Rubra Populations Research Articles

Distance-dependent mating but considerable pollen immigration in an isolated Quercus rubra planting in Germany

AbstractGene flow affects the genetic diversity and structure of tree species and can be influenced by stress related to changing climatic conditions. The study of tree species planted in locations outside their natural range, such as arboreta or botanical gardens, allows us to analyse the effect of severe fragmentation on patterns and distances of gene flow. Paternity analysis based on microsatellite marker genotyping was used to analyse how fragmentation affects gene flow among individuals of Quercus rubra L. distributed in a small isolated group of trees (15 trees) planted in the arboretum on the North Campus of the University of Göttingen. For paternity analysis, 365 seedlings from four seed parents were selected and genotyped using 16 microsatellites. The analysis revealed the majority of pollen (84.89%) originated from trees within the site and identified three large full-sib families consisting of 145, 63 and 51 full-sibs. The average pollen dispersal distance for the four seed parents ranged from 17.3 to 103.6 meters. We observed substantial genetic differentiation among effective pollen clouds of the four seed parents (G’’ST = 0.407) as a result of cross pollination between neighboring trees. No self-fertilization was observed. Gene dispersal via pollen followed the expected distance-dependent pattern, and we observed a significant influx of external pollen (15.11%, ranging from 8.64 to 26.26% for individual seed parents) from a diverse set of donors (30). Long-distance pollen dispersal could explain the presence of significant genetic variation even in isolated natural Q. rubra populations.

Differential effect of climate of origin and cultivation climate on structural and biochemical plant traits

Abstract Exploring patterns and causes of intraspecific trait variation is crucial for a better understanding of the effects of climate change on plant populations and ecosystems. However, our current understanding of the intraspecific trait variation is mainly based on structural (morphological) traits, and we have limited knowledge on patterns and causes of variation in biochemical traits (e.g. leaf pigments), which are also crucial for plant adaptation. As a result, we also do not know how similar the climatic effects on structural versus biochemical traits are. Using plant traits from 110 genotypes representing 11 Festuca rubra populations grown in 4 different climates, we studied trait covariation among structural traits (linked to fitness, resource use, gas exchange and reproduction) and biochemical traits (linked to photosynthesis, photoprotection and oxidative stress). We also disentangled the relative role of the climate of origin and the climate of cultivation in the structural versus biochemical traits and tested for adaptive plasticity in the traits. We found that (1) biochemical traits did not covary with structural traits and represent independent ‘photoharvesting–photoprotection’ strategy dimension of functional variation; (2) interactive effects of climate of origin and cultivation were more pronounced for biochemical than structural traits. (3) Trait plasticity was affected by the climate of origin (precipitation and temperature as well as their interaction); (4) F. rubra showed both adaptive and maladaptive plasticity, and adaptiveness depended upon trait type, cultivation climate and climate of origin. Overall, our results suggest that structural and biochemical plant traits respond differentially to climate and thus the response of one group of traits cannot be predicted from the other. Responses are also strongly determined by interactions between the climate of origin and cultivation. Thus, more studies on variation in biochemical traits, their correspondence to other traits, and their variation with climate are needed. Read the free Plain Language Summary for this article on the Journal blog.

Dynamics of spatial and ontogenetic structure of Cephalanthera rubra (Orchidaceae) populations in the east of European Russia (Middle Volga Region)

