Genetic diversity in the endangered dysploid larkspur Delphinium bolosii and its close diploid relatives in the series Fissa of the Western Mediterranean area

Allozyme diversity was evaluated in four closely-related taxa of the Delphinium series Fissa distributed throughout the Western Mediterranean area. All are considered threatened plants. Delphinium bolosii and Delphinium mansanetianum are narrowly endemic to the Eastern Iberian Peninsula, whereas Delphinium fissum ssp. sordidum is found in a few populations across the Peninsula. Delphinium fissum ssp. fissum is more widely distributed but often in small and isolated populations. In this group, Delphinium bolosii is dysploid (2 n  = 18) whereas the other taxa are diploid (2 n  = 16). A total of 12 populations were surveyed, including all known locations for D. bolosii , D. mansanetianum , and D. fissum ssp. sordidum . Eleven enzyme systems were assayed and 15 loci were resolved. Markedly depauperate values for genetic diversity were obtained for D. mansanetianum ( H _e = 0.013) and D. fissum ssp. sordidum ( H _e = 0.044). The estimates for D. fissum ssp. fissum ( H _e = 0.071) were below the values expected for widespread species. Small population size and marginal distribution have probably contributed to the low variability observed in this group. By contrast, D. bolosii exhibited comparatively larger populations and greater genetic diversity ( H _e = 0.138). We suggest that, apart from population size and local adaptation, genetic diversity during speciation may have been promoted by dysploidy through genomic recombination.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 773–784.     

Molecular phylogeny and diversification history of Prosopis (Fabaceae: Mimosoideae)

The genus Prosopis is an important member of arid and semiarid environments around the world. To study Prosopis diversification and evolution, a combined approach including molecular phylogeny, molecular dating, and character optimization analysis was applied. Phylogenetic relationships were inferred from five different molecular markers ( mat K- trn K, trn L- trn F, trn S- psb C, G3pdh, NIA). Taxon sampling involved a total of 30 Prosopis species that represented all Sections and Series and the complete geographical range of the genus. The results suggest that Prosopis is not a natural group. Molecular dating analysis indicates that the divergence between Section Strombocarpa and Section Algarobia plus Section Monilicarpa occurred in the Oligocene, contrasting with a much recent diversification (Late Miocene) within each of these groups. The diversification of the group formed by species of Series Chilenses, Pallidae, and Ruscifoliae is inferred to have started in the Pliocene, showing a high diversification rate. The moment of diversification within the major lineages of American species of Prosopis is coincident with the spreading of arid areas in the Americas, suggesting a climatic control for diversification of the group. Optimization of habitat parameters suggests an ancient occupation of arid environments by Prosopis species.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 621–640.     

不受欢迎的生物多样性：香港的外来植物物种

香港早在19世纪中叶开始就有外来植物入侵的记录,迄今为止,已发现多达238种已归化的外来或怀疑为外来的植物,其中又以薇甘菊（Mikania micrantha)、五爪金龙（Ipomoea cairica)、假臭草（Eupatorium catarium)、大黍（Panicum maximum)等最常见,外来植物最常见于受人为干扰的生境,例如荒废农田及路旁等,而较少在天然林地生境及贫瘠的灌草丛中发现,外来植物的对本地生态系统的影响主要局限于低地生境,它们常形成单优种群,减少了生境及贫瘠的灌草丛中发现,外来植物对本地生态系统的影响主要局限于低地生境,它们常形成单优种群,减少少了生境及动植物的多样性,外来动物对香港原生植物影响最大的是于20世纪70年代入侵的松树线虫（Bur-saphelenchus xylophilus)。外来的脊椎动物也有可能对香港的植物被演替产生影响,目前香港的外来植物当中,有些在大陆较少分布或没有记录,作为华南最大的港口,香港对外来物种的引入扮演着重要的角色,因此制定控制外来种在香港及华南地区的引入及传播的政策及措施非常重要。     

Genetic diversity and population structure of Pichia guilliermondii over 400 generations of experimental microevolution

An in vitro evolution model was used to study changes in the genetic diversity of 24 strains of Pichia guilliermondii isolated from the midgut of bark beetles of the genus Dendroctonus . The genetic diversity of P. guilliermondii strains over 400 generations was analysed using multilocus enzyme electrophoresis (MLEE) and random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) markers. Resemblance relationships among strains were observed by cluster analysis. From the MLEE and RAPD markers, it was shown that the effective number of alleles, polymorphism and expected heterozygosity varied over the generations. The average heterozygosity among generations was statistically significant. Both the genetic diversity and the average heterozygosity were statistically significant among generations. The reduction in the population size from 10⁹ to 10⁵ yeast mL⁻¹ associated with each transfer in P. guilliermondii strains and the clonal population structure observed along 400 generations suggest that genetic diversity changes and the observed replacement of genotypes are a consequence of a genetic drift process and not of the reproductive mode.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 475–486.     

