range. Sequence characterised amplified region (SCAR) data identified an exotic host-generalist lineage and a native host-specialist lineage of O. minor, suggesting genetic structure in this species is defined by both host specificity and geography. In addition, host-range overlap, discordant tree topologies, and cryptic morphology indicate the presence of gene flow between alien races and endemic populations. Therefore, repeated introductions of alien races of O. minor from disparate sources leading to introgression with native populations, and cryptic race formation, seem to have contributed to the taxonomic confusion associated with this species. We speculate that radiations associated with broad host range and divergent host ecologies may have promoted the unusually wide geographic distribution and diversification of this species. Finally, evidence of multiple shifts to exotic hosts, coupled with the predicted northward shift in climatic suitability, identify the potential for range expansion in alien races of O. minor, which may threaten nationally scarce native taxa with genetic assimilation. Our phylogenetic analysis provides a framework for identifying host races in Orobanche with a view to setting conservation priorities.     

Multiple introgression events and range shifts in Schizocodon (Diapensiaceae) during the Pleistocene

Range shifts during the Pleistocene shaped the unique phylogeographical structures of numerous species. Accompanying species migration, sister taxa may have experienced multiple introgression events. Here, we report the signature of introgression events in multiple areas in Schizocodon, herbs endemic to Japan, using amplified fragment length polymorphism (AFLP) fingerprinting and plastid DNA haplotyping in 48 populations. Although the present distributions of S. soldanelloides and S. ilicifolius are mainly allopatric, the species share plastid DNA haplotypes in each region (north‐eastern, north‐central, south‐central and south‐western Japan); in contrast, the specific groups were highly supported by AFLP analyses. These results support the occurrence of multiple introgression events in Schizocodon. Notably, the disjunct plastid haplotypes found only in S. ilicifolius var. intercedens suggest complete plastid DNA replacement at local areas from S. soldanelloides into S. ilicifolius var. ilicifolius. Furthermore, we found that S. soldanelloides experienced range contraction and expansion during glacial and interglacial cycles based on mismatch distribution analysis and ecological niche modelling. Based on several pieces of evidence, our study supports the idea that historical range shifts associated with Pleistocene climatic oscillations favoured multiple and regional introgression events in Schizocodon. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 46–63.     

Pleistocene climatic fluctuations explain the disjunct distribution and complex phylogeographic structure of the Southern Red-backed Salamander, <Emphasis Type="Italic">Plethodon serratus</Emphasis>

The southeastern United States (U.S.) has experienced dynamic climatic changes over the past several million years that have impacted species distributions. In many cases, contiguous ranges were fragmented and a lack of gene flow between allopatric populations led to genetic divergence and speciation. The Southern Red-backed Salamander, Plethodon serratus, inhabits four widely disjunct regions of the southeastern U.S.: the southern Appalachian Mountains, the Ozark Plateau, the Ouachita Mountains, and the Southern Tertiary Uplands of central Louisiana. We integrated phylogenetic analysis of mitochondrial DNA sequences (1399 base pairs) with ecological niche modeling to test the hypothesis that climate fluctuations during the Pleistocene drove the isolation and divergence of disjunct populations of P. serratus. Appalachian, Ozark, and Louisiana populations each formed well-supported clades in our phylogeny. Ouachita Mountain populations sorted into two geographically distinct clades; one Ouachita clade was sister to the Louisiana clade whereas the other Ouachita clade grouped with the Appalachian and Ozark clades but relationships were unresolved. Plethodon serratus diverged from its sister taxon, P. sherando, ~5.4 million years ago (Ma), and lineage diversification within P. serratus occurred ~1.9–0.6 Ma (Pleistocene). Ecological niche models showed that the four geographic isolates of P. serratus are currently separated by unsuitable habitat, but the species was likely more continuously distributed during the colder climates of the Pleistocene. Our results support the hypothesis that climate-induced environmental changes during the Pleistocene played a dominant role in driving isolation and divergence of disjunct populations of P. serratus.     

