Contrasting phylogeographical patterns of two closely related species, Machilus thunbergii and Machilus kusanoi (Lauraceae), in Taiwan

Aim The purpose of this paper was to study the patterns of genetic variation, demographic history, haplotype relationships and potential location of diversity centres of two closely related species, Machilus thunbergii and Machilus kusanoi. Location The phylogeography of M. thunbergii and M. kusanoi was examined by sampling 110 and 106 individuals from 25 and 16 sampling sites, respectively, across their distributional range in Taiwan. Machilus thunbergii is distributed on the Asian mainland, South Korea, southern Japan, the Ryukyus, Taiwan and the Philippines, whereas M. kusanoi is endemic to Taiwan. These two species are closely related, and both are widely distributed in Taiwan but occupy different altitudinal zones and habitats. Methods The range‐wide variation of M. thunbergii and M. kusanoi in Taiwan was studied using chloroplast DNA (cpDNA) variations. A haplotype network was constructed with the computer program tcs . Nested clade analysis was conducted with the computer program ceodis , and various parameters of genetic diversity were calculated and neutrality tested by the computer program Dna SP. Population differentiation was estimated using the programs arlequin and hapstep . The contribution of the populations to gene diversity and to allelic richness was calculated using the software contrib . The level of divergence for each population from the remaining populations was calculated as the mean value of pairwise F_ST for each population against the rest of the populations. Results Extremely low levels of genetic differentiation were found for both species. This result suggested that these two species probably survived in multiple relict refugia with different population sizes throughout the island during low‐temperature periods of the Pleistocene. In addition, nested clade analysis (NCA) of cpDNA haplotypes indicated that restricted gene flow with isolation‐by‐distance characterized the recolonization after the Pleistocene by Tashueshan and Shiouhluan populations of M. thunbergii in the north‐central area west of the Central Mountain Range (CMR). In contrast, NCA analysis indicated that a major diversity centre on the southern tip of the island (Kending population) and contiguous range expansion characterized the recolonization by M. kusanoi of northern areas along the east side of the CMR. The major diversity centres found for the two species examined were further supported by the results of the mean F_ST for individual populations in comparison with other populations, and of the contribution of the divergence component to the total diversity. Main conclusions This research supports the multiple relict refugia hypothesis for both species investigated. Populations of M. thunbergii at Shiouhluan and Tashueshan in the north‐central area west of the CMR represent a diversity centre currently expanding its size. A diversity centre at the southern‐edge population of M. kusanoi, and a contiguous range expansion from Kending, were found. These results indicate that the M. thunbergii populations at Tashueshan and Shiouhluan and the M. kusanoi population at Kending, and even Soukar, are evolutionarily significant units for conservation programmes.     

Protecting evolutionary significant units for the remnant populations of <Emphasis Type="Italic">Berchemiella wilsonii</Emphasis> var. <Emphasis Type="Italic">pubipetiolata</Emphasis> (Rhamnaceae)

Berchemiella wilsonii var. pubipetiolata (Rhamnaceae) is an endangered tree in eastern China. Habitat destruction has resulted in fragmentation of remnant populations and extinction of local populations. AFLP and cpDNA markers were used to determine the population structure of remnant populations of B. wilsonii var. pubipetiolata. Moderate nuclear genomic diversity was found within each of the four remnant populations (H _S = 0.141–0.172), while the cpDNA haplotype diversity in each population ranged from 0.356 to 0.681. Six haplotypes were identified by a combined cpRFLP and cpSSR analysis in a total of 89 individuals. AMOVA revealed significantly AFLP genetic differentiation within and between regions (Φ_SC = 0.196, Φ_CT = 0.396, respectively), and a high cpDNA haplotype differentiation between regions (Φ_CT = 0.849). The results suggest low gene flow between populations of B. wilsonii var. pubipetiolata. Strong genetic divergence between two regional populations as revealed by both AFLP and cpDNA markers provided convincing evidence that two distinct evolutionary lineages existed, and should be recognized as ‘evolutionary significant units’ (ESUs) for conservation concerns.     

