Geographically congruent large‐scale patterns of plastid haplotype variation in the European herbs Silene dioica and S. latifolia (Caryophyllaceae)

The closely related dioecious herbs Silene latifolia and Silene dioica are widespread and predominantly sympatric in Europe. The species are interfertile, but morphologically and ecologically distinct. A study of large‐scale patterns of plastid DNA (polymerase chain reaction–restriction fragment length polymorphism) haplotypes in a sample of 198 populations from most of the European ranges of both species revealed extensive interspecific haplotype sharing. Four of the 28 detected haplotypes were frequent (found in > 40 populations) and widespread. Three of these frequent haplotypes occurred in both species and the geographic distribution of each haplotype was broadly congruent in both species. Each of these three, shared and widespread haplotypes is likely to have colonized central and/or northern Europe after the last glaciation from one or more of refugial areas in southern Europe. Interspecific hybridization and plastid introgression within refugial regions and/or during the early stages of postglacial expansion is the most plausible explanation for the broadly similar distribution patterns of the shared, frequent chloroplast haplotypes in the two species. The fourth frequent, widespread haplotype was absent from S. latifolia and almost entirely restricted to Nordic S. dioica. It is most likely that this haplotype spread into the Nordic countries from a central or northern European source or from a refugial area in Russia. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 153–170.     

Range expansion during the Pleistocene drove morphological radiation of the fir genus (Abies,Pinaceae) in the Qinghai‐Tibet Plateau and Himalayas

Range expansion caused by climate oscillations in the past probably promoted morphological radiation in a few plant groups. In this study, we aim to test this hypothesis through phylogeographical analysis of the cold‐tolerant fir genus (Abies) in the Qinghai‐Tibet Plateau (QTP) and Himalayas, where it comprises 12 described species. We examined sequence variation in two maternally inherited mitochondrial (mt) DNA fragments (nad5‐4 and nad7‐1) and two paternally inherited plastid DNA fragments (trnS‐G and trnL‐F) for 733 individuals from 75 populations of the species in a monophyletic group. Only six mtDNA haplotypes were recovered, but five were shared between multiple species and one occurred at a high frequency, providing strong evidence of range expansion. Forty‐three plastid DNA haplotypes were detected, 19 of which were shared between species and three occurred at high frequency. Network, mismatch and Bayesian skyline plot analyses of all plastid DNA haplotypes from this clade clearly suggested range expansion. This expansion was dated as having occurred during the longest and most extensive glaciation in the Pleistocene. Our results therefore supported the range expansion hypothesis for this clade of Abies during the Pleistocene; expansion probably drove the morphological radiation of the clade in the QTP and Himalayas, although it remains unclear whether the different morphotypes should be acknowledged as independent, reproductively isolated species. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 444–453.     

Comparative analyses of plastid and AFLP data suggest different colonization history and asymmetric hybridization between Betula pubescens and B. nana

Birches (Betula spp.) hybridize readily, confounding genetic signatures of refugial isolation and postglacial migration. We aimed to distinguish hybridization from range‐shift processes in the two widespread and cold‐adapted species B. nana and B. pubescens, previously shown to share a similarly east–west‐structured variation in plastid DNA (pDNA). We sampled the two species throughout their ranges and included reference samples of five other Betula species and putative hybrids. We analysed 901 individual plants using mainly nuclear high‐resolution markers (amplified fragment length polymorphisms; AFLPs); a subset of 64 plants was also sequenced for two pDNA regions. Whereas the pDNA variation as expected was largely shared between B. nana and B. pubescens, the two species were distinctly differentiated at AFLP loci. In B. nana, both the AFLP and pDNA results corroborated the former pDNA‐based hypothesis that it expanded from at least two major refugia in Eurasia, one south of and one east of the North European ice sheets. In contrast, B. pubescens showed a striking lack of geographic structuring of its AFLP variation. We identified a weak but significant increase in nuclear (AFLP) gene flow from B. nana into B. pubescens with increasing latitude, suggesting hybridization has been most frequent at the postglacial expansion front of B. pubescens and that hybrids mainly backcrossed to B. pubescens. Incongruence between pDNA and AFLP variation in B. pubescens can be explained by efficient expansion from a single large refugium combined with leading‐edge hybridization and plastid capture from B. nana during colonization of new territory already occupied by this more cold‐tolerant species.     