Phylogeny and evolution of Dyckia (Bromeliaceae) inferred from chloroplast and nuclear sequences

The genus Dyckia (Bromeliaceae) comprises more than 150 terrestrial or epilithic species with a strongly xeromorphic habit. Most of its members belong to the azonal rock vegetation of Neotropical savannas and forests of Brazil and adjacent countries. Dyckia is relatively species-rich compared with its closest relatives Encholirium (27 species) and Deuterocohnia (17 species). Here, we present the first molecular phylogenetic analysis of Dyckia using DNA sequence data from six plastid loci (matK gene, rps16 intron, petD intron, rpl32-trnL, rps16-trnK and trnD-trnT) and a portion of the nuclear gene phyC. A total of 124 accessions were included, corresponding to 79 taxa from six genera. Phylogenetic trees were generated using parsimony, likelihood and Bayesian methods. DNA sequence variation among Dyckia species turned out to be extremely low, and phylogenies were poorly resolved. The monophyly of Dyckia is supported, whereas evidence is provided that Encholirium is paraphyletic. Based on a dated plastid DNA tree, Dyckia experienced a recent radiation starting around 2.9 million years ago. Four major clades could be identified that roughly correspond to the geographic origin of the samples. A parsimony network based on plastid DNA haplotypes shows a star-like pattern, indicating recent range expansions. Our data are compatible with a scenario where Dyckia and Encholirium diverged in northeastern Brazil, whereas one lineage of Dyckia dispersed to southern Brazil from where a rapid colonization of suitable habitats was initiated. We discuss our results in relation to species delimitation in Dyckia.     

Multiple glacial refugia and postglacial colonization routes inferred for a woodland geophyte,Cyclamen purpurascens: patterns concordant with the Pleistocene history of broadleaved and coniferous tree species

The phylogeographical history of mid‐altitude woodland herbs that depend on moist and shaded forest habitats is poorly understood. Here, we analysed the genetic structure of Cyclamen purpurascens, a mountainous calcicolous perennial, to test hypotheses regarding its glacial survival in single or multiple refugia and postglacial colonization routes, and to explore how they are congruent with the histories inferred for temperate trees and other mountainous herbs. We gathered AFLP data and chloroplast DNA sequences (trnD‐trnT region) from 68 populations spanning the entire distribution range (the Jura Mountains, Alps, western Carpathians, Dinarides). Both genetic markers revealed two main phylogeographical groups (phylogroups) in C. purpurascens. Additionally, AFLP data detected a more detailed structure of five phylogroups: two widespread, showing east?west geographical separation, and three local ones, restricted to somewhat disjunct, marginal regions of the species range. We suggest that C. purpurascens survived the last glaciation in two main regions, the foothills of the Southern Limestone Alps and the Karst area of the north‐western Dinarides, and possibly also in microrefugia in the Western Carpathians. The glacial persistence and colonization routes of this woodland herb are highly concordant with those inferred for several temperate trees, especially the European beech. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 741–760.     

Post-Glacial Expansion and Population Genetic Divergence of Mangrove Species Avicennia germinans (L.) Stearn and Rhizophora mangle L. along the Mexican Coast

Mangrove forests in the Gulf of California, Mexico represent the northernmost populations along the Pacific coast and thus they are likely to be source populations for colonization at higher latitudes as climate becomes more favorable. Today, these populations are relatively small and fragmented and prior research has indicated that they are poor in genetic diversity. Here we set out to investigate whether the low diversity in this region was a result of recent colonization, or fragmentation and genetic drift of once more extensive mangroves due to climatic changes in the recent past. By sampling the two major mangrove species, Rhizophora mangle and Avicennia germinans, along the Pacific and Atlantic coasts of Mexico, we set out to test whether concordant genetic signals could elucidate recent evolution of the ecosystem. Genetic diversity of both mangrove species showed a decreasing trend toward northern latitudes along the Pacific coast. The lowest levels of genetic diversity were found at the range limits around the Gulf of California and the outer Baja California peninsula. Lack of a strong spatial genetic structure in this area and recent northern gene flow in A. germinans suggest recent colonization by this species. On the other hand, lack of a signal of recent northern dispersal in R. mangle, despite the higher dispersal capability of this species, indicates a longer presence of populations, at least in the southern Gulf of California. We suggest that the longer history, together with higher genetic diversity of R. mangle at the range limits, likely provides a gene pool better able to colonize northwards under climate change than A. germinans.