Witnessing extinction: Population genetics of the last European Rollers (Coracias garrulus) in Austria and a first phylogeographic analysis of the species across its distribution range

Due to broad‐scale habitat loss, European Rollers (Coracias garrulus) have been decreasing in numbers rapidly during the 20th century in parts of their European distribution range. In Austria, as of 2017, only a completely isolated relict population of two breeding pairs and a few non‐breeders remained in Styria compared to about 270 pairs in the 1950s. In 2018, no breeders have been recorded. Since 2002, all nestlings and adult birds in Austria have been ringed. Given the small census size, combined with lack of immigration from other populations, genetic depletion seems likely. In the present study, mitochondrial control region sequence and microsatellite data based on blood samples of nestlings from recent years were collected and compared with museum samples from historical times (when Rollers were more common and widespread in Austria) and with birds across the distribution range to arrive at a first preliminary phylogeographic dataset for the species. The mitochondrial DNA showed a decrease in variation over time in Austria, eventually reaching monomorphism, while genetic diversity of 10 microsatellite loci was higher than expected and a change in genetic structuring through time was observed. These results indicate drift effects in this relict European Roller population caused by the fast population breakdown and small population size. Our phylogeographic analysis indicates a division into a European and an Asian group, roughly (but not exactly) in accordance with the two subspecies C. garrulus garrulus (Europe) and Coracias garrulus semenowi (Asia). The lack of substructuring in the European group along with the results from nuclear DNA markers show the Austrian Rollers to be part of a formerly continuous population and opens the way to restocking the present relict population with birds from Eastern Europe (“genetic rescue”).     

High genetic diversity declines towards the geographic range periphery of Adonis vernalis,a Eurasian dry grassland plant

Genetic diversity is important for species' fitness and evolutionary processes but our knowledge on how it varies across a species' distribution range is limited. The abundant centre hypothesis (ACH) predicts that populations become smaller and more isolated towards the geographic range periphery – a pattern that in turn should be associated with decreasing genetic diversity and increasing genetic differentiation. We tested this hypothesis in Adonis vernalis, a dry grassland plant with an extensive Eurasian distribution. Its life‐history traits and distribution characteristics suggest a low genetic diversity that decreases and a high genetic differentiation that increases towards the range edge. We analysed AFLP fingerprints in 28 populations along a 4698‐km transect from the geographic range core in Russia to the western range periphery in Central and Western Europe. Contrary to our expectation, our analysis revealed high genetic diversity (range of proportion of polymorphic bands = 56–81%, He = 0.168–0.238) and low genetic differentiation across populations (Φ_ST = 0.18). However, in congruence with the genetic predictions of the ACH, genetic diversity decreased and genetic differentiation increased towards the range periphery. Spanish populations were genetically distinct, suggesting a divergent post‐glacial history in this region. The high genetic diversity and low genetic differentiation in the remaining A. vernalis populations is surprising given the species' life‐history traits and points to the possibility that the species has been widely distributed in the studied region or that it has migrated from a diverse source in an East–West direction, in the past.     

The role of disjunction and postglacial population expansion on phylogeographical history and genetic diversity of the circumboreal plant Chamaedaphne calyculata

