Taxonomy of the African giant pouched rats (Nesomyidae: Cricetomys): molecular and craniometric evidence support an unexpected high species diversity

Our study combined a mitochondrial cytochrome b phylogeny with cranial measurements from giant pouched rats collected across sub‐Saharan Africa. The mitochondrial phylogeny resolves two West African clades and a clade with east and central Africa representatives. This last clade can be further divided into four subclades. Altogether they represent six species (Cricetomys gambianus, Cricetomys ansorgei, Cricetomys emini, and three undescribed taxa) that can be distinguished on the basis of their mitochondrial DNA sequences and craniometry. In the absence of adequate craniometric data the existence of Cricetomys kivuensis cannot be confirmed by our data. Our combined molecular and craniometric data allowed us to broadly delineate the distribution ranges of the detected species. Cricetomys gambianus occurs in the savannah and forest clearings of West Africa. Cricetomys ansorgei is distributed in the savannah of East and southern Africa. Cricetomys emini, as currently recognized across the Guineo‐Congolian forest of Africa, is shown to be diphyletic. Cricetomys sp. 1, a separate operational taxonomic unit closely resembling C. emini, occurs in the forest zone of West Africa. An undescribed sister‐species of C. ansorgei, Cricetomys sp. 2, occurs in the forest of Central Africa along the left bank of the Congo River. Cricetomys sp. 3 occurs on the right bank of the Congo River from Cameroon to the Republic of Congo, whereas the true C. emini also occurs on the right bank of the Congo River but appears to be restricted to the Democratic Republic of Congo. Cranial phenotype within the genus tends to conform to ecological zonation (either forest or savannah) rather than to phylogenetic affiliation of the species concerned, suggesting that diversifying selection across environmental gradients could be responsible for biological diversification within the genus.     

Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 show increased susceptibility to a group of fungal and oomycete pathogens

The behaviour of Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 was investigated in response to fungal and oomycete infections. The importance of NpPDR1 in plant defence was demonstrated for two organs in which NpPDR1 is constitutively expressed: the roots and the petal epidermis. The roots of the plantlets of two lines silenced for NpPDR1 expression were clearly more sensitive than those of controls to the fungal pathogens Botrytis cinerea , Fusarium oxysporum sp., F. oxysporum f. sp. nicotianae , F. oxysporum f. sp. melonis and Rhizoctonia solani , as well as to the oomycete pathogen Phytophthora nicotianae race 0. The Ph gene-linked resistance of N. plumbaginifolia to P. nicotianae race 0 was totally ineffective in NpPDR1 -silenced lines. In addition, the petals of the NpPDR1 -silenced lines were spotted 15%–20% more rapidly by B. cinerea than were the controls. The rapid induction (after 2–4 days) of NpPDR1 expression in N. plumbaginifolia and N. tabacum mature leaves in response to pathogen presence was demonstrated for the first time with fungi and one oomycete: R. solani , F. oxysporum and P. nicotianae . With B. cinerea , such rapid expression was not observed in healthy mature leaves. NpPDR1 expression was not observed during latent infections of B. cinerea in N. plumbaginifolia and N. tabacum , but was induced when conditions facilitated B. cinerea development in leaves, such as leaf ageing or an initial root infection. This work demonstrates the increased sensitivity of NpPDR1 -silenced N. plumbaginifolia plants to all of the fungal and oomycete pathogens investigated.     

Molecular and morphometric variation in two sibling species of the genus Praomys (Rodentia: Muridae): implications for biogeography

The rodent genus Praomys is widely distributed in the African tropics. The species are cryptic, rendering the species taxonomy unclear. There are differences of opinion concerning the specific status of Praomys misonnei and Praomys tullbergi, and their geographical distribution. We sequenced the cytochrome b and/or the 16S gene of 221 specimens from 12 countries in order to evaluate the genetic variability within these two species, and to precisely determine their geographical distribution. Morphological and morphometrical analyses on the sequenced specimens were also performed to find criteria useful for the identification of museum specimens. Our results confirm that P. misonnei and P. tullbergi are two valid species that can be separated by molecular data. However, no single discrete morphological character or simple metric measurement can be used to discriminate them. The percentage of misclassified individuals in multivariate discriminant analysis is relatively high (10%). The two species have allopatric distributions: P. tullbergi occurs in West Africa, from eastern Guinea to western Ghana, and P. misonnei is widely distributed from eastern Ghana to western Kenya. Within P. misonnei we identified three or four major geographical clades: a West Central African clade, an East African clade, a Nigerian clade, and a possible West African clade. Within P. misonnei, high geographical morphometrical variability was also identified. The role of both rivers and Pleistocene forest refugia in promoting speciation within the genus Praomys is discussed. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 397–419.     

Theoretical habitat templets, species traits, and species richness: amphibians in the Upper Rhône River and its floodplain

