Phylogeography and historical demography of the orchid bee <Emphasis Type="Italic">Euglossa iopoecila</Emphasis>: signs of vicariant events associated to Quaternary climatic changes

The aim of this study was to investigate whether Pleistocene climatic instability influenced the phylogeographic structure and historical demography of an endemic Atlantic Forest (AF) orchid bee, Euglossa iopoecila Dressler, which shows two main patterns of integument colors over of its geographical distribution. We based our analysis on the concatenated sequence of four mtDNA segments belonging to genes 16S (357 bp), Cytb (651 bp) and COI (1206 bp), totaling 2234 bp. Samples of E. iopoecila populations were collected in 14 AF remnants along its geographic distribution. Median-Joining haplotype networks, SAMOVA and BAPS results indicated three lineages (southern, central and northern clusters) for E. iopoecila, with two important phylogeographic ruptures. We found higher genetic diversity among samples collected in the central region of the AF, which coincides with predicted areas of climatic stability, according to recent AF stability–extinction model. The demographic analysis suggests that only the southern cluster had undergone recent population expansion, which probably started after the last glacial maximum (LGM). Our data suggest that the differentiation observed in the three mitochondrial lineages of E. iopoecila is the result of past disconnections and multiple extinction/recolonization events involving climate fluctuations. In terms of conservation, we would emphasize the importance of considering: (1) the region of the central clade as the location of the highest genetic diversity of mtDNA of E. iopoecila populations; (2) the philopatric behavior of females that tends to restrict mtDNA gene flow in particular, with direct implications for the conservation of the total genetic diversity in euglossine populations.     

Heterosis,transmission genetics,and selection for increased growth rate in a <Emphasis Type="Italic">N. tabacum</Emphasis> × synthetic tobacco cross

Cultivated tobacco (Nicotiana tabacum L.) is a classic amphidiploid, and hybrids between this cultivated species and closely related diploid Nicotiana relatives often exhibit heterotic effects for growth rate and yield. Crosses between N. tabacum and synthetic tobaccos, 4x(Nicotiana sylvestris × Nicotiana otophora) or 4x(N. sylvestris × Nicotiana tomentosiformis), may provide superior routes for genome-wide introgression from diploid relatives and allow increased potential to capitalize on heterotic effects in tobacco. Significant levels of mid-parent heterosis were observed for yield and growth rate in F₁ hybrids between synthetic tobaccos and a standard tobacco cultivar. Microsatellite marker genotyping of an F₂ population derived from a K326 × [4x(N. sylvestris × N. otophora)] cross was carried out to preliminarily investigate the relative importance of different types of gene action on observed heterosis in the original interspecific cross. Results suggested a role for both partial dominance and overdominance. Marker genotyping also indicated an overall reduced level of recombination in the N. tabacum × synthetic tobacco cross relative to a N. tabacum × N. tabacum cross but no evidence of genomic regions with severely restricted levels of recombination. Results suggest that populations derived from N. tabacum × synthetic tobacco crosses may be more efficient for introgressing germplasm from diploid relatives, as compared to populations derived from crosses between N. tabacum and diploid forms where preferential pairing between N. tabacum homologues can reduce the potential for introgression of alien chromatin. Such materials may be useful as sources of favorable alleles influencing quantitative characters in tobacco.     

Massive genetic introgression in threatened northern crested newts (<Emphasis Type="Italic">Triturus cristatus</Emphasis>) by an invasive congener (<Emphasis Type="Italic">T. carnifex</Emphasis>) in Western Switzerland