In the last decade a number of studies has illustrated quite different phylogeographical patterns amongst plants with a northern present‐day geographical distribution, spanning the entire circumboreal region and/or circumarctic region and southern mountains. These works, employing several marker systems, have brought to light the complex evolutionary histories of this group. Here I focus on one circumboreal plant species, Chamaedaphne calyculata (leatherleaf), to unravel its phylogeographical history and patterns of genetic diversity across its geographical range. A survey of 29 populations with combined analyses of chloroplast DNA (cpDNA), internal transcribed spacer (ITS) and AFLP markers revealed structuring into two groups: Eurasian/north‐western North American, and north‐eastern North American. The present geographical distribution of C. calyculata has resulted from colonization from two putative refugial areas: east Beringia and south‐eastern North America. The variation of chloroplast DNA (cpDNA) and ITS sequences strongly indicated that the evolutionary histories of the Eurasian/north‐western North American and the north‐eastern North American populations were independent of each other because of a geographical disjunction in the distribution area and ice‐sheet history between north‐eastern and north‐western North America. Mismatch analysis using ITS confirmed that the present‐day population structure is the result of rapid expansion, probably since the last glacial maximum. The AFLP data revealed low genetic diversity of C. calyculata (P = 19.5%, H = 0.085) over the whole geographical range, and there was no evidence of loss of genetic diversity within populations in the continuous range, either at the margins or in formerly glaciated and nonglaciated regions. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 761–775.     

Phylogeography of Pulsatilla cernua (Ranunculaceae), a grassland species,in Japan

The genetic diversity and structure of Pulsatilla cernua, a continental‐grassland relict, were investigated using variations in chloroplast DNA (cpDNA) and microsatellites of nuclear DNA. In the analyses of three cpDNA regions, 17 haplotypes were found in 24 populations of P. cernua from Japan, Korea, and Russia. Although the route and time of migration between the continent of Asia and Japan could not be well resolved, the cpDNA haplotype network suggests the existence of several ancient lineages in Japan and a recent secondary migration from Japan to the continent. Microsatellite analyses did not indicate genetic structure among the Japanese populations, indicating the existence of gene flow across the distribution area until recently. These results indicate that the present fragmentation of P. cernua in Japan may reflect a rapid, recent reduction from a previously large, continuous distribution.     

Repeated jumps from Northwest Africa to the European continent: The case of peripheral populations of an annual plant

Peripheral populations (i.e., those occurring on the edge of a species’ distribution range) can have different origins and genetic characteristics, and they may be critical for the conservation of genetic diversity. We investigated European peripheral populations of Scrophularia arguta, a widespread, annual plant distributed from Arabia to Northwest Africa and Macaronesia. Only two small disjunct population groups of this species occur in Europe, specifically in West‐Central and Southeast Iberia. To disclose the origin of these populations and determine their importance for the conservation of S. arguta genetic diversity, we analyzed DNA sequences from two nuclear and two plastid regions and amplified fragment length polymorphism markers in populations sampled mainly across the western distribution range of the species, and modeled the species distribution under present and late Quaternary conditions. The analyses revealed the presence of three distinct lineages of S. arguta in Europe, as a result of multiple colonization waves at different times in the Quaternary. Two of these lineages, occurring in Southeast Iberia, are the result of more or less recent dispersal from Northwest Africa. In contrast, West‐Central Iberian populations are strongly differentiated from the remaining range of S. arguta and can be considered as peripheral relict populations. Our study is the first to demonstrate the occurrence of at least three colonizations of the European continent from Africa by a native plant species. The diverse histories and genetic makeup of the resulting populations confirm the importance of peripheral populations, and particularly of ancient relict populations, for the conservation of global genetic diversity in widespread species.     

The east‐west‐north colonization history of the Mediterranean and Europe by the coastal plant Carex extensa (Cyperaceae)

Coastal plants are ideal models for studying the colonization routes of species because of the simple linear distributions of these species. Carex extensa occurs mainly in salt marshes along the Mediterranean and European coasts. Variation in cpDNA sequences, amplified fragment length polymorphisms (AFLPs) and simple sequence repeats (SSRs) of 24 populations were analysed to reconstruct its colonization history. Phylogenetic relationships indicate that C. extensa together with the South American Carex vixdentata and the southern African Carex ecklonii form a monophyletic group of halophilic species. Analyses of divergence times suggest that early lineage diversification may have occurred between the late Miocene and the late Pliocene (Messinian crisis). Phylogenetic and network analyses of cpDNA variation revealed the monophyly of the species and an ancestral haplotype contained in populations of the eastern Mediterranean. The AFLP and SSR analyses support a pattern of variation compatible with these two lineages. These analyses also show higher levels of genetic diversity and differentiation in the eastern population group, which underwent an east‐to‐west Mediterranean colonization. Quaternary climatic oscillations appear to have been responsible for the split between these two lineages. Secondary contacts may have taken place in areas near the Ligurian Sea in agreement with the gene flow detected in Corsican populations. The AFLP and SSR data accord with the ‘tabula rasa’ hypothesis in which a recent and rapid colonization of northern Europe took place from the western Mediterranean after the Last Glacial Maximum. The unbalanced west‐east vs. west‐north colonization may be as a result of ‘high density blocking’ effect.     

