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1.
Guy L. Nesom 《Brittonia》1984,36(4):396-401
Chaptalia dentata (L.) Cass. andC. albicans (Sw.) Vent. ex Steudel incorrectly have been recognized as conspecific in recent treatments. Although they are vegetatively similar, they differ in features of the flowers and fruits—especially the mature achenes. Both species occur in the Bahamas and the Greater Antilles of the West Indies:Chaptalia dentata is endemic to that area, absent only from Jamaica;C. albicans is more widespread, as it occurs in Jamaica as well as in scattered localities on the American mainland—southern Florida, various localities in Belize, Honduras, and Guatemala, and the Mexican states of Veracruz, San Luis Potosí, Chiapas, and Yucatán.  相似文献   

2.
Whereas endosymbiont-induced incompatibility is known to occur in various arthropod taxa, such as spider mites, insects and isopods, it has been rarely reported in plant-inhabiting predatory mites (Acari: Phytoseiidae). Recent cross-breeding studies with the phytoseiid mite Neoseiulus paspalivorus De Leon revealed a complete post-mating reproductive isolation between specimens collected from three geographic origins—Northeast Brazil (South America), Benin and Ghana (West Africa)—even though they are morphologically similar. We carried out a study to assess to what extent these populations exhibit genetic differences and whether endosymbionts are involved in the incompatibility. First, we used the mitochondrial cytochrome oxidase I (COI) gene to assess genetic diversity among the three populations. Second, we used a PCR-based method to check for the presence of Wolbachia and/or Cardinium in these populations, and we determined their phylogenetic relationships using specific primers for Wolbachia and Cardinium 16S rDNA genes. Third, we also conducted a test using an antibiotic (tetracycline) in an attempt to eliminate the symbionts and evaluate their effects on the reproductive compatibility of their host. Based on the DNA sequences of their COI genes, specimens of the three populations appear to be genetically similar. However, the 16S rDNA gene sequences of their associated endosymbionts differed among the three populations: the Benin and Brazil populations harbour different strains of Wolbachia symbionts, whereas the Ghana population harbours Cardinium symbionts. In response to antibiotic treatment females of each of the three populations became incompatible with untreated males of their own population, similar to that observed in crossings between females from one geographic population and males from another. Compatibility was restored in crosses involving uninfected Brazil females and uninfected Benin males, whereas the reciprocal crosses remained incompatible. Cardinium symbionts seem to be essential for oviposition in the Ghana population. It is concluded that their associated bacterial symbionts are the cause of the post-mating reproductive isolation previously observed among the three geographic populations. This insight is relevant to biological control of coconut mites for which N. paspalivorus is an effective predator, because introducing one geographic strain into the population of another (e.g. in field releases or mass cultures) may cause population growth depression.  相似文献   

3.
Two types of electroreceptive neurons — tonic and phasic — were found in acute experiments with extracellular recording of unit activity from the lateral lobes of the medulla in the Turkestan catfishGlyptosternum reticulatum. Tonic neurons were more sensitive to the potential gradient in water (the threshold for most neurons was 1–6 µV/cm) than phasic neurons, they possessed spontaneous activity (mean frequency 4–10 spikes/sec), and their response characteristics depended significantly on the intensity and duration of stimulation. Phasic neurons had no spontaneous activity; their sensitivity was about one order of magnitude lower than that of the tonic neurons, and the response was independent of the parameters of the stimuli. The probable mechanisms of differentiation of neurons into two types, with a possible link with the characteristics of the receptor formations or with the functional organization of the corresponding brain centers, are discussed.  相似文献   

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6.
The genetic diversity of the Uralian moose population and the role of the Ural region in the phylogeographic structure of the European moose were evaluated based on sequence polymorphisms of the mtDNA control region. The nucleotide diversity of the Ural moose was low, whereas haplotype diversity was rather high. It was found that the haplotype pool of the Ural moose reflects both the unique features of their mitochondrial lineages and their connection with Alces alces alces populations of Europe and West Siberia. The structure of median networks and the territorial haplotype distribution support the hypothesis that the mitochondrial lineages typical for this part of the European moose area originate from a late Pleistocene refugium that was located in the Urals.  相似文献   