Genetic pollution through introgressive hybridization of local species by exotic relatives is a major, yet neglected aspect of biological invasions, particularly in amphibians where human introductions are frequent. In Western Switzerland, crested newts make an interesting case: the Italian species Triturus carnifex was introduced at least a century ago within the range of the native and threatened T. cristatus. To understand the genetic consequences of this introduction and inform wildlife management authorities, we conducted a genetic survey on the remaining northern crested newt populations known in the area, using newly-developed species-diagnostic nuclear (microsatellites) and mitochondrial (control region) DNA markers. We documented massive nuclear introgression by the T. carnifex genome, which has completely replaced T. cristatus in most populations, especially in the Geneva area where the introduction was originally reported. However, many of these individuals retained the ancestral T. cristatus mtDNA, which could be explained by asymmetric introgression between the two species, stemming from demographic and/or selective processes. Analyses of genetic diversity support multiple events of T. carnifex releases, most-likely of proximate North Italian origin. We pinpointed the last indigenous populations in the region and recommend to prioritize their protection. Our study demonstrates the invasive potential of introduced taxa through introgressive hybridization, alerts about the underestimated rate of illegal amphibian translocations, and emphasizes the need for genetic analyses to monitor such invasions.     

Distinct diversity patterns of <Emphasis Type="Italic">Planctomycetes</Emphasis> associated with the freshwater macrophyte <Emphasis Type="Italic">Nuphar lutea</Emphasis> (L.) Smith

Members of the phylum Planctomycetes were originally described as freshwater bacteria. Most recent studies, however, address planctomycete diversity in other environments colonized by these microorganisms, including marine and terrestrial ecosystems. This study was initiated in order to revisit the specific patterns of planctomycete diversity in freshwater habitats using cultivation-independent approaches. The specific focus was made on planctomycetes associated with Nuphar lutea (L.) Smith, an emergent macrophyte with floating leaves, which is widespread in the Holarctic. As revealed by Illumina pair-end sequencing of 16S rRNA gene fragments, the bacterial assemblages colonizing floating leaf blades of waterlilies sampled from two different boreal lakes displayed similar composition but were distinct from the planktonic bacterial communities. 16S rRNA gene fragments from the Planctomycetes comprised 0.1–1 and 1–2.2% of total 16S rRNA gene reads retrieved from water samples and plant leaves, respectively. Planktonic planctomycetes were mostly affiliated with the class Planctomycetaceae (77–97%), while members of the Phycisphaerae were less abundant (3–22%). The relative proportion of the latter group, however, increased by 13–45% on leaves of N. lutea. The Phycisphaera-related group WD2101, Pirellula-like planctomycetes, as well as Gemmata, Zavarzinella and Planctopirus species were the most abundant groups of planctomycetes associated with plant leaves, which may suggest their involvement in the degradation of plant-derived organic matter.     

Heat and hypoxia give a global invader, <Emphasis Type="Italic">Gambusia holbrooki,</Emphasis> the edge over a threatened endemic fish on Australian floodplains

Deciphering the mechanisms by which climate change interacts with invasive species to affect biodiversity is a major challenge of global change biology. We conducted experiments to determine whether the global invader, Gambusia holbrooki, was more resistant to high water temperature (heat) and low dissolved oxygen (hypoxia) than a threatened native fish, Nannoperca australis. Metabolic experiments conducted at 25 and 29 °C showed that G. holbrooki had at least four times the capacity for metabolic depression during hypoxia than N. australis. An increase in environmental temperature from 25 to 29 °C had no significant impact on the critical oxygen tension, P _crit, of G. holbrooki, but significantly and strongly increased P _crit of N. australis. Gambusia holbrooki also had a lower Q ₁₀ of standard metabolic rate than N. australis. Our results indicate that G. holbrooki have physiological traits conferring greater resistance to hypoxia than N. australis, and as temperature increases, the resistance of N. australis to hypoxia was more eroded than that of G. holbrooki. Intensive monitoring of the temperature and dissolved oxygen dynamics of wetlands showed that contemporary heat waves are already causing conditions that might give G. holbrooki the edge over N. australis on Australian floodplains. Our study adds weight to recent anecdotal reports of drought and heat waves causing localised extinction of N. australis, but the proliferation of G. holbrooki.     