祁连山区特有物种黑虎耳草的居群遗传多样性研究

利用叶绿体基因(rbcL和trnS-G)及核糖体DNA内转录间隔区(ITS),对祁连山区狭域分布的特有物种黑虎耳草8个居群(115个个体)进行遗传多样性研究,旨在揭示黑虎耳草的居群遗传结构及其历史进化过程。结果表明:(1)所有取样个体共检测到4个cpDNA单倍型和9个ITS单倍型,其中祁连山东南部的居群固定较多的单倍型和特有单倍型,而西北部居群只固定少数几个广泛分布的单倍型,且遗传多样性普遍较低。(2)基于cpDNA数据和ITS数据的分子变异分析(AMOVA)显示,遗传变异主要来源于居群内。(3)基于cpDNA数据的中性检验表明,Tajima’s D(-1.012 30,P 0.05)和FuLi’s D*(-2.066 77,P 0.05)均为负值,均不显著;歧点分布分析结果显示,黑虎耳草居群经历过近期的扩张事件。根据物种现有遗传分布格局推测,黑虎耳草在第四纪冰期时退缩到祁连山东南部的边缘避难所,间冰期或冰期后回迁到祁连山西北部地区,在回迁过程中由于奠基者效应导致祁连山西北部的居群仅固定少数广泛分布的单倍型,并呈现出较低的遗传多样性;由于居群较小且相互隔离,该物种经历了严重的瓶颈效应和遗传漂变,导致该物种总遗传多样性(H_T)和居群平均遗传多样性(H_S)远低于虎耳草属其他青藏高原-喜马拉雅广域分布的物种。     

基于叶绿体DNA非编码序列的蒙古扁桃谱系地理学研究

该研究选取中国西北干旱区第三纪孑遗植物蒙古扁桃（Amygdalus mongolica）,基于叶绿体DNA非编码trnH psbA序列对蒙古扁桃17个居群324个个体进行了谱系地理学研究。结果表明：（1）蒙古扁桃trnH psbA序列长度350 bp,变异位点63个,共有9种单倍型,居群间总遗传多样性为（H_t）为0.758,居群内平均遗传多样性为（H_s）为0.203,贺兰山东麓及阴山南麓边缘的居群具有较高的单倍型多样性及核苷酸多样性并固定较多特有单倍型,推测这2个地区是蒙古扁桃在第四纪冰期时的重要避难所。（2）AMOVA分析表明,居群间的遗传变异为83.84%,居群内的遗传变异为16.16%,居群间遗传分化系数N_st>G_st（N_st=0.733, G_st=0.655, P>0.05）,表明蒙古扁桃不存在明显的谱系地理结构;根据单倍型地理分布及网络关系图,把蒙古扁桃自然地理居群分为东、西两大地理组群,而且东、西地理组群没有共享单倍型;居群遗传结构分析表明,两大地理组群遗传分化较大。（3）蒙古扁桃居群在间冰期或冰期后经历了近期的居群扩张,由于奠基者效应使得多数居群只固定了单一的单倍型。     

Low genetic variability and strong differentiation among isolated populations of the rare steppe grass Stipa capillata L. in Central Europe