The assessment of the spatial and functional features of rare species populations without considering the ontogenetic groups, which are being rarely distinguished at international literature, does not give a complete understanding of the current status of populations and prospects of their development under various management conditions. This paper is aimed to determine the status of a threatened orchid species, Cephalanthera rubra, at the eastern border of its range (Republic of Tatarstan, European Russia). For this purpose, a complex of various population parameters was used. Ontogenetic groups of C. rubra individuals have been reliably identified on the basis of morphometric traits of reproductive and vegetative organs. The obtained results showed that the fruit set is low, ranging at average from 24% for young reproductive individuals (g1) to 39% for mid-mature reproductive individuals (g2); it reflects prospects for seed reproduction of this species at the eastern edge of its range. The abundance dynamics of populations has a fluctuation type; it is related to climatic factors of the growing season. So, we found its significant positive correlations with air humidity (from r = 0.6 to r = 0.7) and precipitation (from r = 0.5 to r = 0.6), and a negative correlation with temperature (from r = -0.5 to r = -0.6). In the Republic of Tatarstan, the base spectrum of C. rubra populations is of the centred type, 1:10:51:38 (j:im:v:g); it corresponds to the general ontogenetic spectrum of rhizomatous orchids. The spatial-ontogenetic structure of populations, and especially its dynamics, reflects the intraspecific relationships of various ontogenetic groups involved in maintaining the stability of C. rubra population in space and time. Under optimal conditions, the spatial structure of all individuals and reproductive groups is characterised by a spatial randomness, which probably reduces intraspecific competition. In contrary, pre-reproductive groups form aggregations with 0.5–0.9-m radius in microloci, favourable for seed germination. A characteristic feature of the spatial structure is the formation of aggregations of reproductive and pre-reproductive individuals with a 0.7–1.0-m radius with a 0.2–0.4-m zone of the random spatial positioning of individuals, which aims to reduce intraspecific competition between them. The probability of meeting an individual of another ontogenetic group increases towards the periphery of the formed aggregation. In C. rubra populations, the abundance and density of individuals, and the fruit set decrease in pessimal conditions of landslides, soil erosion, and habitat shading. Under these conditions, pre-reproductive individuals do not form aggregations, nor aggregations with reproductive individuals. In general, the spatial structure of a population depends on the life-form type of the species, the mechanism of spatial growth of underground organs; it is considered a diagnostic sign of the population status.

Development of novel Quercus rubra chloroplast genome CAPS markers for haplotype identification

Abstract Our main objective was to generate cost-effective chloroplast (cp) DNA markers that are easy to apply and to score. In combination with already published cpSSR markers they should increase haplotype resolution in populations. To discover new cpDNA markers, we sequenced 87-97 % of the entire chloroplast genome (except the second inverted repeat) of 8 trees representing different regions of the Quercus rubra L. natural range with 4,030X-6,297X coverage and assembled the genome sequences using the publicly available chloroplast genome of Quercus rubra L. as a reference. In total, 118 single nucleotide polymorphisms (SNPs) and 107 insertions or deletions (indels) were detected, and 15 cleaved amplified polymorphic sequence (CAPS) markers were developed for Q. rubra. Using these new markers together with five chloroplast microsatellite or simple sequence repeat (cpSSR) markers, we identified 10 haplotypes in our diversity panel of 19 Q. rubra populations. Specifically, two haplotypes based only on the cpSSR markers could now be separated in five haplotypes. These markers are useful to assess haplotype diversity with high resolution and are also transferable to a closely related species, Quercus ellipsoidalis E. J. Hill.

Characterization of 20 new EST-SSR markers for northern red oak (Quercus rubra L.) and their transferability to Fagus sylvatica L. and six oak species of section Lobatae and Quercus

Northern red oak (Quercus rubra L.) is widely distributed in the eastern United States and southeastern Canada. It has also been introduced to Europe, where it has become an economically important plantation species now. Despite growing genomic resources, the number of available EST-SSR (expressed sequence tag – simple sequence repeat) markers for Q. rubra is still limited. Here, we used existing sequence information to provide a new set of EST-SSRs for northern red oak. In total, we report 20 polymorphic EST-SSRs, for which performance was evaluated in three Q. rubra populations from different regions in Michigan. We further tested the transferability of these markers to six additional oak species of section Lobatae (Quercus ellipsoidalis E.J. Hill, and Quercus georgiana M.A. Curtis) and Quercus (Quercus robur L., Quercus alba L., Quercus pedunculiflora K. Koch, and Quercus petraea (Matt.) Liebl.), as well as to European beech (Fagus sylvatica L.). The reported markers can be used in future population genetic studies.