The combined effects of blue light and dilution rate on lipid class and fatty acid composition of <Emphasis Type="Italic">Tisochrysis lutea</Emphasis>

The lipid class and the fatty acid compositions of microalgae highly influence bivalve larval and post-larval development. Light is an essential environmental factor for microalgal culture, and quantity and quality of light may induce changes in the biochemical composition of the algae. The objective of this study was to investigate the effect of light spectrum (blue vs. white light) on lipid class and fatty acid compositions of Tisochrysis lutea cultured in a chemostat. Two different dilution rates (D) were assayed for each light spectrum: 0.2 and 0.7 day^?1. Triacylglycerol (TAG), sterol, and hydrocarbon (HC) content increased sharply at low D. The proportion of alkenones was significantly reduced under blue light. Polyunsaturated fatty acids (PUFA), and particularly n-3 PUFA, content in phospholipids (PL) increased under blue light compared to white light at low D. Thus, blue light raised 22:6(n-3) levels in total lipids of T. lutea at low D. The cultivation of T. lutea in a chemostat at low D under blue light may improve nutritional value as feed for bivalve larvae by modifying the PUFA profile, especially increasing 22:6(n-3).     

Genetic variation and phylogeography of the bank vole (<Emphasis Type="Italic">Clethrionomys glareolus</Emphasis>, Arvicolinae,Rodentia) in Russia with special reference to the introgression of the mtDNA of a closely related species,red-backed vole (<Emphasis Type="Italic">Cl. rutilus</Emphasis>)

Totally, 294 bank voles (Clethrionomys glareolus) and 18 red-backed voles (Cl. rutilus) from 62 sites of European Russia were studied. Incomplete sequences (967 bp) of the mitochondrial cytochrome b gene were determined for 93 Cl. glareolus individuals from 56 sites and 18 Cl. rutilus individuals from the same habitats. Analysis of the cytochrome b gene variation has demonstrated that practically the entire European part of Russia, Ural, and a considerable part of Western Europe are inhabited by bank voles of the same phylogroup, displaying an extremely low genetic differentiation. Our data suggest that Cl. glareolus very rapidly colonized over the presently occupied territory in the post-Pleistocene period from no more than two (central European and western European) refugia from ancestral populations with a small effective size. PCR typing of the mitochondrial cytochrome b gene allowed us to assess the scale of mtDNA introgression from a closely related species, Cl. rutilus, and to outline the geographical zone of this introgression. Comparison with the red-backed vole haplotypes in the habitats shared by both species favors the hypothesis of an ancient hybridization event (mid-Holocene) and a subsequent introgression. These results suggest that the hybridization took place in the southern and middle Pre-Ural region.     

Lost in the hybridisation vortex: high-elevation <Emphasis Type="Italic">Senecio hercynicus</Emphasis> (Compositae,Senecioneae) is genetically swamped by its congener <Emphasis Type="Italic">S. ovatus</Emphasis> in the Bavarian Forest National Park (SE Germany)

Hybridisation is an important evolutionary process. The investigation of hybridisation along elevational gradients, with their steep abiotic and biotic clines, provides insight into the adaptation and maintenance of species in adjacent habitats. The rare Senecio hercynicus and its spreading congener S. ovatus are vertically vicariant species that show hybridisation in their range overlaps. In the present study, we used AFLP fingerprinting of 689 individuals from 38 populations to analyse population structure and introgression patterns along four elevational transects (650–1350 m) in the Bavarian Forest National Park, Gemany. Subsequently, we searched for loci putatively under divergent selection that may maintain ‘pure’ species despite hybrid formation by identifying taxon-specific alleles. A maximum-likelihood based hybrid index shows that the overall genetic differentiation among all populations was very low with a vanishingly small number of pure parental individuals. Almost 75% of the investigated individuals were classified as backcrosses towards S. ovatus. The highest S. hercynicus ancestry was found in the uppermost populations of two transects. Further, we found seven taxon-specific alleles being under divergent selection that correlated with climatic variables and deviating from neutral introgression. According to our results, hybridisation of S. ovatus and S. hercynicus has reached an advanced state of genetic swamping and there seems to be no driving force that is strong enough to keep both species as different lineages. Rather, S. ovatus appears to benefit through putatively adaptive introgression.     

