Genetic analysis of aMicroseris douglasii (Asteraceae) population polymorphic for an alien chloroplast type

Recent evidence suggests chloroplast introgression fromMicroseris bigelovii intoM. douglasii. We have examined 23 plants from a population ofM. douglasii polymorphic forM. douglasii andM. bigelovii chloroplast types. All 23 plants were completely homozygous for morphological and RAPD markers, and inbred lines derived by selfing have been used for DNA analysis. Chloroplast RFLP analysis identified 16 plants withM. bigelovii chloroplasts and seven withM. douglasii chloroplasts. The nuclear genomes of the 16 plants withM. bigelovii chloroplasts were examined with 22 primers for RAPD amplification products shared exclusively withM. bigelovii. Five of 268 markers appeared to be shared betweenM. bigelovii and one or more of these 16 plants on the basis of their position in gels. Detailed examination of these five amplification products showed that none of them are nuclear DNA fromM. bigelovii. Very little, if any, nuclear DNA fromM. bigelovii can be present inM. douglasii plants with chloroplasts typical ofM. bigelovii. The study demonstrates the usefulness of the RAPD technique for screening large numbers of markers to select a few potentially informative ones for rigorous examination.Dedicated to emer. Univ.-Prof. DrFriedrich Ehrendorfer on the occasion of his 70th birthday     

Genetic relationships between European and Siberian larch,Larix spp. (Pinaceae), studied by allozymes. Is the Polish larch a hybrid between these two species?

Thirteen populations ofLarix decidua subsp.decidua and subsp.polonica, and three populations ofL. sibirica were investigated by starch-gel electrophoresis. In the populations assayed 61 alleles at 17 loci were revealed. The allozyme data support the earlier observations about close relationships between these two larch species. Nei's genetic distances betweenL. decidua andL. sibirica were relatively small (D = 0.057), however, almost five times larger, on average, than those between populations of the same species. Results obtained in this study disagree withBobrov's hypothesis about the hybrid origin of the Polish larch and suggest a direct origin from the European larch.     

Biosystematic studies inTulipa sect.Eriostemones (Liliaceae)

Evolutionary relationships and infra- and interspecific variability within the species ofTulipa sect.Eriostemones Boissier were studied. Measurements of 35 morphological characters were used for principal component and canonical variate analyses. Crossing experiments and chromosome counts were carried out. Two axes of morphological variation were encountered within the principal component plot. Variation of subsect.Biflores was traced along one axis, the species of subsect.Australes as well asSaxatiles were found along the other axis. The nomenclature of names of subsect.Biflores was considered on the basis of their geography, specific morphological characteristics and polyploidy. Conspecificity of names of all species was tested based on both morphology and crossability.     

Species relationships and taxonomy inTulipa subg.Tulipa (Liliaceae)

Principal component and canonical variate analyses were used to analyse the variation of 34 morphological characters measured in 98 accessions ofTulipa subg.Tulipa, formerly known as sect.Leiostemones. In addition 43 accessions were analysed cytogenetically by means of C-banding methods. Based on the encountered variation and on geographical distribution data 30 species in five sections were recognized, of which the synonymy is stated. Seven new series in two different sections have been designated.     

Genetic analysis of ecological relevant morphological variability in Plantago lanceolata L.

Summary Morphological variability was analysed in an F₂-generation derived from crosses between two ecotypes of Plantago lanceolata L. Six allozyme loci, localised in five linkage groups, were used as markers. For two marker loci, Got-2 and Gpi-1, segregations did not fit monogenic ratios. In the linkage groups to which these two loci belonged, male sterility genes appeared to be present. In these crosses, male sterility (type 3, as described by Van Damme 1983) may be determined by two recessive loci located in the linkage groups of Got-2 and of Gpi-1. Many correlations of morphological and life history characters with allozyme markers were observed. The quantitative trait loci did not appear to be concentrated in major gene complexes. Often many loci were involved, sometimes with effects opposite to those expected from the population values. Main effects of the linkage groups appeared to be more important than interaction effects in determining variability. It also appeared that there is a positive correlation between the number of heterozygous allozyme loci and generative growth.Grassland Species Research Group Publication No. 115     

Relationships between seven species ofVulpia (Poaceae)

Seven species ofVulpia were subjected to morphological and protein studies using principal component and cluster analysis and theJaccard's Similarity Coefficient. Studies showed all species were uniform and distinct from each other. Species of sect.Loretia were very dissimilar from those of sect.Monachne and sect.Vulpia. The latter section comprises taxa of high mutual affinity.     

