Morphological differentiation among closely related species with disjunct distributions: a case study of Mediterranean Cyclamen L. subgen. Psilanthum Schwarz (Primulaceae)

In Cyclamen subgenus Psilanthum , previous authors have recognized three species ( C. repandum, C. balearicum and C. creticum ), with C. repandum subdivided into three subspecies (ssp. repandum , ssp. peloponnesiacum and ssp. rhodense ), and two varieties (var. vividum and var. peloponnesiacum ) within C. repandum ssp. peloponnesiacum . To examine the validity of this classification and the degree of morphological differentiation among closely related endemic taxa with disjunct distributions, we undertook analyses of three quantitative and eight qualitative morphological traits of flowers and leaves, most of which have previously been used without statistical comparison in the classification of the different taxa. Cyclamen balearicum showed high levels of morphological differentiation from all other taxa in subgenus Psilanthum consistent with its specific status. In contrast, morphological differentiation between C. creticum and subspecies of C. repandum was similar to that among the three subspecies of C. repandum . When compared with a recent molecular phylogeny of this subgenus, our results suggest that C. creticum may best be described as a geographical subspecies of C. repandum . The two varieties of C. repandum ssp. peloponnesiacum showed few significant differences for individual traits and their overall morphology is very similar to each other. The morphology of plants at three sites on Corsica strongly suggest, consistent with molecular data, the occurrence of hybrid populations between C. balearicum (outside of its previously recognized distribution) and local C. repandum .  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 133–144.     

Divergent responses of two cereal aphids to previous infestation of their host plant

The role of pollen odour in resource location by the pollen beetle, Meligethes aeneus (Fabricius) (Coleoptera: Nitidulidae), a pollen-feeding insect regarded as a pest of oilseed rape, Brassica napus L., (Brassicaceae) crops, was investigated in a linear track olfactometer. Both male and female beetles were attracted to the odour of whole oilseed rape flowers, indicating that these insects can locate their host plants using floral odours as cues. The attractive odour of flowers was found to emanate from all floral parts tested: the petals/sepals, the anthers, and from pollen itself. Therefore, at least part of the attractive odour of oilseed rape flowers emanates from pollen. Beetles were more attracted to floral samples containing anthers than those without anthers when these odours were directly compared in a choice-test, and this indicates that there were detectable differences between them. Anthers and pollen may therefore release distinctive odours that are quantitatively and/or qualitatively different from the odour of the rest of the flower. These experiments support the hypothesis that pollen-seeking insects use pollen odour cues to locate this food source.     

Description and phylogeny of a new Neotropical genus of Acalyptini (Coleoptera: Curculionidae: Curculioninae) associated with the staminodes of Cyclanthaceae

The weevil genus Azotoctla gen. nov. (Coleoptera: Curculionidae: Curculioninae: Acalyptini Thomson), is described to accommodate the following 15 new Neotropical species: Azotoctla aecuatorialis sp. nov. (Ecuador), Azotoctla anerunca sp. nov. (Ecuador), Azotoctla angustacra sp. nov. (Ecuador), Azotoctla curvirostra sp. nov. (Peru), Azotoctla dasygastra sp. nov. (Costa Rica and Honduras), Azotoctla femorata sp. nov. (Colombia, Costa Rica, Ecuador and Panama), Azotoctla gomezi sp. nov. (Colombia, Costa Rica and Panama), Azotoctla gottsbergeri sp. nov. (Brazil), Azotoctla clemmyssa sp. nov. (Colombia), Azotoctla melolauta sp. nov. (Colombia), Azotoctla migueli sp. nov. (Colombia), Azotoctla nana sp. nov. (Panama), Azotoctla punctata sp. nov. (Costa Rica), Azotoctla tibiatra sp. nov. (Belize), and Azotoctla tuberquiai sp. nov. (Colombia). Azotoctla is placed in the tribe Acalyptini, subtribe Staminodeina Franz, thus representing the sister taxon of Staminodeus Franz. The monophyly of Azotoctla is supported by the following inferred traits: a noncarinate rostrum that is tumescent above the antennal insertion in males; equilaterally subtriangular hemisternites of the male sternum 8; paired, longitudinal, laterally positioned sclerites of the aedeagus; and a bifurcate lamina of the female sternum 8, which bears explanate, diverging furcal arms. A key to the species of Azotoctla is provided; and the salient features of each species are illustrated and presented along with distributional and natural history data. A morphological cladistic analysis of 23 terminal species (eight outgroup, 15 ingroup) and 33 characters yielded a single most parsimonious cladogram (length = 75 steps, consistency index = 52, retention index = 77), with the ingroup topology ((A. aecuatorialis, (A. anerunca, A. gottsbergeri)), (A. punctata, ((A. angustacra, A. nana), (A. tibiatra, (A. clemmyssa, (A. curvirostra, A. femorata)), (A. melolauta, ((A. gomezi, A. migueli), (A. dasygastra, A. tuberquiai))))))). Species of Azotoctla are reproductively associated with the ephemeral staminodes of different members of the Neotropical monocot family Cyclanthaceae; most commonly with the widespread genus Carludovica Ruiz & Pavón. The interspecific homogeneity in external morphology, coupled with marked differences in genital traits and an apparent absence of narrow geographical ranges mediated by either host plants and/or biogeographical factors, jointly suggest that the diversification of Azotoctla is a relatively recent phenomenon and driven strongly by sexual selection. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 559–623.     