Linkage between the <Emphasis Type="Italic">I</Emphasis>-<Emphasis Type="Italic">3</Emphasis> gene for resistance to Fusarium wilt race 3 and increased sensitivity to bacterial spot in tomato

Key message

The negative association between the I - 3 gene and increased sensitivity to bacterial spot is due to linkage drag (not pleiotropy) and may be remedied by reducing the introgression size.

Abstract

Fusarium wilt is one of the most serious diseases of tomato (Solanum lycopersicum L.) throughout the world. There are three races of the pathogen (races 1, 2 and 3), and the deployment of three single, dominant resistance genes corresponding to each of these has been the primary means of controlling the disease. The I-3 gene was introgressed from S. pennellii and confers resistance to race 3. Although I-3 provides effective control, it is negatively associated with several horticultural traits, including increased sensitivity to bacterial spot disease (Xanthomonas spp.). To test the hypothesis that this association is due to linkage with unfavorable alleles rather than to pleiotropy, we used a map-based approach to develop a collection of recombinant inbred lines varying for portions of I-3 introgression. Progeny of recombinants were evaluated for bacterial spot severity in the field for three seasons, and disease severities were compared between I-3 introgression haplotypes for each recombinant. Results indicated that increased sensitivity to bacterial spot is not associated with the I-3 gene, but rather with an upstream region of the introgression. A survey of public and private inbred lines and hybrids indicates that the majority of modern I-3 germplasm contains a similarly sized introgression for which the negative association with bacterial spot likely persists. In light of this, it is expected that the development and utilization of a reduced I-3 introgression will significantly improve breeding efforts for resistance to Fusarium wilt race 3.

     

Genetic structure of Sakhalin spruce (<Emphasis Type="Italic">Picea glehnii</Emphasis>) in northern Japan and adjacent regions revealed by nuclear microsatellites and mitochondrial gene sequences

The genetic structure of Sakhalin spruce (Picea glehnii) was studied across the natural range of the species, including two small isolated populations in south Sakhalin and Hayachine, by using six microsatellite loci and maternally inherited mitochondrial gene sequences. We also analyzed P. jezoensis, a sympatric spruce in the range. Genetic diversity of P. glehnii was higher in central Hokkaido and the lowest in the Hayachine. Bayesian clustering and principal coordinate analysis by using the microsatellites indicated that the Hayachine was clearly distinct from other populations, implying that it had undergone strong genetic drift since the last glacial period. P. glehnii harbored four mitochondrial haplotypes, two of which were shared with P. jezoensis. One of the two was observed without geographical concentration, suggesting its derivation from ancestral polymorphism. Another was observed in south Sakhalin and in P. jezoensis across Sakhalin. The Bayesian clustering—by using four microsatellite loci, including P. jezoensis populations—indicated unambiguous species delimitation, but with possible admixture of P. jezoensis genes into P. glehnii in south Sakhalin, where P. glehnii is abundantly overwhelmed by P. jezoensis; this might explain the occurrence of introgression of the haplotype of P. jezoensis into P. glehnii.     