Microsatellite markers for evolutionary studies in the sexually deceptive orchid genus Chiloglottis

The orchids in the genus Chiloglottis are pollinated exclusively by sexual deception. We describe 20 variable microsatellite loci that will facilitate the study of the evolution and ecology of this specialized pollination system. Two loci were isolated from Chiloglottis trilabra, with the rest derived from Chiloglottis valida. All loci were polymorphic in C. valida (H_E 0.07–0.87). Most loci amplified, and were variable within close relatives of C. valida, and a number amplified more broadly, including outside the genus.     

Geographic variation of the Greater white-toothed shrew (Crocidura russula Hermann, 1780 Mammalia, Soricidae)

A multivariate morphometric study of the Greater white-toothed shrew ( C. russula ) throughout its Palearctic range was carried out to search for patterns of geographic variation within the species boundary. Burnaby's and multiple group principal component analysis allowed the adjustment of raw data with respect to within-sample allometric variation. Multivariate 'size-free'results show a stepped cline with the phenotypical trait reduction and shape change from the eastern to the western Maghreb. Pleistocene fossil mandibles proved to have low phenetic distances with eastern populations (Tunisia, east Algeria) and it is argued that their character set is the primitive condition. The ancestral Mid-Pleistocene shrews lived in a relatively more humid climate. Geo-climatic changes in the north African range during the Quaternary provoked phenetic variation of C. russula and, it can be argued, evolution of the modern western C.r. yebalensis. A historical process can thus be assumed as the main cause of this categorical variation, by segmentation of the species range due to geo-climatic events. Morphometric discontinuity within the C. russula Maghreb range is shown to be congruent with karyological and biochemical studies. Moroccan and Tunisian shrews differ, for example, in NFa chromosomes and electrophoretical traits. A stasipatric process should be invoked to explain categorical variation in the Maghreb range. Colonization and divergence of insular populations results in more or less differentiated geographic races. The populations of Ibiza and Pantelleria are close to the species threshold (Nei's D ≥ 0.1). The process of speciation undergone by the Greater white-toothed shrew results in a complex pattern of geographic variation, including both allopatric and non-allopatric modes.     

The phylogenetic significance of flavonoids in Crambe L. (Cruciferae)

A total of 21 flavonoid compounds has been detected in 14 species of Crambe. In general, both the sections of the genus and the species can be distinguished easily by their flavonoid patterns. The members of Crambe sections Crambe and Dendrocrambe seem to be the most primitive with their perennial or rhizocarpous habit. They show a diversity of flavonol glycosides, derived from either kaempferol or quercetin. The presumed presence of proanthocyanidins confers an additional primitive character to Crambe section Dendrocrambe. In contrast, members of Crambe section Leptocrambe show a relatively poor pattern where the quercetin glycosides have disappeared. In the case of C. hispanica and C. abyssinica flavonols are completely absent while two flavones, luteolin and apigenin appear in glycosidic form; these are probably the most evolved Crambe species and exhibit an annual habit. A dendrogram exclusively based on data of the presence or absence of flavonoids has been constructed. It is similar to the one that could have been expected from use of morphological data alone, but it does provide some hints on the possible phylogenetic relationships between the species. Flavonoid evidence also supports the hypothesis on an east-west Mediterranean disjunction within the genus.     

Gut-associated yeast in bark beetles of the genus Dendroctonus Erichson (Coleoptera: Curculionidae: Scolytinae)

Scolytine bark beetles are the most destructive pests of conifers; they sometimes aggregate in such large numbers that they actually kill their hosts. They maintain close relationships with yeasts and fungi, in particular those that are assumed to aid in digestive, detoxification processes and pheromone production. In this study, 403 yeast strains were isolated from the guts, ovaries, eggs and frass of nine bark beetle species in the genus Dendroctonus Erichson. The beetles were collected from 10 conifer species at 34 locations in Mexico, Guatemala and the USA. Yeast identification was based on partial DNA sequences from 18S rDNA, 26S rDNA and internal transcribed spacer (ITS1), as well as morphological and physiological characteristics. A combined phylogenetic analysis delimited 11 clades with sequences similar to Candida arabinofermentans , C. ernobii , C. membranifaciens (including C. lessepsii , Pichia mexicana and P. scolyti ), C. oregonensis , C. piceae , Kuraishia capsulata (including K. capsulata and K. cf. molischiana ), Pichia americana , P. canadensis , P. glucozyma , P. guilliermondii and an undescribed species of Candida . Nucleotide divergences between the major clades were at least 5% while, with the exception of 30 isolates, yeasts within clades differed from named reference species at fewer than 1% of the nucleotide sites. There do not appear to be obligate relationships between particular yeasts and specific anatomical partitions, nor between particular yeasts and bark beetle species. Some yeasts do appear to be preferentially associated with bark beetles feeding on different conifer genera and therefore host plant defences may limit yeast community diversity in Dendroctonus .  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 325–342.