西北干旱荒漠区植物属的区系分析

为了分析西北干旱荒漠区种子植物属的组成及其区系特点 ,探讨其起源与演化 ,作者根据多年的调查结果并查阅大量相关资料 ,研究表明 :西北干旱荒漠区分布有种子植物 4 84属 ,其区系特征为单种属、寡种属多 ,优势现象明显 ;植物区系具有强烈的旱生性和古老性 ;区系地理成分复杂多样 ,包含 1 4个分布区类型和 1 4个变型 ,地中海区 -西亚 -中亚分布、北温带分布、旧世界分布、中亚分布类型占据前四位 ,分别占总属的 2 2 .33%、1 7.98%、1 0 .6 9%、7.36 % ;特有成分比较低 ,中国特有成分仅 6属 ,只占总属数的 1 .5 7% ;起源古老 ,多为本土发生     

A MADS domain gene involved in the transition to flowering in Arabidopsis

Flowering time in many plants is triggered by environmental factors that lead to uniform flowering in plant populations, ensuring higher reproductive success. So far, several genes have been identified that are involved in flowering time control. AGL20 (AGAMOUS LIKE 20) is a MADS domain gene from Arabidopsis that is activated in shoot apical meristems during the transition to flowering. By transposon tagging we have identified late flowering agl20 mutants, showing that AGL20 is involved in flowering time control. In previously described late flowering mutants of the long-day and constitutive pathways of floral induction the expression of AGL20 is down-regulated, demonstrating that AGL20 acts downstream to the mutated genes. Moreover, we can show that AGL20 is also regulated by the gibberellin (GA) pathway, indicating that AGL20 integrates signals of different pathways of floral induction and might be a central component for the induction of flowering. In addition, the constitutive expression of AGL20 in Arabidopsis is sufficient for photoperiod independent flowering and the over-expression of the orthologous gene from mustard, MADSA, in the classical short-day tobacco Maryland Mammoth bypasses the strict photoperiodic control of flowering.     

Flower-fruit size allometry at three taxonomic levels in Crepis (Asteraceae)

The present investigation utilizes the major axis technique to examine the allometric relationship between flower and fruit size, two developmentally related characters. Regression of log (corolla length) on log (fruit length) using data from 188 species of Crepis , 52 populations of C. tectorum and 40 sibships from a population of C. tectorum demonstrated that flower size shows a decelerating increase with increasing fruit size at all taxonomic levels, with the allometric slope varying from 0.53 to 0.69. The null hypothesis of isometry was rejected in analyses using species or sibships as observations, while the comparison of populations revealed a slope significantly different from 1 only if two outliers were excluded from the analysis. Numerous species and populations have escaped the constraint linking flower and fruit size, including C. tectorum (which has a high ratio of flower to fruit size within the genus) and C. tectorum subsp. pumila (which has a high ratio of flower to fruit size within the species).     

How shrub encroachment under climate change could threaten pollination services for alpine wildflowers: A case study using the alpine skypilot,Polemonium viscosum

