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11.
Molecular Techniques in the Assessment of Botanical Diversity 总被引:14,自引:2,他引:12
A variety of different molecular techniques can be used forthe study of botanical diversity. Restriction fragment lengthpolymorphism (RFLP), arbitrary primed DNA, amplified fragmentlength polymorphism (AFLP), variable number of tandem repeats(VNTR), sequence-tagged simple sequence repeats (SSRs) and polymerasechain reaction (PCR) sequencing are briefly reviewed here. Thesetechniques differ in the way that they resolve genetic differences,in the type of data that they generate and in the taxonomiclevels at which they may be most appropriately applied. It isimperative to understand the different ways in which the datafrom the different molecular techniques can be utilized beforeembarking upon a programme of applying them to any particulardiversity study. Biodiversity; RFLP; RAPD; AFLP; VNTR; SSR; molecular data; fingerprinting; genetic distances; phylogeny; conservation 相似文献
12.
OLE P. OSTERMANN 《Journal of Applied Ecology》1998,35(6):968-973
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B. L. WOODWORTH B. P. FARM C. MUFUNGO M. BORNER & J. OLE KUWAI 《African Journal of Ecology》1997,35(4):326-334
An aerial photographic census of flamingos ( Phoenicopterus minor and P. ruber) was conducted on 20 July 1994 on nine lakes in Tanzania: Lakes Natron, Manyara, Magadi (Ngorongoro), Burungi, Embagai, Eyasi, Lagarja, Masek, and Ambussel. This census, conducted concurrently with a survey in Kenya, documented the numbers and distribution of flamingos in the Rift Valley Lakes of East Africa. The total population size of flamingos in the Tanzanian lakes surveyed was |mF907,000. The largest concentrations in Tanzania were found in Lake Natron and Embagai Crater Lake. Although flamingos are known to breed in Lake Natron, no evidence of breeding was observed during the survey. The total estimate for the southern Kenya and northern Tanzania Rift Valley was |mF2·8 million. Trends in flamingo populations, survey methodology, and future monitoring needs are discussed. 相似文献
14.
Macromolecular Physiology of Plastids 总被引:1,自引:0,他引:1
The composition and amount of carotenoid pigments were determined in etiolated seedling leaves of 6 barley (Hordeum vulgare L.) mutants, comprising 1 xantha and 5 tigrina mutants. All mutants had on a mole basis approximately the same content of carotenoids as the wild type. The mutants xan-u21, tig-n32, and tig-33 contained significantly higher amounts of carotenes than the wild type, ranging from 32 to 68% of the total carotenoid content as compared to the 4–8% found in the wild type. In the mutants tig-b23 and tig-o34, only a slight increase in the amount of carotenes was notable. The carotene content and composition in tig-d12 was indistinguishable from that of the wild type. The carotenes extracted from xan-u21, tig-b23, tig-n32, tig-33, and tig-o34 were characterized by adsorption chromatography and spectrophotometry. Mutant xan-u21 is in the dark blocked in β-carotene synthesis, and accumulates the aliphatic polyenes: phytofluene, proneurosporene, poly-cis-lycopenes, neo-lycopene and lycopene. The other four mutants synthesize β-carotene, but accumulate in addition various higher saturated carotenes, the main components being ζ-carotene in tig-b23, a lycopenic pigment in tig-n32 and tig-33, and lycopene in tig-o34. Accumulation of higher saturated carotenes appears correlated with specific aberrations of the membrane structure in plastids. The regulation of carotene and protochlorophyllide syntheses in etioplasts are closely linked as shown by the single gene mutants which affect both pathways. However, several mutants have been identified which cause defects in protochlorophyllide synthesis only. 相似文献
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1. Oligotrophic softwater lakes represent a special type of aquatic ecosystem with unique plant communities where generalisations from other aquatic plant communities to rising CO2 in the water column may not apply. 2. In the present study, we set up large in situ mesocosms and supporting laboratory experiments with isoetid vegetation (Littorella uniflora) where water column CO2 and light could be manipulated in order to test whether (i) light and CO2 availability affect nutrient concentrations in isoetid vegetation, and (ii) if changes in light and CO2 climate affect fluxes of inorganic nitrogen (N) and phosphorus (P) from sediment to water column, which potentially could result in increased growth of epiphytic algae. 3. The results showed that the standing stocks of phosphorus and nitrogen in the L. uniflora vegetation were significantly influenced by CO2 concentration and light intensity. Both standing stocks of P and N were significantly higher in the mesocosm treatments with high CO2 concentration than in those at low CO2 concentration. Similarly, standing stocks of P and N enhanced with increasing light intensity. 4. Measurements of nutrient fluxes both in the field and the laboratory did not show any significant release of nutrients to the water column from plants or sediments at any of the light or CO2 treatments. However, mats of epiphytic algae developed from the beginning of June to late September and caused a light reduction for the isoetid vegetation. 5. Increasing CO2 concentrations in the water column may over time potentially result in a change in soft water plant communities. 相似文献
17.