• 1 The purpose of this study was to test predictions of the habitat templet and the patch dynamics concept by analysing the relationship between either the species traits or species richness of amphibians and the spatial–temporal variability of eight habitat types of the Upper Rhône River and its floodplain, France.
• 2 The information on species traits of the twelve amphibian species was accumulated primarily from the literature; that on habitat utilization was based on field surveys. The information was ‘fuzzy coded’, analysed by ordination techniques, and finally linked to the spatial–temporal variability of habitat types elaborated elsewhere in this issue.
• 3 After elimination of the variance caused by the differences between urodeles and anurans, correspondence analysis of the matrix of species traits demonstrated that the flexibility of the temporal pattern of reproduction was the major source of variation among amphibian species. A less significant source of variation within anurans was related to traits usually linked to the concept of r–K selection (potential number of descendants per reproductive cycle and ratio of egg size to female size).
• 4 A correspondence analysis of habitat utilization by amphibian species separated four groups of habitat types, corresponding to different degrees of influence that the active channel had on adjacent waters in the floodplain (i.e. from habitats that are most frequently disturbed by floods, to habitats of braided sections, old oxbow lakes, and the more terrestrialized habitats).
• 5 A co-inertia analysis of the relationship between species traits and habitat utilization separated two habitat types (terrestrialized former meanders and oxbow lakes) from the others. Species of terrestrialized habitats had a reproductive display, a low number of descendants per reproductive cycle, and a high ratio of egg size to female size. Species of oxbow lakes were early or synchronous breeders, and laid a single clutch.
• 6 Neither the predictions of the habitat templet concept nor those of the patch dynamics concept were validated. Species traits were not significantly correlated to the axes of the spatial–temporal variability templet. The highest species richness was observed in habitat types with the highest temporal variability; in addition, richness did not peak at highest spatial variability.
• 7 Deviation from the predictions of the river habitat templet could be explained by: (i) the over-simplification of this model with regard to the evolution of the complex life cycles of the amphibians; and (ii) an underestimation of the importance of phylogenetic constraints and the evolution of community interactions.

     

Tissue and Cell Culture of 'Passe Crassane' Pears: Amylase Pattern of Cultured Tissues Compared with Whole Fruit

Calluses and cell suspension cultures were initiated from young and fully developed fruits and from stem and petiole tissues of ‘Passe Crassane’ pears. On a dry weight basis, proliferation is significantly higher in tissues from full-grown fruits and petioles. Cullus tissues grown in vitro have a protein content up to 25 times higher than the initial quiescent organ. Three amylase fractions (2 β amylases E, and E₂: 1 α amylase E₃) were isolated by gel filtration on Sephadcx G-100 and isoenzymes revealed in these fractions after polyacrylamide gel electrophoresis. Comparison of amylase activity in actively growing cells and in auxin-starved cell suspensions shows that β-amylase activity is mainly a function of cell growth, while α-amylase activity is more related to the age of the cells. The presence of two isoenzymes in the β-amylase E₂ fraction was found to be highly characteristic of young fruits. The same polymorphism was found in all the strain of tissues thus indicating that tissues grown in vitro retain or revert to a juvenile biochemistry. The growth hormone. 2,4-dichlorophenoxyacetic acid, used to support cell division, is demonstrated to be responsible for the reversion of the β-amylase polymorphism from a mature to a juvenile phenotype in mature fruit explants incubated in vitro. The interest of fruit tissue and cell culture for the study of fruit physiology is questioned and discussed.     

Relations polyphénols — croissance: Mise en évidence d'un effet inhibiteur des composés phénoliques sur le transport polarisé de l'auxine

Polyphenols and Growth: Inhibition of Polar Auxin Transport by Phenolic Compounds. The possible effects of polyphenols on auxin transport in tomato plants (Lycopersicum esculentum Mill.) were investigated. For this purpose, the phenolic content of the material was stimulated by exogenously supplied quinic acid. After the apical bud had been excised, labelled compounds were applied to the cut surface, and the radioactivity transported to the roots was measured. Quinic acid treatment significantly delayed polar transport of labelled auxins (IAA or NAA). It did not affect the migration rate of sucrose^?14C and leucine^?3H. A number of evidences seems to demonstrate that the phenolics are responsible for these modifications, since similar results were recorded when the labelled compounds were supplied simultaneously with polyphenols from tomato. Moreover, a decreased polarity of NAA transport could be observed when the plants were submitted to treatments which lead to an increased level of phenols (boron deficiency, infection by Fusarium oxysporum). The data presented in this paper suggest that phenolic compounds could act on growth processes via the regulation of polar auxin transport.     

Assessment of genetic and pheromonal diversity of the Cydia strobilella species complex (Lepidoptera: Tortricidae)

Combining pheromone trapping and genetic analyses can be useful when trying to resolve complexes of closely related insect taxa that are difficult to distinguish based on morphological characters. Nearctic and Palearctic populations of the spruce seed moth, Cydia strobilella L., have been considered taxonomically synonymous since 1983, but more recent work revealing distinct sex pheromones for Canadian and Swedish moths suggest that populations in the two regions belong to different species. In order to test this hypothesis, we performed field trapping using different pheromone lures at ten sites in North America, Europe and Asia, and reconstructed phylogenetic relationships among trapped moths using mitochondrial (cytochrome oxidase subunit I) and nuclear (elongation factor 1 alpha) DNA sequence data. Trapping data and tree topologies for both genes revealed distinct pherotypes in North America and Eurasia. A genetically distinct population from China was investigated further with respect to its sex pheromone. Electrophysiological data indicated that Chinese females produce a deviant ratio of the sex pheromone components (dienic acetates) compared to Swedish females. However, trapping experiments in both areas revealed a similar broad response profile in males to a wide range of acetate ratios, and these populations should be considered taxonomically synonymous. A previous suggestion of an agonistic effect on the attraction of C. strobilella males in Sweden when adding the corresponding alcohols to the binary acetate blend was also tested in Sweden as well as in China, with no observed effect on attraction of males. In conclusion, our study demonstrates the great potential of using pheromone trapping as a tool for identification and delimitation of taxa within cryptic species complexes. Based on our data, Nearctic and Palearctic populations of C. strobilella should be considered different species, and C. youngana Kearfott stat. rev. is resurrected here as valid name for North American populations, which was the case before the revision in 1983.