Genetic diversity and evolutionary history of the Tyrrhenian treefrog Hyla sarda (Anura: Hylidae): adding pieces to the puzzle of Corsica–Sardinia biota

The Corsica–Sardinia archipelago is a hotspot of Mediterranean biodiversity. Although tempo and mode of arrival of species to this archipelago and phylogenetic relationships with continental species have been investigated in many taxa, very little is known about the current genetic structure and evolutionary history subsequent to arrival. In the present study, we investigated genetic variation within and among populations of the Tyrrhenian treefrog Hyla sarda, a species endemic to the Corsica–Sardinia microplate and the surrounding islands, by means of allozyme electrophoresis. Low genetic divergence (mean D_nei = 0.01) and no appreciable differences in the levels and distribution of genetic variability (H_E: 0.06–0.09) were observed among all but one populations (Elba). Historical demographic and isolation‐by‐distance analyses indicated that this diffused genetic homogeneity could be the result of recent demographic expansion. Along with paleoenvironmental data, such expansion could have occurred during the last glacial phase, when wide and persistent land bridges connected the main islands and a widening of lowland areas occurred. This scenario is unprecedented among Corsica–Sardinia species. Together with the lack of concordance even among the few previously studied species, this suggests either that species had largely independent responses to paleoenvironmental changes, or that most of the history of assembly of the Corsica–Sardinia biota is yet to be written. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 159–167.     

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.     

High gene flow in two thrips‐pollinated South‐East Asian pioneer trees: genetic diversity and population structure of Macaranga hypoleuca and M. beccariana (Euphorbiaceae)

As a result of intensive exploitation, disturbed forests now dominate large areas of lowland tropical rainforest in South‐East Asia. The genus Macaranga comprises some of the most important pioneer tree species of the region, among them M. beccariana and M. hypoleuca, two closely related obligate ant‐plants pollinated by thrips. We used nuclear and plastid DNA markers to address questions of genetic diversity and population structure. Twelve plastid haplotypes were detected among 281 samples, three of which were shared between the two study species. Hybrids between the two species appear to be rare. Overall, genetic diversity in both species was moderate to high, with low levels of population differentiation, consistent with other tropical pioneer trees. Genetic structure was generally more pronounced in plastid than in nuclear data, indicating that gene flow via pollen may be more efficient than via seeds. Thrips apparently also serve as efficient pollinators over long distances, perhaps through a combination of passive dispersal by wind and active search for inflorescences in the target area. Our results indicate that M. beccariana and M. hypoleuca populations from recently disturbed habitats do not yet suffer from reduced genetic diversity or increased inbreeding. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 606–621.     

Plastid DNA haplotype diversity and morphological variation in the Dactylorhiza incarnata/maculata complex (Orchidaceae) in northern Poland

To gain an overview of the variation in the Dactylorhiza incarnata/maculata complex in northern Poland, ten plastid DNA regions (seven microsatellite and three indel loci) and 23 morphometric characters were used. In total, 972 and 480 samples from 64 and 31 populations were utilized for the genetic and morphometric analyses, respectively. One hundred and forty‐one haplotypes that have not been reported previously were recognized. The continuity of morphological characters between the studied species and the impact of post‐glacial colonization on the observed complexity in the Dactylorhiza incarnata/maculata complex were concluded. It was confirmed that the allotetraploid group of D. majalis s.s. has inherited its plastid genome from D. maculata s.l., specifically from D. maculata ssp. fuchsii. In addition, some of the haplotypes found in D. majalis s.s. were distinct and evidently not present in the preserved D. maculata s.l. Although possible gene flow and introgression between two subspecies of the D. maculata s.l. group were indicated, we suggest that they should be treated as separate evolutionary units. Both the common and rare haplotypes show a similar pattern of geographical distribution for all four taxa analysed, which suggests that hybridization took place relatively recently, shortly after the retreat of the ice sheet. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178 , 121–137.     