The seeds of Cuscuta pedicellata have been investigated by transmissionand scanning electron microscopy. Additional observations havebeen made on seeds of C. campestris by SEM only. The seed coatconsists of an outer single epidermis, two different palisadelayers, and an inner multiparenchyma layer. The outer epidermalwall in C. pedicellata has a thick cuticle and zones rich inpectic substances. The thicker U-shaped cell wallsin the outer palisade layer are strengthened by a wall layerof hemicellulose. The inner palisade layer has thick walledcells with a light line. The inner cell wall ofthe compressed multiparenchyma layer has a thin cuticle. A fairlythick cuticle is positioned directly on the endosperm surface.The aleurone cell walls are different from the remaining endospermwalls. The latter are thick and believed to be of galactomannans.There is a clear zone between the plasmalemmaand the cell wall in the aleurone cells. The embryo cells arepacked with lipids and proteins. In Cuscuta campestris mostendosperm has been absorbed during the seed development. Theembryo apex has two minute leaf primordia. The features of theCuscuta seeds are discussed in relation to functional and environmentalconditions. Cuscuta pedicellata, Cuscuta campestris, seed, seed coat, cuticle, cell walls, endosperm, aleurone cells, galactomannan, embryo, TEM, SEM 相似文献
18.
Female mating preferences and male coloration covary with water transparency in a Lake Victoria cichlid fish 总被引:1,自引:0,他引:1
MARTINE E. MAAN OLE SEEHAUSEN JACQUES J. M. VAN ALPHEN 《Biological journal of the Linnean Society. Linnean Society of London》2010,99(2):398-406
Rapid speciation in Lake Victoria cichlid fish of the genus Pundamilia may be facilitated by sexual selection: female mate choice exerts sexual selection on male nuptial coloration within species and maintains reproductive isolation between species. However, declining water transparency coincides with increasingly dull coloration and increasing hybridization. In the present study, we investigated the mechanism underlying this pattern in Pundamilia nyererei, a species that interbreeds with a sister species in turbid but not in clear water. We compared measures of intraspecific sexual selection between two populations from locations that differ in water transparency. First, in laboratory mate‐choice experiments, conducted in clear water and under broad‐spectrum illumination, we found that females originating from turbid water have significantly weaker preferences for male coloration than females originating from clear water. Second, both the hue and body coverage of male coloration differ between populations, which is consistent with adaptation to different photic habitats. These findings suggest that the observed relationship between male coloration and water transparency is not mediated by environmental variation alone. Rather, female mating preferences are indicated to have changed in response to this variation, constituting the first evidence for intraspecific preference‐trait co‐evolution in cichlid fish. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 398–406. 相似文献
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20.
OLE SEBERG FLS SIGNE FREDERIKSEN 《Botanical journal of the Linnean Society. Linnean Society of London》2001,136(1):75-97
A cladistic analysis, primarily based on morphology, is presented from 40 diploid taxa representing the 24 monogenomic genera of the Triticeae. General problems related to the treatment of hybrids and supposedly allopolyploid heterogenomic taxa are highlighted. Special emphasis is given to taxa not traditionally included in Aegilops s.J. Most of the 33 characters used in the analysis are coded as binary. The only four multistate characters in the matrix are treated as unordered. Three diploid species of Bromus are used as outgroup. The number of equally parsimonious trees found is very large (approx. 170000; length = 107, ci = 0.36, ri = 0.75) and the strict consensus tree has an expectedly low level of resolution. However, most of the equally parsimonious trees owe their existence to an unresolved Aegilops clade. If this clade is replaced by its hypothetical ancestor, the number of equally parsimonious trees drops dramatically (48; length = 78, ci = 0.45, ri = 0.76). When trees for which more highly resolved compatible trees exist are excluded, only two trees remain. Bremer support is used as a measure of branch support. The trees based on morphology and on molecular data are largely incongruent. 相似文献