Restricted responsiveness to noise interference in two anurans from the southern temperate forest

Animals adopt different strategies to communicate by means of sound in noisy environments such that some species increase, while others decrease their vocal activity in the presence of interference. Anuran amphibians from diverse latitudes exhibit both kinds of responses. Recent studies have shown that males of Batrachyla taeniata and Batrachyla antartandica from the temperate austral forest do not call in response to the presentation of advertisement calls of sympatric congeneric species. In contrast, Batrachyla leptopus responds to these signals in a similar way as to conspecific calls. The responsiveness of B. taeniata to natural abiotic interference has also been tested and found that noises of such sources produce strong increases in vocal activity. To assess the diversity in responsiveness to acoustic intrusion in this group, we exposed males of B. leptopus and B. antartandica to prolonged pre‐recorded natural abiotic noises of wind, creek, rain, and to a band‐pass noise centered at 2,000 Hz, at 67 dB Sound Pressure Level (SPL). The subjects did not increase their vocal activity significantly when exposed to these sounds and to band‐pass noise at increasing intensities (55–79 dB SPL). These results contrast with the increase in vocal activity observed previously in B. taeniata to continuous abiotic noise and point to the existence of diverse strategies to confront acoustic intrusion among related species. The lack of vocal activation observed also contrasts with the responsiveness of B. leptopus to heterospecific signals, but parallels the lack of response to such sounds in B. antartandica. Furthermore, the results obtained contrast with the responsiveness of these species to synthetic prolonged sounds observed in previous studies, suggesting that the modes of responses to acoustic intrusion may depend on previous experience, rather than having a species‐specific nature.     

Vocal Responsiveness to Interfering Sounds By a Frog From The Southern Temperate Forest,Batrachyla leptopus

Interfering sounds from biotic and abiotic origins are likely to shape the responsiveness of sound communicating animals. Among these sources of interference, interactions among acoustically active species have been studied to quite a limited extent. The vocal responses of 20 male frogs Batrachyla leptopus from the temperate austral forest in Chile were tested with conspecific calls and with the calls of two sympatric species: Batrachyla taeniata and Batrachyla antartandica, broadcast at amplitudes of 73, 79, 85, 91 and 97 dB SPL peak. Also, the vocal activity of the subjects during exposure to a 3‐min continuous broadband noise presented at 67 dB SPL RMS was monitored. The subjects gave higher responses on average to the conspecific relative to the heterospecific calls, but in most comparisons, these differences did not reach levels of significance. In addition, the vocal activity of males of B. leptopus did not increase in the presence of the continuous broadband noise. The lack of clear preferential responses for conspecific signals contrasts with the sharp selectivities that B. taeniata and B. antartandica have shown for their own calls in previous studies. Such different vocal behavior could be related to the extensive geographic overlap of B. leptopus with the two other species in the temperate austral forest, where mixed choruses of this species with each of the two congeneric taxa have been reported to occur occasionally. The lack of vocal activation in the presence of continuous noise also contrasts with the increased vocal output with which the other two taxa respond to this intrusion and is likely to result from a relatively high spontaneous vocal activity in B. leptopus.     

Heterospecific Vocal Interactions in a Frog from the Southern Temperate Forest,Batrachyla taeniata

Animals using sound communication employ different strategies to overcome interferences from biotic and abiotic sources. However, interactions among acoustically active species have been studied to a very limited extent. The evoked vocal responses of 20 male frogs Batrachyla taeniata from the temperate austral forest in Chile were tested with conspecific calls and with the calls of two sympatric species: B. antartandica and B. leptopus, broadcast at amplitudes of 73, 79, 85, 91 and 97 dB peak SPL. The subjects responded actively to the conspecific call, but only responded weakly to the call of B. leptopus at the highest intensity. The preferential responses to conspecific calls could contribute to the typical segregation in monospecific choruses observed in areas where these frogs breed in sympatry.     