Intraspecific divergences of Rhodiola alsia (Crassulaceae) based on plastid DNA and internal transcribed spacer fragments

In the present study, we used two maternally inherited plastid DNA intergenic spacers, rpl20‐rps12 and trnS‐trnG, and the biparentally inherited nuclear ribosomal internal transcribed spacer (ITS) region to explore genetic variation and phylogeographical history of Rhodiola alsia, a herb endemic to the Qinghai‐Tibetan Plateau (QTP). Based on range‐wide sampling (18 populations and 227 individuals), we detected 45 plastid DNA haplotypes and 19 ITS sequence types. Only three plastid DNA haplotypes were widespread; most haplotypes were restricted to single sites or to neighbouring populations. Analysis of molecular variance revealed that most of the genetic variance was found within populations (51.24%) but that populations were also distinct (F_ST = 0.48759). We found three areas with relatively high plastid DNA diversity and these could further be recognized as potentially isolated divergence centres based on the ITS sequence type distribution. These represent three potentially isolated glacial refugia for R. alsia: one of them has long been recognized as an important refugium on the south‐eastern edge of the QTP, whereas the others are new and located in the north and south of the Tanggula Mountains on the plateau platform. Divergence time estimates based on ITS suggest that the main lineages of R. alsia diverged from each other 0.35–0.87 Mya, indicating that climatic oscillations during the Pleistocene may have been an important driver of intraspecific divergence in R. alsia. Rhodiola alsia probably experienced a phylogeographical history of retreat to isolated glacial refugia during Quaternary glaciations that led to different degrees of allopatric intraspecific divergence. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 204–215.     

Strong genetic differentiation and postglacial origin of populations in the marine midge Clunio marinus (Chironomidae,Diptera)

The marine midge Clunio marinus (Chironomidae, Diptera) is characterized by a one‐dimensional distribution along the European Atlantic coast, where its lunar and circadian emergence rhythms are genetically adapted to the local tidal regimes, resulting in a series of ‘temporal races’. Clunio marinus is restricted to rocky coasts and thus the temporal races occur in different rocky patches. We studied 10 populations of Clunio marinus from five different regions, spanning the major rocky mainland coasts from Spain to Norway, using amplified fragment length polymorphisms (AFLP), microsatellites and mitochondrial cytochrome oxidase I (COI) sequences. Star‐like patterns of COI haplotypes within regions indicate postglacial colonization. A high degree of shared polymorphisms in AFLP markers suggests colonization from a single source, implying postglacial evolution of timing adaptations in relation to the local tidal regime. In contrast, no COI haplotypes are shared among regions. We hypothesize that different levels of differentiation of nuclear vs. mitochondrial markers in the source region were carried forward during postglacial expansion. Despite the recent origin of populations, all markers reveal distinct genetic differentiation between rocky coasts on a scale of 650–1150 km. Differentiation between rocky coasts is not correlated to timing adaptations, suggesting that geographic isolation is prevalent between rocky coasts and that this facilitated the evolution of local timing adaptations. At the same time there is little genetic differentiation within rocky coasts on a scale of 2–6 km; leaving open the possibility that within rocky coasts with large variation in tidal regimes, temporal adaptations evolved in the face of gene flow.     