Stipa capillata L. (Poaceae) is a rare grassland species in Central Europe that is thought to have once been widespread in post‐glacial times. Such relict species are expected to show low genetic diversity within populations and high genetic differentiation between populations due to bottlenecks, long‐term isolation and ongoing habitat fragmentation. These patterns should be particularly pronounced in selfing species. We analysed patterns of random amplified polymorphic DNA (RAPD) variation in the facultatively cleistogamous S. capillata to examine whether genetic diversity is associated with population size, and to draw initial conclusions on the migration history of this species in Central Europe. We analysed 31 S. capillata populations distributed in northeastern, central and western Germany, Switzerland and Slovakia. Estimates of genetic diversity at the population level were low and not related to population size. Among all populations, extraordinarily high levels of genetic differentiation (amova : φ_ST = 0.86; Bayesian analysis: θ^B = 0.758) and isolation‐by‐distance were detected. Hierarchical amova indicated that most of the variability was partitioned among geographic regions (59%), or among populations between regions when the genetically distinct Slovakian populations were excluded. These findings are supported by results of a multivariate ordination analysis. We also found two different groups in an UPGMA cluster analysis: one that contained the populations from Slovakia, and the other that combined the populations from Germany and Switzerland. Our findings imply that S. capillata is indeed a relict species that experienced strong bottlenecks in Central Europe, enhanced by isolation and selfing. Most likely, populations in Slovakia were not the main genetic source for the post‐glacial colonization of Central Europe.     

Chloroplast DNA diversity associated with protected slopes and valleys for hybridizing Eucalyptus species on isolated ranges in south‐eastern Australia

Aim To relate genetic diversity to topographic features and to investigate genetic interactions between Eucalyptus species in a local centre of endemism and diversity in south‐eastern Australia. Location Grampian Ranges, Victoria, Australia. Methods We documented chloroplast DNA (cpDNA) variation for a group of endemic Eucalyptus species (E. serraensis, E. verrucata and E. victoriana) that dominate rocky, high‐elevation ridgelines of the Grampian Ranges and for one closely‐related, widespread species (E. baxteri) occupying flanking slopes and valleys. We documented genetic patterns across the landscape using cpDNA microsatellites, and related them to topographic features (exposed west‐facing versus protected east‐facing slopes and valleys). We also determined the extent of local haplotype sharing between populations of endemic species and neighbouring E. baxteri downslope with cpDNA microsatellites, and haplotype sharing between the endemic group and more distantly related species (E. obliqua, E. pauciflora and E. willisii) with sequences of the J_LA+ chloroplast region. Results We detected 26 cpDNA microsatellite haplotypes in a relatively small area of c. 20 km × 50 km. Populations of E. baxteri on east‐facing slopes and valleys had greater cpDNA microsatellite diversity than E. baxteri and endemic species on exposed west‐facing slopes. Endemic species frequently shared chloroplast haplotypes with E. baxteri downslope. Sharing of J_LA+ haplotypes with species outside the endemic group was mostly restricted to E. victoriana, which had cpDNA more similar to the species from other sections of Eucalyptus (E. obliqua, E. willisii and E. pauciflora). Main conclusions Intensive sampling of related species on small isolated mountain ranges allowed us to relate genetic diversity to fine‐scale habitats and to document extensive local haplotype sharing between species. This study contributes to a general understanding of the environmental conditions that enable plant population persistence by linking concentrations of genetic diversity to particular habitats.     

Local genetic structure of a montane herb among isolated grassland patches: implications for the preservation of genetic diversity under climate change