Disentangling the effects of plant species invasion and urban development on arthropod community composition

Urban development and species invasion are two major global threats to biodiversity. These threats often co‐occur, as developed areas are more prone to species invasion. However, few empirical studies have tested if both factors affect biodiversity in similar ways. Here we study the individual and combined effects of urban development and plant invasion on the composition of arthropod communities. We assessed 36 paired invaded and non‐invaded sample plots, invaded by the plant Antigonon leptopus, with half of these pairs located in natural and the other half in developed land‐use types on the Caribbean island of St. Eustatius. We used several taxonomic and functional variables to describe community composition and diversity. Our results show that both urban development and A. leptopus invasion affected community composition, albeit in different ways. Development significantly increased species richness and exponential Shannon diversity, while invasion had no effect on these variables. However, invasion significantly increased arthropod abundance and caused biotic homogenization. Specifically, uninvaded arthropod communities were distinctly different in species composition between developed and natural sites, while they became undistinguishable after A. leptopus invasion. Moreover, functional variables were significantly affected by species invasion, but not by urban development. Invaded communities had higher community‐weighted mean body size and the feeding guild composition of invaded arthropod communities was characterized by the exceptional numbers of nectarivores, herbivores, and detritivores. With the exception of species richness and exponential Shannon diversity, invasion influenced four out of six response variables to a greater degree than urban development did. Hence, we can conclude that species invasion is not just a passenger of urban development but also a driver of change.     

ELECTROPHORETIC ANALYSIS OF ENZYMES FROM THREE SPECIES OF CHLAMYDOMONAS

Isoenzyme patterns of acetone-extracted proteins revealed a close similarity between Chlamydomonas eugametos and C. moewusii but a distant relationship between the two and C. reinhardtii. Chlamydomonas eugametos and C. moewusii had identical banding patterns of malate dehydrogenase (MDH) and leucine aminopeptidase (LAP) in starch gels. These two species exhibited the same MDH distribution spectrum in analytical disc polyacrylamide gels but neither species showed definitive LAP or glutamate dehydrogenase (GDH) activity. There were differences in the starch gel alpha esterase (α-EST) patterns of C. eugametos and C. moewusii due to an additional weak band at Rf 0.75 in the latter species and a slight variation in the position of another band at Rf 0.80–0.82. Some variations between the two species also occurred in the α-EST banding in disc gels at Rf 0.70–0.85 and at Rf 0.06–0.14 with C. moewusii exhibiting the greatest number of bands. Chlamydomonas reinhardtii displayed patterns of all four enzymes but the band characteristics were distinctively different from those of C. eugametos and C. moewusii. There appeared to be no obvious isoenzyme difference between mating types of either species. It is concluded that C. eugametos and C. moewusii are not identical species but are closely related in regard to the enzymes assayed. Isoenzyme analysis is considered to be a useful approach to algal systematics.     

Two subtypes of BfF by isoelectrofocusing: Differential linkage to other HLA markers

Summary By isoelectrofocusing in agarose, the properdin factor allotype BfF could be split into two subtypes: BfFa with one major cathodic band and BfFb with the same cathodic band but in addition a major anodic band. By scanning, BfFaFb heterozygotes were distinguished from BfFbFb homozygotes by the stronger intensity of the anodic band in the latter. The two subtypes were segregated perfectly with HLA in 40 families and showed different association patterns with HLA markers. BfFa seemed to be linked to B35 while BfFb showed a strong linkage with all the components of the following haplotype: HLA-A29, Cw-, B44, BfFb, C4A3B1, DR7. The frequency of BfFa among BfFS heterozygotes was 41% (46/113) and that of BfFb 59% (67/113).     

Cytological differences and chromosomal rearrangements in four members of the Anopheles dirus complex (Diptera: Culicidae)

A reference photomap of the larval salivary gland, polytene chromosomes of the Anopheles dirus complex (species A) is presented. Samples of species A, B, C, and D from natural populations in Thailand were compared to this standard map using the larval progeny of wild-caught females. All species show differences in their chromosome banding patterns involving band size, number, and shape, particularly at the free ends of the X, 2R, and 2L. These differences provide useful diagnostic characters for separating members of the species complex. However, overall banding patterns are conservative in the group: species A, B, and C are virtually homosequential. Species D is highly polymorphic for a single paracentric inversion in each of the four autosomal arms and has a fixed inversion on the X chromosome. This same X chromosome inversion occurs at low frequency in species A.     