Cryptic hybrids between Pinus uncinata and P. sylvestris

We tested the performance of molecular markers and biometric traits in the identification of hybrids between closely related mountain pine (Pinus uncinata) and Scots pine (Pinus sylvestris). A plastid DNA marker and a set of morphological and anatomical needle traits were applied in analyses of individuals from several sympatric stands of the species and a single‐species' population from southern Europe, used as a reference. A polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) marker from the plastid trnL–trnF region and morphological and anatomical traits clearly discriminated between the pure species. Significant differences were found between P. uncinata and P. sylvestris, mostly in the shape of epidermal cells and the number of stomata. Four putative hybrids with P. sylvestris morphology, but with P. uncinata plastid DNA haplotypes, were found in a population from Sierra de Gúdar near Valdelinares, the southernmost locality of the latter species in eastern Spain. Discrimination analyses between and within populations placed these individuals on the edge of an agglomeration of P. sylvestris individuals. The results suggest that hybridization between the species is rare, but can result in cryptic hybrids morphologically similar to the maternal species. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 473–485.     

Phylogeography and palaeodistribution modelling of Nassauvia subgenus Strongyloma (Asteraceae): exploring phylogeographical scenarios in the Patagonian steppe

The Patagonian steppe is an immense, cold, arid region, yet phylogeographically understudied. Nassauvia subgen. Strongyloma is a characteristic element of the steppe, exhibiting a continuum of morphological variation. This taxon provides a relevant phylogeographical model not only to understand how past environmental changes shaped the genetic structure of its populations, but also to explore phylogeographical scenarios at the large geographical scale of the Patagonian steppe. Here, we (1) assess demographic processes and historical events that shaped current geographic patterns of haplotypic diversity; (2) analyze hypotheses of isolation in refugia, fragmentation of populations, and/or colonization of available areas during Pleistocene glaciations; and (3) model extant and palaeoclimatic distributions to support inferred phylogeographical patterns. Chloroplast intergenic spacers, rpl32–trnL and trnQ–5′rps16, were sequenced for 372 individuals from 63 populations. Nested clade analysis, analyses of molecular variance, and neutrality tests were performed to assess genetic structure and range expansion. The present potential distribution was modelled and projected onto a last glacial maximum (LGM) model. Of 41 haplotypes observed, ten were shared among populations associated with different morphological variants. Populations with highest haplotype diversity and private haplotypes were found in central‐western and south‐eastern Patagonia, consistent with long‐term persistence in refugia during Pleistocene. Palaeomodelling suggested a shift toward the palaeoseashore during LGM; new available areas over the exposed Atlantic submarine platform were colonized during glaciations with postglacial retraction of populations. A scenario of fragmentation and posterior range expansion may explain the observed patterns in the center of the steppe, which is supported by palaeomodelling. Northern Patagonian populations were isolated from southern populations by the Chubut and the Deseado river basins during glaciations. Pleistocene glaciations indirectly impacted the distribution, demography, and diversification of subgen. Strongyloma through decreased winter temperatures and water availability in different areas of its range.     

Upslope movements and large scale expansions: the taxonomy and biogeography of the Coenonympha arcania –C. d arwiniana –C. gardetta butterfly species complex

Sibling species groups are suitable models for the understanding of inter‐ and intraspecific processes in taxonomy and biogeography. We analysed 262 individuals from the Alps of the Coenonympha arcania/gardetta species complex by allozyme electrophoresis. These taxa showed high variance amongst populations (F_ST: 0.391) and strong intertaxon genetic differentiation (F_CT: 0.376). Although morphologically similar, Coenonympha gardetta and Coenonympha arcania clearly differ in their genetic characteristics; the morphologically intermediate taxa Coenonympha darwiniana darwiniana and Coenonympha darwiniana macromma are genetically well distinguished from each other and the two other taxa. Coenonympha arcania and C. d. macromma most probably share a common ancestor and evolved by cladogenesis, whereas the taxonomic situation of C. d. darwiniana is still unresolved: This taxon might be the result of hybridization between C. arcania and C. gardetta or it might have a common ancestor together with C. gardetta. We suggest species rank for all four taxa. The distribution of genetic diversity of these populations and the differentiation amongst populations suggest rather different biogeographical scenarios: C. arcania most probably is of Mediterranean origin with postglacial range expansion northwards; C. gardetta survived the last ice age in peripheral refugia of the Alps and has spread all over this high mountain system in the postglacial; C. darwiniana and C. macromma survived the Würm in geographic proximity to their actual distribution areas and only have performed moderate uphill translocations during postglacial warming. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 890–904.     