Nucleotide diversity and phylogenetic relationships among <Emphasis Type="Italic">Gladiolus</Emphasis> cultivars and related taxa of family Iridaceae

The plastid genome regions of two intergenic spacers, psbA–trnH and trnL–trnF, were sequenced to study the nucleotide diversity and phylogenetic relationships among Gladiolus cultivars. Nucleotide diversity of psbA–trnH region was higher than trnL–trnF region of chloroplast. We employed Bayesian, maximum parsimony (MP) and neighbour-joining (NJ) approaches for phylogenetic analysis of Gladiolus and related taxa using combined datasets from chloroplast genome. The psbA–trnH and trnL–trnF intergenic spacers of Gladiolus and related taxa-like Babiana, Chasmanthe, Crocus, Iris, Moraea, Sisyrinchium, Sparaxis and two out group species (Hymenocallis littoralis and Asphodeline lutea) were used in the present investigation. Results showed that subfamily Iridoideae have sister lineage with subfamily Ixioideae and Crocoideae. H. littoralis and A. lutea were separately attached at the base of tree as the diverging Iridaceae relative’s lineage. Present study revealed that psbA–trnH region are useful in addressing questions of phylogenetic relationships among the Gladiolus cultivars, as these intergenic spacers are more variable and have more phylogenetically informative sites than the trnL–trnF spacer, and therefore, are suitable for phylogenetic comparison on a lower taxonomic level. Gladiolus cultivars are extensively used as an ornamental crop and showed high potential in floriculture trade. Gladiolus cultivation still needs to generate new cultivars with stable phenotypes. Moreover, one of the most popular methods for generating new cultivars is hybridization. Hence, information on phylogenetic relationships among cultivars could be useful for hybridization programmes for further improvement of the crop.     

Comparative phylogeography of capitulate <Emphasis Type="Italic">Campanula</Emphasis> species from the Balkans,with description of a new species, <Emphasis Type="Italic">C. daucoides</Emphasis>

Capitulate inflorescence is a specific, strongly adaptive and rare feature in the genus Campanula. We studied morphologically eight capitulate Campanula taxa from the Balkans (1537 individuals/52 populations) and one more species from Caucasus at the molecular level (using chloroplast markers trnG^UCC-trnS^GCU and psbA-trnH, 130 individuals/58 populations) to assess their relations and evolutionary histories. Although all studied taxa were well circumscribed at both the morphological and molecular levels (except morphologically distinct but genetically invariable C. moesiaca which acquired its single haplotype via past cytoplasmic introgression from C. cervicaria), their relations inferred from the two datasets were incongruent possibly due to the homoplasy of morphological characters frequently reported in Campanula. Interspecific hybridization and introgression affected majority of studied species and may be more common in Campanula than previously thought. These processes, along with incomplete lineage sorting and retention of ancestral polymorphisms, hampered our phylogenetic reconstructions and prevented us to fully resolve species relations, and to support monophyletic origin of capitulate Campanula species. Nonetheless, several cryptic taxa were delineated, and C. daucoides was described as a new capitulate Campanula species. Different evolutionary histories and multiple glacial refugia were inferred for all species represented by multiple samples (except C. moesiaca). According to our dating, their speciation was in most cases triggered by various geo-historic events such as the uplift of the Alpide belt, Messinian Salinity Crisis, or desiccation of the Pannonian Sea/Pliocene Lakes from the central Balkans, while their further diversification was mainly driven by the onset of the Quaternary and cycles of glacials/interglacials.     

Conservation of the Endemic Fern Lineage <Emphasis Type="Italic">Diellia</Emphasis> (Aspleniaceae) on the Hawaiian Islands: Can Population Structure Indicate Regional Dynamics and Endangering Factors?