7.
Glucose-6-phosphate dehydrogenase deficiency (G6PD) is the most common enzyme pathology in humans; it is X-linked inherited and causes neonatal hyperbilirubinaemia, chronic nonspherocytic haemolytic anaemia and drug-induced acute haemolytic anaemia. G6PD deficiency has scarcely been studied in the northern region of Mexico, which is important because of the genetic heterogeneity described in Mexican population. Therefore, samples from the northern Mexico were biochemically screened for G6PD-deficiency, and PCR-RFLPs, and DNA sequencing used to identify mutations in positive samples. The frequency of G6PD deficiency in the population was 0.95% (n = 1993); the mutations in 86% of these samples were G6PD A?202A/376G , G6PD A?376G/968C and G6PD Santamaria376G/542T . Contrary to previous reports, we demonstrated that G6PD deficiency distribution is relatively homogenous throughout the country (P = 0.48336), and the unique exception with high frequency of G6PD deficiency does not involve a coastal population (Chihuahua: 2.4%). Analysis of eight polymorphic sites showed only 10 haplotypes. In one individual we identified a new G6PD mutation named Mexico DF193A>G (rs199474830), which probably results in a damaging functional effect, according to PolyPhen analysis. Proteomic impact of the mutation is also described.  相似文献   

8.
Thomas Morley 《Brittonia》1971,23(4):413-424
Geographic variation inMouriri myrtilloides (Swartz) Poiret is analyzed on a morphological basis. Plants from Central America have medium puberulence, long calyx lobes, and short petioles and pedicels; those from Jamaica and Haiti are glabrous and have short calyx lobes, petioles, and pedicels; while those from Cuba have maximum puberulence, medium calyx lobes and pedicels, and long petioles. Glabrous or near-glabrous plants also appear rarely and more or less at random in Central and South America. Distribution in South America is limited to the northwest quarter of the continent. Most plants of this region are similar to those of Central America except that they have slightly shorter calyx lobes. However, the very short calyx lobes of plants from Jamaica and Haiti often occur in South America and rarely in Panama. Furthermore, most features of the Cuban plants appear in those of the Orinoco Basin, while individuals with one of these features, strong puberulence, are occasional elsewhere in South America. It is suggested that the complex originated in northwest South America and diversified there, subsequently radiating north and west. Considerations and problems related to such a dispersal are discussed. Taxonomically the complex is treated as consisting of four subspecies: ssp.parvifolia of Central America and much of the north-west quarter of South America, ssp.myrtilloides of Jamaica and southwest Haiti, ssp.acuta of Cuba, and ssp.orinocensis of the Orinoco Basin, the latter being a new taxon.  相似文献   

9.
Kerry Barringer 《Brittonia》1985,37(2):195-198
Barringer, Kerry (Department of Botany, Field Museum of Natural History, Chicago, IL 60605). Two new species of Esterhazya (Scrophulariaceae) from Brazil. Brittonia 37: 195–198. 1985.—Esterhazya petiolata is a distinctive species with ovate, petiolate leaves, spreading brances, and broadly tubular-campanulate flowers. It is known from the Serra Dourada of Goiás. Esterhazya eitenorum has narrow, lanceolate leaves, acute calyx lobes, and purple-pink flowers and is known from the planalto of Mt. Itatiaia.  相似文献   

10.
Mass rearing of the legume podborer Maruca vitrata (Fablicius) can be a very labor-intensive process. To improve the labor-saving method for larval raising, rearing experiments were conducted using 14 diet regimens, with and without diet-switching between the earlier and latter larval stages. Six different semi-synthetic diets were used, including four crude commercial diets. Larvae showed the highest performance in survival rate, developmental duration and pupal weight when reared on the following diet regimen: (1) 1st to 2nd instars—Insecta F-II (a commercial semi-synthetic diet for herbivorous insects, containing no mulberry leaf powder) mixed with 50 % azuki bean powder; (2) 3rd to 5th instars—switch to a crude commercial diet, either Insecta LFS (a semi-synthetic diet for herbivorous insects, containing mulberry leaf powder) or Insecta F-II mixed with 10 % azuki bean powder. In the feeding experiments, larvae in the earlier stages tended to prefer diets containing azuki bean or mulberry leaf powder, whereas larvae in the latter stages were non-selective in their feeding preference. The exception was Insecta F-II mixed with 50 % azuki bean powder, for which the larvae showed a significantly high preference between 24 and 96 h following release.  相似文献   