Studies on theStellaria longipes complex (Caryophyllaceae): Isozyme variability and the relationship betweenStellaria longipes andS. longifolia

Genetic variation within and the relationship betweenStellaria longipes Goldie andS. longifolia Muhl. were studied. Ten enzyme systems were assessed in eight natural populations ofS. longipes (25 loci) and three ofS. longifolia (20 loci) using starch and polyacrylamide gel electrophoresis. Patterns of population differentiation corresponded to geographic distance. There was no evidence that polyploidS. longipes had greater electrophoretic variability than diploidS. longipes. The isozyme data confirmed extensive population differentiation in these species and, within that context, a relatively close relationship betweenS. longipes andS. longifolia. It was postulated that diploids of these two species might be the progenitors of tetraploidS. longipes.     

Analysis of F ST outliers at allozyme loci in Pacific salmon: implications for natural selection

Natural selection has been invoked to explain the observed geographic distribution of allozyme allele frequencies for a number of teleost species. The effects of selection on allozyme loci in three species of Pacific salmon were tested. A simulation-based approach to estimate the null distribution of population differentiation (F _ST) and test for F _ST outliers was used. This approach showed that a majority of allozyme loci conform to neutral expectations predicted by the simulation model, with relatively few F _ST outliers found. No consistent F _ST outlier loci were found across species. Analysis of population sub-groups based on geography and genetic identity reduced the number of outlier loci for some species, indicating that large geographic groups may include genetically divergent populations and/or that there is geographic heterogeneity in selection pressure upon allozyme loci. Two outlier allozyme loci found in this analysis, lactate dehydrogenase-B and malic enzyme, have been shown to be influenced by selection in other teleost species. This approach is also useful in identifying allozyme loci (or other genetic markers) that meet assumptions for population genetic study.     

Sero-systematics ofCytisus sect.Trianthocytisus (Fabaceae)

The serological reaction of seed proteins provides evidence for a partly new systematic arrangement ofCytisus sect.Trianthocytisus and ofCytisus s.l. Proposed modifications agree with recent advances in morphological taxonomy. Sect.Trianthocytisus includes only two species,C. villosus andC. aeolicus. Its position is central within the genus, and this fact agrees with the proposed retypification ofCytisus (type species:C. villosus).C. emeriflorus, formerly included in the same section, constitutes the monospecific sect.Emeroides, which is intermediate towards the genusLembotropis. This is serologically isolated and includes onlyL. nigricans. It is confirmed thatC. sessilifolius should be removed from the genusCytisus as a monospecific genus:Cytisophyllum Lang which is closely allied toHesperolaburnum and toPodocytisus, the most primitive genera ofGenisteae.     

Subdivision ofPelargonium sect.Cortusina (Geraniaceae)

The sect.Cortusina (Dc.)Harv. s.l. is divided into the sectt.Cortusina (Dc.)Harv. s. str. andReniformia (Knuth)Dreyer, comb. nov.,P. cortusifolium L'Hérit.,P. crassicaule L'Hérit.,P. echinatum Curt.,P. magenteum J. J. A. Van der Walt, andP. sibthorpifolium Harv. remain in the sect.Cortusina s. str., while the speciesP. album J. J. A. Van der Walt,P. dichondrifolium Dc.,P. odoratissimum (L.)L'Hérit.,P. reniforme Curt., andP. sidoides Dc. are removed from the sect.Cortusina s.l. and included in the revised sect.Reniformia. Both sections are well characterized by morphological, anatomical, karyological and palynological features. The chromosomes ofCortusina s. str. are small and based upon x = 11; those ofReniformia are larger and based upon x = 8. The size and surface sculpture of the pollen grains differ markedly between the two sections. Flavones and hydrolysable tannins occur in sect.Reniformia, but are absent in sect.Cortusina s. str. After hydrolysis hydroxybenzoic acids, which are present in large amounts inReniformia, occur only in traces inCortusina. The two sections also occupy distinctly different geographical areas. A close relationship between sect.Reniformia and some species of sect.Ligularia (Sweet)Harv. is indicated by the occurrence of artificial hybrids.     

Isoenzyme variation in the wild relatives ofVicia faba (Fabaceae)

Electrophoretic analysis of five enzyme systems, LAP, PGI, SKDH, SOD and 6-PGDH, among 102Vicia accessions representingV. bithynica and seven species of theV. narbonensis complex, namelyV. eristalioides, V. kalakhensis, V. johannis, V. galilaea, V. serratifolia, V. narbonensis andV. hyaeniscyamus, has been performed. The recorded variation was tentatively assigned to 41 allelic genes at eight loci; intraspecific variation was observed in all species except forV. eristalioides. The results obtained were compared with the corresponding data reported earlier forV. faba. Hierarchical grouping of the investigated taxa, includingV. faba, was based onNei's genetic identities calculated from the allozyme frequency data.Vicia faba andV. bithynica were shown to be most distantly related to one another and to the remaining species investigated.Vicia serratifolia appeared to be a peripheral member of theV. narbonensis complex. The results are discussed with reference to genetic diversity and taxonomic relationships of the species under study.     