Habitat loss, fragmentation of meadow patches, and global climate change (GCC) threaten plant communities of montane grasslands. We analyzed the genetic structure of the montane herb Geranium sylvaticum L. on a local scale in order to understand the effects of habitat fragmentation and potential GCC impacts on genetic diversity and differentiation. Amplified fragment length polymorphism (AFLP) fingerprinting and cpDNA sequencing was performed for 295 individuals of 15 G. sylvaticum populations spanning the entire distribution range of the species in the Taunus mountain range in Germany. We found patterns of substantial genetic differentiation among populations using 150 polymorphic AFLP markers (mean F _ST = 0.105), but no variation in 896 bp of plastid DNA sequences. While populations in the center of their local distribution range were genetically diverse and less differentiated, higher F _ST values and reduced genetic variability was revealed for the populations at the low-altitudinal distribution margins. Projections of GCC effects on the distribution of G. sylvaticum in 2050 showed that GCC will likely lead to the extinction of most edge populations. To maintain regional genetic diversity, conservation efforts should focus on the diverse high-altitude populations, although a potential loss of unique variations in genetically differentiated peripheral populations could lower the overall genetic diversity and potentially the long-term viability in the study region. This study documents the usefulness of fine-scale assessments of genetic population structure in combination with niche modeling to reveal priority regions for the effective long-term conservation of populations and their genetic variation under climate change.     

Range-edge effects promote clonal growth in peripheral populations of the one-sided wintergreen Orthilia secunda

Existing in suboptimal conditions is a frequent occurrence for species inhabiting the cusp of their ecological range. In range‐edge populations of plants, the scarcity of suitable habitat may be reflected in small population sizes which may result in increased self‐pollination and/or inbreeding and an increase in the incidence of clonal reproduction. These factors may result in a decrease in levels of genetic diversity and a loss of potential adaptive variation that may compromise species’ ability to cope with changes in their environment, an issue that is particularly relevant today with the current concern surrounding global climate change and its effect on species’ distributional ranges. In the present study, we have compared the levels of clonal reproduction in the one‐sided wintergreen Orthilia secunda (L.) House in (1) populations from its main continuous distribution range, (2) populations occurring on the limits of the continuous range, and (3) peripheral populations outwith the species’ continuous distribution range. Range‐edge populations in Scotland and Sweden displayed significantly lower genotypic richness and diversity than those from the main area of the species’ distribution in these countries. Populations from Ireland, which occur in the temperate zone rather than the boreal conditions that are the preferred habitat for the species, and which represent relict populations left over from cooler periods in the Earth's history, displayed no within‐population genetic diversity, suggesting a complete lack of sexual reproduction. Furthermore, the genetic distinctiveness of the Irish populations, which contained alleles not found in either the Scottish or the Swedish populations, highlights the value of ‘trailing edge’ populations and supports the concept of ‘parochial conservation’, namely the conservation of species that are locally rare but globally common.     

Comparison between mitochondrial and chloroplast DNA variation in the native range of Silene vulgaris

A detailed survey of mitochondrial and chloroplast diversity in eight populations of Silene vulgaris from Central Europe was conducted for comparison with previously published data on diversity from S. vulgaris populations in the introduced range. Mitochondrial DNA (mtDNA) variation around the coxI gene was assessed with Southern blotting/restriction fragment length polymorphism methods. Chloroplast variation was assessed by sequencing the intergenic spacer separating the trnH and psbA genes. Thirty mtDNA haplotypes and 24 chloroplast DNA (cpDNA) haplotypes were found within 86 individuals. The overall genetic diversity h (0.941 for mitochondrial, and 0.893 for chloroplast markers) and within-population diversity were higher than reported in previous population studies of S. vulgaris in the USA and Europe. The frequency of private alleles was surprisingly high - more than 90% for both kinds of markers. Most of our populations were large and located in relatively undisturbed meadows, whereas surveys in Virginia consisted of smaller roadside populations. The slow rate of population turnover in European populations is discussed as a factor responsible for the relatively high diversity of S. vulgaris in undisturbed areas of its native range. Association between mtDNA and cpDNA haplotypes was also demonstrated. Finally, gender and mtDNA haplotype were associated in the Alps populations, where females were very rare.     