11.
Northwest of Lake Izabal, Guatemala, G. C. Jones and L. Facey collected in 1966 abundant material of what we have calledMacromitrium crumianum Steere & Buck. This new species is characterized by linear-lanceolate leaves which are long acuminate, with leaf cells which are smooth and linear throughout, a smooth seta and capsule, and a naked calyptra. It is most closely related toM. dubium Schimp. of the West Indies and perhaps also toM. leprieurii Mont. (M. dussii Broth.) of the West Indies, French Guiana and Suriname.  相似文献   

12.
An almost complete calvaria of an adult macaque was found among remain from the Shikimizu limestone quarry at Hijikawa-cho, Kita-gun, Ehime Pref., Shikoku, Japan. Its exact age is unknown, but probably Pleistocene because mammalian bones from this quarry include not only recent but some Pleistocene elements. The Shikimizu skull has a somewhat different feature as compared with the skull of livingMacaca fuscata, mainly in that its facial region is much broader. In this feature, the Shikimizu skull seems to somewhat resembleMacaca robustus from China, suggesting that the older the lineage offuscata is traced back in the Pleistocene, the more its ancestral type would becomerobustus-like in the morphology.  相似文献   

13.
Die Chromosomenzahlen von den tschechoslowakischen Sippen der GattungKnautia L. sind angegeben:K. drymeia Heuffel subsp.drymeia—2n = 40 (41,42),K. slovaca ?těpánek— 2n = 20,K. arvensis (L.)Coulter subsp.arvensis—2n = 20, 40 (39, 41),K. arvensis (L.)Coulter s. 1.—2n = 20,K. kitaibelii (Schult.) Borbás—2n = 20 (39, 41),K. dipsacifolia Kreutzer subsp.dipsacifolia—2n = 60,K. dipsacifolia agg.—2n = 40, 50, 60. Keine taxonomisch wertvolle morphologische Unterschiede zwischen diploiden und tetraploiden Zytotypen vonK. arvensis subsp.arvensis wurden gefunden. Für die Populationen von Pflanzen, deren Morphologierauf Kreuzung oder Introgression zwischen tetraploiden Sippen (K. arvensis subsp.arvensis—4x,K. drymeia subsp.drymeia, K. kitaibelii undK. dipsacifolia agg.) zeigt, wurden ím Einklang mit dieser Voraussetzung die tetraploiden Chromosomenzahlen—2n = 40 (39, 41)— festgestellt. Einige ungelöste taxonomische Fragen hauptsächlich über die diploiden Populationen vonK. arvensis s. l. in Böhmen und überK. dipsacifolia agg. in den Westkarpaten werden diskutiert.  相似文献   

14.
Peninsular Malaysia is a strategic region which might have played an important role in the initial peopling and subsequent human migrations in Asia. However, the genetic diversity and history of human populations—especially indigenous populations—inhabiting this area remain poorly understood. Here, we conducted a genome-wide study using over 900,000 single nucleotide polymorphisms (SNPs) in four major Malaysian ethnic groups (MEGs; Malay, Proto-Malay, Senoi and Negrito), and made comparisons of 17 world-wide populations. Our data revealed that Peninsular Malaysia has greater genetic diversity corresponding to its role as a contact zone of both early and recent human migrations in Asia. However, each single Orang Asli (indigenous) group was less diverse with a smaller effective population size (N e) than a European or an East Asian population, indicating a substantial isolation of some duration for these groups. All four MEGs were genetically more similar to Asian populations than to other continental groups, and the divergence time between MEGs and East Asian populations (12,000—6,000 years ago) was also much shorter than that between East Asians and Europeans. Thus, Malaysian Orang Asli groups, despite their significantly different features, may share a common origin with the other Asian groups. Nevertheless, we identified traces of recent gene flow from non-Asians to MEGs. Finally, natural selection signatures were detected in a batch of genes associated with immune response, human height, skin pigmentation, hair and facial morphology and blood pressure in MEGs. Notable examples include SYN3 which is associated with human height in all Orang Asli groups, a height-related gene (PNPT1) and two blood pressure-related genes (CDH13 and PAX5) in Negritos. We conclude that a long isolation period, subsequent gene flow and local adaptations have jointly shaped the genetic architectures of MEGs, and this study provides insight into the peopling and human migration history in Southeast Asia.  相似文献   