Molecular phylogenetics of the juno irises,Iris subgenus Scorpiris (Iridaceae), based on six plastid markers

Relationships among the roughly 55 species of Iris subgenus Scorpiris have been studied. A matrix of six plastid DNA regions (matK, rpl14‐rps8 spacer, infA‐rpl36 spacer, trnE‐trnT spacer, trnL intron and trnL‐F spacer) was produced from 57 accessions (52 taxa) and analysed with both parsimony and Bayesian methods. Five major clades are identified, of which four have strong geographical correlations, whereas the fifth corresponds to Iris section Physocaulon. In our results, several species are placed with species not previously considered to be related, although, in some cases, there are morphological characters that suggest that these newly indicated relationships are reasonable. For some of the other oddly grouped species, we can only assume that remarkable parallelisms in morphology have occurred or hybridization is involved. Presently, with plastid DNA as our only comprehensive data resource, we are not able to evaluate more thoroughly these more puzzling associations of species. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 281–300.     

Geographical variation and systematics of the tetraploid marsh orchid Dactylorhiza majalis subsp. sphagnicola (Orchidaceae) and closely related taxa

Dactylorhiza majalis subsp. sphagnicola is an allotetraploid marsh orchid derived from parents closely similar to present‐day D. incarnata and the western European form of D. maculata subsp. maculata, suggesting that it has a postglacial origin. It extends from northwestern continental Europe into areas formerly covered by the Weichselian ice sheet in mid‐Scandinavia. Here, we studied the variation at both the plastid and nuclear marker systems to describe the geographical variation in subsp. sphagnicola and its evolutionary history. We investigated whether subsp. sphagnicola is affected by secondary hybridization and gene flow from its parental lineages or from other allotetraploid marsh orchids, and we also compared subsp. sphagnicola with other allotetraploids of similar origins. We analysed 492 plants from 50 populations. Thirty‐seven populations were collected as potential Dactylorhiza majalis subsp. sphagnicola, five as subsp. sesquipedalis (D. elata), one as D. elata subsp. brennensis, one as subsp. calcifugiens, one as subsp. occidentalis and the remaining five as populations with some affinity to subsp. lapponica (including D. traunsteineri). All populations were analysed for plastid haplotypes and nuclear internal transcribed spacer (ITS) allele frequencies, and a subset of 43 populations was analysed for five nuclear microsatellite loci. Dactylorhiza majalis subsp. sphagnicola was dominated by a single plastid haplotype that was also dominant in western European D. maculata subsp. maculata, and most of the alternative haplotypes differed by only one mutation from the dominant one. There was more variation in nuclear microsatellites and ITS, and the variation was geographically structured in these markers. Subspecies occidentalis and calcifugiens shared haplotypes with subsp. sphagnicola, whereas subsp. sesquipedalis and brennensis had other haplotypes. Dactylorhiza majalis subsp. sphagnicola may have a postglacial origin within its present continental distribution. It has incorporated genetic material from D. maculata subsp. maculata by secondary hybridization and introgression, and some northern populations have assimilated strongly divergent haplotypes from the northeastern form of D. maculata subsp. maculata. Subspecies sphagnicola has also evolved morphologically divergent local populations in the north that do not differ from the typical populations in genetic markers. It may form mixed populations with other allotetraploid subspecies of D. majalis and, at least at one site, it has become integrated with subsp. lapponica, demonstrating that independently derived allotetraploids may contribute to a common gene pool. Subspecies calcifugiens seems to be derived from subsp. sphagnicola, and further studies based on a larger sample may confirm that it is better recognized as a variety. The so‐called D. elata subsp. brennensis is of hybrid origin and combines markers from subsp. sesquipedalis with markers from the D. majalis core complex, possibly subsp. majalis. The new combination Dactylorhiza majalis subsp. sesquipedalis (Willd.) H.A.Pedersen & Hedrén comb. nov. is provided. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 174–193.     