Disposition of ribosomal DNAs in the chromosomes of perennial oats (Poaceae: Aveneae)

The chromosomal loci of 5S and 45S ribosomal DNAs (rDNAs) and the activity of nucleolar‐organizing regions (NORs) were analysed in perennial oats of the genera Ammophila, Amphibromus, Arrhenatherum, Avena, Deschampsia, and Helictotrichon s.l. (Poaceae: Aveneae) using fluorescence in situ hybridization, staining with chromomycin/4′,6‐diamidino‐2‐phenylindole (DAPI), and silver impregnation. All chromosomes with a secondary constriction were nucleolar active. In chromosomes without a secondary constriction, NORs corresponded exclusively to broad bands of 45S rDNA with chromomycin‐positive, DAPI‐negative, and silver‐positive stainability. Additional minor bands of 45S rDNA showed no nucleolar activity. 5S rDNA was localized mostly in loci different from the nucleolar‐active 45S rDNA. If both rDNAs occurred within the same chromosome, they were at largely corresponding distances from the centromere, irrespective of their particular localization in either the same chromosome arm or in opposite arms. In the latter case, 5S rDNA was never more distal to the centromere than 45S rDNA. A new model was devised to explain this non‐random distribution of both rDNAs in nucleolar‐organizing chromosomes, which identified the Rabl orientation of chromosomes as ensuring a spatial proximity of 5S to 45S rDNA in interphase nuclei, even if they were localized in opposite arms. The possible role of the Rabl orientation in determining the spread and accumulation of 5S rDNA sequences in further chromosomes of the genome was discussed. B chromosomes were devoid of 5S rDNA, but most contained 45S rDNA and were nucleolar active. In some large groups of species, the number and arrangement of 5S and 45S rDNA sites in the chromosomes were remarkably uniform, especially in Helictotrichon subgenus Helictotrichon and Helictotrichon subgenus Pratavenastrum. Such distribution patterns have survived many speciation processes and have also remained widely unchanged in polyploids. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155 , 193–210.     

Dynamics of Nutrient Contents (Phosphorus,Nitrogen) in Water,Sediment and Plants After Restoration of Connectivity in Side‐Channels of the River Rhine

During the last century, canalization of the Rhine river led to disconnection of side‐arms, over‐sedimentation of these channels, loss of the fluvial dynamics, and aquatic vegetation change or disappearance. Recent restoration projects aim to reconnect disconnected arms to the main channel. The objective of this study was to assess the nutrient dynamics in restored channels during the vegetation colonization process. In spring, summer, and autumn 2009, the phosphorus and nitrogen contents were measured in water, sediment, and plants, sampled in six channels, two reference sites and four restored ones at different dates. Aquatic vegetation was monitored during the same period. Sites were mesotrophic related to the water nutrient concentrations. However, vegetation communities indicated a eutrophic level, as they were dominated by species like Elodea nuttallii, Myriophyllum spicatum, and Potamogeton perfoliatus. Sites were discriminated by P content and mineral nitrogen in the sediment. We showed an effect of species and season on the plant nutrient content, but there was no relationship between plant nutrient content and nutrients in water and sediment. A negative correlation between mean N plant content and the cover of each species was found. Vegetation characteristics (species richness and cover) and bioavailable phosphorus in the sediment were also correlated. In the restored side‐arms of the river Rhine, phosphorus‐rich sediment seems to be important in the recolonization dynamics, as it was linked to higher species richness, whereas nitrogen played a role in the colonization patterns as a growth limiting factor.     

Vocal Strategies in Confronting Interfering Sounds by a Frog from the Southern Temperate Forest,Batrachyla antartandica

Animals are communicating by sound face interference from biotic and abiotic sources. Contrasting strategies have been reported in different taxa in the presence of prolonged noises, but in particular, interactions among acoustically active species have been studied to a very limited extent. In addition, reactions of a single species to interferences having contrasting structural patterns have not been explored systematically. The vocal responses of 16 male frogs Batrachyla antartandica from the temperate austral forest in Chile were tested with conspecific calls and with the calls of two sympatric species: B. taeniata and B. leptopus, broadcast at amplitudes of 73, 79, 85, 91, and 97 dB peak sound pressure level (SPL). Also, the vocal activity of the subjects during exposure to a 3‐min continuous broadband noise presented at 67 dB root mean square (RMS) SPL was monitored. The subjects gave significantly higher responses to the conspecific relative to the heterospecific calls but increased their vocal output in the presence of continuous noise. The preference of vocal responses for the conspecific relative to heterospecific signals bears a general resemblance to those exhibited by B. taeniata in a previous study and potentially contributes to the typical segregation in conspecific choruses observed in areas where these frogs breed in sympatry. Such lack of vocal responses to heterospecific stimuli contrasts with the increase in vocal activity during exposure to continuous noise lacking a temporal fine structure and points to identify different strategies in confronting interferences of diverse origin.     