Environmental variation shapes genetic variation in Bouteloua gracilis: Implications for restoration management of natural populations and cultivated varieties in the southwestern United States

With the increasing frequency of large‐scale restoration efforts, the need to understand the adaptive genetic structure of natural plant populations and their relation to heavily utilized cultivars is critical. Bouteloua gracilis (blue grama) is a wind‐dispersed, perennial grass consisting of several cytotypes (2n = 2×–6×) with a widespread distribution in western North America. The species is locally dominant and used regularly in restoration treatments. Using amplified fragment length polymorphism (AFLP) and cpDNA analyses, we assessed the genetic variability and adaptive genetic structure of blue grama within and among 44 sampling sites that are representative of the species’ environmental and habitat diversity in the southwestern United States. Five cultivars were also included to investigate genetic diversity and differentiation in natural versus cultivated populations. Three main findings resulted from this study: (a) Ninety‐four polymorphic AFLP markers distinguished two population clusters defined largely by samples on and off the Colorado Plateau; (b) substructure of samples on the Colorado Plateau was indicated by genetic divergence between boundary and interior regions, and was supported by cytotype distribution and cpDNA analysis; and (c) six AFLP markers were identified as “outliers,” consistent with being under selection. These loci were significantly correlated to mean annual temperature, mean annual precipitation, precipitation of driest quarter, and precipitation of wettest quarter in natural populations, but not in cultivated samples. Marker × environment relationships were found to be largely influenced by cytotype and cultivar development. Our results demonstrate that blue grama is genetically variable, and exhibits genetic structure, which is shaped, in part, by environmental variability across the Colorado Plateau. Information from our study can be used to guide the selection of seed source populations for commercial development and long‐term conservation management of B. gracilis, which could include genetic assessments of diversity and the adaptive potential of both natural and cultivated populations for wildland restoration.     

The central Mediterranean as a phytodiversity hotchpotch: phylogeographical patterns of the Anthemis secundiramea group (Compositae,Anthemideae) across the Sicilian Channel

Aim We investigated the phylogeography of the Anthemis secundiramea group (Compositae, Anthemideae) to assess the role of palaeogeographical events in its genetic and taxonomic differentiation. We also evaluated the contribution of hybridization to the complexity of these diversification processes in an area of phytogeographical overlap. Location Central Mediterranean: North Africa, Tyrrhenian Islands, Sicily, and its surrounding islands and islets. Methods The geographical distribution of the genetic variability and differentiation of 207 individuals belonging to 42 populations was analysed through chloroplast DNA variation (sequences of the two spacer regions psbA–trnH and trnC–petN), and 290 individuals belonging to 35 populations were analysed using amplified fragment length polymorphism (AFLP) fingerprinting. Results We found three well‐defined groups of taxa. The first includes all populations located in North Africa belonging to the species Anthemis confusa, A. glareosa and A. ubensis, which show a significant pattern of isolation by distance from one another. They share the same chloroplast DNA haplotypes, possibly reflecting range expansion/contraction during the Quaternary. Within the second group, which comprises all populations belonging to A. secundiramea, an absence of genetic structure suggests contemporary or at least recent gene flow among its populations. The third group includes the populations belonging to Anthemis urvilleana, which is endemic to the Maltese archipelago. While hybridization with Anthemis arvensis or A. peregrina is hypothesized for four populations of A. urvilleana, the sharing of a haplotype between one population and A. muricata, endemic to Sicily, is interpreted as a relict of the ancient connection between the Maltese archipelago and south‐eastern Sicily. Main conclusions The strong genetic differentiation observed between circum‐Sicilian and North African populations of the A. secundiramea group suggests the paramount importance of the Sicilian Strait as a barrier to dispersal and gene flow. The present distribution of A. secundiramea, however, demonstrates that this barrier may be crossed by long‐distance dispersal overseas, or by anthropogenic dispersal. Sea‐level oscillations during the Pleistocene were responsible for the divergence between the Sicilian endemic A. muricata and the Maltese endemic A. urvilleana. Incongruent AFLP patterns and chloroplast haplotype distributions indicate that hybridization of members of the A. secundiramea group with eastern (A. arvensis or A. peregrina) as well as with western (the clade of A. maritima and A. pedunculata) Mediterranean elements has strongly influenced the genetic and taxonomic diversity in this species group.     