A geographical pattern of Antirrhinum (Scrophulariaceae) speciation since the Pliocene based on plastid and nuclear DNA polymorphisms

Aim To infer phylogenetic relationships among Antirrhinum species and to reconstruct the historical distribution of observed sequence polymorphism through estimates of haplotype clades and lineage divergence. Location Antirrhinum is distributed primarily throughout the western Mediterranean, with 22 of 25 species in the Iberian Peninsula. Methods Plastid (83 trnS‐trnG and 83 trnK‐matK) and nuclear (87 ITS) sequences were obtained from 96 individuals representing 24 of the 25 Antirrhinum species. Sequences were analysed using maximum parsimony, Bayesian inference and statistical parsimony networking. Molecular clock estimates were obtained for plastid trnK‐matK sequences using the penalized likelihood approach. Results Phylogenetic results gave limited support for monophyletic groups within Antirrhinum. Fifty‐one plastid haplotypes were detected and 27 missing haplotypes inferred, which were all connected in a single, star‐like network. A significant number of species shared both the same haplotypes and the same geographical areas, primarily in eastern Iberia. Furthermore, many species harboured populations with unrelated haplotypes from divergent haplotype clades. Plastid haplotype distribution, together with nucleotide additivity in 59 of the 86 nuclear ribosomal ITS sequences, is interpreted as evidence of extensive hybridization. Lineage divergence estimates indicated that differentiation within Antirrhinum post‐dates the Miocene, when the Mediterranean climate was established. Main conclusions Incongruence between plastid sequences, nuclear sequences and taxonomic delimitation is interpreted as strong evidence of limited cladogenetic processes in Antirrhinum. Rather, extensive nucleotide additivities in ITS sequences in conjunction with haplotype and haplotype‐clade distributions related to geographical areas support both recent and ancient hybridization. This geographical pattern of Antirrhinum speciation, particularly in eastern Iberia, is congruent with isolation–contact–isolation processes in the Pleistocene.     

A morphologically intergrading population facilitates plastid introgression from diploid to tetraploid Dodecatheon (Primulaceae)

Polyploidy may promote diversification by generating reproductive isolation between ploidy levels, but this reproductive barrier may not be absolute. Several recent analyses of diploid–tetraploid contact zones have found evidence for hybridization. In these cases, inter‐cytotype gene flow is often associated with morphologically intergrading populations. In this study, we combine cytological, fitness and population genetic data to examine the evolutionary role of a morphologically intergrading population at a contact zone between species with different ploidy levels in Dodecatheon. Diploid D. frenchii and tetraploid D. meadia are usually distinguished by leaf‐shape characters. In southern Illinois, where these taxa occur in parapatry, a morphologically intergrading population includes the first documented tetraploid with D. frenchii morphology. Most plants in this intergrading population are fertile, and a nearby typical population of D. meadia has plastid DNA haplotypes that only occur in D. frenchii elsewhere in southern Illinois. These results suggest that fit neo‐tetraploids in this intergrading population have facilitated local introgression between ploidy levels. Similar patterns in other regions where these taxa co‐occur may explain weak range‐wide genetic differentiation between these species. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 91–100.     