Chromosome 1 in crested and marbled newts (Triturus)

The heteromorphic chromosomes 1 of Triturus cristatus carnifex and T. marmoratus were studied in mitotic metaphase after staining with the Giemsa C-banding technique and with the fluorochromes, DAPI (AT-specific) and mithramycin (GC-specific). They were also examined in the lampbrush form under phase-contrast before fixation and after fixation and staining with Giemsa. Chromosomes 1 of T.c. carnifex are asynaptic and achiasmatic throughout most of their long arms. They are also heteromorphic in most of their long arms for the patterns of Giemsa and fluorochrome staining and the distribution of distinctive lampbrush loops. The heteromorphic regions correspond to the regions that are asynaptic and achiasmatic. They stain more strongly with mithramycin and more weakly with DAPI than the remainder of the chromosomes, signifying that their DNA is relatively rich in GC. The patterns of staining with Giemsa and fluorochromes and the distributions of distinctive lateral loops vary from one animal to another in the same species and even in the same population. The asynaptic and achiasmatic regions of chromosomes 1 in T. marmoratus extend throughout the whole of the long arms and well beyond the heterochromatic region. Chiasmata form only in the short arm and occasionally in the short euchromatic segment at the tip of the long arms. The staining patterns of chromosomes 1 in T. marmoratus differ from those in T.c. carnifex although, like carnifex, their DNA is relatively GC-rich. The chromosomes 1 of T. marmoratus are more submetacentric than those of T.c. carnifex. In T. marmoratus chromosome 1B is about 12% shorter than 1A. There is a short paracentric inversion heterozygosity in the long arm of chromosome 1B in T. marmoratus which probably accounts for the lack of chiasmata in the euchromatin that separates the centromere from the start of the heterochromatin. In both carnifex and marmoratus, embryos that are homomorphic for chromosome 1 arrest and die at the late tailbud stage of development. The same applies to F₁ hybrid embryos T.c. carnifex x T. marmoratus, and this has permitted identification of chromosomes 1A and 1B in both species. There is no correspondence between patterns of Giemsa or fluorochrome staining of the heteromorphic regions of chromosome 1 and any feature of the lampbrush chromosomes. However, the short euchromatic ends of the long arms of chromosomes 1 in both species are distinguished in the lampbrush form by a series of uniformly small loops of fine texture associated with very small chromomeres. The Giemsa C-staining patterns of both chromosomes 1A and 1B are different in each of the four subspecies of T. cristatus. T.c. karelinii stands out by having unusually large masses of Giemsa C-staining centromeric heterochromatin on all but 1 of its 12 chromosomes. A scheme is proposed for the evolution of chromosome 1 in T. cristatus and T. marmoratus, based on all available cytological and molecular data.     

Phylogeography of a Patagonian lizard and frog: Congruent signature of southern glacial refuges

Pleistocene glaciations produced significant increases in continental ice cover in polar and mid‐latitude temperate areas, sea‐level declines and shifts and reshuffling of biomes, all of which promote either isolation, coalescence or fragmentation in the distribution of land biota. If populations of several taxa have been co‐distributed for a prolonged time, and if the periods between perturbation or vicariance processes have been more or less stable, it is expected that divergence patterns of closely related and ecologically similar species will be congruent because of their similar biological and demographic characteristics. Based on this premise, we analysed the phylogeographic structure (cytochrome b) of Liolaemus pictus and Batrachyla leptopus, two widely co‐distributed lizard and frog species, respectively, in the Chiloé Archipelago of southern Chile, to decipher their genetic structure in response to a common climatic and environmental history. Haplotype network analysis and Bayesian inference suggest an evolutionary pattern of genetic diversity for the two species that is consistent with the Quaternary glacial history of southern Chile, and suggests a complex phylogeographic history in the Liolaemus and Batrachyla species. High‐divergence levels among haplotypes in some island populations of the archipelago also suggest genetic connectivity between putative refuges from Chiloé Island and the mainland along the exposed continental shelf during sea level minima associated with the most recent Quaternary glaciations. Our results are consistent with our hypothesis that two species have responded to parallel historical events in which the historical process during the last glacial maximum (approximately 41°S) has been sufficient to influence their phylogeographic structure.     