15.
16.
The three subtribes which are recognized within the tribe Vandeae are represented in the tropical African and Malagasy regions. All taxa of the Vandeae have a monopodial growth habit. The first subtribe, Sarcanthinae, is mainly Asian-Australasian, but a few of its species occur in Madagascar and in Africa. The other two subtribes. Angraecinae and Aerangidinae, are both represented in the latter two regions. The Angraccinae is characterized by the presence of a short rostellum, but this is elongated in the Aerangidinae. According to earlier authors there is a correlation between presence of the short rostellum and a basic chromosome number of x=19 in the Angraecinae, and between the presence of an elongated rostellum and a basic number of x=25 in the Aerangidinae. The results presented in this paper are placed in perspective with the chromosome numbers recorded by other authors. From the resulting chromosome number survey it appears that only part of the Angraecinae (Aeranthes, several species of Angraecum, Cryptopus and Jumellea) have a basic number of x=19; some members of the Angraecinae (other species of Angraecum) were found to have a basic number of x=21, 24 and 25. The Aerangidinae is not characterized by a single basic number of x=25 but by a series ranging from x=23 to x=27, of which x=23, 24 and 25 are the most frequent. The genus Calyptrochilum, although having a distinetly elongated rostellum, is characterized by a basic number of x=19 and its position within the Aerangidinae may therefore be questioned. The present evidence suggests that too much weight has been attributed to a single character, i.e. the shape of the rostellum, in distinguishing the two subtribes. As there appear to be two groups according to basic number in Angraecum, it appears questionable whether Angraecum, as presently conceived, is a ‘natural’ genus. Further chromosomal and other taxonomic evidence is needed to substantiate the challenge to the present views in respect of Angraecum. Taxa with x=19 appear to be frequent in Madagascar and the other islands in the Indian Ocean, whereas taxa with x=21 to 27 mainly occur on the African continent. The predominance of x=19 in the Malagasy flora suggests a link with the monopodial taxa of the Asian and Australasian floras, which are exclusively based on x=19.  相似文献   

17.
Flow cytometry was used to determine ploidy levels in the Czech and Slovak taxa of the genusPseudolysimachion (W.D.J. Koch)Opiz (=Veronica auct. p.p.,Scrophulariaceae). In total, 123 populations from the Czech Republic, Slovakia, Ukraine (one locality), Austria (one locality) and Hungary (one locality) were analyzed. InP. maritimum (L.)Á. Löve etD. Löve andP. spicatum (L.)Opiz, two cytotypes were found: diploid (2n=2x=34) and tetraploid (2n=4x=68). In both species the tetraploid cytotype predominated (P. maritimum: 41 tetraploid populations out of 45;P. spicatum: 57 tetraploid populations out of 58). The two cytotypes ofP. maritimum have no taxonomic significance because ploidy level is not obviously correlated with morphology, distribution pattern or ecology. Tetraploid populations ofP. spicatum belong to two morphologically different subspecies, subsp.spicatum and subsp.fischeri Trávní?ek. The diploid cytotype (one population only) should be provisionally classified as a third subspecies ofP. spicatum, which is morphologically similar to the Asian subsp.porphyrianum (Pavlov)Trávní?ek. Only diploid plants (2n=2x=34) ofP. orchideum (Crantz)Wraber were found; all 13 populations that were analyzed belong toP. orchideum s.str. One diploid population sample ofP. spurium subsp.foliosum (Waldst. etKit.)Holub (2n=2x=34) and one tetraploid sample ofP. incanum subsp.pallens (Host)Trávní?ek (2n=4x=68) were also analyzed. In addition, three tetraploid populations of hybrid origin were investigated:P. maritimum ×P. spicatum subsp.spicatum (one population) andP. maritimum ×P. spurium subsp.foliosum (two populations). While hybrid plants ofP. maritimum ×P. spicatum arose from tetraploid parental species, plants ofP. maritimum ×P. spurium probably resulted from a cross between tetraploidP. maritimum and diploidP. spurium. The putative origin and evolutionary importance of polyploids in thePseudolysimachion are discussed.  相似文献   