Under climate change, shrubs encroaching into high altitude plant communities disrupt ecosystem processes. Yet effects of encroachment on pollination mutualisms are poorly understood. Here, we probe potential fitness impacts of interference from encroaching Salix (willows) on pollination quality of the alpine skypilot, Polemonium viscosum. Overlap in flowering time of Salix and Polemonium is a precondition for interference and was surveyed in four extant and 25 historic contact zones. Pollinator sharing was ascertained from observations of willow pollen on bumble bees visiting Polemonium flowers and on Polemonium pistils. We probed fitness effects of pollinator sharing by measuring the correlation between Salix pollen contamination and seed set in naturally pollinated Polemonium. To ascertain whether Salix interference occurred during or after pollination, we compared seed set under natural pollination, conspecific pollen addition, and Salix pollen addition. In current and past contact zones Polemonium and Salix overlapped in flowering time. After accounting for variance in flowering date due to latitude, Salix and Polemonium showed similar advances in flowering under warmer summers. This trend supports the idea that sensitivity to temperature promotes reproductive synchrony in both species. Salix pollen is carried by bumble bees when visiting Polemonium flowers and accounts for up to 25% of the grains on Polemonium pistils. Salix contamination correlates with reduced seed set in nature and when applied experimentally. Postpollination processes likely mediate these deleterious effects as seed set in nature was not limited by pollen delivery. Synthesis: As willows move higher with climate change, we predict that they will drive postpollination interference, reducing the fitness benefits of pollinator visitation for Polemonium and selecting for traits that reduce pollinator sharing.     

Floral ontogeny of the Afro-Madagascan genus Mitrasacmopsis with comments on the development of superior ovaries in Rubiaceae

BACKGROUND AND AIMS: Members of Rubiaceae are generally characterized by an inferior ovary. However, Mitrasacmopsis is cited in the literature as having a semi-inferior to superior ovary. It has previously been hypothesized that the gynoecial development of Rubiaceae with semi-inferior to superior ovaries takes place in the same way as in Gaertnera, one of the most commonly cited rubiaceous genera with a superior ovary. To test this hypothesis, a floral ontogenetic study of Mitrasacmopsis was carried out with special attention paid to the gynoecial development. METHODS: Floral ontogeny and anatomy of Mitrasacmopsis were examined using scanning electron and light microscopy. KEY RESULTS: At an early developmental stage, a concavity becomes visible in the centre of the floral apex simultaneously with the perianth initiation. A ring primordium surrounding this concavity expands vertically forming the corolla tube (early sympetaly). Stamen primordia develop inside the corolla. From the bicarpellate gynoecium only two carpel tips are visible because the ovary is formed by a gynoecial hypanthium. In the basal part of each carpel, a placenta primordium is initiated. Two septa divide the ovary into two locules. In each locule, the placenta becomes mushroom shaped and distinctly stalked. Eventually, the inferior ovary of Mitrasacmopsis develops into a beaked capsule. Only very late in the fruiting stage, the continuously expanding ovary is raised above the insertion point of the persistent calyx, changing the ovary position of Mitrasacmopsis from basically inferior to secondarily semi-inferior. CONCLUSIONS: Mitrasacmopsis follows an epigynous pattern of floral development. However, the presence of a prominent beak in the fruiting stage gives the whole ovary a semi-inferior appearance. This kind of secondarily semi-inferior ovary is shown to be different from the secondarily superior ovary observed in Gaertnera.     

Phenylacetaldehyde attracts male and female apple clearwing moths,Synanthedon myopaeformis,to inflorescences of showy milkweed,Asclepias speciosa

Synanthedon myopaeformis Borkhausen (Lepidoptera: Sesiidae) is a diurnal clearwing moth native to Eurasia that was recently introduced into British Columbia (BC) and Ontario, Canada, where it has become a serious pest in apple orchards. In BC, these moths commonly feed on nectar of inflorescences, particularly that of showy milkweed, Asclepias speciosa Torrey (Apocynaceae). We investigated the relative importance of visual and olfactory cues, and the key floral semiochemical(s) mediating attraction of S. myopaeformis to A. speciosa. In field experiments, inflorescences left exposed or enclosed in cheesecloth bags dyed green induced similar visitation rates by moths, indicating that olfactory cues are attractive. Among the >10 floral odourants that elicited responses from moth antennae in coupled gas chromatographic‐electroantennographic detection analyses, phenylacetaldehyde induced the most frequent proboscis extension reflexes of male and female moths. Among eight floral odourants that were field‐tested singly, phenylacetaldehyde attracted 35 times more male and female moths than any other candidate semiochemical. Attractiveness of phenylacetaldehyde could not be enhanced by admixture with other floral odourants at the ratios or concentrations tested indicating that it alone may mediate attraction of S. myopaeformis to the inflorescences of A. speciosa. The potential use of phenylacetaldehyde as bait to monitor or mass‐trap populations of male and female S. myopaeformis should be investigated.     

诸葛菜花柄切段和花托离体培养中直接长出小花

在ＭＳ附加ＢＡ的几种培养基上首次从诸葛菜花柄切段和花托部位直接诱导出小花及花枝开花。花发育不正常,无花粉。该花花茎、叶柄、子房等的切段培养仍能再生出小枝,说明成花诱导态是稳定的,不可逆的．