A phenetic comparison of someFumaria spp. (Fumariaceae)

The taxonomy of the genusFumaria has not been considered in detail sincePugsley's work in 1919 ff., and few modern methods have been applied to it. In a phenetic study, 33 populations of 11Fumaria spp. were grown in uniform conditions, and seven morphological characters measured. After re-expression and transformation the data were analysed by cluster analysis and principal components analysis. Alternative analyses did not indicate contradictory taxonomic conclusions. Artificial crosses gave some evidence on interfertility, and suggestedF. occidentalis to be an allopolyploid ofF. bastardii ×F. capreolata. Pugsley's subsectional classification is supported within sect.Parviflora, but not within sect.Grandiflora. His two sections are seen to be meaningful, but not discrete.     

One Species or Several? Discordant Patterns of Geographic Variation between Allozymes and mtDNA Sequences among Spiders in the Genus Metepeira (Araneae: Araneidae)

Paradoxically, an allozyme study of Metepeira “spinipes” (sensu lato) demonstrated extensive gene flow among four populations whose members are nevertheless morphologically and behaviorally distinct. Initially, the authors tentatively concluded that the populations exhibited panmixis and suggested that local environmental effects accounted for the apparent morphological and behavioral differences. However, they later concluded that such differences were too great to be accounted for by the environment alone and that the four populations actually represented three different species. To confirm that the allozyme results were, in fact, artifactual, we reexamined the relationships among these populations by sequencing a portion of the 12S mtDNA ribosomal subunit. In contrast to the allozyme result, our results demonstrate good agreement between patterns of genetic and morphological/behavioral variation. We suggest (1) that the allozyme allele frequencies are homogenized by balancing selection, not gene flow as was previously concluded, and therefore (2) that this study provides another instance in which inferences about population structures from allozyme data are misleading.     

Isozyme evidence and the origin ofSenecio vulgaris (Compositae)

An electrophoretic survey of isozyme variation was conducted to test the hypothesis thatSenecio vulgaris L. (2n = 40) is of autotetraploid origin fromS. vernalis Waldst. & Kit. (2n = 20). It was established thatS. vulgaris exhibited fixed heterozygosity at three loci examined, showed disomic inheritance at all polymorphic loci, and contained a gene (Est-1) and an allele (Aat-3b) which were not present in the single population ofS. vernalis surveyed. From this it is concluded thatS. vulgaris is not of autotetraploid origin. Instead, the genetic evidence is in keeping with an allopolyploid origin ofS. vulgaris with the possibility thatS. vernalis acted as one of its two parents.     

Genetic variation in a subtropical population of Daphnia

We assayed a subtropical population of Daphnia ambigua for genetic variation using protein electrophoresis (9 loci) and quantitative genetics approaches (life history characters). Our goal was to obtain information about relative levels of variation in a subtropical population, and compare them with extensive previous studies in the temperate and arctic zones. The observed level of allozymic variation (H = 0.11) was consistent with those previously observed in other temperate zone Daphnia populations. However, variation for quantitative traits (heritability) was lower than typically observed in previously-studied temperate populations: estimates were not statistically different from zero. Because allozyme heterozygosity was consistent with previous temperate zone estimates, and the polymorphic allozyme loci did not depart from the expectations of Hardy-Weinberg equilibrium, we concluded that a period of clonal selection was the most likely explanation for the low heritabilities observed. We do not conclude that this study provides evidence to suggest that subtropical populations harbor lower levels of genetic variation because of their location.     

Phenetic investigation of non-nodulating African species ofAcacia (Leguminosae) using morphological and molecular markers

Morphological and RAPD markers were used to assess the relationships among nodulating and non-nodulating species of AfricanAcacia. Non-nodulating species of AfricanAcacia are only found within subg.Aculeiferum sect.Monacanthea. African species of sect.Monacanthea examined were found to form a group distinct from the other African species examined on a morphological and molecular basis. All lack the ability to nodulate, suggesting that non-nodulation may be used as a taxonomic tool. The species of sect.Aculeiferum were separated by RAPD and morphological analysis into two groups depending on whether they were armed with prickles in pairs and/or prickles in threes, or solitary. A third group of species was identified within sect.Acacia: further subdivision of this group was achieved into subsectt.Pluriseriae andUniseriae. The position ofA. albida relative to other AfricanAcacia species was found to be distinct but not totally independent of the genus. The partitioning and distribution of the genetic variability within the genus is further elucidated by the RAPD analysis of populations ofAcacia species. A population analysis ofA. polyacantha demonstrated geographical and site-specific variation.     