18.
Karyotypes of twelve species from twenty-four localities in southern Moravia and one locality in Slovakia were investigated. Their counts or karyotypic formulae are as follows:Chenopodium foliosum (Moench) Ascherson: K (2n)=18=16 Am+2 Bsm;Astragalus austriacus Jacq.: K (2n)=16=8 Am+8 Bsm;Astragalus exscapus L.: K (2n)=16=10 Am+4 Bsm+2 Cst;Astragalus cicer L.: K (2n)=64;Astragalus onobrychis L.: K (2n=64 and K (2n)=64+1;Vicia dumetorum L.: K (2n=14=10 Am+4 Bsm;Vicia sylvatica L.: K (2n)=14=2 Am+10 Bsm+2 Cst;Vicia pisiformis L.: K (2n)=12=8 Am+4 Bsm;Vicia cassubica L.: K (2n)=12=4 Am+6 Bsm+2 Cst;Vicia cracca L. (from five localities in southern Moravia): K (2n)=28=4 Am+12 Bsm+12 Cst and K (2n)=28+1=5 Am+12 Bsm+12 Cst;Vicia cracca L. (from one locality in Slovakia): K (2n)=14=2 Am+6 Bsm+6 Cst;Vicia tenuifolia Roth: K (2n)=24=4 Am+16 Bsm+4 Cst;Serratula lycopifolia (Vill.) Kern.: K (2n)=60.  相似文献   

19.
Somatic DNA from Heteropeza pygmaea separated in CsCl gradients into a main band DNA (?=1.685 g/cm3) and a satellite band (?=1.716 g/cm3) comprising 15% of the total DNA. The satellite melted sharply at 93.0°C in SSC, 10.4°C higher than the main band DNA. Satellite DNA reassociated rapidly, banding in CsCl heavier than native satellite but lighter than denatured satellite. The complementary strands of the satellite formed a single band in alkaline gradients and hence are apparently similar in G+T composition. — Filter hybridization experiments with Xenopus ribosomal RNA showed that the satellite band does not contain ribosomal cistrons. — Complementary RNA (cRNA) transcribed in vitro from isolated satellite bound extensively to satellite DNA but not to main band DNA. — The strain of Heteropeza used here contained about 58 chromosomes in germ-line cells and reproduced only paedogenetically. During early cleavage, the presumptive somatic nuclei eliminate most of their chromosomes (E-chromosomes) and retain only ten (S-chromosomes). In situ hybridizations with satellite-cRNA showed satellite DNA (prepared from predominately somatic tissues) to be localized in the centromeric heterochromatin of S- and E-chromosomes. Silver grain comparisons suggested that the amount of satellite is equivalent in both types of chromosomes. — Lastly we found that both diploid and polyploid cells contain similar amounts of satellite DNA. We interpreted this to mean that during polyploidization, as has been demonstrated during polytenization, satellite DNA does not replicate or replicates only slightly while other DNA fractions increase.  相似文献   

20.
Up-to-date results of taxonomic and phytogeographic studies ofOenothera subsect.Oenothera in the eastern part of the Czech Republic (Moravia and Silesia) are presented. A new hybridogenous species,Oe. moravica Jehlík etRostański (=Oe. fallax × Oe. victorini), is described from S Moravia. Several taxa and hybrids are reported for the first time for the Czech Republic:Oe. victorini Gates etCatcheside (=Oe. rostanskii Jehlík),Oe. × wienii Renner exRostański,Oe. acutifolia × Oe. victorini. Other taxa are recorded from the eastern part of the Czech Republic for the first time:Oe. acutifolia Rostański,Oe. hoelscheri Renner exRostański,Oe. parviflora L.,Oe. subterminalis Gates. The taxonomy ofOe. pycnocarpa Atkinson etBartlett is discussed. A survey of species and hybrids ofOenothera subsect.Oenothera in the Czech Republic is added.  相似文献   

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