Myrmica rubra microhabitat selection and putative ecological impact

1. Myrmica rubra (European fire ant) has invaded northern latitude coastal areas in North America. This macroscale distribution suggests that M. rubra is moisture‐ and temperature‐limited, but the distribution of the invaded range may reflect the legacy of original introduction locations preserved by limited dispersal.2. This study examined a two‐decade population change in M. rubra (1994–2015) and the microscale abiotic (moisture and temperature), biotic (plants), anthropogenic (pesticide) and physiological (thermal tolerance) limits on the invasion at the Tifft Nature Preserve in Buffalo, NY (U.S.A.). Changes in the abundance of native ants and other invertebrates were also examined.3. Despite localised declines with pesticide treatments, overall M. rubra forager abundance increased 27% between 1994 and 2015. Abundance increased the most in the warmest areas (native ants were unaffected by temperature), but M. rubra colony locations were strongly linked to higher soil moisture and lower soil temperature. Myrmica rubra ants also exhibited relatively low thermal tolerances consistent with high‐latitude and high‐elevation ants.4. Where local M. rubra populations increased the most, native ant species decreased, and where local M. rubra populations declined, native ant species increased. Some arthropod species had lower abundance with M. rubra presence, but the impacts were less striking.5. Myrmica rubra population growth was promoted at the microhabitat scale where relatively higher temperatures prompted foraging, and relatively lower temperatures and high moisture supported nesting. These results suggest that macroscale M. rubra invaded‐range distributions in northern climates near coastal areas are replicated at the microscale where the ant prefers cooler, moister microsites.

Population differentiation related to climate of origin affects the intensity of plant–herbivore interactions in a clonal grass

With ongoing climate change, it is likely that shifts in species distribution ranges will lead to changes in the type and intensity of plant–herbivore interactions. Plants currently exposed to lower levels of herbivory could have less developed defensive mechanisms and therefore could suffer in case of increased herbivore pressure.We performed a common garden experiment using clones of Festuca rubra originating from four populations experiencing contrasting temperature and precipitation regimes. Clones of identical genotype were subjected to both the control and the herbivory treatment using larvae of the nymphalid butterfly Coenonympha pamphilus, a generalist herbivore feeding on several grass species. Various measures of constitutive and induced defence as well as growth response to herbivory were assessed, compared between populations of different climatic origin and related to herbivore performance (larval survival).The four F. rubra populations significantly differed in constitutive defence (content of Si and total phenols), nutritional quality (content of C) and inducibility of defence (change in total phenols), but not in growth response to herbivory. Herbivores survived better on populations from colder climate and better survival was generally related to lower Si content and lower initial plant size.We demonstrated population differentiation in both constitutive and induced defence against insect herbivory, which directly affected survival of a generalist herbivore. Our findings confirmed the expectation that plants from higher elevations are more prone to herbivory. Moreover, differences in various aspects of plant defence between populations from the same altitude stresses the need of considering multiple factors when assessing the effect of climate on plant–herbivore interactions.

High genetic variation among closely related red oak (Quercus rubra) populations in an ecosystem under metal stress: analysis of gene regulation

Metal toxicity is a major abiotic stressor of plants. It has been established that changes in genetic variation occur very rapidly in plants in response to environmental stressors such as increased levels of metals. Quercus rubra (red oak) is a pioneer species in mining regions contaminated with metals in Northern Ontario (Canada). The objectives of the study were to (1) determine the level of genetic variation in Q. rubra populations from mining damaged ecosystems using RAPD marker system and (2) assess the level of gene expression of candidate genes for nickel resistance. Total gene diversity (HT) and the mean gene diversity among populations (HS) were 0.22 and 0.19, respectively. The percent of polymorphic loci within populations was high ranging from 61 % (Capreol) to 72 % (Daisy Lake) despite a high level of gene flow (2.4). The population differentiation (GST) value was low (0.17). No significant difference was found among the contaminated and reference sites for all the genetic parameters estimated. Hence, all the Q. rubra populations from the metal-contaminated and damaged ecosystems are genetically sustainable. Moreover, this study reveals that all populations were genetically closely related with genetic distance values varying from 0.17 to 0.35. A zinc finger protein of Arabidopsis thaliana (ZAT11) gene involved in nickel resistance was differentially expressed in samples analyzed. There was a 120 times higher of ZAT11 expression in samples from metal contaminated areas of Wahnapitae Dam compared to other metal contaminated and uncontaminated sites, but no association between soil metal levels and expression of ZAT11 was established.