Gene variation and gene flow inOrchis morio (Orchidaceae) from Italy

Data are presented on genetic variation at 27 enzyme loci of the Green-Winged orchid,Orchis morio, in 18 population samples from Italy. The existence in Italy of two subspecies, i.e. subspp.morio andpicta, is not supported by allozyme data. No genetic heterogeneity was found betweenmorio-like andpicta-like samples and specimens. Moreover, morphological transition between the two forms was observed in different Italian populations. The parameters of genetic variability estimated forO. morio populations are consistent with those found among monocotyledon plants, and among those outcrossing, animal-pollinated and with wind-dispersed seeds. Genetic diversity of ItalianO. morio is mostly within populations. Correspondingly, low values of interpopulational genetic distance were found. This appears to be due to high levels of gene flow, which were estimated with different methods. The lack ofO. longicornu from Italian samples, as well as of any hybrid withO. morio (F₁, backcrossed or recombinant individuals) is demonstrated on the basis of genetic data. It is concluded that recurrent reports ofO. longicornu from Italy are due to confusion withO. morio or with otherOrchis species.     

A phylogenetic and allozyme approach to understanding rarity in three “green ash” eucalypts (Myrtaceae)

Phylogenetic relationships among the 12 species of the green ash group of eucalypts were examined using allozyme data, to investigate the causes of rarity in three localized endemics of the group. The relationships suggested by the allozyme data showed both similarities to and differences from those estimated from morphological data byLadiges and coworkers. The phylogenetic relationships suggest that rarity inEucalyptus burgessiana may be related to recent divergence, whileE. paliformis andE. rupicola are relatively old species, more likely to be relicts, and/or restricted to a rare habitat.     

Genetic diversity and morphological differentiation in Liatris helleri (Asteraceae), a threatened plant species

Liatris helleri (Asteraceae) is an insect-pollinated herbaceous perennial endemic to several high-elevation sites in the Blue Ridge Mountains of North Carolina. Allozymes were used to describe the genetic diversity and population structure in nine populations of this rare, federally listed species. Differences in leaf morphology were also examined for greenhouse-grown plants representing several populations. The proportion of the total genetic diversity found among populations, as indicated by the allozyme data, was 16%. Higher levels of population differentiation were found for differences in leaf shape; population of origin accounted for 37% of the variation in maximum leaf width, while families within populations accounted for 7%. In contrast to many endemic species, L. helleri maintains fairly high levels of genetic diversity. For the species, the percent polymorphic loci was 87.5, the average number of alleles at variable loci was 3.00 and the gene diversity was 0.276. Mean population values were percent polymorphic loci =58.4, mean number of alleles per polymorphic locus =2.59 and gene diversity =0.219. The estimated gene flow was low (Nm=0.85–1.32) and a relatively high correlation (r=0.55; p<0.005) was found between linear geographic and genetic distance. This suggests that the populations are partially isolated by distance, despite the limited range (<60 km) of the species. We recommend that population distinetiveness be maintained in restoration efforts.     

Australian lungfish (Neoceratodus forsteri: Dipnoi) have low genetic variation at allozyme and mitochondrial DNA loci: a conservation alert?

Genetic variation at allozyme and mitochondrialDNA loci was investigated in the Australianlungfish, Neoceratodus forsteri Krefft1870. Tissue samples for genetic analysis weretaken non-lethally from 278 individualsrepresenting two spatially distinct endemicpopulations (Mary and Burnett rivers), as wellas one population thought to be derived from ananthropogenic translocation in the 1890's(Brisbane river). Two of 24 allozyme lociresolved from muscle tissue were polymorphic.Mitochondrial DNA nucleotide sequence diversityestimated across 2,235 base pairs in each of 40individuals ranged between 0.000423 and0.001470 per river. Low genetic variation atallozyme and mitochondrial loci could beattributed to population bottlenecks, possiblyinduced by Pleistocene aridity. Limited geneticdifferentiation was detected among rivers usingnuclear and mitochondrial markers suggestingthat admixture may have occurred between theendemic Mary and Burnett populations duringperiods of low sea level when the drainages mayhave converged before reaching the ocean.Genetic data was consistent with theexplanation that lungfish were introduced tothe Brisbane river from the Mary river. Furtherresearch using more variable genetic loci isneeded before the conservation status ofpopulations can be determined, particularly asanthropogenic demands on lungfish habitat areincreasing. In the interim we recommend amanagement strategy aimed at conservingexisting genetic variation within and betweenrivers.