Dispersal and establishment: spatial patterns and species–area relationships

According to the equilibrium theory of island biogeography, high colonization ability of species is associated with low exponents (z) of the species–area relationship (SAR) and weak spatial patterns in species number and dissimilarity. However, the relationship between z and the strength of these spatial patterns has not been investigated systematically. We used a multispecies metapopulation model to investigate these relationships in an archipelago of islands. We conclude that this relationship can only be predicted if either the dispersal ability or the power of establishment of species is known. With species richness limited by establishment, we generated high z‐values associated with weak spatial patterns in species number and dissimilarity. If species richness was constrained by the dispersal ability of species, we observed low to medium z‐values but strong spatial patterns. If the dispersal ability and the abilities of species to establish were both high, z‐values and spatial pattern tend to be low and species numbers were limited by the size of the regional species pool.     

Factors influencing the degree of sexual size dimorphism within and among calanoid copepod species

Populations of Diaptomus leptopus (Copepoda: Calanoida) and other calanoid copepods exhibit varying degrees of sexual size dimorphism. We examined whether intraspecific or interspecific variation in dimorphism could be explained by allometry, and we examined the relationship between adult size attained and development rate to determine any relationship between the two. We compared the degree of sexual size dimorphism in D. leptopus and in other calanoid copepods inhabiting temporary and permanent habitats. Allometry did not explain variation in sexual size dimorphism within or among populations or among species. Permanence of habitat affected the degree of dimorphism: dimorphism was greater within and among species inhabiting temporary environments. Non-significant differences in development rate were found among populations and significant differences were found between sexes of D. leptopus when reared under identical laboratory conditions: males developed more rapidly than females but there was no general relationship between development rate and adult size. Potential adaptive hypotheses to explain the differences between populations inhabiting temporary and permanent habitats are discussed.     

Chromosome studies in Orchidaceae: karyotype divergence in Neotropical genera in subtribe Maxillariinae

Here, we study karyotype divergence in the closely related genera Brasiliorchis, Christensonella and Trigonidium belonging to subtribe Maxillariinae of subfamily Epidendroideae (Orchidaceae). We compare karyotypes in 15 species by (1) measuring 1C genome sizes, (2) mapping the distribution of 4′,6‐diamidino‐2‐phenylindole and chromomycin A3 chromosome bands and (3) localizing 5S and 45S nuclear ribosomal DNA (rDNA) sequences using fluorescent in situ hybridization. Recently, phylogenetic studies have been conducted to resolve species and genera relationships in subtribe Maxillariinae. We used these phylogenetic trees to map the cytogenetic characters in an evolutionary framework. This has enabled a better understanding of the patterns of genomic divergence in the group. Genome sizes range from 1C = 1.85 to 4.1 pg. The largest, B. schunkeana, shows evidence of genome upsizing, probably through the acquisition of tandem repeats that now form large 4′,6‐diamidino‐2‐phenylindole‐positive blocks of heterochromatin. Our cytogenetic data are consistent with a base chromosome number of 2n = 40, although Christensonella is characterized by a dysploid reduction in chromosome number to 2n = 36. The number of 5S and 45S rDNA sites is variable between species, consistent with high rates of karyotype divergence. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170 , 29–39.     

Methemoglobin reductase in three species of Bovidae

Isoelectric focusing of red cell hemolysates revealed several isozymes that stain for NADH-methemoglobin reductase. Evidence for two different genetic loci controlling the banding patterns was obtained. One locus controlled a single band present in all animals tested. The second locus controlled ten different banding patterns that could be accounted for by four codominant alleles. Band B occurred in Bison bison. Bands A and C occurred in Bos indicus and band D occurred in both Bos indicus and Bos taurus. Bands A, C, and D were not observed in Bison bison and bands A, B, and C were not observed in Bos taurus.     

Chromosome relationships in the genus Blennius (Blenniidae Perciformes) C-banding patterns suggest two karyoevolutional pathways

The karyotypes of the Mediterranean blenniid species: Blennius gattorugine, B. ponticus incognitus, B. pavo, B. sanguinolentus, B. galerita, B. trigloides and B. pholis were analyzed by means of conventional, silver staining and C-banding techniques. All have shown 2n=48, except B. pholis with 2n=46, while the NF varies from 54 to 72. Only two NORs, in terminal position on the short arms of the carrier pair, were detected in all species. These regions have proved to be structurally polymorphic in four species. Two markedly different C-banding patterns lead us to separate the species into two different karyoevolutionary categories, whose taxonomic and specialization implications are discussed.     