Fine-scale spatial genetic structure of two red oak species, Quercus rubra and Quercus ellipsoidalis

Peripheral populations located at their range edge, may be at risk due to geographical isolation, environmental changes, human disturbances or catastrophic events such as wildfires. Fine-scale spatial genetic structure (SGS) investigations provide a way to examine the spatial arrangement of genetic variation within populations. SGS can result from restricted seed and pollen dispersal and might be affected by geographic isolation and environmental changes and disturbances even in outcrossing wind-pollinated species like oaks. Studying the SGS of peripheral populations provides information that can be used to develop improved conservation and management plans at the species’ range edge. We assessed the level of genetic variation and SGS in twelve range edge populations in northern Wisconsin and the Upper Peninsula of Michigan (USA): eight Quercus rubra and four Quercus ellipsoidalis populations that were subject to different management regimes and natural disturbances. In contrast to Q. rubra populations, the drought tolerant Q. ellipsoidalis populations are isolated from the species’ main distribution range. These populations are not actively managed but are especially prone to recurring fire events. The four managed and four old growth (“unmanaged”) Q. rubra populations displayed similar levels of genetic variation. Likewise the Sp statistic showed similar SGS levels in managed and unmanaged Q. rubra populations (Sp = 0.005) comparable to other Quercus species (European Q. robur: Sp = 0.003). Q. ellipsoidalis populations showed similar or more pronounced SGS than neighboring Q. rubra populations extending up to 83 m in one population. A significant excess of homozygotes across markers in two of the Q. ellipsoidalis populations suggests potential inbreeding. In summary, diverse management activities combined with various natural disturbances are likely both influencing SGS patterns. Outcrossing forest trees like oaks hold large amounts of genetic diversity allowing adaptation to environmental changes over their long life spans. Reductions of these genetic stores, through inbreeding for example, can inhibit a species’ ability to adapt to changing environmental conditions.

Genetic Diversity of Natural Myrica rubra Sieb.et Zucc Populations in Guangxi Revealed by ISSR Markers

The present study was conducted to assess the molecular characterization and genetic diversity amongst natural populations of Myrica rubra in Guangxi Zhuang Autonomous Region, China, thus to provide scientific evidence for germplasm conservation and exploitation. Using ISSR (inter-simple sequence repeats) markers, the level of genetic variation and the molecular characterization of 10 natural populations of M. rubra, originated from Guangxi Zhuang Autonomous Region in China, were performed. Based on 11 primers, 123 clear and reproducible DNA fragments were generated, of which 95 (77.24%) were polymorphic. The average value of Nei's gene diversity (He) was 0.268. The coefficient of genetic differentiation (Gst) was 0.341, revealing that 34.1% of the total molecular variance existed among populations. The Mantel statistical testing showed that the genetic distance was correlated to the geographic distance, but the correlation was not significant. Ten populations were divided into two big clusters according to unweighted pair group method with arithmetic mean (UPGMA) analysis. One consisted of populations of Rongxian (RX), Hepu (HP), Liangqing (LQ), Marshan (MS), Lingshan (LS) and Shansi (SS), which originated from the southern Guangxi, while the other was composed of Guanyang (GY) and Lingui (LG) populations of northern Guangxi, Huanjiang (HJ) populations of northwestern Guangxi and Shanglin (SL) populations of southern Guangxi. The level of genetic variation in wild M. rubra population distributed in Guangxi is high. Gene drift within the population was responsible for genetic variation in wild M. rubra in Guangxi, and the effect of the genetic flow among inter-populations was not significant. Classification of wild M. rubra populations was correlated to climate and environment. The molecular characterization and diversity assessment of M. rubra is of immense value for planning conservation of its genetic resources and their exploitation for further studies.