We aimed to understand the regional population dynamics of the endemic fern lineage Diellia (D. erecta, D. erecta f. alexandri, D. falcata, D. mannii, D. pallida, and D. unisora) in mesic forests on the Hawaiian Islands. In particular, we were interested in whether studying life-stage structure would contribute to setting conservation management priorities and understanding regional dynamics. A repeated field survey of historically recorded population locations and most of the known populations were performed between 1999 and 2005. Distribution data available since 1838 show that these ferns have become extinct from 86% of the formerly recorded locations and the number of recorded extinction events exceeds the number of recorded appearance events. A significantly stronger cumulative impact of alien animals and plants distinguishes the habitats of extinct populations from other sites. The status of 19 local populations was assessed on the basis of stage structure as ‘dynamic’ (2 populations, sporelings predominate), ‘normal’ (8 populations), or ‘regressive’ (9 populations, mature plants predominate). Population size was negatively dependent on soil disturbance by alien animals. The existence of small regressive Diellia populations possibly indicates a delayed extinction process due to habitat deterioration. The study of life-stage structure, together with information about population size, is a useful tool to evaluate conservation management priorities and understand regional dynamics in conditions where demographic and precise distribution data are lacking. We conclude that the whole lineage is critically endangered and the impact of alien ungulates is obviously the main threat.     

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.     

Small genome size variation across the range of European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis>)

Interpopulation variation of relative and absolute genome size was studied in Fagus sylvatica subsp. sylvatica and subsp. orientalis. The study included 18 populations of beech planted in a common-garden experiment in central Slovakia and three additional populations from the Caucasus. Nuclear DNA content was determined by means of flow cytometry using the AT-specific fluorochrome 4′,6-diamidino-2-phenylindole and non-specific propidium iodide, and its associations with climate, growth, phenology and physiological traits were assessed. The approximate average nuclear DNA content (2C) across all samples was 1.178 ± 0.020 pg. The lowest mean relative genome sizes were observed in the Alpine range, whereas they increased toward the range margins; no clear trend was observed for 2C values. Temperature seasonality and temperature annual range were found to be negatively associated with genome size. Among phenotypic traits, the maximum chlorophyll a fluorescence yield (Fv/Fm) was found to be negatively correlated with relative genome size, whereas phenology and some photosynthetic parameters were correlated with the 2C values.     

Maintaining morphological specificity and genetic introgression in populations of the great tit <Emphasis Type="Italic">Parus major</Emphasis> and the Japanese tit <Emphasis Type="Italic">P. minor</Emphasis> in the middle Amur region

The ranges of the great tit Parus major and the Japanese tit P. minor overlap in the middle Amur region, where hybridization of these two species occur. These species have contacted for nearly a century on the western slope of the Malyi Khingan Ridge (the central part of the sympatry zone), but the great tit has colonized territories to the east of the ridge only in the last two decades. The percentage of the P. minor’s allele of intron 2 of the mioglobin gene has significantly increased from 8.9% in the west to 27.8% in the east in phenotypically major’s populations. Thus, the percentage of foreign mtDNA in P. major populations did not change significantly from west (6.2%, n = 120) to east (3.2%, n = 61). Simultaneous use of two genetic markers (one nuclear and the other mitochondrial) supports our conclusion on strong introgression in the populations of both species, which nevertheless maintain their morphological specificity in the contact zone.     

Metabolic plasticity of the corals Porites lutea and Diploastrea heliopora exposed to large amplitude internal waves

The metabolic plasticity of the two mounding coral species Porites lutea (Milne-Edwards and Haime, 1860) and Diploastrea heliopora (Lamarck, 1816) was investigated in the Similan Islands (Thailand), an offshore Andaman Sea island group subjected to large amplitude internal waves (LAIW). Nutrient concentrations were highly correlated with LAIW intensity and contributed to 3- and 10-fold higher symbiont densities in P. lutea and D. heliopora, respectively, along with elevated pigment concentrations, protein content, host tissue, and symbiont biomass. The comparison of LAIW-exposed and LAIW-sheltered island faces, and LAIW-intense and LAIW-weak years suggests a species-specific metabolic plasticity to LAIW, where D. heliopora benefits more from increased nutrient and organic matter availability than P. lutea. The ubiquitous LAIW in Southeast Asia and beyond may provide so far unexplored clues to coral acclimatization to disturbances on various scales, and hence, a potential key to coral resilience to climate change.     