Genetic Evidence of the Contribution of Ethnic Migrations to the Propagation and Persistence of the Rare and Declining Scrambling Shrub Caesalpinia bonduc L

This paper examines the contribution of human migrations to the propagation and maintenance of Caesalpina bonduc by means of an analysis of its population genetics and distribution patterns. One hundred and forty seven sites were surveyed in the three climatic zones of Benin and all individuals of the species were recorded. A set of individuals was randomly selected and sampled from seven populations and morphological variation and genetic diversity were assessed. The study confirmed the presence of the species in all climatic zones but its abundance varied greatly. Morphological variability between populations and zones was low in comparison with the high amount of variation within populations. AFLP and cpDNA fingerprinting revealed an extremely low genetic diversity within populations and a low genetic differentiation, suggesting parental links between populations. The results support the hypothesis of human involvement in Caesalpinia dispersal and persistence in Benin. However, the low genetic diversity may imply high risks for future extinction. We recommend that gene flow among the remaining populations be supported in order to conserve the species.     

Population size,center–periphery,and seed dispersers’ effects on the genetic diversity and population structure of the Mediterranean relict shrub Cneorum tricoccon

The effect of population size on population genetic diversity and structure has rarely been studied jointly with other factors such as the position of a population within the species’ distribution range or the presence of mutualistic partners influencing dispersal. Understanding these determining factors for genetic variation is critical for conservation of relict plants that are generally suffering from genetic deterioration. Working with 16 populations of the vulnerable relict shrub Cneorum tricoccon throughout the majority of its western Mediterranean distribution range, and using nine polymorphic microsatellite markers, we examined the effects of periphery (peripheral vs. central), population size (large vs. small), and seed disperser (introduced carnivores vs. endemic lizards) on the genetic diversity and population structure of the species. Contrasting genetic variation (H_E: 0.04–0.476) was found across populations. Peripheral populations showed lower genetic diversity, but this was dependent on population size. Large peripheral populations showed high levels of genetic diversity, whereas small central populations were less diverse. Significant isolation by distance was detected, indicating that the effect of long‐distance gene flow is limited relative to that of genetic drift, probably due to high selfing rates (F_IS = 0.155–0.887), restricted pollen flow, and ineffective seed dispersal. Bayesian clustering also supported the strong population differentiation and highly fragmented structure. Contrary to expectations, the type of disperser showed no significant effect on either population genetic diversity or structure. Our results challenge the idea of an effect of periphery per se that can be mainly explained by population size, drawing attention to the need of integrative approaches considering different determinants of genetic variation. Furthermore, the very low genetic diversity observed in several small populations and the strong among‐population differentiation highlight the conservation value of large populations throughout the species’ range, particularly in light of climate change and direct human threats.     

Morphological characterization of new populations of the copepod Eurytemora velox (Lilljeborg, 1853) (Calanoida,Temoridae) found in Austria and Hungary

The calanoid copepod Eurytemora velox (Lilljeborg, 1853) was found in the backwater system of the Danube River upstream of Vienna (km 1948) in 1994. Since that time, the species has invaded the side arms of the river between kms 1897 and 1988, as confirmed by findings from 10 different localities. In Hungary, the species has been known since 1992. In the present article, we report 15 new sites in the westernmost part of this country.A brief diagnosis of the morphology of male and female of the Austrian specimens is presented, including detailed illustrations of the structures used in this paper for taxonomic analysis. Females show morphological variability mainly on the structure of the fifth leg pair. Right and left legs frequently have a different spinulation pattern. Males show less morphological variability, particularly in the structure of the basis and the distal section of exopod 2 of the fifth left leg. Morphological variation within E. veloxwas determined by comparing specimens from Austria, Hungary and Rumania. The geographic distribution of the species in the Palearctic region, Austria and Hungary is presented.