Behavioral Responses of the Endemic Shrimp Halocaridina rubra (Malacostraca: Atyidae) to an Introduced Fish, Gambusia affinis (Actinopterygii: Poeciliidae) and Implications for the Trophic Structure of Hawaiian Anchialine Ponds

In the Hawaiian Islands, intentionally introduced exotic fishes have been linked to changes in native biodiversity and community composition. In 1905, the mosquito fish Gambusia affinis was introduced to control mosquitoes. Subsequently, G. affinis spread throughout the Islands and into coastal anchialine ponds. Previous studies suggest that presence of invasive fishes in anchialine ponds may eliminate native species, including the endemic shrimp Halocaridina rubra. We examined effects of G. affinis on H. rubra populations in anchialine ponds on the Kona-Kohala coast of the island of Hawai‘i. In the presence of G. affinis, H. rubra exhibited a diel activity pattern that was not seen in fishless ponds. Shrimp in ponds with fish were active only at night. This pattern was evident in anchialine ponds and in laboratory experiments. In laboratory predation experiments, G. affinis preferentially consumed smaller H. rubra, and in the field the H. rubra collected from invaded sites were larger than those from fishless ponds. Analysis of trophic position using stable isotope analyses showed that feeding of H. rubra was not significantly distinct from that of snails, assumed to feed at trophic level 2.0 on epilithic algae, but G. affinis was slightly omnivorous, feeding at tropic level 2.2. The mosquito fish diet was apparently composed primarily of algae when the defensive behavior of H. rubra made them substantially unavailable as prey. The effect of successful establishment of G. affinis on shrimp behavior has the potential to alter abundance of benthic algae and processing and recycling of nutrients in anchialine pond ecosystems.

Evidence of genetic subdivision among populations of blacklip abalone (Haliotis rubra Leach) in Tasmania

The scale over which populations exchange individuals (migration) is central to ecology, and important for understanding recruitment and connectivity in commercial species. Field studies indicate that blacklip abalone (Haliotis rubra) have localised larval dispersal. However, genetic studies show differentiation only at large scales, suggesting dispersal over more than 100 km. Most genetic studies, however, have failed to test for subdivision at scales equivalent to field experiments. We used microsatellite DNA to investigate genetic structure at small scales (100 m to 10 km) in blacklip abalone in south-east Tasmania. We found significant subdivision (FST = 0.021; P < 0.05) among sites, and hierarchical FST analysis indicated 64% of genetic variation was at the smallest scale, supporting field studies that concluded larval dispersal is less than 100m. We also tested if genetic differentiation varied predictably with wave exposure, but found no evidence that differences between adjacent sites in exposed locations varied from differences between adjacent sites in sheltered populations (mean FST = 0.016 and 0.017 respectively). Our results show the usefulness of microsatellites for abalone, but also identify sampling scales as critical in understanding gene flow and dispersal of abalone larvae in an ecologically relevant framework. Importantly, our results indicate that H. rubra populations are self-recruiting, which will be important for the management of this commercial species.

Occurrence and Genetic Structure of the Systemic Grass Endophyte Epichloë festucae in Fine Fescue Populations

Epichloë species are systemic fungal endophytes that usually specialize in a certain group of related grass species. We examined the infection frequency of Epichloë festucae in populations of two fine fescue species (Festuca rubra and F. ovina) in natural and seminatural habitats at 86 study sites (total=2514 plants) across Finland and northern Norway. Infection incidence varied significantly among grass species and populations. A substantial number of the F. rubra and F. ovina populations (53 out of 77 and 25 out of 30, respectively) were either endophyte-free or had very low (<20%) infection frequencies. The highest infection frequencies were found in subarctic areas. Moreover, infection incidence differed between habitats. In the area with the highest infection frequencies, we used microsatellite markers to study genetic diversity and the rates of gene flow of E. festucae among 12 F. rubra populations. Twenty out of the 25 fungal genotypes detected with four microsatellite markers were carrying multiple alleles in at least one locus, indicating multiple infections or vegetative hybridization of the fungus. One dominant genotype occurred in all 12 populations, representing 63.5% of all isolates. We found a moderate level of average genotypic variation and a low level of genetic differentiation (Fst=0.0814). There was no correlation between infection frequency and genotypic diversity. Although the existence of a dominant genotype and the detected linkage disequilibrium suggest that the fungus is mainly asexual and vertically transmitted, the multiallelic loci and variation of genetic diversity among populations indicate occasional contagious spread and sexual or parasexual recombination of the fungus in some populations. Furthermore, the genotypes carrying multiallelic loci suggest the possibility of multiple infections or hybridization of the endophyte.