Cytogenetic characteristics of species of the Chironomus plumosus group (Chironomidae, Diptera) in Finland

The cytogenetic characteristics of species of the Chironomus plumosus group in Finland were examined. The species included C. balatonicus Devai, Wülker, Scholl, C. entis Shobanov, C. plumosus L., C. muratensis Ryser, Scholl, Wülker, and two karyotypes of unknown species. All belonged to the thummi complex having 2n = 8 chromosomes, with arm combinations of AB, CD, EF, G. In C. balatonicus arms A to G the band sequences corresponded with those of other populations. A new band sequence was found in arm B. In C. entis an arm A had a band sequence similar to those in C. agilis. A large pericentric inversion was observed in chromosome AB. The arms B to G had band sequences typical for C. entis. The chromosome arms A and B in C. plumosus from Lake Marsjon had band sequences corresponding to those of C. agilis and C. entis, respectively. C. plumosus from Helsinki may be a more divergent population with a large amount of centromere heterochromatin. C. muratensis was not distinguishable by band sequences from those of other Palaearctic populations. Two new karyotypes similar to those of species of the plumosus group have been described.     

Chromosomal polymorphism and small karyotypic differentiation in a group of Ctenomys species from Central Argentina (Rodentia: Octodontidae)

Cytogenetic analysis was performed in six nominal taxa of the genus Ctenomys with a diploid number of 2n=47/48. The studied species were: C. australis (2n=48, FN=76); C. mendocinus (2n=47/48, FN=68/75/76); C. porteousi (2n=47/48, FN=71/72/73); C. azarae (2n=47, FN=71); C. sp. (chasiquensis) (2n=47/48); and C. talarum (2n=48, FN=80). The first three species shared the whole complement, C. talarum shares with them 19 arms from a total of 43 (44%). In all species analyzed constitutive heterochromatin was detected in most short arms, and in several centromeres. Polymorphisms for several pairs involving the heterochromatic short arms together with a complex polymorphism of pair A1 were found in C. azarae, C. sp., C. mendocinus and C. porteousi. Intraindividual variation found in one specimen of C. porteousi involving heterochromatic arms is discussed.These results lead us to propose the inclusion of all species except C. talarum, within a complex called the mendocinus-group. A new case of conservatism for chromosomal number in the genus Ctenomys is found in this group.     

A sugar beet (Beta vulgaris L.) reference FISH karyotype for chromosome and chromosome‐arm identification,integration of genetic linkage groups and analysis of major repeat family distribution

We developed a reference karyotype for B. vulgaris which is applicable to all beet cultivars and provides a consistent numbering of chromosomes and genetic linkage groups. Linkage groups of sugar beet were assigned to physical chromosome arms by FISH (fluorescent in situ hybridization) using a set of 18 genetically anchored BAC (bacterial artificial chromosome) markers. Genetic maps of sugar beet were correlated to chromosome arms, and North–South orientation of linkage groups was established. The FISH karyotype provides a technical platform for genome studies and can be applied for numbering and identification of chromosomes in related wild beet species. The discrimination of all nine chromosomes by BAC probes enabled the study of chromosome‐specific distribution of the major repetitive components of sugar beet genome comprising pericentromeric, intercalary and subtelomeric satellites and 18S‐5.8S‐25S and 5S rRNA gene arrays. We developed a multicolor FISH procedure allowing the identification of all nine sugar beet chromosome pairs in a single hybridization using a pool of satellite DNA probes. Fiber‐FISH was applied to analyse five chromosome arms in which the furthermost genetic marker of the linkage group was mapped adjacently to terminal repetitive sequences on pachytene chromosomes. Only on two arms telomere arrays and the markers are physically linked, hence these linkage groups can be considered as terminally closed making the further identification of distal informative markers difficult. The results support genetic mapping by marker localization, the anchoring of contigs and scaffolds for the annotation of the sugar beet genome sequence and the analysis of the chromosomal distribution patterns of major families of repetitive DNA.