Global phylogeography in Sanionia uncinata (Amblystegiaceae: Bryophyta)

Global phylogeographic patterns in Sanionia uncinata are addressed based on information in internal transcribed spacer (ITS) (214 specimens) and the plastid markers trnL‐trnF (221) and rpl16 (217). ITS suggests a monophyletic Sanionia and a paraphyletic S. uncinata; this was neither supported nor rejected by plastid data. Northern or Eastern Eurasia and Alaska appear important in the early evolution of Sanionia and some populations dispersed into the Southern Hemisphere relatively early. Some haplotypes or groups of haplotypes are morphologically and ecologically distinct, biologically meaningful units that correspond with S. orthothecioides, S. symmetrica and S. georgicouncinata s.l. The latter includes two species that are indistinguishable by morphology, S. georgicouncinata s.s. (Southern Hemisphere) and S. nivalis (Northern Hemisphere). Tropical African and South American S. uncinata populations have separate origins and the Southern Hemisphere was colonized at least twice. In the northern circum‐Arctic region, the haplotype composition differs between the North Atlantic and Beringian areas. Eastern Eurasia has a higher S. uncinata haplotype diversity than other Holarctic regions, implying less devastating effects of recurrent glacial periods. For Eastern and Western Eurasia, North America and the Southern Hemisphere, most of the haplotype variation was found within the regions, but 14–18% can be referred to among region variation. Plastid haplotype diversity was lower in the Southern Hemisphere than in the Arctic to subarctic, possibly attributable to founder effects. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 19–42.     

Replicated shape variation between simple and complex habitats in two estuarine fishes

A replicated pattern of habitat‐associated morphology among different lineages may represent adaptive convergence. Deviation from the replicated (shared) pattern of diversification reflects unique (e.g. species specific) effects resulting from site‐ or species‐specific selection, intrinsic factors (e.g. G matrix differences) or chance historical events (e.g. genetic drift). For two distantly‐related estuarine fishes [Lagodon rhomboides (Sparidae; Linnaeus) and Leiostomus xanthurus (Sciaenidae; Lacepède)], we examined shared and unique instances of body shape variation between seagrass (complex) and sand (simple) microhabitats at four sites. We found extensive shape variation between microhabitats for both species. As a shared response, both species from sand had subterminal snouts and long caudal peduncles, whereas those from seagrass had terminal snouts and deep bodies. Unique responses involved a greater difference in Lagodon rhomboides head shape between microhabitats compared to L. xanthurus. Patterns of shape variation fit ecomorphological predictions for foraging in the respective microhabitats (simple versus complex) because deep bodies are expected for fish that must negotiate complex habitats and subterminal snouts facilitate benthic foraging common in barren habitats. Parallel differentiation between microhabitats simultaneously suggests that individuals of each species use a particular microhabitat within estuaries for development and the differentiation in shape represents adaptive convergence. Spatial variation in the magnitude of shape differences between microhabitats was an unexpected finding and suggests that phenotypic variation operates at multiple scales within estuaries. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 147–158.     

Horticulture,hybrid cultivars and exotic plant invasion: a case study of Wisteria (Fabaceae)

Exotic Wisteria species are highly favoured for their horticultural qualities and have been cultivated in North America since the early 1800s. This study determines the identity, genetic diversity and hybrid status of 25 Asian Wisteria cultivars using plastid, mitochondrial and nuclear DNA data. Fifteen (60%) hybrid cultivars were identified. All of the ‘Wisteria sinensis’ cultivars sampled are hybrids with W. floribunda. Although W. sinensis and W. floribunda are recognized invasive species in the southeastern USA, the relationships of horticultural cultivars to naturalized plants was previously unknown. Haplotype analysis of nuclear data identifies four haplotypes shared between cultivated stock and naturalized populations in the southeastern USA. In addition, US invasive haplotypes are present in New Zealand‐derived cultivars although, to date, naturalized Wisteria has not been documented in New Zealand. Finally, these data are used to make recommendations to horticulturalists of select species cultivars which may be less likely to invade US landscapes. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 593–601.