춘계 금강 하구에서 혼합영양 섬모류인 Myrionecta rubra (=Mesodinium rubrum) 개체군의 단주기 변동

Myrionecta rubra, a mixotrophic ciliate, is a cosmopolitan red tide species which is commonly found in neritic and estuarine waters. M. rubra had long been listed as an “nculturable protist”until 2 different laboratory strains were finally established in 2 research groups at the beginning of this century, enabling us to perform initiative investigation into various aspect of the live M. rubra strains (Gustafson et al. 2000; Yih et al. 2004b; Johnson and Stoecker 2005). Field sampling was carried out on high tide at 2 fixed stations around Kunsan Inner Harbor (St.1 near the Estuarine Weir and St.2 off Kunsan Ferry Station) every other day for 4 months from mid-February 2004 to understand detailed figure of the recurrent spring blooms of M. rubra following the onset of the water gates operation of the Keum River Estuarine Weir on August 1994. With its maximum abundance of 272 cells mL in St.1, fluctuation pattern of the M. rubra population at the 2 stations was strikingly similar. Notable growth of M. rubra population started on late April, to cause M. rubra red tides during one month from mid-May in which “xceptionally low salinity days”without its red tide were intermittently inserted. High abundance of M. rubra over 50 cells mL was recorded at samples with their water temperature and salinity higher than 15 and 4.0 psu, respectively. During pre-bloom period when salinity fluctuation is moderate and the water temperature is cooler than 15°C, Skeletonema costatum, a chain-forming centric diatom, was most dominant. Cyanobacterial species such as Aphanizomenon flos-aquae and Phormidium sp. replaced other dominant phytoplankters on the days with “xceptionally low salinity”even during the main blooming period of M. rubra. To summarize, M. rubra could form spring blooms in Keum River Estuary when the level of salinity fluctuation was more severe than that for the dominant diatom Skeletonema costatum and milder than that for the predominance by freshwater cyanobacteria. Therefore, optimal control of the scale and frequency of freshwater discharges might lead us to partially modify the fluctuation pattern of M. rubra populations as well as the period of spring blooms by M. rubra in Keum River Estuary. Sampling time interval of 2 days for the present study or daily sampling was concluded to be minimally required for the detailed exploration into the spring blooms by M. rubra populations in estuaries with weirs like Keum River Estuary.

Genetic variation and clonal diversity in island Cephalanthera rubra populations from the Biebrza National Park, Poland

Three populations of the orchid species Cephalanthera rubra localized on neighbouring mineral islands in the Biebrza National Park (north-east Poland) were examined using 16 allozyme loci. The percentage of polymorphic loci in these C. rubra populations ranged from 25 to 31.3% and the mean number of alleles per polymorphic locus from 1.25 to 1.31. The levels of observed heterozygosity at polymorphic loci were higher than expected for all populations. The overabundance of heterozygotes was noted in every population. The values of fixation indices were highly negative. The genetic differentiation among the three populations was small ( F ST = 0.0173), albeit statistically significant ( P < 0.001). The level of gene flow varied from 13 to 16. Fourteen multilocus genotypes were found among the 401 ramets sampled from the populations. Only four of them were common for all populations. The frequency of genotypes was different in these three populations of C. rubra . Some of the multilocus genotypes dominated in the given populations, others were found sporadically. Genetic variation within C. rubra populations is mainly the result of small population sizes and reflects the influences of breeding system and type of reproduction. On the other hand, these properties are also connected with habitat conditions. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 99‐108. l S ¢ l

Analysis of genetic structure of blacklip abalone ( Haliotis rubra ) populations using RAPD, minisatellite and microsatellite markers