Genomic clues to the parental origin of the wild flowering cherry <Emphasis Type="Italic">Prunus yedoensis</Emphasis> var. <Emphasis Type="Italic">nudiflora</Emphasis> (Rosaceae)

Prunus yedoensis Matsumura is one of the popular ornamental flowering cherry trees native to northeastern Asia, and its wild populations have only been found on Jeju Island, Korea. Previous studies suggested that wild P. yedoensis (P. yedoensis var. nudiflora) is a hybrid species; however, there is no solid evidence on its exact parental origin and genomic organization. In this study, we developed a total of 38 nuclear gene-based DNA markers that can be universally amplifiable in the Prunus species using 586 Prunus Conserved Orthologous Gene Set (Prunus COS). Using the Prunus COS markers, we investigated the genetic structure of wild P. yedoensis populations and evaluated the putative parental species of wild P. yedoensis. Population structure and phylogenetic analysis of 73 wild P. yedoensis accessions and 54 accessions of other Prunus species revealed that the wild P. yedoensis on Jeju Island is a natural homoploid hybrid. Sequence-level comparison of Prunus COS markers between species suggested that wild P. yedoensis might originate from a cross between maternal P. pendula f. ascendens and paternal P. jamasakura. Moreover, approximately 81% of the wild P. yedoensis accessions examined were likely F1 hybrids, whereas the remaining 19% were backcross hybrids resulting from additional asymmetric introgression of parental genotypes. These findings suggest that complex hybridization of the Prunus species on Jeju Island can produce a range of variable hybrid offspring. Overall, this study makes a significant contribution to address issues of the origin, nomenclature, and genetic relationship of ornamental P. yedoensis.     

Genetic analysis of the traits introgressed from <Emphasis Type="Italic">Aegilops speltoides</Emphasis> Tausch. to bread wheat and determined by chromosome 5A genes

A winter bread wheat accession from the Arsenal collection was genetically examined to study the results of introgression, which substantially changed the physiological and morphological traits of the original spring cultivar Rodina. Apart from its winter habit, the accession was characterized by awned speltoid spikes, suggesting introgression into chromosome 5A, which carries marker genes in the order Vrn-A1-Q-B1. Genetic analysis showed that the chromosome fragment introgressed from Aegilops speltoides recombined well with the homeologous region of bread wheat chromosome 5A in the region between the Vrn-A1 and Q genes. Recombination between the Vrn-A1 and B1 genes was not detected, and it was assumed that the order of the marker genes of chromosome 5A was inverted to produce Q-Vrn-A1-B1. When the winter introgression line was crossed with Triticum spelta L., an interaction of two dominant genes determining the spike character was for the first time detected in F₁, increasing the spike length and the number of spikelets, and followed with transgression in F₂. It was assumed that Ae. speltoides had a homeoallelic speltoid gene, which was designated as Q ^S .     

Sleeping with the ‘enemy’: hybridization of an endangered tree weta

While hybridization is an important part of the evolutionary process, for rare species mating with more common species hybridization can increase the risks of extinction. By mating with heterospecifics rare species waste valuable reproductive resources and as a result population sizes may decline. If introgression occurs, the rare species can become genetically swamped by alleles from the more common species, rendering it effectively extinct. As a consequence of these risks, hybridization with the more common species Hemideina femorata (Canterbury tree weta) may lead to the extinction of the range restricted species H. ricta (Banks Peninsula tree weta) on Banks Peninsula. The current study uses spatial interpolation to model the distribution of each species and the potential sympatric zone to guide sampling efforts. Polymorphic microsatellite markers and mitochondrial sequence data were used to determine the extent of hybridization between H. ricta and H. femorata. The results confirm that hybridization is possible between these species. However, hybrids and introgression appear to be very rare, suggesting that reproductive isolating barriers are present but incomplete. The threat of extinction to H. ricta via hybridization with H. femorata is low but extreme loss of habitat may cause changes to population densities that could increase the risks of hybridization. Therefore, landowners should be encouraged to conserve native bush.