We investigated the utility of three polymerase chain-reaction (PCR)-based DNA molecular markers in analysing genetic structure of the populations of the blacklip abalone Haliotis rubra (Leach) of Victoria, Australia. The DNA markers included 84 randomly amplified polymorphic DNA (RAPD) bands amplified using six random primers, two minisatellites, GHR (putative growth-hormone-gene-repeat) and MIPR (putative mollusca-insulin-like peptide-gene-repeat), and three microsatellites, RUBGT1 [containing (GT)n repeats], RUBCA1 [containing (CA)n repeats] and RUBGACA1 [containing (GACA)n repeats]. All three types of DNA markers revealed significant subdivision in the H. rubra populations along the coastline. This is postulated as being related to the abalone's relatively short pelagic period and limited dispersion. Further analysis revealed that a Point Cook population sampled from within the semi-enclosed Port Phillip Bay was distinct from two other central zone populations (Apollo Bay and Cape Schanck). The genotypes of microsatellites indicated excessive homozygotes across all the populations at all three microsatellite loci, and possible causes such as larval recruitment pattern and asynchronous spawning are discussed. The excessive homozygotes recorded for the three microsatellite loci contrast with those observed in the minisatellite loci GHR and MIPR, the heterozygosities of which were at Hardy–Weinberg equilibrium.

Genomic in situ hybridization identifies parental chromosomes in the wild grass hybrid × Festulpia hubbardii

Genomic in situ hybridization (GISH) was used to discriminate between the parental chromosomes of the grass × Festulpia hubbardii (2n = 5x = 35 ± 2B), a naturally occurring pentaploid hybrid between Festuca rubra (2n = 6x = 42±2B) and Vulpia fasciculata (2 n = 4 x = 28). Biotinylated total genomic DNA of V. fasciculata, mixed with an excess of unlabelled F. rubra genomic DNA as a block, hybridized preferentially in situ to mitotic Vulpia chromosomes. Unlike Giemsa C-banding, which provided a physical marker only for the terminal regions of the parental chromosomes, GISH unequivocally identified chromatin from all regions along every Vulpia chromosome. Clearly, GISH has the potential for testing the theory that Vulpia genetic material has been transferred into Festuca rubra populations by introgressive hybridization. Genomic probing also discriminated between homogenetic (Vulpia-Vulpia and Festuca-Festuca) and heterogenetic (Vulpia-Festuca) bivalents, showing that GISH can aid the interpretation of chromosome behaviour in meiotic nuclei of hybrids.

Isozyme polymorphism in Festuca rubraL.

Six Festuca rubra populations from Europe and Scandinavia were studied for variation at three isozyme loci; phosphoglucoisomerase (PGI-2), glutamate oxaloacetate transaminase (GOT-3) and superoxide dismutase (SOD-1). Seven alleles were found at the Pgi-2 locus, four at the Got-3 locus and five at the Sod-1 locus. Most plants were heterozygous and up to five alleles were found in the same plant at the Pgi-2 locus. Each population could be distinguished by the presence or absence of certain alleles or by differences in the frequencies of the alleles present. Values for the Shannon diversity index were calculated which showed that there was considerable heterogeneity both within and between loci. In general, 53% of this diversity could be attributed to within population variation.

Macro-elements within shoots of tall-tussocks (Chionochloa), and soil properties on Mt Kaiparoro, Wairarapa, New Zealand

Abstract Soils and shoots from opposite ends of a topographically controlled drainage gradient were analysed. Soil bulk densities and nutrients, especially inorganic P fractions, decrease from Chionochloa flavescens to C. rubra sites down the gradient. Between-site differences in macro-element concentrations within the shoots are small, apart from higher Na concentrations in the sheaths of C. rubra, and higher K and Mg concentrations in the green blades of C. flavescens. Major changes in macro-element status down the gradient are related to shoot dry weight, which drops several-fold from C. flavescens to C. rubra. Macro-element concentrations in green blades of Mt Kaiparoro C. flavescens are similar to those of C. flavescens populations on the Tararua Range, whereas C. rubra populations have lower P, S, and Ca concentrations than does C. rubra on volcanic ash soils of the North Island.